Smart window in Sweden

A comparative analysis of an office building simulation model with conventional windows, and electrochromic windows, based on Miljöbyggnad certification criteria

Marcus Waldron

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Master of Science Thesis TRITA-ITM-EX 2018:19

Smart window in Sweden

A comparative analysis of an office building simulation model with conventional windows, and electrochromic windows, based on Miljöbyggnad

certification criteria

Marcus Waldron

Approved

2017-12-13

Examiner

Joachim Claesson

Supervisor

Jaime Arias Commissioner

Contact person

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Abstract The building sector is one of the sectors that consume most energy in Sweden. Sweden aims thereby to reduce energy use in buildings by 20% by 2020 and 50% by 2050. To achieve these goals, more energy-efficient buildings must be produced, and more energy-efficient measures must be implemented on existing buildings. Electrochromic windows are claimed to reduce the need for heating and cooling, as well as the need for artificial lighting. However, there is limited research on smart windows in the Nordic climate.

This thesis examines electrochromic windows in Sweden, using the IDA ICE 4.7.1 simulation program. The study includes a comparative analysis of an office building model with conventional windows and motorized awnings, versus electrochromic windows with different control strategies, to investigate the building’s impact. In total, eight different scenarios are simulated in Stockholm, Umeå and Malmö. The electrochromic window scenarios consist of control algorithms where the windows are always on or off, as well as algorithms that respond to sunlight, daylight, operative temperature or scheduling. The conventional windows and awnings scenario represents the reference building. The Swedish building certification system "Miljöbyggnad" is used as a guideline for evaluating energy use, heating power demand, solar heat load, thermal climate, and daylight.

The results show that electrochromic windows have little impact on the building. None of the scenarios succeed in obtaining higher certification than BRONZE, which corresponds to the authority's requirements for newly built buildings. However, electrochromic windows have a significant effect on the solar heat load and the lux level in the building, but unfortunately not enough to get a better building grade. There is no remarkable difference between the indicators and scenarios. Furthermore, the results show that scenarios that are shaded often (Always on, Daylight Control, Solar Control strategy) achieve GOLD ratings in solar heat load, but have the least impact on energy consumption and vice versa. Always off, Operative Temperature Control, and Schedule, Façade and Window strategy upgrades by one level in energy use. This confirm previous studies that claim that electrochromic windows have the greatest potential in energy saving in hot climate. This explains why there is hardly any difference between scenarios and cities.

The thesis lacks specific costs for electrochromic windows. Thus, the cost estimate is based on generalizations and assumptions, in which the cheapest and most expensive options are investigated. If the building has well-functioning windows and awnings, it is not cost effective to switch to electrochromic windows, since the payback time is far too long. But if the building was between conventional windows and electrochromic windows during the planning phase, it might be interesting to conduct a detailed cost analysis. According to this study, the Operative Temperature Control strategy saves approximately 6 333kr during the simulation period. The cost differences between conventional windows with motorized awnings, and the cheapest version of electrochromic windows is around 60 000kr. This would provide a refund within 10 years, given that energy prices, energy consumption and currency value are the same. After that, the window would cut the energy costs in the form of saved energy.

However, the study concludes that electrochromic windows are not necessary in this project from a Miljöbyggnad perspective, since the building grade remains the same and the economic gain is uncertain.

Keywords: IDA ICE, Miljöbyggnad, Electrochromic window, Smart window

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Sammanfattning

Byggnadssektorn är en av de sektorer som använder mest energi i Sverige. Därmed har Sverige som mål att minska energianvändningen i byggnader med 20% år 2020, och 50% år 2050. För att uppnå dessa mål måste fler energieffektiva byggnader produceras, samt fler energieffektiva åtgärder måste genomföras på befintliga byggnader. Elektrokroma fönster hävdas minska behovet av uppvärmning och kylning, samt behovet av artificiell belysning. Det finns dock begränsad forskning om smarta fönster i det nordiska klimatet.

Detta examensarbete undersöker elektrokroma fönster i Sverige, med hjälp av simuleringsprogrammet IDA ICE 4.7.1. Arbetet omfattar en jämförande analys av en kontorsbyggnadsmodell med vanliga fönster och motoriserade markiser, kontra elektrokroma fönster med olika kontrollstrategier, för att undersöka byggnadens påverkan. Sammanlagt simuleras åtta olika scenarier i Stockholm, Umeå och Malmö. De scenarier med elektrokroma fönster består följaktligen av kontroll algoritmer där fönsterna är alltid på eller avstängda, samt algoritmer som reagerar på solljus, dagsljus, operativa temperatur eller schemaläggning. Scenariot med vanliga fönster och markiser representerar referensbyggnaden. Det svenska byggnadscertifieringssystem ”Miljöbyggnad” används som riktlinje för evaluering av energianvändning, värmeeffektbehov, solvärmelast, termiskt klimat, och dagsljus.

Resultaten visar att elektrokroma fönster har liten påverkan på byggnaden. Ingen av scenarierna lyckas få högre certifiering än BRONS, vilket motsvarar myndighetens krav på nybyggda byggnader. Dock så har elektrokroma fönster signifikant inverkan på solvärmelasten och lux nivån i byggnaden, men tyvärr inte tillräckligt för att få ett bättre byggnads betyg. Det är ingen anmärkningsvärd skillnad sinsemellan indikatorerna och scenarierna. Vidare visar resultaten att scenarier som är skuggade ofta (Alltid på-, Dagljuskontroll-, Solljuskontrollstrategin) uppnår GULD betyg inom solvärmelast men har minst inverkan på energiförbrukningen och vice versa, Alltid av-, operativa temperaturkontroll, samt schemaläggning, fasad och fönster strategin uppgraderas ett steg inom energianvändning. Detta styrker tidigare studier som påstår att elektrokroma fönster har störst potential i energibesparing i varma klimat. Detta förklarar den minimala skillnaden av byggnadens påverkan mellan städer och scenarier.

I denna rapport saknas specifika kostnader för elektrokroma fönster. Därmed baseras kostnadsuppskattningen på generaliseringar och antagande, där billigaste och dyraste alternativet undersökts. Om byggnaden har väl fungerande fönster och markiser, är det inte kostnadseffektiv att byta till elektrokroma fönster, då återbetalningstiden är alldeles för lång. Men om byggnaden stod mellan vanliga fönster och elektrokroma fönster i planeringsfasen kan det vara intressant att göra en noggrann analys. Enligt denna studie så sparar den Operativa Temperatur strategin ca. 6 333kr per år. Det skiljer ca 60 000kr mellan vanliga fönster med markiser, och elektrokroma fönster. Detta skulle ge en återbetalning inom 10 år förutsatt att energipriserna, energiförbrukningen samt valuta värdet är desamma. Därefter skulle fönstret minska utgifterna i form av sparad energi.

Slutsatsen är dock att elektrokroma fönster inte är nödvändiga i detta projektet från en Miljöbyggnads synpunkt, eftersom att det inte förbättrar byggnadsbetyget. Dessutom kvarstår osäkerheten med kostnader.

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Acknowledgements

First, I would like to express my gratitude to my supervisor and examiner Jaime Arias Hurtado, for his enthusiasm, guidance and mentorship. He was there from the very beginning of the research process to the final touch of the master thesis. Without his continuously feedback, support, and valuable advice, this thesis would not have been possible.

I would also like to thank my examiner Joachim Claesson for his contribution.

I would like to show my appreciation to Marco Molinari for his engagement and support with IDA ICE.

I would like to thank EQUA Simulation AB for providing me with license for IDA ICE. Without this tool, I would have not been able to conduct this thesis. I especially want to thank Bengt Hellström at EQUA for his support with the software.

Finally, but not least, I am very thankful and blessed to have the support from my family and friends throughout my educational journey, during good and more difficult times. Thank you!

Thank you very much!

Marcus Waldron

December 2017

Stockholm, Sweden

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Abbreviations

ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning

BBR Boverkets byggregler

BREEAM BRE Environmental Assessment Method

COP Coefficient of performance

CW Conventional window

DF Daylight factor

ECW Electrochromic window

GHG Greenhouse gases

HVAC Heating, Ventilation and Air-conditioning

IAQ Indoor Air Quality

ICE Indoor Climate and Energy

IEQ Indoor Environmental Quality

IR Infrared

ISO International Organization for Standardization

IG Insulated glass

IGU Insulated glass unit

LCCA Life-cycle cost analysis

LC/PDLC Liquid Crystal Devices

LEED Leadership in Energy and Environmental Design

Low-e Low emissivity

MEMS Micro-blinds

MET Metabolic Equivalent of Task

PPD Predicted Percentage of Dissatisfied index

PMV Predicted Mean Vote index

SBGC Sweden Green Building Council

kr Swedish krona, Swedish crown

SPD Suspended Particle Devices

SVL Solar Heat Load value

UV Ultraviolet

WWR Window-to-Wall Ratio

lx Lux

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Glossary

Aspect is a measurement used in the assessment calculation in Miljöbyggnad

BRONZE rating is the basic requirements for Miljöbyggnad which correspond to the government authority requirements such as Swedish Work Environment Authority, Boverket (National Board of Housing, Building and Planning), Swedish Radiation Authority, and The Public Health Agency of Sweden

Building envelope is defined as the physical separator between the exterior and the interior of a building.

Conventional window refers to triple glazed windows in this study

clo is the value of the clothing insulation

Daylighting natural light, illuminance

Glare is the sensation of annoyance caused by brightness. It can also reduce the visibility due to intense light source

g-value the total incident radiation that enters through the glass. This includes the direct radiant influx as well as the infrared radiation that is absorbed by the glass and then re-emitted internally

Glazing refers to both single glass and IGU, such as single/double/triple/quadruple glazing.

GOLD rating is the highest ranking and proves that it utilizes the most environmentally friendly application available

Indicator factors that quantify the building’s environmental qualities, which are used in the assessment calculation in Miljöbyggnad

Insulated glass consists of two or more glass window panes separated by a vacuum or gas filled space to reduce heat transfer. Most common application are double glazing or triple glazing.

Lux is the unit of illumination. It measures the intensity of light (perceived by the human eye) that hits or passes through a surface. One lux is defined as one lumen per square metre.

Operative temperature is the average of the air temperature and the radiation temperature at a given point. This is the temperature that is felt by a person in a room, and thus the operative temperature tends to be lower than the mean air temperature during winter and vice versa in the summer.

SILVER rating corresponds to a more ambitious building code than BRONZE.

Single glass consists of only one glass pane

Spacer is used to separate the two pieces of glass in an insulating glass panel

Smart glass market refers to architecture, transportation, power generation, and consumer electronics

RATED rating shows that the indicators are evaluated but do not fulfil Miljöbyygnad’s requirements. However, newly constructed building must fulfil at least BRONZE requirements since it is equivalent to the government authority requirements

Reference year is the average value of the outdoor climate (e.g. temperature) for an extended period. In this study, it is one year

TSol Fraction of incident radiation that passes the glazing as direct radiation

Tvis measures the amount of light that passes through a window

U-value measures how effective a material is an insulator.

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Table of Contents 1 Introduction ................................................................................................................................. - 1 -

1.1 Background ......................................................................................................................... - 1 -

1.2 Objective and Research questions ....................................................................................... - 2 -

1.3 Problem statement ............................................................................................................... - 2 -

1.4 Methodology ....................................................................................................................... - 2 -

1.5 Thesis outline ...................................................................................................................... - 3 -

2 Theory ......................................................................................................................................... - 5 -

2.1 Parameters that affects the thermal energy performance in buildings ................................. - 5 -

2.2 Energy heat balance in buildings ......................................................................................... - 8 -

2.3 Windows .............................................................................................................................. - 9 -

2.3.1 Heat energy flows in windows .................................................................................. - 10 -

2.3.2 Window technologies ................................................................................................ - 12 -

2.4 Smart windows .................................................................................................................. - 13 -

2.4.1 Electrochromic windows ........................................................................................... - 13 -

2.5 Indoor Environmental Quality ........................................................................................... - 16 -

2.5.1 Thermal comfort ........................................................................................................ - 16 -

2.5.2 Visual comfort ........................................................................................................... - 17 -

3 Environmental certification system in Sweden ......................................................................... - 18 -

3.1 Sweden Green Building Council ....................................................................................... - 18 -

3.1.1 Miljöbyggnad ............................................................................................................ - 18 -

3.1.2 BREEAM SE ............................................................................................................. - 23 -

3.1.3 LEED ......................................................................................................................... - 23 -

3.1.4 GreenBuilding ........................................................................................................... - 23 -

3.2 Nordic Swan ...................................................................................................................... - 23 -

4 Office model .............................................................................................................................. - 25 -

4.1 Building description .......................................................................................................... - 25 -

4.2 Building Envelope ............................................................................................................. - 27 -

4.3 Internal heat loads ............................................................................................................. - 28 -

4.4 HVAC system .................................................................................................................... - 29 -

4.5 Climate condition and Location ........................................................................................ - 30 -

5 Scenarios ................................................................................................................................... - 31 -

5.1 Reference scenario ............................................................................................................ - 31 -

5.2 Electrochromic window scenarios ..................................................................................... - 32 -

5.2.1 Schedule .................................................................................................................... - 33 -

5.2.2 Sun and Schedule ...................................................................................................... - 33 -

5.2.3 Daylight Control ........................................................................................................ - 33 -

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5.2.4 Solar Control ............................................................................................................. - 33 -

5.2.5 Schedule, Façade and Window .................................................................................. - 33 -

5.2.6 Operative Temperature Control ................................................................................. - 33 -

6 Results ....................................................................................................................................... - 35 -

6.1 Miljöbyggnad .................................................................................................................... - 35 -

6.1.1 Energy use ................................................................................................................. - 35 -

6.1.2 Heating power demand .............................................................................................. - 37 -

6.1.3 Solar heat load ........................................................................................................... - 38 -

6.1.4 Thermal climate ......................................................................................................... - 38 -

6.1.5 Daylight ..................................................................................................................... - 39 -

6.1.6 Building grade ........................................................................................................... - 40 -

6.2 Detailed analysis ................................................................................................................ - 41 -

6.2.1 Reference ................................................................................................................... - 42 -

6.2.2 Always Off ................................................................................................................ - 43 -

6.2.3 Always On ................................................................................................................. - 44 -

6.2.4 Sun and Schedule ...................................................................................................... - 45 -

6.2.5 Solar Control ............................................................................................................. - 47 -

6.2.6 Daylight Control ........................................................................................................ - 49 -

6.2.7 Operative Temperature Control ................................................................................. - 51 -

6.2.8 Schedule, Façade and Window .................................................................................. - 53 -

6.2.9 Comparison between scenarios ................................................................................. - 54 -

6.3 Cost analysis ...................................................................................................................... - 56 -

7 Discussion ................................................................................................................................. - 60 -

8 Conclusions ............................................................................................................................... - 62 -

8.1 Future work and Limitations ............................................................................................. - 62 -

9 Bibliography .............................................................................................................................. - 63 -

10 Appendix A ............................................................................................................................... - 69 -

11 Appendix B ............................................................................................................................... - 73 -

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List of Figures

Figure 1- Thesis outline ................................................................................................................................. - 4 - Figure 2 - Parameters that influence the thermal performance of a building .............................................. - 5 - Figure 3 - The electromagnetic spectrum and visible spectrum [15] ........................................................... - 6 - Figure 4 - Example of a building's typical heat gains and losses [26]. ........................................................ - 8 - Figure 5 - Elements included in the heat balance calculation of a building [22]. ....................................... - 9 - Figure 6 - Cross section of a double-glazed window [29] ............................................................................ - 10 - Figure 7 - The energy flow of a window [31] ................................................................................................ - 11 - Figure 8 - Heat transmission and radiation from a window [35] ................................................................ - 12 - Figure 9 - Schematic diagram of typical electrochromic window [40] ........................................................ - 14 - Figure 10 - PPD as a function of PMV [53] .................................................................................................. - 17 - Figure 11 - Illustrates the ratio between the outdoor and indoor illuminance. The CIE Standard Overcast

Sky is three times brighter at zenith than at the horizon ................................................................... - 22 - Figure 12 - Office building model ............................................................................................................... - 25 - Figure 13 - Ground floor of the office building ........................................................................................... - 26 - Figure 14 - Top floor of the office building ................................................................................................. - 26 - Figure 15 - Reference building ..................................................................................................................... - 31 - Figure 16 - Energy usage in Stockholm....................................................................................................... - 36 - Figure 17 - Energy usage in Umeå .............................................................................................................. - 36 - Figure 18 – Energy usage in Malmö ............................................................................................................ - 37 - Figure 19 - Heating power demand of each city and scenario ................................................................... - 37 - Figure 20 – Solar heat load in the worst room of each scenario and city ................................................... - 38 - Figure 21 - PPD-level in the worst room of each scenario and city ............................................................ - 39 - Figure 22 - DF of each window type ........................................................................................................... - 40 - Figure 23 – Illustration of the selected rooms and its windows .................................................................. - 41 - Figure 24 – Reference Scenario, daylight level (lx) in Big office 2 and Recreation room 1 ....................... - 42 - Figure 25 - Always Off Control strategy, daylight level (lx) in Big office 2 and Recreation room 1 ......... - 43 - Figure 26 - Always Off Control strategy, daylight level (lx) in Big office 2 and Recreation room 1 ........ - 44 - Figure 27 – Sun and Schedule Control Strategy, average shading signal per month in Big office 2 &

Recreation room 1 ................................................................................................................................ - 45 - Figure 28 – Sun and Schedule Control strategy, daylight level (lx) in Big office 2 and Recreation room 1 . - 46

- Figure 29 – Solar Control Strategy, average shading signal per month in Big office 2 & Recreation room 1 .. -

47 - Figure 30 - Solar Control strategy, daylight level (lx) in Big office 2 and Recreation room 1 .................... - 48 - Figure 31 - Daylight Control Strategy, average shading signal per month in Big office 2 & Recreation room

1 ............................................................................................................................................................ - 49 - Figure 32 - Daylight Control Strategy, daylight level (lx) in Big office 2 and Recreation room 1 ............. - 50 - Figure 33 - Operative Temperature Control Strategy, average shading signal during a year .................... - 51 - Figure 34 – Operative Temperature Control Strategy, daylight level (lx) in Big office 2 and Recreation room

1 ............................................................................................................................................................ - 52 - Figure 35 – Schedule, Façade and Window Strategy, average shading signal during a year .................... - 53 - Figure 36 – Schedule, Façade and Window Strategy, daylight level (lx) in Big office 2 and Recreation room

1 ............................................................................................................................................................ - 54 - Figure 37 - Average shading signal in Big office 2 and Recreation room 1 during a year ......................... - 55 - Figure 38 - Average daylight level in Big office 2 and Recreation room 1 during a year ........................... - 55 - Figure 39 – Total saving of each electrochromic window scenario compared to the Reference scenarios . - 57

- Figure 40 - Simple payback of the electrochromic window scenarios (cheap version electrochromic

windows) .............................................................................................................................................. - 57 - Figure 41 - Simple payback time, the time it would take for ECW to break even with CW + motorized

awnings. This is based on the cheap version ECW ............................................................................ - 58 - Figure 42 - Overview of the scenarios grading in each city ........................................................................ - 69 - Figure 43 – Miljöbyggnad grading of each scenario in Stockholm ............................................................ - 70 - Figure 44 - Miljöbyggnad grading of each scenario in Umeå ..................................................................... - 71 -

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Figure 45 - Miljöbyggnad grading of each scenario in Malmö .................................................................. - 72 - Figure 46 –Sun and Schedule, shading signal in Stockholm ..................................................................... - 73 - Figure 47 - Sun and Schedule, shading signal in Umeå ............................................................................ - 73 - Figure 48 - Sun and Schedule, shading signal in Malmö ........................................................................... - 74 - Figure 49 - Sun and Schedule, daylight level in Stockholm ........................................................................ - 74 - Figure 50 - Sun and Schedule, daylight level in Umeå ............................................................................... - 75 - Figure 51 - Sun and Schedule, daylight level in Malmö .............................................................................. - 75 - Figure 52 – Solar Control, shading signal in Stockholm ............................................................................. - 76 - Figure 53 - Solar Control, shading signal in Umeå ..................................................................................... - 76 - Figure 54 – Solar Control, shading signal in Malmö.................................................................................. - 77 - Figure 55 - Solar Control daylight level in Stockholm- Big office 2(red) and Recreation room 1(green) . - 77 - Figure 56 - Solar Control daylight level in Umeå- Big office 2(red) and Recreation room 1(green) ........ - 78 - Figure 57 - Solar Control daylight level in Malmö- Big office 2(red) and Recreation room 1(green) ...... - 78 - Figure 58 - Daylight Control, Shading signal in Stockholm ....................................................................... - 79 - Figure 59 - Daylight Control, Shading signal in Umeå............................................................................... - 79 - Figure 60 - Daylight Control, shading signal in Malmö ............................................................................. - 80 - Figure 61 - Daylight Control, daylight level in Stockholm- Big office 2(red) and Recreation room 1(green) .. -

80 - Figure 62 - Daylight Control, daylight level in Umeå, Big office 2(red) and Recreation room 1(green) ... - 81 - Figure 63 - Figure 36 - Daylight Control, daylight level in Malmö, Big office 2(red) and Recreation room

1(green) ................................................................................................................................................. - 81 - Figure 64 - Operative Temperature Control, shading signal in Stockholm .............................................. - 82 - Figure 65 - Operative Temperature Control, shading signal in Umeå ....................................................... - 82 - Figure 66 - Operative Temperature Control, shading signal in Umeå ....................................................... - 83 - Figure 67 – Operative Temperature Control, daylight level in Stockholm- Big office 2(red) and Recreation

room 1(green) ...................................................................................................................................... - 83 - Figure 68 - Operative Temperature Control, daylight level in Umeå- Big office 2(red) and Recreation room

1(green) ................................................................................................................................................ - 84 - Figure 69 - Operative Temperature Control, daylight level in Malmö- Big office 2(red) and Recreation room

1(green) ................................................................................................................................................ - 84 - Figure 70 – Schedule, Façade and Window, shading signal in Stockholm ................................................ - 85 - Figure 71 - Schedule, Façade and Window, shading signal in Umeå ........................................................ - 85 - Figure 72 - Schedule, Façade and Window, shading signal in Malmö ...................................................... - 86 - Figure 73 - Schedule, Façade and Window, daylight level in Stockholm- Big office 2(red) and Recreation

room 1(green) ...................................................................................................................................... - 86 - Figure 74 – Schedule, Façade and Window, daylight level in Umeå- Big office 2(red) and Recreation room

1(green) ................................................................................................................................................ - 87 - Figure 75 - Schedule, Façade and Window, daylight level in Malmö- Big office 2(red) and Recreation room

1(green) ................................................................................................................................................ - 87 -

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List of Tables

Table 1 – An example of a certified building. The table is developed under influenced of Miljöbyggnad - 19 - Table 2 - Selected indicators for this study ................................................................................................. - 20 - Table 3 - Miljöbyggnad Energy use criteria which is a proportion of BBR ............................................... - 20 - Table 4 - Max allowed energy use in respectively city, expressed in kWh/m2, Atemp ................................ - 20 - Table 5 - Max heating power demand according to the different cities, P [W/m2, Atemp at DVUT] ......... - 21 - Table 6 – Max allowed solar heat load according to Miljöbyggnad ............................................................ - 21 - Table 7 - Max allowed PPD according to Miljöbyggnad .......................................................................... - 22 - Table 8 - The daylight criteria according to Miljöbyggnad ........................................................................ - 23 - Table 9 - Overview of the building envelope............................................................................................... - 27 - Table 10 - Internal heat loads of the building ............................................................................................. - 28 - Table 11 - The buildings HVAC system ...................................................................................................... - 29 - Table 12 - Technical properties of the conventional window ...................................................................... - 31 - Table 13 - Technical properties of generic awning material ...................................................................... - 32 - Table 14 - Technical properties of SAGE EC IGUs [66] ............................................................................ - 32 - Table 15 – Reference Scenario, summary of daylight level (lx) in Big office 2 and Recreation room 1 .... - 42 - Table 16 - Always Off Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room

1 ............................................................................................................................................................ - 43 - Table 17 - Sun and Schedule Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation

room 1 .................................................................................................................................................. - 44 - Table 18 - Sun and Schedule Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation

room 1 .................................................................................................................................................. - 46 - Table 19 - Solar control strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1 . - 48 - Table 20 - Daylight Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1 . -

50 - Table 21 - Daylight Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1 . -

52 - Table 22 – Schedule, Façade and Window Strategy, summary of daylight level (lx) in Big office 2 and

Recreation room 1 ................................................................................................................................ - 54 - Table 23 – Total cost for electrochromic window ....................................................................................... - 56 - Table 24 – Total cost for windows and motorized awnings ....................................................................... - 58 -

List of Equations Equation 1 - Heat balance calculation of a building .................................................................................... - 9 -

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1 Introduction

This chapter covers background, followed by the objective and research questions. Thereafter, the problem statement, methodology, and thesis outline are presented.

1.1 Background Buildings are responsible for global energy use, resource consumption and greenhouse gas (GHG) emissions that is damaging our world. Of course, this put pressure on policymakers as the demand for new constructions and renovations increases across the globe, as a result of growing population, urbanisation and economy. Due to this, there is an ongoing transformation process in the construction sector where companies, organisations, and institutes try to change the traditional construction way towards sustainable developments. “Green building” is a concept that includes design, construction and operational practise to reduce negative impact on developments. Green building uses materials and processes that are cost effective, environmentally friendly, energy efficient and resource efficient [1].

In Sweden, the building sector alone accounts for 40% of the energy demand and 20% of the national GHG emissions. The Swedish Parliament announced that the country aims to reduce the energy use in buildings by 20% in 2020, and by 50% in 2050 [2]. To achieve these goals, more energy efficient buildings must be developed, as well as technological improvements and behavioural adaptation that provide more efficient use of energy [3].

Over the last century, glass technologies for buildings have undergone radical changes and have extended its functions in modern architecture. In fact, architecture glazing is one of the most common and complex building material used today. In addition, windows are used in buildings to provide occupants with daylight, natural ventilation, aesthetic beauty and a connection to the outside world, which are essential for our well-being. However, despite all the great benefits, windows are considered as the weakest part of the envelope area since heat pass through them easily [4]. According to the Department of the United States, inefficient windows account for 25% to 35% of the building’s energy loss [5]. This makes them a prime target for further improvements.

Nowadays there are a wide range of glass and glazing solutions available in the building sector to meet the requirements of the most ambitious building codes. However, the conventional energy-saving windows are considered static as they do not change with fluctuating environmental condition. In recent years, a new generation of high performing glazing systems with dynamic shading properties are emerging in the western market, so called smart windows, also defined as dynamic or switchable glazing. Some of these glazing systems are shading and blocking unwanted solar heat, while ensuring the maximum amount of daylight without glare. The major benefit by using smart windows is that they adapt to its surrounding and are claimed to significantly reduce the energy consumption and GHG emission from buildings. The previous highlighted issue is used as an advantage. In colder climates, the windows will allow solar heat for passive heating the building, which will reduce the usage of space heating. In warmer region and countries with Mediterranean climate, the windows will block solar heat to limit the consumption of air-conditioning. Another great benefit is that some of the smart window technologies preserves the view by reducing the need for shading devices, overhangs or drapes that affects the view. This gives architects the freedom to incorporate much more glazing, in the knowledge that glazing can help to achieve great energy performance, with low environmental impact as well as providing optimal comfort for the occupants [5]. Ultimately, smart windows can contribute to achieve net zero energy buildings.

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According to research, electrochromic windows claims to be the most promising smart window technology available today [5] [6] [7] [8] [9]. Nevertheless, there is limited research about smart window solutions in colder climates e.g. Nordic climate [10]. This makes it interesting to investigate electrochromic windows in Sweden.

1.2 Objective and Research questions The objective of the thesis is to carry out a comparative analysis of an office building simulation model with conventional windows, and electrochromic windows to explore the impact of the building. The study examines the building’s performance based on Miljöbyggnad certification system, where six indicators are evaluated according to; (1) energy use, (2) heating power demand, (3) solar heat load, (4) thermal climate winter, (5) thermal climate summer, and (6) daylight.

Ultimately, the study aims at answering the following research questions:

I. “What are the differences between an office building with conventional windows and motorized awnings, compared to electrochromic windows with various control strategies?”

II. “Does the local climate have a significant impact on the electrochromic window performance?” III. “Are electrochromic windows economically viable for the office building?”

1.3 Problem statement The first challenge of this study is to design the office building, so it meets the criteria of Miljöbyggnad according to the selected indicators. This is due to the fact, that the selected indicators are each other’s counterparts. Maximum solar heating and daylighting can be achieved by large windows, but can cause overheating and glare during summer and more need for space heating during winter. On the other hand, small windows can keep the solar heat load value low, but at the cost of limiting the access of daylight, and thus more need for artificial lighting.

The second main task is to develop control algorithms for the electrochromic windows so that the windows can be fully utilized. In other words, to create the optimum operation settings so that the window can balance these indicators in an efficient manner. The question is “When and how much solar heat should be blocked by the electrochromic windows?”

1.4 Methodology To achieve these goals, quantitative research manner was used. The first step in the process was to gather information about smart window technologies through literature studies and peer reviews documents. Based on this, the electrochromic window was selected since it has the highest degree of controllability compared to other smart window solutions. Thereafter, the fundamental theory was gathered to identify the factors that influence both the window and the overall building.

The second step was to find a way to measure the impact of electrochromic windows. Miljöbyggnad, a Swedish environmental certificate system for building was chosen as a reference, where six indicators were selected to determine the effect of using a building with conventional windows compared to electrochromic windows [11]. Furthermore, multi-dynamic simulation software called IDA Indoor Climate and Energy (IDA ICE) was used to develop a reference office building and to perform simulations [12]. The reference building had conventional windows, and was designed so it fulfilled the requirements according to the six chosen indicators from Miljöbyggnad. Afterwards, control algorithms for electrochromic windows were developed so that the shading properties were optimally utilized. The

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office building was then simulated with conventional-, and electrochromic windows in three different Swedish cities (Stockholm, Malmö and Umeå) to investigate the outcome. The simulation process can be defined as an iterative process of trials and error, where each change of variables influences the entire outcome of the building’s performance. The third step in the process was to investigate if the electrochromic window was economically feasible. The cost is a crucial factor for implementing new solutions, and thus a cost analysis was used to get an indication of the overall cost of using electrochromic window.

1.5 Thesis outline The thesis is divided into eight chapters (see figure 1). Chapter 1 includes the background, objective and research questions, problem statement, and finally the thesis outline.

Chapter 2 provides the necessary theory to get an understanding of the building and its interaction with the surroundings. It also includes theory about electrochromic windows, and how it can improve the energy efficiency and occupancy comfort.

Chapter 3 presents the environmental certification system used in Sweden. The chapter go through the various certification schemes, with focus on Miljöbyggnad since it is used as a reference to determine the impact of the office building using electrochromic windows.

Chapter 4 represents the office building, which go through the building design; from the building envelope to internal heat loads and the heating ventilation and air-conditioning (HVAC) system. The reference office which has conventional windows is designed to fulfil the Miljöbyggnad standard according to the six indicators.

Chapter 5 focuses on the development of the scenarios. Each scenario is simulated in three Swedish cities; the reference scenario is using conventional windows with motorized awnings, while the other scenarios are using electrochromic windows with different control strategies.

Chapter 6 is the main chapter of this thesis, which analyses the obtained results from the simulated scenarios. This chapter includes also a cost analysis to see if the electrochromic window is economically viable for the office building.

Chapter 7 summarize and discusses the results, which is the foundation for the conclusion.

Chapter 8 which is the last chapter draws conclusions based on the results and discussions, followed by limitations and thoughts of future work.

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Figure 1- Thesis outline

Ch

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Introduction

-Background

-Objective and Reserach questions

- Problem statement

-Methodology

-Thesis outline

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Theory

- Parameters affecting the thermal performance in buildings

- Energy heat balance in buildings

- Windows

-Smart windows

- Indoor Environmental Quality

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Certification system in Sweden

-Miljöbyggnad

-BREEAM

- LEED

-GreenByuilding

- The Nordic Swan

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Building office model

- Building description

- Building envelope

- Internal heat loads

- HVAC system C

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Scenarios

- Reference

- Always Off

- Always On

- Sun and Schedule

- Solar Control

- Daylight Control

- Operative Temperature

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Results

- Results from the scenarios according to Miljöbyggnad

- Detailed analysis

- Cost analysis

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Conclusions

- Conclusion

- Future work and Limitations

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2 Theory

This chapter provides the necessary theory to get an understanding of a building’s interaction with its surrounding, including climate condition, building design, building components, and indoor climate. It also highlights electrochromic window and how it can improve energy efficiency and occupancy comfort.

2.1 Parameters that affects the thermal energy performance in buildings

Figure 2 shows the various parameters that influence the thermal performance of a building.

Figure 2 - Parameters that influence the thermal performance of a building

Climate condition

The climate condition, refers to the building’s exposure to solar radiation, wind speed, air temperature and relative humidity at a given location. The amount of heat gains or losses is determined by the degree of these elements as well as the length of this period. The building’s location and surroundings are vital in regulating the indoor climate and illuminance [13].

This section focuses on solar radiation, which refers to electromagnetic radiation that reaches Earth from the sun. The electromagnetic spectrum includes all radiations which is classified by wavelength () and frequency (). Most of solar radiation consist of infrared (IR) radiation (49, 4%), followed by visible light (42,4%) and ultraviolet (UV) light, which is approximately 8% of the total solar radiation. Figure 3 shows the electromagnetic spectrum. The shorter the wavelength is, the higher the frequency

Thermal performance in

buildings

Building material

Building design

Building usage

Climate condition

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will become, and thus it obtains higher energy content. This explains why UV light is more dangerous than IR radiation, since it has enough energy to damage DNA [14].

Figure 3 - The electromagnetic spectrum and visible spectrum [15]

All solar radiation emitted from the sun does not reach the surface of Earth. This is due to the following atmospheric processes that determine the amount of solar radiation the Earth will receive.

Scattering is a process that occurs when radiation change its direction randomly due to gases and suspended particles in the atmosphere. This process does not change the radiation’s wavelength or intensity. However, some of the radiation may not reach Earth and thereby it reduces the incoming solar radiation [16] [17].

Absorption refers to a process where solar radiation is absorbed by particles or gasses in the atmosphere, then transferred into thermal energy within the substance. This causes the substance to emit its own radiation, long-wave radiation according to Wien’s Law. Atmospheric absorption has an important role since it preventing harmful high-energy radiant to reach Earth. It functions also as a heat source for Earth [16] [17].

Reflection is an atmospheric process that occurs when solar radiation hits a particle where the direction of radiation changes 180°. This results in 100% loss of insolation. Clouds are typical medium where reflection appears due to particles of liquid and frozen water [16] [17].

Solar radiation that is not affected by reflection, scattering or absorption is called direct solar radiation. The term diffused solar radiation is defined by solar radiation that has reached Earth after being altered by the scattering process. Global radiation includes both direct and diffused solar radiation. The atmospheric processes are vital for our existence since they are preventing Earth from receiving too much solar radiation [16] [17].

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Building material

The building envelope is defined as the physical separator between the exterior and interior of a building. Typically, envelope components include walls, floors, roofs, windows and doors [18]. Its overall function is to provide structural support of internal and external loads, as well as controlling exchange between air, water, and heat between the interior and exterior of the building. Aside from the practical aspect, the building envelope provides also aesthetic beauty [19] Understanding the fundamentals of building materials and heat transfer mechanisms (conduction, convection and radiation) will therefore provide the right foundation for building design and its trade off [19]. Thus, the building material plays a key role for determine the building’s ability to withstand natural elements. The envelope is made upon a variety of building materials with different characteristics such as reflection, absorption, storage, transmitting, and insulation properties. Energy heat flows through materials can be reduced by using materials with good insulation properties. There are some technical values that quantifies materials thermal performance, which are presented below.

Thermal conductivity (k-value) is expressed in W/mK and measures how easily heat flows through a material, regardless of that material’s thickness. The k-value is used to compare various materials. A common application is to assess the potential heat transfer between the inside and outside of a building [20]. The lower thermal conductivity of a material, the better the thermal performance, since it will take longer time for heat to travel through the material [21].

Thermal resistance (R-value) is a measure of resistance to heat flow across a given thickness of material. The R-value is measured in m2K/W, where greater values provide more thermal resistance. The R-value is a simple method for comparing two insulating materials, given that the thermal conductivity is known. However, the method does not consider convection and radiation, which makes the heat transfer coefficient more reliable as it includes all heat transfer mechanisms [21].

Heat transfer coefficient (U-value) measure the heat loss through a given thickness of a material, and is thus the inverse of the R-value. The U-value is expressed in W/m2K. Lower U-value gives better insulation, which means that less energy is needed to maintain desired condition in the building. The U-value is an important indication as it takes into accounts all mechanisms i.e. conduction, convection, and radiation. In fact, building standards have required lower U-values to perform better thermal performance in buildings [21].

Building design

The building design includes the building’s layout, orientation, window’s size/placement/shading condition, and colour of walls and roofs. It also includes the HVAC system, daylighting control, electrical strategies, and other schemes. A well-designed envelope should be able to handle the local climate in all seasons (see figure 4). Thus, it is important to carefully analyse the location as well as the building material and design. Figure 4 shows a building that have heat losses during winter and heat gains during summer. By placing windows towards south in Sweden, solar energy can be utilized for passive heating as well as access to daylighting. Additional roof overhung over the southern windows is ideal to block the solar radiation during summer, while allowing solar heat during winter due to lower position of the sun in the sky. This may reduce the need for HVAC system as well as artificial lighting [22] [23]. Other measures for improving the building’s performance is to determine if a “tight” or “loose” building envelope should be used. A tight building design allow minimal air leakage, and can thereby reduce the building’s heat loss by 25-50%. This requires well-sealed doors, efficient windows, additional thermal insulation of walls, slabs, and foundation to keep the building sealed. A loose building

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envelope let more air into the building, which results in better indoor air quality (IAQ) but makes the building become less comfortable due to drafts. It will also be harder to control the indoor climate as heat flow easily through the building, leading to higher energy demand [24] [13] [25].

Figure 4 - Example of a building's typical heat gains and losses [26].

Building usage

An important aspect is to determine the activity level inside the building. People, electrical equipment, artificial lighting, and warm goods generating a significant amount of heat. Typical building with high internal heat loads are commercial buildings such as offices and hospitals since they have high occupancy level with great number of electric devices. This affects the rate of the building’s heat gains or loses [22].

2.2 Energy heat balance in buildings The energy heat balance of a building is defined as the equilibrium between the energy that is entering the building and the energy that is leaving the building. According to the Second Law of Thermodynamics; heat will always flow from a higher temperature object to an object at a lower temperature. Consequently, heat gains and losses are linked to the temperature difference between the indoor and outdoor.

Heat flows can be divided into the following five categories. Transmission loss is the amount of heat that flows through the building envelope (see figure 5). Ventilation loss refers to natural ventilation loss caused by air leakage and infiltration, and loss from mechanical ventilation. The heat gains consist of solar gains, internal gains and supplied heat. The different heat flows are shown in figure 5. Equation 1 represents the heat balance calculation. It should be noted that the supplied heat (QHeat) is used to compensate the heat losses. However, if the indoor temperature exceeds the heat gains for a longer period, then cooling (QCold) would be supplied to the building. In northern European countries, the winter scenario is generally considered [27]. Each of these heat flows is determined by an array of variables which may varying over time. An energy simulation software is therefore usually used to capture the energy behaviour in a building.

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Equation 1 - Heat balance calculation of a building

(Eq.1)

Where,

QTrans: - Transmission loss through the building envelope

Qvent: - Ventilation loss refer to losses from natural ventilation and mechanical ventilation.

QSol: - Solar gain from solar radiation.

QInt: - Internal gains from occupancy, equipment, and lighting.

QHeat: - The amount of heating that is required in order to maintain the desired indoor climate.

Figure 5 - Elements included in the heat balance calculation of a building [22].

2.3 Windows All windows consist of glazing and framing components (see figure 6). This is a simplified figure since a window can be breakdown into even further components. The frame forms the structural part of the window and is installed in the opening of the building’s wall. It holds the window sash, which in turn keep the glazing unit in place. The glazing unit consists of a single glass pane (single-glazed), or insulated glazing (IG) which means it includes more than one glass pane referred as double-, triple- or quadruple-glazed depending on the number of glass panes. The spacer’s function is to uniformly separate the glass layers in the glazing unit of the window [28].

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Figure 6 - Cross section of a double-glazed window [29]

2.3.1 Heat energy flows in windows

An important feature of a window is its ability to handle heat loss and gains. Heat flows from warmer to cooler side of windows due to conduction, convection and radiation. Conduction occurs directly through materials such as glass, window’s spacer and frames. Convection appears in the interior and exterior glazing surfaces, and within the air cavity between the glazing layers, this causes a draftee feeling by the window. Radiation, unlike the other mechanisms does not need any medium for its transfer. Additionally, heat is transferred by electromagnetic radiation from space. The mode of heat transfers often changes during the process of heat flow. This is because all objects emit and absorb radiation from its surroundings. For instance, when solar radiation strikes a window, heat is absorbed. The heat is then transferred by conduction through the window, but also transferred to the indoor air by convection as well as the indoor space by radiation. Air infiltration occurs due to cracks in the window assembly causing air leakage and thereby resulting in heat losses and gains (see figure 7) [30].

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Figure 7 - The energy flow of a window [31]

2.3.1.1 Technical properties for energy performance

The following properties of windows are the basis for quantifying the energy performance:

The U-value represents the rate of heat flow due to conduction, convection, and radiation through a window, as a result of a temperature difference between the inside and outside (see section 2.2) [32].

Solar Factor (g-value) is commonly used in Europe and is the total incident radiation that enters through the glass. This includes the direct radiant influx as well as the infrared radiation that is absorbed by the glass and then re-emitted internally (see figure 8). The g-value is expressed as a number between 0 to 1, where a higher number gives greater solar energy transmittance [33].

Visible light transmittance (Tvis) measures the amount of light that passes through a window or other glazing unit. Tvis is ranging from 0 to 100%, where a higher percentage letting in more natural light [32]. Much daylighting is preferable in buildings since it has been shown that it improve the well-being and productivity. However, in some cases a lower value is more desirable due to overheating and glare [34].

Solar transmittance (Tsol) is the fraction of incident radiation that passes the glazing as direct radiation. It is always smaller than the g-value. Tsol is a number between 0 to 1 [12].

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Figure 8 - Heat transmission and radiation from a window [35]

2.3.2 Window technologies

The extent of heat transfers can be controlled by using windows that are appropriate to the building and its surroundings (see also building design in section 2.1). The glazing can be considered as the most important component of the window as it will determine the impact of thermal and visual comfort. The glazing in general cover most of the window area and thus it has the biggest effect on the overall U-value of the window.

Today there are many types of advanced glazing solutions available in the market to help control heat loss or gain. Insulated glazing is popular in North America and Europe, where triple glazing is most common for low U-value. The U-value can be further improved by using gas fill of either argon or krypton since they have higher resistance to heat flow than air [9].

Low emissivity (low-e) coating on glazing can reduce the energy loss by 30 to 50%. It was developed to control IR- and UV-light without compromising visible light. The coating usually contains transparent metals or metallic oxides layer that are placed on one or several glass panes. These metals reflect the solar heat either back into the room, or blocking it to entering the space. Low-e coatings can be designed to allow high-, moderate-, or low solar heat gain. However, a low-e coating can reduce Tvis [36]. The next generation of low- e technologies is Spectrally Selective Coatings. This improved coating gives a very low emissivity by screening out 40 to 70% of solar heat, while permitting most of the visible light. In other words, it has low U-value and g-value but a high Tvis [37].

Heat absorbing glazing also known as Tint, changes its colour due to absorption of heat from solar radiation and thus it can lower the g-value, glare and Tvis. However, the glass still permits some of the heat in to the building because of conduction and re-radiation from the window. Due to this, the window is not able to lower the U-value. To improve heat absorbing glazing, spectrally selective coating can be applied on IG to prevent these heat transfers [36]. The colour of the glass depending on the make-up, but the most common is grey-, and bronze-tinted.

Reflective coating limits the transmission of solar radiation, but reduces more visible light rather than heat. Yet, the g-value differs from product to product since it relies on reflectivity and thickness of the

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coating as well as its location in the glazing system. Like the other coatings, it consists of metallic oxides plates, and comes in different colours such as gold, silver and bronze [38].

There are also other glazing make-ups such as self-cleaning-, laminated-, bullet resistance-, hurricane resistance-, noise reduction-, and bird-friendly glazing. However, this may not be interesting from an energy efficient point of view. Noteworthy, is that many of these technologies can be combined to improve performance or to meet the users’ needs i.e. customized glazing system.

The demand for balancing the energy use and light environment has led to the next-generation of products so called chromogenic materials. These “smart” materials allow dynamic control of thermal energy by changing optical properties in conjunction to environmental, electrical, or chemical stimulus. Chromogenic materials are used in architecture application to provide dynamic glazing i.e. smart windows [5].

Furthermore, the glazing is not the only part that matters when it comes to the energy performance of a window. In fact, the framing system is often associated with air leakage and heat loss through conduction and poor installation. Framing systems can be manufactured from various materials, and thereby offering different characteristics. Vinyl, wood, fiberglass, and some composite frame material are the most common since they provide better thermal resistance than metal. There are also a variety of framing design where some is fixed while other is open able [9].

2.4 Smart windows Smart windows are distinguished in two main categories which is based on their mode of operation. The passive dynamic systems do not need any electric supply since it reacts independently on environmental condition such as heat (thermochromic and termotropic) or sunlight (photochromic). Thus, these systems are much easier to install and maintain compared to the active ones. Another great benefit is that they will always adapt to its surroundings which is impossible for people to frequently respond to [5]. However, lack of controllability and integration functionality are major drawbacks [39].

The active dynamic systems on the other hand require electricity and respond on demand. These systems offer a wider functionality as it can be connected to a building management system in order to react to external elements (sunlight, temperature) or internal (indoor climate, artificial and natural lighting, presence of people etc.) or the users need. The active dynamic systems consist of several glazing technologies such as electrochromic, suspended particle devices (SPD), liquid crystal devices (LC/PDLC) and micro-blinds (MEMS). Each of these technologies has different characteristics, performances and costs, making them applicable for all kind of purposes such as architecture, automotive, marine and aircraft [5]. Out of these, the most promising candidate is the electrochromic window. It provides the best flexibility and thus the greatest potential in energy savings for window application [6]. Electrochromic windows are also available for commercial production of large scale architectural applications. Therefore, the thesis focuses on electrochromic windows.

2.4.1 Electrochromic windows

Electrochromic glazing utilizes the properties of certain materials to change the parameters of transmission, reflection, and absorption of solar radiation when an electric field is applied [5]. Tungsten oxide (W03) was the first electrochromic material to be observed, and it is still until today the most promising material, the most studied and the most commonly used material for electrochromic windows and devices [10].

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Electrochromic coatings are composed of a thin film stack that is deposited on a glass substrate. The centre part of the stack is constituted by an ion conductor electrolyte which is sandwiched between an active electrochromic layer and a passive counter-electrode layer. The transparent conductors form the two outer layers of the stack (see figure 9). When an electric potential is applied to the outer transparent conductors, ions from the passive counter electrode layer moves across to the active electrochromic layer, thereby changing the optical properties to a darker state. Vice versa, when there is no electric supply, the ions return to the passive counter electrode layer resulting in a clear state. Thus, electricity is only needed to change the state not to maintain it. [40].

Figure 9 - Schematic diagram of typical electrochromic window [40]

The configuration of electrochromic coatings and manufacturing process can vary significantly which differentiates the manufacturer. These properties include e.g. switching range, switching speed versus temperature characteristics, electric consumption, colour, physical makeup, lifetime and costs [40]. In general, it takes approximately three to ten minutes for electrochromic windows to tint, depending on the size and the temperature of the glass. The typical colour is blue or green but there are other colours as well. The glass has four different levels, where the darkest state sill gives visibilities. However, there are some room for improvements such as switching speed, more energy efficient, ability to provide privacy and of course lower the costs [5].

2.4.1.1 Previous studies of electrochromic windows

According to Zhengrong, et al. there are several studies about electrochromic windows for different applications, since electrochromic windows offers great versatility. However, regarding architectural glazing, the present studies focuses mainly on their impact on building’s energy consumption as well as the indoor climate and light environment [41]. Studies are usually based on e.g. simulations, laboratory tests or field tests of a room or a building. This is commonly examined by comparing the electrochromic windows with conventional windows (with or without shading devices). The general conclusion is that electrochromic windows have great potential to reduce the energy consumption considerably by decreasing the heat load, cooling load and the demand for artificial lighting [42] [43] [5]. It can also be concluded that electrochromic windows should be integrated to the building management system in order to obtain maximum energy efficiency. Thus, the development of control strategies is crucial for the performance of electrochromic windows [44] [45] [46]. In addition, studies have shown that an efficient control strategy is to link the electrochromic window with the amount of daylight the space receives [47] [48]. Furthermore, a study highlighted the importance to have control strategies that are

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based on the user presence. When the space is unoccupied the electrochromic window should use the most appropriate strategy to achieve the minimum energy requirements [45].

Nevertheless, there is a general lack of measured data of realistic occupied condition. Long-term post evaluation studies of the occupancy condition are needed to better understand user acceptance and satisfaction with automatically controlled windows [49]. The general criticism is the high investment cost associated with electricians and automation system engineers. Regular calibration may be needed for improvement of operations and adaptation of user preferences. Therefore, it is important for the building manager as well as the occupants to understand the electrochromic windows system; its balance between energy savings and occupant comfort [46]. Another issue is the limited knowledge and information in the building sector due to lack of standardization of the technology [5].

2.4.1.1.1 Simulating control strategy of electrochromic windows using IDA ICE

Mäkitalo investigated how efficient IDA ICE simulates electrochromic windows as well as the potential of energy savings of an office building. The simulation software offers an in-built window and shading control, but is designed for shading devices with an on/off input signal. Since electrochromic windows have intermediate shading states as well, Mäkitalo developed new control algorithms for more accurate simulations by using IDA ICE’s customisation control. These customised control strategies were based on daylight level at workplane, sunlight on façade, operative temperature and manual control. The results showed that the in-built control algorithms for electrochromic windows slightly reduced the energy usage compared to the reference scenario which had regular windows and blinds. However, the sunlight and manual control algorithm which was designed for further improvement, had similar outcome as the in-built algorithm. That means the additional setting had minor impact. The operative temperature-, and the workplane algorithm reduced the overall energy consumption compared to the reference building. Moreover, tinting speed and the control levels of the window proved to have negligible effect on the energy usage of the building. Due to this, PI controller could be used to simplify custom algorithms. The study concluded that IDA ICE has potential for further simulations of a building’s energy usage while using electrochromic windows. Yet, the study underlined that more investigation is needed to determine if the software is accurately enough to represent the energy usage when changing the control settings for electrochromic windows [50]. The control strategies developed by Mäkitalo will be used in this thesis, with some additional adjustment. For more information se chapter 5.

Furthermore, Reynisson conducted a study based on Mäkitalo control strategies. The aim of the study was to explore the energy performance of electrochromic windows in different locations such as Kiruna, Reykjavik, Stockholm, Copenhagen, Paris and Madrid. Three scenarios were developed; (1) without a window shading, (2) with an external blind, and (3) with electrochromic window shading. The electrochromic window used one control strategy which was a combination of Mäkitalo algorithms with some additional adjustment. The control strategy determined if solar heat gain should be used or rejected. Mean internal air temperature and a 24-hour sliding average of external air temperature were used as controls. It used also different setpoints for when the building was occupied and vacant. A vacant building had either clear or fully shaded windows depending if heating or cooling was wanted. When the building was occupied; global radiation on the façade as well as workplane illuminance were used as setpoints for the window to either turn to 50% of shading with 500 lx or 100% of shading with 800 lx at workplane. When no direct solar radiation hits the façade, the settings became inactive, also when solar heat gain was rejected the shading was kept with daylighting of 500 lx. It should be noted that Reynisson assumed instant shading for the electrochromic window since Mäkitalo’s study showed that the response time had little effect on the building’s energy consumption. Furthermore, the external blind used a similar control strategy as the electrochromic window. However, the biggest difference was that

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the external blind does not have the ability to maintain a fixed workplane illuminance since the component can only be on or off. Due to this, the blind was fully shaded when direct radiation or global radiation exceeded the threshold compared to electrochromic windows that had an intermediate state as well. The study showed that electrochromic window can reduce the energy demand for lighting, heating and cooling by 10-30% more than operational blinds, depending on the building’s location. Also, it reduces as much as 50-75% compared to unshaded window. It was also concluded that electrochromic window has its biggest energy saving potential in warmer countries [51]. This confirm what other studies have shown that Mediterranean and hot climate are more appropriate for electrochromic windows [5] [42].

2.5 Indoor Environmental Quality People strive to create comfortable indoor environment as we spend more than 80% of our time indoors. Occupant’s health and comfort is therefore an important standpoint when evaluating a building’s overall quality and performance. In addition, Indoor Environmental Quality (IEQ), was established to define the condition inside a building. It encompasses a wide range of areas such as thermal condition, visual comfort, air quality, and acoustic quality. Studies have shown that IEQ, is strongly linked to the occupants’ health, comfort and productivity. However, the perceptions of good indoor climate can differ considerably among occupants with regards to behaviour patterns and psychological parameters, which make the relationship between IEQ and well-being very complex. Nevertheless, the design of buildings needs to consider from start the well-being parameter, as well as the desire environment, and the acceptable level of disturbances [52]. Below highlights IEQ factors of interest in this study.

2.5.1 Thermal comfort

Thermal comfort can be considered as the most important IEQ factor. It is defined as “that condition of mind that express satisfaction with the thermal environment”, according to ISO 7730 standard and ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning). Thermal comfort is based on the heat exchange between a person and its surroundings [53]. In addition, human body has its own temperature regulatory mechanism that strives to keep the core body temperature at approximately 37°C. During undesired thermal condition the regulation mechanism will correlate the body temperature through blood flow, respirations, sweating or shivering. Besides, from the autonomic responses, people tend to use the HVAC systems to achieve desirable level of comfort. Thus, there is a direct link between thermal comfort and the building’s energy consumption. Furthermore, the thermal comfort is influenced by six factors, which are classified in two groups. The environmental factors consist of air temperature, mean radiant temperature, air relative humidity, and air velocity. The personal factors include metabolic rates and clothing insulations. All these factors need to be considered at the design phase as well as post construction to evaluate the thermal condition. The individual’s perception of comfort differs since it depends on behavioural adjustment, physiological adaptation, and psychological habitations. Nonetheless, there are well-established methods for measuring thermal comfort such as Predicted Percentage of Dissatisfaction index (PPD), and Predicated Mean Vote index (PMV) [52].

2.5.1.1 PMV and PPD

The PMV and PPD index was developed by Professor Fanger, and has become an ISO standard for estimating the thermal comfort. The PMV index predicts the mean vote of a group of people voting on how comfortable they are in an environment. The calculation is based on an equation of thermal balance of the human body and its surroundings [53]. A sensation scale is used to define the level of comfort. It

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ranges from Cold (-3) to Hot (+3), where a range of 0,5 is considered as acceptable for an interior space [54].

The PPD index indicates how many people that are dissatisfied with a given thermal condition. Figure 10 shows the relationship between PPD and PMV. A PPD of 10 % correspond to the PMV range of 5. It is noteworthy that even with a PMV equal to zero; it will still be around 5% of occupants that are dissatisfied. This is due to the individual perception of comfort [53].

Figure 10 - PPD as a function of PMV [53]

2.5.2 Visual comfort

Visual comfort refers to lighting conditions and the view from the space. There are several studies that have analysed the effect of visual comfort on occupant work performance, productivity, comfort and satisfaction. The general conclusion is that the visual comfort has a significant impact on well-being, which in turn encourages productivity and work performance [52]. Consequently, insufficient light, daylight or glare limits the ability to see properly that makes you uncomfortable and distracted. Moreover, it is scientifically proven that natural light plays such a crucial role, that it even affects e.g. the quality of sleep, and thus it has physiological, behavioural and psychological effects. Due to this, architects need to use a holistic approach to address these needs, to maximum daylighting and view without providing glare or overheating the workspace [52].

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3 Environmental certification system in Sweden

This chapter gives an overview of the various environmental certification system for buildings in Sweden. The core of the chapter is the structure of Miljöbyggnad.

3.1 Sweden Green Building Council The World Green Building Council (WorldGBC) is an international network consisting of more than 70 countries across the globe. Their mission is to create green buildings for everyone and everywhere. They take actions through local and global leadership by empower communities for sustainable living standards [55]. Furthermore, Sweden Green Building Council (SGBC) is the largest organization for sustainable buildings in Sweden and was established in 2009. The SGBC aims to deploy the green building concept through a set of certification system that includes building technology, environmental impact, and sustainability in the building sector. The following section gives an overview of SGBC four certification systems that assess the performance of buildings.

3.1.1 Miljöbyggnad

SGBC is responsible for Miljöbyggnad, an environmental certification system for buildings that was developed by the Swedish construction and property sector together with government agencies among other key players in the market. It aims is to facilitate the development of buildings with improved energy efficiency and indoor environment that uses less hazardous materials, and thereby meet the Swedish environmental objectives. Miljöbyggnad is the most used certification system in Sweden, because it is simple, cost effective and it can be applied for new constructions, refurbished buildings and existing building, regardless of size [56]. The building is reviewed by a third party before SGBC certifies it.

Miljöbyggnad certifies a building in three different categories depending on how successfully it is implemented. BRONZE is the basic requirements for Miljöbyggnad, which correspond to the government authority requirements such as Swedish Work Environment Authority, Boverket (National Board of Housing, Building and Planning), Swedish Radiation Authority, and The Public Health Agency of Sweden. SILVER corresponds to a more ambitious building code, and GOLD is the highest ranking and proves that the building utilizes the most environmentally friendly application available. Nevertheless, there is a RATED rating which shows that the indicators are evaluated but do not fulfil Miljöbyggnad’s requirements. However, newly constructed building must fulfil at least BRONZE requirements since it is equivalent to the government authority requirements.

The assessment of newly constructed building consists of 15 factors that quantify the building’s environmental qualities, referred as indicators. The indicators are then merged into 11 aspects, and then further aggregated into three major areas according to energy, indoor environment and material. The rating system is based on an aggregation method, which is designed so that buildings with deficiencies should not be able to obtain high rating. That means that the lowest indicator rating determines the aspects rating. The same procedure applies the other assessments i.e. the area rating consists of the lowest rating of the aspects, and the final rating is based on the lowest aspect rating. Nevertheless, a field rating can be raised one level if more than 50% of the total assessed indicators has a higher rating. This method creates an incitement to fix the gaps to get a higher rating. Furthermore, GOLD certified building cannot have any indicators that are BRONZE rated, and the building must also fulfil a questionnaire given to the users/tenants where at least 80% of the answers regarding the indoor

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environment are “very good”, “good”, or “acceptable”. [56]. Table 1 shows a certified building and illustrates the aggregation method. It should be noted that the building would obtain a GOLD certificate but due to the BRONZE indicator it is not possible.

Table 1 – An example of a certified building. The table is developed under influenced of Miljöbyggnad

.

3.1.1.1 Selected indicators

Although, there are 15 indicators in Miljöbyggnad for newly constructed buildings, the study investigates only six indicators which are considered relevant for this study (see table 2). These indicators are used to design a reference building that meets the requirements of Miljöbyggnad. They are also used to evaluate the performance of the building using electrochromic windows instead of conventional windows and motorized awnings, to explore the outcome.

Indicator  Aspect  Area  BuildingEnergy use GOLD Energy use GOLD

Energy GOLD

SILVER

Heat. power demand GOLD Power demand SILVER

Solar heat load SILVER

Type of energy GOLD Type of energy GOLD

Noise environment SILVER Noise environment SILVER

Indoor environment

SILVER

Radon gas SILVER

Air quality SILVER Ventilation standard SILVER

Nitrogen dioxide GOLD

Moisture resistance BRONZE Moisture BRONZE

Thermal climate winter GOLD Thermal climate GOLD

Thermal climate summer GOLD

Daylight SILVER Daylight SILVER

Legionella GOLD Legionella GOLD

Documentation of building materials

SILVER Documentation of building materials

SILVER

Materials GOLD

Phasing out dangerous substances

GOLD Phasing out dangerous substances

GOLD

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Table 2 - Selected indicators for this study

Energy use

The objective with this indicator is to design and construct building with low energy consumption. Energy use is defined as “the energy, which in normal use during a reference year needs to be supplied to a building” [57]. The energy use should be calculated for the intend use of the building. This includes e.g. indoor air temperature winter and summer, number of occupants and attendance time, operating hours, operation hours of air conditioning including door opening, manual sun shading system, business-related displacement of ventilation, empty spaces etc. The energy use is then assessed by comparing the obtain simulation results with Miljöbyggnad’s criteria, which is a proportion of BBR’s requirements (see tables 3 and 4.) [58]

Table 3 - Miljöbyggnad Energy use criteria which is a proportion of BBR

Table 4 shows the requirements for each grade and city. Noteworthy, is that the energy use requirements are based on BBR’s requirements for building without electric heating systems

Table 4 - Max allowed energy use in respectively city, expressed in kWh/m2, Atemp

City BRONZE SILVER GOLD

Umeå ≤ 130 ≤ 91 ≤ 78

Stockholm ≤ 90 ≤ 63 ≤ 54

Malmö ≤ 80 ≤ 56 ≤ 48

Heating power demand

The purpose of this indicator is to design and construct building with low demand for heating during cold periods. The heating power demand can be determined by both simulation and simplified calculation method. The simulations should be adjusted so it includes ventilation in operation, but not solar radiation and internal gains. The following constrains are highlighted below:

Indicator Aspect Area

Energy use Energy use

Energy Heat. power demand Power demand

Solar heat load

Thermal climate winter Thermal climate

Indoor environment Thermal climate summer

Daylight Daylight

Energy use BRONZE SILVER GOLD

(% of BBR)  ≤ BBR ≤ 70 % ≤ 60 %

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1. Indoor temperature should be at least at 20°C 2. Winter temperature should be determined by DVUT 3. The building’s normal ventilation flow should be used 4. Air leakage 1 l/s m2 Aom at 50 Pa 5. Thermal bridges

The results obtain from the simulations are then compared to Miljöbyggnad requirements (see table 5) [58].

Table 5 - Max heating power demand according to the different cities, P [W/m2, Atemp at DVUT]

City Climate zone BRONZE SILVER GOLD

Umeå I ≤ 84 ≤ 56 ≤ 34

Stockholm III ≤ 60 ≤ 40 ≤ 25

Malmö IV ≤ 60 ≤ 40 ≤ 25

Solar heat load

Solar heat load in a room indicates the heat gain through windows from the sun during hot periods. The purpose of this indicator is to limit the building’s solar heat load, and thereby reducing excess heat in rooms or the need for comfort cooling. Solar heat load (SVL), can be calculated through a simplified method or by simulations. The simulation should be executed when the solar heat load is the highest, during the period of spring- and autumn equinox. However, it does not need to be the same day when it is the warmest outside.

Solar heat load is assessed by room level, which means that a floor plan, which has the worst solar heat load prospective is selected. Thereafter, the most critical room is rated, and then with the second worst and so forth, until just over 20 % of the floor area is assessed. The indicator rating is based on the worst room rating, and can be increased by one level if at least half of the rated area has higher grades [58]. Table 6 shows the requirements in each rating for solar heat load according to Miljöbyggnad

Table 6 – Max allowed solar heat load according to Miljöbyggnad

Solar heat load BRONZE SILVER GOLD

SVL [W/m2] ≤ 40 ≤ 32 ≤ 22

Thermal climate

Thermal climate is defined by two parameters according to the occupant’s thermal comfort, and the effect on the building itself. The thermal climate indicators can be assessed by calculating the PPD-index from measurement or simulations. Although, thermal climate consists of two different categories, winter and summer, both use the same PPD reference (see section 2.3.1). There are also two simplified calculation methods that can be used, so called transmission factor (TF) and solar heat factor (SVF). However, PPD calculation is more accurate with computer aid and is thereby used in this study.

Thermal climates are assessed by selecting the floor plan with the least prospective of good thermal climate condition for winter respectively summer. In the same manner goes for choosing the room i.e. the room with worst thermal climate condition. However, it is important that the selected rooms have

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present occupants rather than occasionally. After the room is rated, then the second worst room is assessed and so forth, until the room areas correspond to 20% of the floor plan, Atemp. The results are then compared to the requirements. The reference values for rating the thermal climate indicators are presented in table 7 [58].

Table 7 - Max allowed PPD according to Miljöbyggnad

Thermal climate BRONZE SILVER GOLD

PPD [%] ≤ 15 % ≤ 10 % ≤ 10 % + questionnaires

Daylight

The daylight indicator refers to the relationship between the occupants and the amount of natural light the space receives. This can be assessed through calculation of daylight factor (DF) or by the AF-method, which is a simplified method for existing building that calculates the proportion of windows in a room.

The DF determines the relation between the illuminance in a point indoors and an unshaded point outdoors with a standard sky called CIE Overcast Sky. This artificial sky represents a dull sky condition and it is does not include climate, weather, cities, seasons and time. The only variation is that the sky at zenith is three times brighter than at the horizon (see figure 11). The DF is not intended to evaluate whether the daylighting in a room is good, but to determine if the room meets the minimum requirement. Nonetheless, it is influenced by the glass area, measurement point, floor area, light transmission of the window, and the room’s ability of reflection.

100

Figure 11 - Illustrates the ratio between the outdoor and indoor illuminance. The CIE Standard Overcast Sky is three times brighter at zenith than at the horizon

Furthermore, the rating of the daylight indicator is also determined by room level, which means that the same procedure for determine solar heat load and thermal climate is applied. The floor plan with worst daylight condition should be selected, where the most critically rooms should account for more than

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20% of the floor plan. Furthermore, the room rating can increase by one level if more than half of the rated area have higher grades. The results are then compared to the requirements according to table 8 [58]. Also, the limits for simulated DF are reduced by 0,20 %. The study uses a simulation software to determine the DF.

Table 8 - The daylight criteria according to Miljöbyggnad

Daylight BRONZE SILVER GOLD

DF [%] ≥ 1,0% ≥ 1,2% ≥ 1,5%

Simulated DF [%] ≥ 0,8 % ≥ 1,0 % ≥ 1,3 %

3.1.2 BREEAM SE

BRE Environmental Assessment Method (BREEAM), is a British environmental certification system that was developed since 1990. The SGBC has adopted the concept and further developed it to meet the Swedish legislation and building code, so called BREEAM SE. The certification system can be used for newly constructed buildings as well as reconstruction purposes. The control points include energy, material, indoor environment, water, management, construction waste, infrastructure and communication, ecology, pollution and innovations. Each area is evaluated and get points for their performance. When the building does not reach to 30% of the total score, it will not get certification. The different levels are PASS, GOOD, VERY GOOD, EXCELLENT and OUTSTANDING. To be certified as OUTSTANDING requires 85 percent of maximum points and good innovative solutions [59].

3.1.3 LEED

Leadership in Energy and Environmental Design (LEED), is the world’s most known certification system. It is developed and administrated by U.S. Green Building, a non-profit organisation which is a member of the WorldGBC. LEED can be applied for existing buildings, newly constructed and for reconstructions. Furthermore, LEED consist of rating system which gives points for how successfully the buildings perform in the different areas such as energy, material, indoor environment, water, management, construction waste, infrastructure and communication, ecology, pollution and innovations. Buildings that fulfil the requirements are classified as Certified, Silver, Gold or Platinum [60].

3.1.4 GreenBuilding

GreenBuilding was initiated by the European Union (EU) during 2004 and 2014. The objective was to promote energy efficiency in the building and property sector. The certification system refers to commercial buildings, where buildings should have at least 25% lower energy demand compared to the BBR requirements in order to be GreenBuilding certified. Currently, the SGBC is responsible for the certification system since the EU agreement is finished [61].

3.2 Nordic Swan Nordic Swan also referred as the “Nordic Ecolabel” is an eco-labelling system for products and services to ensure that they are environmentally friendly. A Nordic Swan-labelled building is evaluated from a life-cycle perspective which means that each building element is carefully analysed. The building is considered as low energy usage, using material with low environmental impact, good indoor climate, high quality in general, a proper management control [62]. The labelling system put emphasize on

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renewable energy and sustainable solutions. The building will then be certified if it meets the requirements. However, check-ups are required every five years to obtain renewed licence [63] .

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4 Office model

This chapter represents the office building model, which includes building description, building envelope, internal heat loads, HVAC system, and climate condition.

EQUA has developed IDA Indoor Climate and Energy (IDA ICE), a multi-dynamic simulation software that has become an industry standard for building simulation of indoor climate and energy characteristics [64]. This tool enables to develop a model that has similar attribute as the reality, depending on how well the model is designed. IDA ICE simulates the energy balance dynamically, according to the building’s geometry, construction, HVAC system, and internal heat loads [65]. The advantage by creating an artificial building is the ability to change the building’s characteristics, as well as external stimuli, without any major efforts. In this study, a drawing of a typical office building from IDA ICE has been used. From the drawing, construction material and system configuration could be selected in order to develop a 3D model. This chapter provides the design of the office building. It should be noted that some additional changes have been made of the office design to fulfil the criteria of the selected indicators.

4.1 Building description Figures 12-14 illustrates the constructed office building. It is a two-storey building with a total floor area of 675,5 m2. The building has two long facades in north and south, and two short facades respectively in east and west. The windows accounts for 5,4 % of the building envelope, where larger windows are situated on the south side to obtain maximum solar heat and daylighting, while smaller windows can be found on the north side to minimize heat loss. The east and west wings do not have any windows.

Figure 12 - Office building model

The two floor plans are almost identical. The ground floor consists of six small offices, two toilets, two bathrooms including shower and toilet, one reception with the main entrance, two open offices, one big office, one recreation room with kitchen and toilet, and an elevator shaft for connection to

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other parts of the building. The small office rooms are located on the north side, and the larger office rooms are placed at the south side with connection to all small office rooms (see figure 13).

Figure 13 - Ground floor of the office building

The differences between the two floors, is that the top floor have two meeting rooms instead of the reception (see figures 13 and 14).

Figure 14 - Top floor of the office building

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4.2 Building Envelope The building envelope has a significant impact on the overall construction performance as it determines the building’s ability to withstand stress from its surroundings. Most of the heat transfers occurs between e.g. walls, slabs and windows, which makes their thermal insulation properties crucial [19]. The structural design consists of cement with light insulation, and triple glazed windows due to its performance in cold climate. The parts of the building envelope that have considerably poorer insulation, called thermal bridges. This arise when building elements are in contact with warm and cold parts (e.g. connection and junction), and thus contributing to conduction. Thermal bridges in IDA ICE can be defined for each joint by a five-graded scale according to None, Good, Typical, Poor, and Very poor [12]. Since this study strive to represent a typical modern office building, the grade “Typical” was chosen for each joint. Buildings have also heat losses from infiltration, which can be defined as unintentionally air leakage into or from the building. This can cause major problems to both thermal comfort and energy usage of the building. However, the extent of infiltration relies on the building design and the pressure coefficient [66] [12]. The building is assumed to have an infiltration of 0,3 L/ (s. m2ext.surf) at 50 Pa, and a pressure coefficient defined as “Exposed”.

Table 9 gives an overview of the building elements its thermal insulation properties.

Table 9 - Overview of the building envelope

Building component Value Description

External wall UExt.Wall = 0,2236 W/m2K Concrete 150 mm Light insulation 15 mm,

Concrete 80 mm

Internal wall UInt.Wall = 0,6187 W/m2K Double gypsum on 95 mm frame, 30 mm light

insulation

Internal slab UInt.Slab = 0,2385 W/m2K Coating, l/w concrete 20 mm, concrete 150 mm

External slab UExt.Slab = 2,9 W/m2K Coating, Concrete 250 mm

Roof URoof = 0,172 W/m2K Insulation 200 mm, Concrete 15 mm

Glazing UGlazing,North = 1,1 W/m2K

UGlazing, South = 0,95 W/m2K

Triple pane glazing for both glazing. The south facade

has better insulation properties.

Frame UFrame = 2,0 W/m2K 10 % fraction of the total window area

Thermal bridges “Typical” value for all joints

Infiltration

0,3 L/ (s.m2ext. surf)

at 50 Pa

Wind driven flow. Pressure coefficient is set to

“exposed”.

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4.3 Internal heat loads There are three main sources in IDA ICE that determines the amount of internal heat in the building so called; lighting, equipment and the presence of occupant. However, it is difficult to predict the internal gains from occupancy due to their activity level, mobility and clothing type. Thus, the occupants are assigned in terms of number per square meter, so that the simulation software can automatically distribute the occupants in the building. In this study, it is assumed that each person requires 10 m2 for all zones. According to Miljöbyggnad, the metabolic rate should be fixed at 1,2 MET, which correspond to an engagement in near sedentary work. The clothing insulation is ranging between the limits of 0,7 0,25 CLO to obtain comfort [58]. The occupants will be at the office during weekdays, from 08:00 to 17:00 with one-hour lunchbreak between 12:00 and 13:00 where the occupants are not present in the building. No occupancy occurs during weekends and holidays [67]. Lighting system, and office equipment such as computers, printers and other electric machines are also producing internal heat. The interior lighting system is set to 7,5 W/m2, and the equipment to 9 W/m2. These values correspond to a typical modern office building according to Sveby [67]. However, the lights will only light if the rooms are occupied and the daylight is below 300 lx, which is the minimum lux-level at workplace according to the Swedish Work Environment Authority [68] . It should be noted that IDA ICE simulates the heat load for equipment, and lighting in the same manner as for occupancy. The equipment is assumed to be in operation during occupancy (08:00-17:00 on weekdays), while lights are assumed to be in operation during 06:00 to 18:00 on weekdays, otherwise it is turned off including holidays. Table 10 shows a summary of the internal loads in the building.

Table 10 - Internal heat loads of the building

Building component Value Description

Occupant

1 person per 10 m2

Activity level: 1,2 MET clothing:

0,7 0,25 CLO

Number of persons is auto assigned.

Constant, Same for all zones, According to Miljöbyggnad

Occupant schedule 08:00 – 17:00 in

weekdays. Weekends and holidays off

According to Sveby

Lunchbreak at 12:00-13:00

Interior lighting 7,6 W/m2

76 W per unit

According to Sveby. Number of unit auto assigned.

Same for all zones, Facility lighting

Interior lighting schedule

06:00-18:00 in weekdays. Off at

weekends and Holidays

The lights are only turned on if the rooms are occupied and the

daylight is below 300 lx. Minimum requirements according

to the Swedish Environment Authority.

They are turned off during night, weekends and holidays

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Equipment 9 W/m2

90 W/ per unit

According to Sveby Number of units is auto assigned.

Same for all zones, tenant schedule

Equipment schedule

08:00-17:00 in weekdays. Off at

weekends and Holidays

Turned off during night, weekends and holidays

4.4 HVAC system In this study, the HVAC system consist of a plant and an air handling unit (AHU), which have unlimited capacity to supply the building with air and water at any given temperature. Fuel heating (COP 0,9) is chosen for heating and domestic water, while the cooling is electrical (COP 3). According to the Swedish Work Environment, the indoor climate should be between 20-24°C in the winter and 20-26°C during summer [69]. The room unit for heating and cooling are set to keep the indoor air temperature between 21°C and 25°C. This is because 20°C and 26°C may feel too cold and warm with large WWR. In winter, the room appears colder than the actual temperature due to the cold surface of the window, and during the summer the room feels warmer from the sunlight striking the window. The room unit has no physical location and will thereby deliver heat and cooling uniformly in the selected zone. This will give an indication of how much energy that is required to maintain the desired set point. The fans are scheduling to operate during 06:00 to 18:00 when the office is open. Table 11 gives an overview of the HVAC system.

Table 11 - The buildings HVAC system

Building component Value Description

Temperature set points Minimum: 21°C Maximum: 25°C

According to Swedish Work Environment

HVAC system Ideal heater/cooler, AHU

Air flows Supply air: 1 L/s.m2 Return air: 1 L/s.m2

Constant air volume

Supply air temperature set points

16°C constant

Relative humidity Minimum: 20 % Maximum: 80 %

Level of CO2 Minimum: 700 ppm Maximum: 1100 ppm

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AHU schedules Schedule Fan operation during 06:00-18:00 weekdays

Chiller type Unlimited capacity Electric cooling

Heating type Unlimited capacity Fuel heating

Hot water 2 kWh/m2

According to Sveby

Uniform distribution, Fuel heating

4.5 Climate condition and Location The building is simulated in Stockholm, Umeå and Malmö. Each city has different characteristics due to location and climate. The collected climate file from IDA ICE Database, includes information such as air temperature, relative humidity, wind direction and speed, direct and diffuse solar radiation based on the building’s location and geometry, as well as the public holidays in Sweden. IDA ICE is then able to simulate the building and its surroundings, on a time step basis.

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5 Scenarios

This chapter represent the various scenarios that are simulated, where each scenario is simulated in Stockholm, Umeå and Malmö. The scenarios use the same office building, but with different window design and characteristics such as glazing type, motorized awnings, and control strategies.

5.1 Reference scenario

Table 12 represents the technical properties of the conventional windows in the reference building.

Table 12 - Technical properties of the conventional window

Glazing State U-value g-value Tsol Tvis

Plinkington Otitherm S3(6-

15Ar-S(3)4)

Fully clear

1,1

0,59

0,52

0,79

Saint Gobain T4-12m. Planitherm

ONE+ar

Fully clear

0,95

0,46

0,38

0,65

The reference building is equipped with two different types of windows. The north façade has windows with slightly poorer U-value, but a higher g-value that is appropriate for receiving more solar gain and daylighting. This is because the highest solar heat load value in the north side of the building is around 20 w/m2. Although, the south side has improved glazing properties, awnings are still needed to decrease the solar heat load. This indicator is influenced by the g-value and the size of the window, compared to daylight that changes in relation to location and geometry of the window.

The selected awning is a generic awning obtained from IDA ICE’s database (see table 13 and figure 15). The awnings will operate during the 15th of March to the 1st of October. However, the awnings will withdraw if the solar radiation level is below 100 W/m2.

Figure 15 - Reference building

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Table 13 - Technical properties of generic awning material

Transmittance Reflectance upper for slats

Reflectance lower for slats

Total shortwave 0,05 0,3 0,3

Visible 0,05 0,3 0,3

Diffusion 1 1 1

Emissivity

Longwave 0 0,9 0,9

Total:

Thickness 0,6 mm

k-value 0,3 W/Km

5.2 Electrochromic window scenarios The electrochromic windows are only used on the south façade of the building. However, the smallest windows in Big offices 1 & 2, and the Recreation rooms 1 & 2 remains the same since they are too small to have a substantial impact. The same reasoning is for the north side of the building as the conventional windows are not exposed to significant solar radiation.

Table 14 shows the technical properties of the SAGE’s electrochromic window in a fully clear and shaded state.

Table 14 - Technical properties of SAGE EC IGUs [66]

State U-value g-value Tsol Tvis

Fully clear 0,28 0,41 0,33 0,60

Fully shaded 0,28 0,09 0,004 0,001

In this study, the electrochromic windows are treated as an integrated shading device. An integrated shading device could be any type of shading in the windows’ plane that influences the shading coefficient of the glazing. The shading module in IDA ICE is defined by three constants according to U-value, g-value, and Tsol. These values provide multipliers, which determine the effects of the shading in combination with the window parameters [12]. The electrochromic window has a fully clear state in default mode. When the shading signal is activated, the constants from the shading module are multiplied with the clear window parameters. The shading module can receive any value between the two-extreme states 0 and 1 i.e. fully- clear and shaded. This means that the software calculates the shaded states rather than manually entering the values [50]. The following control strategy scenarios are presented below.

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5.2.1 Schedule

Schedule is an in-built algorithm in IDA ICE, where a schedule file determines the shading signal. The shading signal has two extreme level 0 (fully clear) and 1 (fully shaded). A schedule smoothening can also be applied in this algorithm, which means that the shading can start/finish one hour earlier/later [50]. This algorithm is used in the “Always Off” and “Always On” scenarios.

5.2.2 Sun and Schedule

The Sun and Schedule algorithm, is also an in-built algorithm that IDA ICE offer. The strategy is based on the schedule algorithm with one additional setting. First it checks if the schedule file is active or not, then it compares the global radiation intensity through the window with a given setpoint. If the global intensity is higher than the setpoint, the window will activate the shading. This scenario will use the same setpoint as the default mode which is 100 W/m2 of global radiation, and shading is assigned between 08:00 and 17:00. It should be noted that scheduling smoothing can be applied here as well [50].

5.2.3 Daylight Control

The Daylight Control algorithm regulates the shading signal of the electrochromic windows via natural illuminance at the workplace. It is controlled dynamically through a proportional-integral controller so called PI-controller, which can have any shading signal between 0 and 1. The setpoint for the control is 500 lx which correspond to the recommended illuminance for a typical office building [50].

5.2.4 Solar Control

This algorithm controls the window shading through solar radiation. Unlike the previous algorithms, the strategy has three different shading levels. The window must at least receive 150 W/m2 of global radiation to turn to 33,33% shading, while 66,67 % shading occurs when the global radiation exceeds 300 W/m2. The windows are fully shaded at a global radiation above 450 W/m2. The thresholds are based on a study where the occupants preferred blinds down at a global radiation of 450W/m2 [70].

5.2.5 Schedule, Façade and Window

The Schedule, Façade and Window algorithm consist of two control strategies to avoid unwanted solar radiation into the indoor space. The windows are scheduled to be activated from 15th of March to 1st of October. The façade, and window algorithm controls the shading through direct and global radiations. It uses three thresholds for activating the shading. The façade must receive at least 50 W/m2 of direct radiation, regardless of the global radiation to get activated. If the global radiation outside of the windows exceeds 225 W/m2, the shading signal is set to 50%, and to get 100% of shading a global radiation above 450 W/m2 is acquired [50].

5.2.6 Operative Temperature Control

This algorithm uses the operative temperature and schedule file to regulate the shading level of the electrochromic window. The device reacts when the operative temperature exceeds 22.5C. The threshold is set from trials and errors, based on Miljöbyggnad’s recommendation level for operative temperatures (22.5-28C) [58]. Yet, the windows are only activated during 06:00 to 18:00, to prevent unnecessary

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shading at night when there is no solar radiation. It should be mentioned that this strategy has only one shading level.

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6 Results

This chapter covers the obtained results from the simulated scenarios.

Summary of scenarios:

Reference scenario: conventional windows with motorized awnings Always off: electrochromic windows that are fully clear at all time Always on: electrochromic windows that are fully shaded at all time Sun and Schedule: electrochromic windows that are turned on during 08-17 Daylight Control: electrochromic windows respond to given lux-level Solar Control: electrochromic windows reacts on the intensity of the solar radiation Schedule, Façade, and Window: electrochromic windows react on the solar radiation intensity

on the façade as well as the window. It can only be activated according to the schedule file. Operative Temperature Control: electrochromic windows activate at a given operative

temperature

6.1 Miljöbyggnad This section focuses on the results obtained from the scenarios with regard to Miljöbyggnad criteria. Appendix A provides a summary of each scenario per city, which contains results and grades for indicator, aspect, area and final building grade.

6.1.1 Energy use

Figures 16-18 represent the building’s energy consumption for each scenario and city. The scenarios have the same energy pattern, but with different values as the location and weather condition differ. In fact, Stockholm and Malmö attains the same ratings for all scenarios. The Reference scenario, as well as the Daylight Control, Solar Control and Always on scenarios receives BRONZE ratings, while the Schedule, Façade and Window, Operative Temperature Control, Sun and Schedule, and Always Off scenarios have SILVER ratings. In Umeå, all the scenarios are upgraded by one level, except the Solar Control scenario that is increased by two levels to GOLD rating.

The differences between scenarios are the demand for fuel heating, the other parameters such as domestic hot water, HVAC aux and electric cooling are the same. However, the Always On strategy has slightly higher cooling needs because it has no shading.

Furthermore, the graphs show that the scenarios with least shading have most energy reduction and vice versa. This proves that passive heating plays a crucial role for energy efficiency. Thus, the Always Off strategy has best energy savings, followed by Operative Temperature Control, Schedule, Façade and Window, and Sun and Schedule.

The Always On strategy has higher energy demand than the Reference scenario, while Daylight control as well as the Solar control strategy managed to slightly reduce the energy usage compared to the reference scenario.

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Figure 16 - Energy usage in Stockholm

Figure 17 - Energy usage in Umeå

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Figure 18 – Energy usage in Malmö

6.1.2 Heating power demand

Figure 19 shows the heating power demand for each city with and without electrochromic windows. The indicator is slightly improved with electrochromic windows due to its better U-value. However, the electrochromic windows manage to level up to GOLD rating in Stockholm. The other scenarios remain the same according to; Stockholm (except reference scenario) and Malmö attains GOLD ratings, while Umeå receives SILVER rating.

Figure 19 - Heating power demand of each city and scenario

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6.1.3 Solar heat load

This is the most interesting indicator to investigate because the control strategies have significant impact on the solar heat load. Figure 20 represents the solar heat load value in the worst room, for each city and scenario. Daylight Control, Solar Control and Always On achieves GOLD ratings in all cities. However, the worst room in Umeå has SILVER rating, but since most of the rooms’ floor plan area have GOLD ratings, the grade is increased by one level.

The Schedule, Façade and Window, Operative Temperature Control, and Sun and Schedule strategies have SILVER ratings in Umeå and Malmö. Their grades are also upgraded by one level, due to most of their rooms have higher ratings than BRONZE. However, the Schedule, Façade and Window, and Sun and Schedule strategies receives BRONZE ratings in Stockholm.

The Reference scenario has BRONZE rating in Stockholm and Malmö, but exceeds the limit of 40 W/m2 of solar heat in Umeå, and thus become RATED. The same goes for Always Off strategy that receives SILVER rating in Malmö, because most of the rooms have higher ratings, but failed in Stockholm and Umeå. This means that the Reference scenario in Umeå, and the Always Off strategy in Stockholm and Umeå cannot obtain Miljöbyggnad certificate, even though they have GOLD ratings in the other indicators.

Figure 20 – Solar heat load in the worst room of each scenario and city

6.1.4 Thermal climate

All scenarios achieve BRONZE ratings in thermal climate winter and summer. Figure 21 represent the worst room in each scenario and city. The thermal climate is slightly improved in the electrochromic window scenarios in Umeå and Malmö, but it is not enough to upgrade the indicator. It is noteworthy that the scenarios have GOLD ratings in many rooms, but since the Open offices together with small offices account for most of the floor plan area, the entire building get BRONZE rating.

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Figure 21 - PPD-level in the worst room of each scenario and city

6.1.5 Daylight

All shading devices are withdrawn including shading of the electrochromic window. This is because the DF is determined by simulating the building under a CIE Overcast Sky. Thus, the electrochromic window scenarios as well as the reference scenarios have the same DF, since this method does not consider climate, weather or location.

Figure 22 presents the DF for each room replaced with electrochromic windows. The conventional windows provide better DF, which can be explained by its higher Tvis and g-value versus the electrochromic window. However, it should be highlighted that this standard is not used to evaluate if the room has good daylighting, but to see if it meets the minimum requirements.

Furthermore, the electrochromic window scenarios receive SILVER ratings, except the Always On scenario being RATED because the windows are completely shaded during the simulation period. The reference scenario achieves GOLD rating.

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Figure 22 - DF of each window type

6.1.6 Building grade

Appendix A contains the results and grading for each scenario and city. The results show that electrochromic windows have neglectable effect on thermal climate and daylight condition in the building. The heating power demand is slightly improved in the electrochromic window scenarios, which manage to upgrade in Stockholm, the other scenarios remains the same.

The electrochromic windows influence the energy consumption in the scenarios. The ratings are ranging between BRONZE and SILVER in Stockholm and Malmö, while the energy ratings in Umeå are between SILVER and GOLD. The strategies with least shading provide best energy savings and vice versa.

Electrochromic windows have major impact on the solar heat load in the building, where the grade ratings vary between RATED and GOLD. Thus, analysis of control strategy as well as location are crucial to determine the amount of solar heat gain the building will receive. Electrochromic window must consequently have a significant influence on the daylight condition as well, since solar gain and daylight goes hand in hand.

Furthermore, none of the scenarios manage to get higher than BRONZE certificate, which is the same as the Reference scenarios. However, the reference scenario in Umeå is RATED because the building receives too much solar heat. The same applies for the Always Off scenario, as Stockholm and Umeå exceed the solar heat limit. This is an example of the previous mentioned importance of control strategy and local climate. The Always off scenario is also RATED since the windows are completely shaded throughout the simulation period.

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6.2 Detailed analysis Two rooms are investigated for a more detailed analysis of the electrochromic window strategies. This is based on the amount of daylight and solar gain the rooms receive, since the results show that electrochromic window has significant impact on solar heat load.

The higher the windows are located, the more likely it is for better daylighting. The orientation of the window such as southwest or southeast plays also a decisive role. With this in mind, it is interesting to see if this is the case, since the windows that have most potential for solar gain and daylight may be shaded at all time, compared to the rooms that do not have these benefits.

The selected rooms are from the DF simulation which are using the CIE Overcast Sky. The best and worst DF rooms are chosen, which makes it interesting to see if this correlates to the average lux level at the rooms. Also, Big office 2 has the highest solar heat value in all scenarios. The following rooms are presented below (see figure 23).

Big office 2: located on top floor with windows facing southeast may have most potential for maximum solar gain and daylighting.

Recreation room 1: located on ground floor with windows facing southwest may have least potential for maximum solar gain and daylighting.

Figure 23 – Illustration of the selected rooms and its windows

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6.2.1 Reference

The Reference scenario uses conventional windows with motorized awnings, to protect from excessive solar heat and glare. Figure 24 shows the daylight level (lx) in Big office 2 and Recreation room 1, for each month and city. The Recreation room 1 receives most average daylight throughout the simulation period, where Umeå has most, then Stockholm, and lastly Malmö (see table 15). Furthermore, the mean value is about 220 lx, and the maximum amount of daylight is below 500 lx. Nonetheless, the Reference scenario in Umeå is not fulfilling the solar heat load criteria (se section 6.3.1).

Figure 24 – Reference Scenario, daylight level (lx) in Big office 2 and Recreation room 1

Table 15 – Reference Scenario, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 221 229 238 247 183 201

min 35 35 35 33 53 43

max 413 412 399 418 308 370

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6.2.2 Always Off

The electrochromic windows are completely clear (i.e. no shading) throughout the simulation period. Therefore, the strategy is used as the baseline to investigate the daylight level in the other control strategies.

Figure 25 - Always Off Control strategy, daylight level (lx) in Big office 2 and Recreation room 1

Table 16 - Always Off Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 427 497 423 494 330 418

min 33 33 33 31 49 41

max 1120 1298 965 1245 728 1112

Figure 25 and table 16 shows the average daylight level (lx) in Big office 2 and Recreation room 1. The Recreation room 1 receives most average daylight in all cities, where Stockholm has most followed by Umeå and Malmö. This is unexpected since Big office 2 has the best DF while Recreation room 1 has the poorest among the rooms. Big office 2 has also maximum solar gain in all scenario which means that the room receives great amount of solar radiation. However, this might just occur for a short time period. There is a big difference between the lux level in this scenario, with an average of 432 lx, compared with the reference scenario’s 220 lx. This seems realistic because the windows are exposed to sunlight throughout the day, while the reference scenario is protected by awnings. Because of this, the scenario is RATED in Stockholm and Umeå. The rooms are likely to have glare problems since the maximum lux level is well over 500 lx.

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6.2.3 Always On

The electrochromic windows are completely shaded throughout the simulation period. However, it should be noted that the selected rooms have small conventional windows that obtain solar heat and daylight. Nevertheless, this strategy gives an indication of the extent of shading in the other scenarios. Figure 26 shows the average daylight level for each room and city. The average daylight level is extreme low in all cities, which explains why this scenario has the highest demand for space heating and artificial lighting (see table 17).

Figure 26 - Always Off Control strategy, daylight level (lx) in Big office 2 and Recreation room 1

Table 17 - Sun and Schedule Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 58 51 73 70 38 37

min 10 9 10 10 11 11

max 99 79 168 165 58 56

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6.2.4 Sun and Schedule

The Sun and Schedule Strategy is schedule for full shading during 08:00-17:00, given that the solar radiation is above 100 W/m2. This section focuses on the shading signal throughout the year, as well as shading signal during peak heating and cooling.

In Appendix B – Sun and Schedule Strategy the graphs show that the shading signal in all scenarios are in general fully activated at some time during the day throughout the simulation period. Unlike the other strategies, this control algorithm has slightly different control signal for each room, which is probably due to the solar position as well as the small amount of global radiation (100 W/m2) that is needed to activate the windows. This scenario is not optimal from an energy perspective, because the windows have no intermediate states, and the sun is sufficiently light to fully activate the windows in winter. The windows in Stockholm are shaded during 11:30-13:30, while Umeå and Malmö are fully clear at peak heating day. At peak cooling day the Big office 2 is shaded about 10:30 – 17:30, while the Recreation room 1 is shaded 08:00-15:30, with approximately ±30 min differences between the scenarios.

Figure 27 represents the average shading signal each month in a year. In general, there are little shading in winter, but on the other hand when shading do occur the windows are completely shaded resulting in more need for space heating and artificial lighting. This reasoning can be applied for summer months as well because it might be some days when 100% shading is not wanted.

Figure 27 – Sun and Schedule Control Strategy, average shading signal per month in Big office 2 & Recreation room 1

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Figure 28 – Sun and Schedule Control strategy, daylight level (lx) in Big office 2 and Recreation room 1

Figure 28 gives the average daylight level at the desktop for each room and city. The Recreation room 1 in Stockholm receives most daylight of all rooms in all scenarios. However, in comparison to the Always Off strategy the Big office 2 gets slightly more daylight than Big Office 2 in Stockholm and Malmö. Although, the windows in Big Office 2 are more active in all scenarios, the Recreation room 1 would still receive most average daylight throughout the simulation period. Furthermore, Malmö has the poorest average daylighting of all the scenarios (see table 18).

Table 18 - Sun and Schedule Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 275 343 286 323 187 298

min 23 22 27 25 32 30

max 697 904 676 773 450 878

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6.2.5 Solar Control

The Solar control strategy reacts when the solar radiation on the window surface is above 150 W/m2,

300 W/m2 and 450 W/m2, which gives 33,33 % 66,67% and 100% shading respectively. This section explores the shading signal throughout the year, and at peak heating and cooling demand.

Appendix B - Solar Control Strategy contains the various graphs of the shading signal and the daylight level at the desktop, for each city during the year. In this strategy, the shading signal is the same for both rooms, even though they have different locations. The graphs of the shading signal are shaped as a triangle which is due to the three-shading state. The windows are mostly 33,33% shaded at some point during the day in January-April and October-December, thereafter the windows turn to 66,67% and 100% shading between May and September. However, the windows are fully clear at peak heating day in all scenarios. At peak cooling day the windows in Stockholm and Malmö are completely shaded from 07:00 to 19:00 and semi shaded during 05:00-07:00 and 20:00-21:00. The windows start approximately one hour earlier and withdrawn one hour later in Umeå.

Figure 29 illustrates the average shading signal per month during a year. Umeå has most shading throughout the year, with 1/3 of shading for six months, compared to Stockholm and Malmö which have 4 months of average shading. The average shading during the other months is very low, which makes sense as the sun is not up for as long, and thus less solar intensity.

Figure 29 – Solar Control Strategy, average shading signal per month in Big office 2 & Recreation room 1

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Figure 30 provides the average daylight level (lx) at desktop, for each month and city. In this strategy the average lux level has drastically decreased compared to the previous strategy. This is because of the operation hours; the Sun and Schedule Strategy has lower threshold but operates only during office hours, while this strategy can be active throughout the day. Umeå is the city with most daylight, followed by Stockholm and Malmö that slightly differ (see table 19).

Figure 30 - Solar Control strategy, daylight level (lx) in Big office 2 and Recreation room 1

Table 19 - Solar control strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 119 114 142 146 108 112

min 25 24 30 28 40 34

max 166 159 223 219 162 175

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6.2.6 Daylight Control

The Daylight control strategy controls the windows via natural illuminance, where the threshold is set to 500 lx. This section focuses on the shading signal throughout the year, and at peak heating and cooling demand.

The electrochromic windows in this scenario can obtain any shading state between 0 and 100% due to the PI-controller. The graphs in Appendix B - Daylight Control Strategy shows that the windows in both rooms are almost fully shaded at some point during the day throughout the year for all scenarios. This seems realistic as the lux level is at least 500 lx, which correspond to the given threshold for the window to become activated. Although, the rooms have identical shading signal, the lux levels are still differing. As mentioned before, this is mainly because of the windows position. It should be noted that Big office 2 and Recreation Room 1 have both electrochromic windows and small conventional windows. Thus, the room have slightly higher lux level. In Appendix B – Daylight Control Strategy graphs, the peaks (above 500lx) are caused by the conventional windows.

The windows are semi shaded to fully shaded for a short time period during some days in winter. In addition, at peak heating day the windows in Stockholm are 50 % shaded from approximately 11:30 to 13:30. This may be beneficial from an indoor environment point of view, because the sunlight is bright enough to turn the windows into semi shading and might thereby preventing from glare. Umeå and Malmö has neglectable shading. In contrary the windows are most of the time activated during summer months. At peak cooling day, all the cities have almost fully activated windows throughout the day from 06:00-20:00 where the windows are semi shaded during 12:00-16:00. This is optimal from an energy efficient and indoor environment standpoint.

Figure 31 presents the average shading signal of the Daylight Control strategy. The graph shows that the average shading signals during Jan-Feb and Nov-Dec are more or less neglectable as it has very little impact.

Figure 31 - Daylight Control Strategy, average shading signal per month in Big office 2 & Recreation room 1

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Figure 32 - Daylight Control Strategy, daylight level (lx) in Big office 2 and Recreation room 1

Umeå has most average daylight during the year followed by Stockholm and Malmö (see figure 32 and table 20). Unlike the previous scenario, receives Big office 2 more daylight than the Recreation room 1 in all locations. Also, the average lux level is very similar to the Solar Control Strategy.

Table 20 - Daylight Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 128 119 144 140 116 116

min 20 19 28 27 32 28

max 208 197 226 220 202 200

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6.2.7 Operative Temperature Control

The Operative Temperature Control strategy activates the windows when the operative temperature exceeds 22,5°C during the schedule time. This section analyses the shading signal by looking at the shading throughout the year and during peak heating and cooling demand.

Appendix B – Operative Temperature Control provides various graphs of the shading signal and daylight level for each location. The shading signal is the same for both rooms in all scenarios. The graphs show that the windows are in general, fully shaded at some point during May to August, while withdrawn in the other moths. This seems realistic as the temperature setpoint is 22,5°C, which usually occur during summer months.

Figure 33 gives the average shading signal per month and city. As previous mentioned, the shading signal is only active during summer, the other months are neglectable. It is remarkable, that Malmö located in South of Sweden has least shading, which is defined by the operative temperature.

Figure 33 - Operative Temperature Control Strategy, average shading signal during a year

Figure 34 illustrate the daylight level (lx) at the desktop for each month and city. The Recreation room 1 in Umeå has most daylighting throughout the year, followed by Stockholm and Malmö. However, Malmö has the highest peak daylighting which occur during May and July (see table 21). Moreover, the peak value in all the scenarios are above 500 lux which would most likely causing glare at the workplace.

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Figure 34 – Operative Temperature Control Strategy, daylight level (lx) in Big office 2 and Recreation room 1

Table 21 - Daylight Control Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Room Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 224 249 261 284 207 263

min 33 33 33 31 50 41

max 601 562 586 625 540 649

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6.2.8 Schedule, Façade and Window

The Schedule, Façade and Window strategy activates the windows if the façade receives at least 50 W/m2 of direct radiation. The windows turn to 50% of shading if the surface of the glass receives more than 225 W/m2, while 100% shading occur at 450 W/m2 of global radiation. However, shading occurs only from 15th of March to 1st of October. This section analyses the shading signal by looking at the shading throughout the year and during peak heating and cooling demand.

Appendix B – Schedule, Façade and Window contains the graphs of the shading signal and daylight level for each city. In this scenario, the shading signal slightly differ between the rooms. Furthermore, the graphs show that the windows are semi shaded to fully shaded from March to October. Thus, the windows are completely clear at peak heating day, and most of the cold months. The opposite occurs during warmer months with higher solar intensity. At peak cooling day, the windows are semi shaded in the morning and evening, while completely shaded in the middle of the day. This strategy seems to be the most optimal solution as it allows solar gain during cold months for passive heating, while blocking solar heat during warmer months. Also, the windows are not activated in cloudy days.

Figure 35 represent the average shading signal per month and city. The figure shows the schedule months where the windows are shaded. Generally, the Recreation room 1 has slightly more shading than the Big office 2.

Figure 35 – Schedule, Façade and Window Strategy, average shading signal during a year

Figure 36 provides the average daylight level (lx) at desktop, for each month and city. The Recreation room 1 in Umeå has most daylighting throughout the year, followed by Stockholm and Malmö (see table 22). The building in Umeå receives also the highest amount of daylight 420 lx, which is below 500 lx.

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Figure 36 – Schedule, Façade and Window Strategy, daylight level (lx) in Big office 2 and Recreation room 1

Table 22 – Schedule, Façade and Window Strategy, summary of daylight level (lx) in Big office 2 and Recreation room 1

City STOCKHOM UMEÅ MALMÖ

Unit Big office 2

Recreation room 1

Big office 2

Recreation room 1

Big office 2

Recreation room 1

mean 198 199 236 243 193 205

min 34 33 33 31 50 41

max 349 350 408 420 356 385

6.2.9 Comparison between scenarios

This section gives a summary of the various scenarios. Figure 37 shows the average shading signal in Big office 2 and Recreation room 1 during a year. The Always on scenario is most active, followed by Solar Control, Daylight Control, Reference scenario, Sun and Schedule, Operative Temperature Control, Schedule, Façade and Window, and lastly Always Off. Umeå has most shading among the cities, which is due to the weather condition.

Figure 38 represent the average lux level among the scenarios. The Always Off scenario receives the highest amount of daylight, then Sun and Schedule, Operative Temperature Control, Reference, Schedule, Façade and Window, Solar Control, Daylight Control, and Always On least. However, those scenario with most lux level will most likely suffer from glare. In general, the Recreation room 1 has maximum daylight, where Umeå and Stockholm shifting between the first place, while Malmö has least lux level in all scenarios. This shows that the DF do not correlate with lux level.

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Figure 37 - Average shading signal in Big office 2 and Recreation room 1 during a year

Figure 38 - Average daylight level in Big office 2 and Recreation room 1 during a year

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6.3 Cost analysis This section provides a cost analysis of the electrochromic windows. Since this study has not been able to get in touch with any glass manufacturer, there is a lack of specific costs. Generalization and assumption has thereby been taken to make this assessment feasible. Thus, the study gives only an indication of what the cost of electrochromic window might be in this project.

The cost analysis consists of two scenarios to cover different situations. In scenario 1; the building is already equipped with conventional windows and motorized awnings, but the property manager considers replacing these with electrochromic windows. In scenario 2; the building is not developed yet, and investigation is carry out whether the building should have conventional windows with motorized awnings or electrochromic windows.

General data for both scenarios

The general investment cost for electrochromic windows are assumed to be in the range between 4 510 and 9 020 kr/m2. The costs of electrochromic windows rely on manufacture, application, as well as the size of the project [71] [72] [73]. The power requirement for electrochromic windows is assumed to be neglectable. This is due to the fact, that the manufacturer of SageGlass claims that it takes less electricity to operate 186 m2 of SageGlass than it does to power a single 60-watt light bulb [74]. The lifetime of electrochromic windows is estimated to be at least 30 years [5]. Table 23 represents the total cost for electrochromic windows.

Table 23 – Total cost for electrochromic window

Electrochromic window scenarios

Price Total cost

Cheap version 4 510 kr/m2 184 733 kr

Expansive version 9 020 kr/m2 369 466 kr

The cost for fuel heating is estimated to 1,79 kr/kWh in all cities [75]. The electricity costs are assumed to be fixed in each city [76];

0,8831 kr/kWh (Stockholm) 0,8875 kr/kWh (Umeå) 0,8953 kr/kWh (Malmö)

Scenario 1 – Replacement of conventional windows and motorized awnings?

Figure 39 shows the savings in each scenario and city during the simulation period. The biggest savings occur in Umeå, where the Always Off strategy followed by Operative Temperature Control, and Schedule, Façade and Window saves most energy and thus cut the energy costs. Figure 40 presents the time it would take to break even with the investment cost. This is a simplification since this method is based on the simulation period, and do not consider e.g. value of money or projection of energy prices. None of these scenarios seems attractive as the payback time is too long. The Operative Control scenario is at the end of its lifetime except in Umeå, while the Always off strategy may have been interesting to further investigate, but since the scenario failed to fulfil the Miljöbyggnad criteria it can be neglected.

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Figure 39 – Total saving of each electrochromic window scenario compared to the Reference scenarios

Figure 40 - Simple payback of the electrochromic window scenarios (cheap version electrochromic windows)

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Scenario 2 – Electrochromic window or conventional window?

The conventional window is assumed to cost 990 kr/m2 [77]. The motorized awnings used in this study reacts on both solar intensity and the schedule file. Thus, the chosen awnings have some additional technologies such as SOMFY’s engine (radiomotor) and their solar & wind sensor (Sol & Vindautomatik) [78]. The awnings for Open offices are assumed to cost 11618 kr/per room, and 10060 kr/ per room for Recreation rooms and Big offices [79]. The lifetime of the motorized blind is estimated to 20 years [80]. Table 24 shows the total cost of conventional windows and awnings

Table 24 – Total cost for windows and motorized awnings

Reference scenario

Price Total Cost

Triple pane glazing 990 kr/m2 40 550 kr

Large blind 10 060 kr/piece 40 240 kr

Small blind 11 618 kr/piece 46 472 kr

127 262 kr

Figure 41 - Simple payback time, the time it would take for ECW to break even with CW + motorized awnings. This is based on the cheap version ECW

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Figure 41 presents the time it would take for electrochromic windows to break even with conventional windows and motorized awnings. The electrochromic windows might be interesting, as it would take approximately 10 years for Operative Temperature Control, and Schedule, Façade and Window to break even. The electrochromic windows would thereafter save around 5 400 - 7 900 kr per year. This would give a total saving between 108 000 – 158 000 kr, since the lifetime of the windows are at least 30 years. However, this is a very rough cost estimation. As previously mentioned, this cost assessment does not consider the value of money or projection of energy prices. The building’s energy consumption is based on the simulation period, and thus assumed to have the same energy use and energy prices throughout the years. The energy consumption in reality would vary from year to year due to local climate. More accurate cost estimation would be needed to take any decision, but this can give an indication of the potential of electrochromic windows. It is also noteworthy to optimize the control strategy since they will determine the impact of electrochromic windows. It should be further mentioned, that the reference scenario in Malmö is RATED, while the electrochromic window scenarios attains BRONZE certificate, except the Always Off- and Always On strategies.

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7 Discussion

This chapter summarize and discuss the obtain results, which is the foundation for the conclusions.

EQUA has developed an input module for the use of Miljöbyggnad certification system. This module facilitates the assessment of the building performance through a default setup with the correct settings in the software [81]. This tool would probably have given a more accurate evaluation. The module would also contribute with time saving, as IDA ICE would only require different input values for the building in order to calculate the building's grade as well as the individual rating of the indicators.

Smart windows technologies have not yet been developed in IDA ICE version 4.7.1. To imitate these type of shading properties requires deep knowledge in both the software and the technologies. Due to this, the results of this study may not be accurate enough to represent electrochromic window, but may instead provide an indication of its characteristics.

The results obtained for the simulations show that the electrochromic windows have little impact on the performance of the building. None of the scenarios have succeeded in getting a higher building grade than BRONZE, which corresponds to the government's requirement for newly built buildings. However, the electrochromic windows have a significant effect on the amount of solar heat that the building gets. They also have an influence on the building’s energy consumption, where control strategies with least shading provide best energy savings and vice versa. The results for heating power demand, thermal climate and daylight were almost the same among the scenarios. Yet, the study shows that electrochromic windows have major impact on the lux level in the rooms. However, it does not determine if the daylighting is good in the scenarios since Miljöbyggnad is using the DF method. This study may provide an indication of the daylight level in the scenarios. The Swedish Work Environment Authority can be used as a guideline to get some perspective. The general illuminance for normal office work should be around 300 lx and 500 lx at the desk [68].

The Reference scenario has BRONZE certificate in Stockholm and Umeå, but does not meet the requirements in Umeå, as the building gets too much solar heat. It is also noteworthy that the building has GOLD rating in daylight, since the DF is determined under a CIE Overcast Sky. The average lux level is 220, with an average maximum of 387 lx.

The Daylight Control strategy is the most dynamic algorithm as it can obtain any shading state between 0 % and 100 %. The strategy fulfils the criteria in all cities, where it has the biggest impact on solar heat load (GOLD rating in all cities). This scenario attains the same rating in energy use as the reference scenario, but it decreases the energy consumption slightly, with an average energy savings of 1 443 kr per year. The average lux level is around 125 lx, with an average maximum daylight level of 209 lx.

The Solar Control strategy has three shading states, and thus the second most dynamic algorithm. This strategy is very similar to Daylight control. The strategies have the same gradings, except the energy use indicator, where Solar Control is upgraded by one level in Umeå. The average energy savings end up at 1 598 kr per year compared to the reference scenario. The average lux level is also 125 lx, but with a maximum lux level at 184 lx.

The Operative Temperature Control strategy meet the criteria in all cities. This scenario is most attractive from an economic point of view as it has the second lowest energy usage. The average energy saving is 6 333 kr compared to the reference scenarios. This control strategy manages to upgrade the energy use indicator, and solar heat load indicator by one level compared to the Reference scenario. Nevertheless, it is not optimal to control the windows with operative temperature, as the windows may be shaded on cloudy or rainy days, which is not beneficial from an illuminance perspective. A disadvantage is that

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the control strategy only has one shading level. A higher threshold would exceed the acceptable level of solar heat load, and there is no need to use a lower threshold for semi shading as the given operative temperature is already low. The average lux level is 248, with an average maximum lux of 594. Glare might occur in this scenario.

The Schedule, Façade and Window strategy has an average energy savings of 5 703 kr compared to the reference scenario. This control strategy has slightly higher energy consumption than Operative Temperature Control. However, the strategies attain the same ratings except the solar heat load indicator in Stockholm where the Schedule, Façade and Window strategy has BRONZE. Yet, this control strategy is more dynamic as it has semi shading as well. The windows operate during a longer period since it can be activated from March to October throughout the day, while the Operative Temperature Control strategy is only activated during 08:00 – 17:00 given that the temperature is above the threshold. The average lux level is 212 lx, and the average maximum level is 378 lx.

The Sun and Schedule strategy has the same ratings as the Schedule, Façade and Window strategy. However, the energy demand is slightly higher. The average energy saving is 3 622 kr compared to the reference scenario. The strategy has an average lux level of 285 and an average maximum level about 730 lx. The occupants might have problem with glare.

The Always Off strategy has too much solar heat to meet the requirements in Stockholm and Umeå. However, the building has the lowest energy demand of all scenarios. The average savings in this strategy amounts to 9 132 kr during the simulation period. The location plays a crucial role in this scenario since Malmö is certified. The strategy certainly has glare problems because the average lux level is 432, and the average maximum level ends up at 1 078 lx.

The Always On strategy is RATED in all cities, because of its poor performance in daylight indicator. Its energy use is the highest among scenarios because the building is barely exposed to daylight and solar heat, which leads to more artificial lighting and fuel heating. In addition, the building consumes more energy compared to the reference scenario. The average daylight is 55 lx, with a maximum level around 104 lx, which is extremely low.

The cost analysis is based on generalizations and assumptions, due to lack of specific costs. However, the cost analysis gave an indication that, if the building has well-functioning windows and awnings, it is not cost-effective to switch to electrochromic windows, since the payback time is far too long. But if the building was between conventional windows and electrochromic windows during the planning phase, it might be interesting to conduct a detailed cost analysis. According to this study, the Operative Temperature Control strategy saves approximately 6 333kr per year. The cost differences between conventional windows with awnings, and the cheap version of electrochromic windows is around 60 000kr. This would provide a refund within 10 years, given that energy prices, energy consumption and currency value are the same. After that, the window would cut the energy costs in the form of saved energy.

However, electrochromic windows are not considered necessary in this project, as the building grade remain the same and the economic gain is uncertain. A life-cycle cost analysis should be conducted to get the total cost of ownership. Furthermore, the local climate has minor impact on the electrochromic windows in this study. As mentioned before, this is because the electrochromic windows have significant influence on solar heat load in buildings. This confirms previous studies claiming that electrochromic windows have the greatest potential for energy savings in hot climate.

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8 Conclusions

This chapter presents the final conclusions of the thesis, as well as future remarks

The thesis aims at examining the effect of an office building model with conventional windows and motorized awnings, compared to electrochromic windows with different control strategies. The building is simulated in eight different scenarios in Stockholm, Umeå and Malmö. The Swedish Building Certification System “Miljöbyggnad” is used to evaluate energy use, heating power demand, solar heat load, thermal climate and daylight. The results show that electrochromic windows have little impact on the building. In fact, none of the scenarios succeed in getting higher than BRONZE certificates, which is the minimum requirement for newly built buildings. However, the study shows that electrochromic windows have a significant effect on the solar heat load, and some influence on the building’s energy use. The electrochromic windows are thereby most active during summer when overheating occur. Furthermore, the study shows that there is hardly any difference between the building in different cities. This confirms previous studies claiming that electrochromic windows have the greatest potential for energy savings in hot climate. Furthermore, the cost for electrochromic windows remains uncertain as no specific costs has been found. However, electrochromic windows have poor prospect for reducing the energy costs as the solar radiation is limited in Sweden. The study concludes that electrochromic windows are not necessary in this project as the building grade remains the same and the economic gain is uncertain.

8.1 Future work and Limitations This study shows that there are major differences in lux level among the scenarios, but it does not determine if the daylighting is appropriate in the scenarios. This is because The DF used in Miljöbyggnad is not intended to evaluate whether the daylighting in a room is good, but to determine if the room meets the minimum requirement. It would be interesting for future work to investigate the electrochromic window’s impact on daylight. This should include the level of outlook without any obstacle that preventing the view as well as glare. However, there is no glare feature in IDA ICE yet.

It would be also interesting to explore the impact of electrochromic windows in different office design and building geometry e.g. by changing the orientation, size and number of windows, number of floor plans, and the design of the office rooms.

As this study is based on generalization and simplifications such as ideal heater and cooler, it would be interesting to conduct a study on an existing building. The simulation model would thus become more realistic, as the model would have the right components and settings such as HVAC system, equipment, lighting systems and their locations. This would provide a more precise result of thermal climate, energy use and thus costs. This applies to electrochromic windows as well. It would be good to collaborate with a smart glass manufacturer where both parties benefit. They would have access to research materials based on their product, while the project would have access to technical features and specific costs. They would probably also assist with appropriate shading strategies to balance energy efficiency and indoor environment. A life-cycle cost analysis could be then performed to determine the total cost of ownership.

Lastly, as the smart glass market is predicted to grow, it would be a necessity for IDA ICE to establish a module for smart window simulations to obtain reliable results. This should also include the most common control strategies to make the simulation seamless and fast.

- 63 -

9 Bibliography

[1] U.S. Green Building Council USGBC, “http://www.usgbc.org/about,” [Online]. [Accessed 08 12 2016].

[2] M. Böruhan, M. odlare, P. Stigson, W. Fredrik and V. Iana, “Buildings in the future energy system - Perspective of the Swedish energy and buildings sectors on current energy challenges,” Elsevier, Västerås, 2015.

[3] D. Hening, “Naturvårdsverket,” 15 09 2017. [Online]. Available: http://www.naturvardsverket.se/Miljoarbete-i-samhallet/Miljoarbete-i-Sverige/Uppdelat-efter-omrade/Energi/Energieffektivisering/Bostader-och-lokaler/. [Accessed 12 November 2017].

[4] Glass for Europe, “The Smart use of glass in sutainable buildings”.

[5] M. Casini, “Smart windows for energy efficiency of buildings,” Institute of Research Engineers and Doctors, USA, 2015.

[6] Efficient Windows Collaborative, “Windows for high-performance commercial buildings,” 20 02 2015. [Online]. Available: http://www.commercialwindows.org/about.php. [Accessed 20 02 2017].

[7] R. Baetens, B. P. Jelle and A. Gustavsen, “Properties, Requirements and Possibilities of Smart Windows for Dynamic Daylight and Solar Energy Control in Buildings: State-of-the-Art,” Elsevier, 2009.

[8] M. Ferrara and M. Bengisu, Materials that Change Color: Smart Materials, Intelligent Design, Milano: Springer Cham Heidelberg New York Dordecht London, 2014, p. 34.

[9] B. P. Jelle, A. Hynd, A. Gustavsen, D. Arasteh, H. Goudey and R. Hart, “Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities,” Elsevier, 2012.

[10]

R. Baetens, J. P. Björn and G. Arild, “Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the art review,” Elsevier Ltd, 2009.

[11]

Sweden Green Building Council (SGBC), “Miljöbyggnad - a Swedish certification that cares about People and the Environment,” Sweden Green Building Council (SGBC), 2014.

[12]

EQUA Simulation AB, “User Manual - IDA Indoor Climate and Energy, Version 4,5,” EQUA Simulation AB, 2013.

[13]

O. Onyebuchi, “Energy Heat Balance for Buildings, A Review Analysis,” INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH, Umudike, 2013.

[14]

Fondriest Environmental, “Fondriest Environmental,” [Online]. Available: http://www.fondriest.com/environmental-measurements/parameters/weather/photosynthetically-active-radiation/. [Accessed 06 03 2017].

[15]

“memorang,” [Online]. Available: https://www.memorangapp.com/flashcards/128084/Light%2C+Particles%2C+and+Waves%3A+Atomic+and+Molecular+Structure/. [Accessed 17 November 2017].

- 64 -

[16]

Physical Geography, “Physical Geography,” [Online]. Available: http://www.physicalgeography.net/fundamentals/7f.html. [Accessed 07 03 2017].

[17]

M. Günther, “Advanced CSP Teaching Materials,” enerMENA.

[18]

A. S. Workshop, “Autodesk Sustainability Workshop,” [Online]. Available: https://sustainabilityworkshop.autodesk.com/buildings/building-envelope. [Accessed 05 04 2017].

[19]

J. Hanania, J. Jenden, M. Lasby, D. Paul and P. Ghia, “Energy Education,” University of Calgary, [Online]. Available: http://energyeducation.ca/encyclopedia/Building_envelope. [Accessed 03 06 2017].

[20]

Designing Buildings Wiki, “Designing Buildings Wiki,” 17 07 2016. [Online]. Available: https://www.designingbuildings.co.uk/wiki/Thermal_conductivity. [Accessed 15 06 2017].

[21]

J. Alcock, “TheGreenAge,” 18 06 2013. [Online]. Available: https://www.thegreenage.co.uk/article/thermal-conductivity-r-values-and-u-values-simplified/. [Accessed 15 06 2017].

[22]

SEED ENGINEER, “SEED ENGINEER,” 30 05 2014. [Online]. Available: http://www.seedengr.com/Blog/?author=1. [Accessed 15 06 2017].

[23]

U. Janson, “Passive houses in Sweden, Experience from design and construction phase,” KFS AB, Lund, 2008.

[24]

Reichel Insulation, “Reichel Insulation,” [Online]. Available: http://www.reichelinsulation.com/Understanding-The-Building-Envelope.html. [Accessed 15 06 2017].

[25]

Autodesk Sustainability Workshop, “ Autodesk Sustainability Workshop,” 2017. [Online]. Available: https://sustainabilityworkshop.autodesk.com/buildings/building-envelope. [Accessed 14 06 2017].

[26]

Save Energy Plus, “Save Energy Plus,” 06 09 2015. [Online]. Available: http://www.saveenergyplus.com.au/energy-efficiency-presentations/. [Accessed 20 03 2017].

[27]

University of Siegen, “University of Siegen,” [Online]. Available: http://nesa1.uni-siegen.de/wwwextern/idea/keytopic/3.htm. [Accessed 16 06 2017].

[28]

Sil to Sash, “Sil to Sash,” [Online]. Available: http://www.silltosash.com/windows/basic-window-terminology/sash-and-frames/. [Accessed 27 06 2017].

[29]

Rob Levesque, “HomeStyleChoices.com,” [Online]. Available: http://www.home-style-choices.com/window-construction.html#materials. [Accessed 29 06 2017].

[30]

Designing Buildings Wiki, “Designing Buildings Wiki,” 26 11 2016. [Online]. Available: https://www.designingbuildings.co.uk/wiki/Heat_transfer_in_buildings. [Accessed 10 03 2017].

[31]

R. Kent, “Tangram Technology,” 1999. [Online]. Available: http://www.tangram.co.uk/TI-Polymer-Plastic&Composite_Windows.html. [Accessed 09 03 2017].

[32]

WBDG Whole Building Design Guide, “WBDG,” [Online]. Available: https://www.wbdg.org/resources/windows-and-glazing. [Accessed 23 02 2017].

- 65 -

[33]

IQ GLASS, Modern Architectural Glazing, “IQ GLASS,” [Online]. Available: https://www.iqglassuk.com/technical/heat-gain-and-g-factor/1480/. [Accessed 23 02 2017].

[34]

ES-SO European Solar Shading Organization, “ES-SO,” [Online]. Available: http://www.es-so.com/component/content/category/179-solar-shading-benefits. [Accessed 23 02 2017].

[35]

Autodesk® Sustainability Workshop, “Autodesk® Sustainability Workshop,” [Online]. Available: https://sustainabilityworkshop.autodesk.com/buildings/glazing-properties. [Accessed 23 02 2017].

[36]

ENERGY. GOV, “ENERGY. GOV,” U.S Department of Energy, [Online]. Available: https://energy.gov/energysaver/window-types. [Accessed 28 06 2017].

[37]

The U.S. Department of Energy, “Spectrally Selective Glazings - A well proven window technology to reduce energy costs while enhancing daylight and view,” U.S. Department of Energy, 1998.

[38]

Efficient Windows Collaborative (EWC), “Windows for high-performance commercial buildings,” 29 06 2015. [Online]. Available: http://www.commercialwindows.org/reflective.php. [Accessed 29 06 2017].

[39]

NanoMarkets, “Smart Windows Markets 2012,” Virginia, 2012.

[40]

Pier Public Interest Energy Research, “Advancement of Electrochromic Windows,” 2006.

[41]

L. Zhengrong, J. Junling and X. Weipeng, “ScienceDirect,” 07 10 2015. [Online]. Available: http://ac.els-cdn.com/S1877705815027423/1-s2.0-S1877705815027423-main.pdf?_tid=6183d58e-0979-11e7-b806-00000aab0f6c&acdnat=1489580439_261a85ef276042fcd4629b78df53bf6b. [Accessed 15 03 2017].

[42]

E. Lee, M. Yazdanian and S. Selkowitz, “The Energy-savings Potential of Electrochromic Windows in the US Commercial Building Sector,” California, 2004.

[43]

F. Tavares, R. A. Gaspar, G. A. Martins and F. Frontini, “Evaluation of electrochromic windows impact in the energy performance of buildings in Mediterranean climates,” Elsevier Ltd, 2014.

[44]

M. Assimakopoulos, A. Tsangrassoulis and M. G. G. Santamouris, “Comparing the energy performance of an electrochromic window under various control strategies,” Elsevier Ltd, 2006.

[45]

A. Jonsson and A. Roos, “Evaluation of control strategies for different smart window combinations using computer simulations,” Elsevier Ltd, Uppsala, 2009.

[46]

GSA Public Building Service , “Electrochromic and Thermochromic Windows,” Denver, 2014.

[47]

R. Sullivan, E. Lee, K. Papamichael, M. Rubin and S. Selkowitz, “Effect of Switching Control Strategies On The Energy Performance Of Electrochromic Windows,” California, 1994.

[48]

L. N. Sbar, L. Podbelski, M. H. Yang and B. Pease, “Electrochromic dynamic windows for office buildings,” Elsevier Ltd, 2012.

[49]

E. Lee, E. Claybaugh and M. LaFrance, “End user impacts of automated electrochromic windows in a pilot retrofit application,” 06 12 2011. [Online]. Available: http://ac.els-

- 66 -

cdn.com.focus.lib.kth.se/S0378778811005986/1-s2.0-S0378778811005986-main.pdf?_tid=d18e37ec-08c1-11e7-a908-00000aacb35e&acdnat=1489501599_2b97f375b16fb9877913413324528df9. [Accessed 14 03 2017].

[50]

J. Mäkitalo, “Simulating control strategies of electrochromic windows,” 2013.

[51]

H. Reynisson, “Energy Performance of Dynamic Windows in Different Climates,” KTH, Stockholm, 2015.

[52]

Y. Al horr, M. Arif, M. Katafygiotou, A. Mazroei, A. Kaushik and E. Elsarrag, “Impact of indoor environmental quality on occupant well-being and comfort: A review of the literature,” Elsevier, 2016.

[53]

H. Havtun and P. Bohadanowicz, Sustainable Energy Utilisation, Fourth edition. First printing ed., Stockholm: KTH Energy Technology, 2014.

[54]

Designing Buildings Wiki, “Designing Buildings Wiki,” 08 07 2014. [Online]. Available: https://www.designingbuildings.co.uk/wiki/Predicted_mean_vote. [Accessed 05 04 2017].

[55]

World Green Building Council, “World Green Building Council,” [Online]. Available: http://www.worldgbc.org/our-mission . [Accessed 30 05 2017].

[56]

Sweden Green Bulding Council, “Miljöbyggnad Metodik nyproducerade och befintliga byggnader Manual 2.2 141001,” ©Sweden Green Building Council, 2014.

[57]

Boverket, “Boverket´s building regulations – mandatory provisionsand general recommendations, BBR,” 2016.

[58]

Sweden Green Building Council, “Miljöbyggnad Bedömningskriterier för nyproducerade byggnader,” ©Sweden Green Building Council, 2017.

[59]

Sweden Green Building Council, “Sweden Green Building Council,” [Online]. Available: https://www.sgbc.se/om-breeam-se-meny. [Accessed 30 05 2017].

[60]

Sweden Green Building Council, “Sweden Green Building Council,” [Online]. Available: https://www.sgbc.se/certifiering-i-leed. [Accessed 30 05 2017].

[61]

Sweden Green Building Council, “Sweden Green Building Council,” [Online]. Available: https://www.sgbc.se/om-greenbuilding. [Accessed 30 05 2017].

[62]

MADE-BY, “MADE-BY,” [Online]. Available: http://www.made-by.org/consultancy/standards/nordic-swan/. [Accessed 21 06 2017].

[63]

Svanen, “Svanen,” [Online]. Available: http://www.svanen.se/Documents/FAQ/FAQ_Svanenmarkta_hus_kosument.pdf . [Accessed 21 06 2017].

[64]

EQUA, “EQUA,” [Online]. Available: http://www.equa.se/en/ida-ice. [Accessed 02 02 2017].

[65]

K. Hilliaho, J. Lahdensivu and V. Juha, “Glazed space thermal simulation with IDA-ICE 4.61software — Suitability analysis with case study,” Elsevier, 2014.

- 67 -

[66]

Autodesk® Sustainability Workshop, “Autodesk® Sustainability Workshop,” [Online]. Available: https://sustainabilityworkshop.autodesk.com/buildings/infiltration-moisture-control. [Accessed 13 10 2017].

[67]

Sveby, “Sveby Branchstandard för energi byggnader, Brukarindata kontor,” Stockholm, 2009.

[68]

Arbetsmiljöverket, “Arbetsmiljöverket,” 01 07 2016. [Online]. Available: https://www.av.se/inomhusmiljo/ljus-och-belysning/belysning-pa-kontor/. [Accessed 24 10 2017].

[69]

Arbetsmiljöverket, “Arbetsmiljöverket,” 01 07 2015. [Online]. Available: https://www.av.se/inomhusmiljo/temperatur-och-klimat/?hl=temperatur. [Accessed 13 10 2017].

[70]

C. F. Reinhart and K. Voss, “Monitoring manual control of electric lighting and blinds,” National Research Council Canada, 2003.

[71]

Allan R. Hoffman, “Thoughts of a Lapsed Physicist - Perspectives on energy and water technologies and policy,” 2014. [Online]. Available: http://www.lapsedphysicist.org/2014/03/16/electrochromic-windows-we-need-to-get-the-costs-down/. [Accessed 14 November 2017].

[72]

E. Vaughan, “modernize,” 2016. [Online]. Available: https://modernize.com/home-ideas/32437/smart-windows-cost. [Accessed 14 November 2017].

[73]

S. Lacey, “Greentech Media,” 2013. [Online]. Available: https://www.greentechmedia.com/articles/read/will-smart-glass-ever-be-more-than-a-boutique-product#gs.8RkcQoA. [Accessed 14 November 2017].

[74]

SageGlass, “SageGlass,” [Online]. Available: https://www.sageglass.com/faqs. [Accessed 13 11 2017].

[75]

Värmepumpsguide, “Värmepumpsguide,” [Online]. Available: http://xn--vrmepumpsguiden-0kb.se/pris-per-kwh-bergvarme-luftvatten-och-andra-uppvarmningsformer/. [Accessed 13 11 2017].

[76]

Kundkraft, “Kundkraft,” 2017. [Online]. Available: https://www.kundkraft.se/elpriser/jamfor. [Accessed 13 11 2017].

[77]

GlasNet AB, “GlasNet AB,” 2017. [Online]. Available: http://www.glasnet.nu/isolerglas-1368465. [Accessed 15 November 2017].

[78]

Markisrea.se, “Markisrea,” 2017. [Online]. Available: http://markisrea.se/automatik.html#radio. [Accessed 15 November 2017].

[79]

Markisrea.se, “Markisrea.se,” 2017. [Online]. Available: http://markisrea.se/prisma.html. [Accessed 15 November 2017].

[80]

Sol & Skugga, “Sol & Skugga,” 2017. [Online]. Available: http://www.solochskugga.se/vanliga-fragor. [Accessed 15 November 2017].

[81]

EQUA, “Miljöbyggnadsmodul i IDA ICE,” EQUA, Stockholm, 2015.

- 68 -

- 69 -

10 Appendix A This section provides the results from each scenario, which are graded according to Miljöbyggnad certification system.

Figure 42 - Overview of the scenarios grading in each city

STRATEGY INDICATOR STOCKHOLM UMEÅ MALMÖ

Energy use BRONZE SILVER BRONZE

Heating power demand SILVER SILVER GOLD

Solar heat load BRONZE RATED BRONZE

ENERGY GRADE BRONZE RATED BRONZE

Thermal climate BRONZE BRONZE BRONZE

Daylight GOLD GOLD GOLD

INDOOR ENVIRONMENT SILVER SILVER SILVER

Energy use BRONZE SILVER BRONZE

Heating power demand GOLD SILVER GOLD

Solar heat load GOLD GOLD GOLD

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use BRONZE GOLD BRONZE

Heating power demand GOLD SILVER GOLD

Solar heat load GOLD GOLD GOLD

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use SILVER GOLD SILVER

Heating power demand GOLD SILVER GOLD

Solar heat load BRONZE SILVER SILVER

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use SILVER GOLD SILVER

Heating power demand GOLD SILVER GOLD

Solar heat load SILVER SILVER SILVER

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use SILVER GOLD SILVER

Heating power demand GOLD SILVER GOLD

Solar heat load BRONZE SILVER SILVER

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use SILVER GOLD SILVER

Heating power demand GOLD SILVER GOLD

Solar heat load RATED RATED SILVER

ENERGY GRADE RATED RATED SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight SILVER SILVER SILVER

INDOOR ENVIRONMENT BRONZE BRONZE BRONZE

Energy use BRONZE SILVER BRONZE

Heating power demand GOLD SILVER GOLD

Solar heat load GOLD GOLD GOLD

ENERGY GRADE SILVER SILVER SILVER

Thermal climate BRONZE BRONZE BRONZE

Daylight RATED RATED RATED

INDOOR ENVIRONMENT RATED RATED RATED

BUILDING GRADE

BUILDING GRADE

BUILDING GRADE

BUILDING GRADE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

RATED

BRONZE BRONZE BRONZE

SOLA

R CONTROL

OPERATIVE TEM

P. CONT.

SUN AND SCH

EDULE

ALW

AYS OFF

ALW

AYS ON

BRONZE RATED

BRONZE BRONZE

BRONZE BRONZE

BRONZEBRONZE

BRONZE BRONZE

RATED RATED

RATED RATED

Schedule, Facade and 

Window

BUILDING GRADE

BUILDING GRADE

BUILDING GRADE

BUILDING GRADE

REFEREN

CEDAYLIGHT CO

NTR

OL

- 70 -

Figure 43 – Miljöbyggnad grading of each scenario in Stockholm

Indica

tor

Reference

Daylig

ht C

ontrol 

Solar  C

ontrol

Schedule, Fa

cade and 

Window

Operativ

e Te

mp. C

ontro

lSun a

nd Sch

edule

 Always O

ffAlways O

n

Electric co

oling

2.3

2.3

2.3

2.3

2.3

2.3

2.6

2.3

HVAC aux

5.0

5.0

5.0

5.0

5.0

5.0

5.0

5.0

Fuel h

eatin

g50.7

49.4

49.1

46.2

45.9

47.2

43.0

50.8

Dom

estic h

ot w

ater

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

Energy

 use  [k

Wh/m

2]

65.1

63.8

63.5

60.6

60.3

61.6

57.7

65.2

Heatin

g power d

emand  P

 [W/m

2]

25.52

24.65

24.65

24.65

24.65

24.65

24.65

24.65

HEATING POWER DEMAND RATING

SILV

ER

GOLD

GOLD

GOLD

GOLD

GOLD

GOLD

GOLD

Solar h

eat lo

ad [w

/m2]

39.91

16.19

14.71

38.38

37.61

38.81

40.23

14.68

Majority o

f the ro

om's a

rea

BRONZE

GOLD

GOLD

BRONZE

SILVER

BRONZE

BRONZE

GOLD

Worst‐R

oom with

 EC window

 [w/m

2]

N/A

16.19

14.71

38.38

37.61

38.78

40.23

14.68

Worst‐R

oom w/o E

C wind

ow [w

/m2]

39.91

13.53

13.52

13.54

13.55

13.50

13.53

13.52

Critica

l rooms

Recre

ation ro

om 1‐2

Big office 1

‐2Big office

  1‐2

Recre

ation

 room 1‐2

Big office

 1‐2

Big office

 1‐2

Big office

 1‐2

Big o

ffice 1‐2

SOLA

R HEAT LO

AD RATING

BRONZE

GOLD

GOLD

BRONZE

SILVER

BRONZE

RATED

GOLD

Themal clim

ate [P

PD%]

11.34

11.34

11.34

11.34

11.34

11.34

11.34

11.34

Worst‐R

oom with

 ECW always o

n [P

PD%]

N/A

11.00

10.98

10.91

10.91

10.92

10.91

11.05

Worst‐R

oom w/o EC

 window

 [ PPD%]

11.34

11.34

11.34

11.34

11.34

11.34

11.34

11.34

Majority o

f rooms' a

rea

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

Critica

l room

Office

 7, 12

Office 1

2Office

 7, 12

Office

 7, 13

Office

 7,  1

2Office

 7,12

Office

 7, 12

Office

 7,12

Daylight [D

F %]

1.15

1.13

1.13

1.13

1.13

1.13

1.13

0.00

Worst‐R

oom with

 ECW always o

ff [DF %

]N/A

1.13

1.13

1.13

1.13

1.13

1.13

N/A

Worst‐R

oom

 w/o ECW [D

F %]

1.15

1.15

1.15

1.15

1.15

1.15

1.15

1.15

Majority o

f the ro

om's are

aGOLD

SILVER

SILVER

SILVER

SILVER

SILVER

SILVER

RATED

Critica

l room

Meetin

g ro

om 1

Recre

atio

n roo

m 1

Recre

atio

n room 1

Recrea

tion ro

om 2

Recrea

tion ro

om 1

Recre

ation

 room 1

All ro

oms w

ith EC

WALL  EC

W

ST

OC

KH

OL

M

POWER DEMAND RATING

ENER

GY GRADE

THERMAL C

LIMATE W

INTER & SUMMER RATIN

GBRONZE

SILVER

SILVER

ENERGY USE RATING

BRONZE

BRONZE

BRONZE

BRONZE

DALIG

HT R

ATING

GOLD

SILV

ER

SILV

ER

SILVER

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

SILVER

IND

OO

R E

NV

IRO

NM

EN

T G

RA

DE

BUILD

ING GRADE

BRONZE

BRONZE

BRONZE

SILVER

BRONZE

SILVER

BRONZE

SILVER

BRONZE

BRONZE

BRONZE

GOLD

BRONZE

GOLD

SILVER

SILVER

SILV

ERSILV

ERBRONZE

BRONZE

SILVER

SILVER

SILVER

RATED

SILVER

GOLD

RATED

SILV

ER

SILV

ERSILV

ER

RATED

RATED

BRONZE

BRONZE

BRONZE

RATED

RATED

- 71 -

Figure 44 - Miljöbyggnad grading of each scenario in Umeå

Indicator

Reference

Dayligh

t Control

Solar  Control

Schedule, Faca

de and 

Wind

owOperative T

emp. Con

trolSun and Sched

ule Always O

ffAlways O

n

Electric cooling2.2

2.22.2

2.22.2

2.22.5

2.2

HVAC au

x5.0

5.05.0

5.05.0

5.05.0

5.0

Fuel heating

64.863.9

63.1

59.7

58.360.9

56.0

65.0

Domestic hot w

ater7.1

7.17.1

7.17.1

7.17.1

7.1

Energ

y use  [kW

h/m

2]79.1

78.2

77.4

74.0

72.675.2

70.6

79.3

Heatin

g power d

emand  P

 [W/m

2]52.0

751.13

51.13

51.1351.13

51.13

51.13

51.13

HEA

TING POWER

 DEM

AND RATING

SILVER

SILVER

SILV

ERSILV

ERSILV

ERSILV

ERSILV

ERSILV

ER

Solar h

eat lo

ad [w

/m2]

41. 25

26.05

26.18

37.8039.95

34.96

42.92

26.38

Majority of the

 room's area

BRONZE

GOLD

GOLD

SILVER

SILVER

SILVER

BRONZE

GOLD

Worst‐R

oom

 with EC

 window

 [w/m

2]N/A

11.99

14.73

37.8039.95

34.96

42.90

14.71

Worst‐R

oom w/o EC

 window

  [w/m

2]41.5

326.05

26.18

25.9626.16

25.96

26.15

25.93

Critical room

sBig office

s 1‐2Offices 3

,4,9,10Offices 3

,4,9,10Big office

s 1‐2Big offices 1‐2

Big offices 1‐2

Big office

s 1‐2Offices 3

,4,9,10

SOLA

R HEA

T LOAD RATIN

GRATED

GOLD

GOLD

SILVER

SILVER

SILVER

RATED

GOLD

Them

al climate

 [PPD%]

13.80

13.02

13.01

13.0113.01

13.01

13.01

12.82

Majority  of the room

's area

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

Worst‐R

oom with

 EC window

 PPD%

N/A

13.00

13.01

13.0113.01

13.01

13.01

12.82

Worst‐R

oom w/o EC

 window

 PPD%

13.80

12.00

12.00

11.9911.57

12.00

12.00

11.99

Critical roo

mOpen offices 3

‐4Open

 offices 3‐4Open

 offices 3‐4Open o

ffices 3‐4

Open offices 3‐4

Open

 offices 3‐4Open o

ffices 3‐4

Open

 offices 3‐4

Dayligh

t [DF %

]1.15

1.13

1.13

1.13

1.131.13

1.13

0.00

Worst‐R

oom

 with EC

W alw

ays off [DF %

]N/A

1.13

1.13

1.13

1.131.13

1.13

N/A

Worst‐R

oom w/o EC

 window

 [DF %

]1.15

1.15

1.15

1.15

1.151.15

1.15

1.15

Majority of the

 room's area

GOLD

SILVER

SILVER

SILVER

SILVER

SILVER

SILVER

RATED

Critical roo

mMeeting ro

om 1

Recreatio

n room 1

Recrea

tion room 1

Recreatio

n room 1

Recre

ation room 1

Recre

ation room 1

All room

s with E

CW

ALL EC

W

IND

OO

R E

NV

IRO

NM

EN

T G

RA

DE

SILVER

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

RATED

BRONZE

BRONZE

BRONZE

SILVER

SILVER

RATED

RATED

RATED

BRONZE

SILVER

RATED

SILVER

RATED

BUILD

ING GRADE

SILVER

SILVER

SILV

ERSILV

ER

GOLD

GOLD

GOLD

BRONZE

BRONZE

BRONZE

RATED

BRONZE

BRONZE

BRONZE

ENER

GY U

SE RATIN

G

POWER

 DEM

AND RATIN

G

ENER

GY GRADE

RATED

SILVER

SILVER

SILVER

SILV

ERSILV

ER

SILVER

SILV

ER

SILVER

SILVER

BRONZE

SILVER

BRONZE

DAYLIG

HT R

ATIN

GGOLD

THERMAL CLIM

ATE W

INTER

 & SUMMER

 RATIN

GBRONZE

RATED

SILVER

SILVER

GOLD

GOLD

SILVER

UM

EÅ

- 72 -

Figure 45 - Miljöbyggnad grading of each scenario in Malmö

Indica

tor

Reference

Daylight Co

ntro

lSolar  con

trolSch

edule, Fa

cade an

d 

Window

Opreativ

e Te

mp. C

ontro

lSun

 and Sche

dule 

Always O

ffAlways O

n

Electric coo

ling

2.6

2.6

2.6

2.6

2.6

2.6

2.72.6

HVAC au

x5.0

5.0

5.0

5.0

5.0

5.0

5.05.0

Fuel h

eatin

g43.9

42.5

42.6

39.3

39.1

40.9

37.3

44.1

Dom

estic h

ot wate

r7.1

7.1

7.1

7.1

7.1

7.1

7.17.1

Energy use  [kW

h/m

2]

58.6

57.2

57.3

54.0

53.8

55.6

52.1

58.8

Heatin

g power d

emand  P

 [W/m

2]22.52

21.96

21.96

21.96

21.96

21.96

21.9

621.96

HEA

TING POWER

 DEM

AND RATING

GOLD

GOLD

GOLD

GOLD

GOLD

GOLD

GOLD

GOLD

Solar h

eat lo

ad [w

/m2]

36.31

18.81

18.56

33.06

33.06

36.88

37.0

318.76

Majority o

f the ro

om's a

reaBRONZE

GOLD

GOLD

SILVER

SILVER

SILVER

SILVER

GOLD

Worst‐R

oom with

 EC window [w

/m2]

N/A

15.71

12.54

33.06

33.06

36.88

37.0

212.47

Worst‐R

oom w/o EC  window [w

/m2]

36.35

18.81

18.56

18.80

18.27

26.37

18.4

418.38

Critica

l rooms

Big office

s 1‐2

Office

s 3,4,9,10

Office

s 3,4,9,10

Big office

 1‐2

Big office

s 1‐2

Big office

s 1‐2

Big office

s 1‐2Office

s 3,4,9,10

SOLA

R HEAT LO

AD RATING

BRONZE

GOLD

GOLD

SILV

ER

SILV

ER

SILV

ER

SILV

ER

GOLD

Themal clim

ate [P

PD%]

11.69

11.62

11.59

11.61

11.59

11.59

11.6

011.59

Majority  o

f the ro

om's a

reaBRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

Worst‐R

oom

 with

 EC wind

ow PPD%

N/A

11.32

11.30

11.25

11.26

11.32

11.2

611.37

Worst‐R

oom

 w/o EC wind

ow PPD%

11.69

11.62

11.59

11.61

11.59

11.59

11.6

011.59

Critica

l room

Open o

ffice 3‐4

Office

 7,12

Office 7

,12

Office

s  7,12

Office

 7,  1

2Office

 7, 12

Office

 7, O

ffice 12

Office 7

, Office

 12

Daylight [D

F %]

1.15

1.13

1.13

1.13

1.13

1.13

1.13

0.00

Worst‐R

oom with E

CW always off o

r blinds [D

F%]

N/A

1.13

1.13

1.13

1.13

1.13

1.13

N/A

Worst‐R

oom w/o E

CW [D

F %]

1.15

1.15

1.15

1.15

1.15

1.15

1.15

1.15

Majority o

f room are

aGOLD

SILVER

SILVER

SILVER

SILVER

SILVER

SILVER

RATED

Critica

l room

Meetin

g roo

m 1

Recrea

tion ro

om 1

Recrea

tion ro

om 1

Recre

atio

n roo

m 1

Recre

atio

n roo

m 1

Recre

atio

n ro

om 1

All roo

ms w

ith ECW

ALL E

CW

BRONZE

BRONZE

RATED

RATED

BRONZE

BRONZE

BRONZE

BRONZE

BRONZE

SILVER

SILVER

SILV

ER

SILV

ER

SILV

ER

SILV

ER

SILV

ER

SILV

ER

I ND

OO

R E

NV

IRO

NM

EN

T G

RA

DE

SILVER

THER

MAL C

LIMATE

 WINTER

 & SUMMER RATIN

GBRONZE

BRONZE

BRONZE

ENER

GY U

SE R

ATIN

GBRONZE

BRONZE

BRONZE

SILV

ER

POWER

 DEM

AND RATING

SILVER

GOLD

GOLD

SILV

ER

BRONZE

BRONZE

DAYLIG

HT RATING

GOLD

SILV

ER

SILV

ER

SILV

ER

BRONZE

SILV

ER

SILV

ER

SILV

ER

SILVER

BRONZE

BRONZE

GOLD

SILVER

ENER

GY GRADE

BRONZE

SILVER

SILVER

BUILD

ING GRADE

BRONZE

BRONZE

BRONZE

BRONZE

SILVER

BRONZE

BRONZE

BRONZE

RATED

MALM

Ö

- 73 -

11 Appendix B This section consists of shading signal graphs, and daylight level graphs, for each scenario and city.

Sun and Schedule Control Strategy

Figure 46 –Sun and Schedule, shading signal in Stockholm

Figure 47 - Sun and Schedule, shading signal in Umeå

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

- 74 -

Figure 48 - Sun and Schedule, shading signal in Malmö

Figure 49 - Sun and Schedule, daylight level in Stockholm

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31 Lux

0.0·10 4

0.2·10 4

0.4·10 4

0.6·10 4

0.8·10 4

1.0·10 4

1.2·10 4

1.4·10 4

1.6·10 4

1.8·10 4

2.0·10 4

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 75 -

Figure 50 - Sun and Schedule, daylight level in Umeå

Figure 51 - Sun and Schedule, daylight level in Malmö

From 2017-01-01 to 2017-12-31 Lux

0·10 3

2·10 3

4·10 3

6·10 3

8·10 3

10·10 3

12·10 3

14·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

2·10 3

4·10 3

6·10 3

8·10 3

10·10 3

12·10 3

14·10 3

16·10 3

18·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 76 -

Solar Control Strategy

Figure 52 – Solar Control, shading signal in Stockholm

Figure 53 - Solar Control, shading signal in Umeå

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

- 77 -

Figure 54 – Solar Control, shading signal in Malmö

Figure 55 - Solar Control daylight level in Stockholm- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

From 2017-01-01 to 2017-12-31 Lux

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 78 -

Figure 56 - Solar Control daylight level in Umeå- Big office 2(red) and Recreation room 1(green)

Figure 57 - Solar Control daylight level in Malmö- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

1·10 3

2·10 3

3·10 3

4·10 3

5·10 3

6·10 3

7·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

From 2017-01-01 to 2017-12-31 Lux

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 79 -

Daylight Control Strategy

Figure 58 - Daylight Control, Shading signal in Stockholm

Figure 59 - Daylight Control, Shading signal in Umeå

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

- 80 -

Figure 60 - Daylight Control, shading signal in Malmö

Figure 61 - Daylight Control, daylight level in Stockholm- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

From 2017-01-01 to 2017-12-31 Lux

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 81 -

Figure 62 - Daylight Control, daylight level in Umeå, Big office 2(red) and Recreation room 1(green)

Figure 63 - Figure 36 - Daylight Control, daylight level in Malmö, Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

1·10 3

2·10 3

3·10 3

4·10 3

5·10 3

6·10 3

7·10 3

8·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

From 2017-01-01 to 2017-12-31 Lux

0

50

100

150

200

250

300

350

400

450

500

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 82 -

Operative Temperature Control Strategy

Figure 64 - Operative Temperature Control, shading signal in Stockholm

Figure 65 - Operative Temperature Control, shading signal in Umeå

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

- 83 -

Figure 66 - Operative Temperature Control, shading signal in Umeå

Figure 67 – Operative Temperature Control, daylight level in Stockholm- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31 Lux

0·10 3

2·10 3

4·10 3

6·10 3

8·10 3

10·10 3

12·10 3

14·10 3

16·10 3

18·10 3

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 84 -

Figure 68 - Operative Temperature Control, daylight level in Umeå- Big office 2(red) and Recreation room 1(green)

Figure 69 - Operative Temperature Control, daylight level in Malmö- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

2·10 3

4·10 3

6·10 3

8·10 3

10·10 3

12·10 3

14·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

2·10 3

4·10 3

6·10 3

8·10 3

10·10 3

12·10 3

14·10 3

16·10 3

18·10 3

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 85 -

Schedule, Façade and Window Strategy

Figure 70 – Schedule, Façade and Window, shading signal in Stockholm

Figure 71 - Schedule, Façade and Window, shading signal in Umeå

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

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1.0

- 86 -

Figure 72 - Schedule, Façade and Window, shading signal in Malmö

Figure 73 - Schedule, Façade and Window, daylight level in Stockholm- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31

Window Big office 2.Wall 4.Window Window_1.Shading control, dimlessWindow Recreation room 1.Wall 7.Window Window_2.Shading control, dimless (Recreation room 1)

0 1000 2000 3000 4000 5000 6000 7000 8000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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From 2017-01-01 to 2017-12-31 Lux

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Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

- 87 -

Figure 74 – Schedule, Façade and Window, daylight level in Umeå- Big office 2(red) and Recreation room 1(green)

Figure 75 - Schedule, Façade and Window, daylight level in Malmö- Big office 2(red) and Recreation room 1(green)

From 2017-01-01 to 2017-12-31 Lux

0·10 3

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)

From 2017-01-01 to 2017-12-31 Lux

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daylight at desktop (at first occupant), lxDaylight at desktop (at first occupant), lx (Recreation room 1)