Post on 07-May-2018
Wooden passive holiday house for Lapland. Design principles andenergy simulation
Iina ValkeisenmäkiResearch AssistantAalto University,School of Science andTechnology,Department ofArchitectureFinland
iina.valkeisenmaki@tkk.fi
Minna JokirantaResearch AssistantAalto University,School of Science andTechnology,Department of EnergyTechnologyFinland
minna.jokiranta@optiplan.fi
Extended Abstract
The design of the passive house is part of the research project “Sustainable Tourism Destinations– Land Use, Architecture and Energy (MATKA)”. The pilot location of the research is a futureholiday area in the ski resort of Ylläs, where the principles are tested in practice. Ylläs is situated inthe municipality of Kolari, approximately 100 kilometres north of the Arctic Circle.
The purpose of the house design is to develop a building concept that could be built in the pilotarea in Ylläs, based on principles of sustainability. Passive house was selected as the target forenergy efficiency, whereas wood was chosen as the building material for its environmentalperformance and role as a traditional material for buildings in Lapland. The model house is a semidetached holiday house that has two apartments of 100 square meters each, in two floors. Itcontains three bedrooms, kitchen, living room, bathroom and a sauna heated by wood.
This research examines the possibilities to reach the passive house standard for a holiday home inthe extremely cold arctic climate of the Finnish Lapland. In order to reach the passive house target,architectural and technical solutions were investigated and applied to the model passive housebuilding. Thermal comfort was examined through simulating the maximum summertimetemperature in order to define whether overheating is a challenge for passive houses in Lapland.The impacts of structural solutions such as window blinds and awnings on controlling the indoortemperature were also investigated.
After the development of the concept, the design of the model house was simulated by using theyearly climatic data of Ylläs. The tools used were the dynamic simulation tool Ida Ice 4.0 and thecalculation method D5 of the Finnish building code. As for the passive house target, a localdefinition published by the Finnish Association of Civil Engineers “RIL” was used. Other localdefinitions are also discussed and the results are compared in this paper.
The results of the simulation prove that it is possible to build passive houses in a ski resort inLapland, when aiming at the RIL definition for passive houses, although the requirements areextremely demanding. The results and the success to reach the target demand greatly on technicalsolutions that should be optimised in order to reach the results.
Architectural qualities of the house, such as orientation, size of windows and building shape alsoaffected the calculation results. Architectural form of the passive house should respond to twoopposing design challenges. In the heating period, maximum solar irradiation is needed to lowerthe supplementary heating load, whereas overheating poses a threat to extremely insulatedhouses in the summertime. Adjusting the orientation and size of windows are a main tool inaddressing these challenges; windows permit solar irradiation to enter the building during the
heating period but also cause the overheating challenges. This also emphasizes the critical role ofwindows.
Summertime overheating was confirmed to be a major challenge, even in the Arctic. With the helpof window blinds and opening of the windows, the maximum temperature of the house is 26.4 °C,while without them the maximum temperature is 31 °C.
Optimal results for the heating energy demand were obtained with a water radiator heat system,32,8 kWh/m²a. Consequently, the energy efficiency number for a house with water radiator is 60kWh/m²a, resulting in energy class A.
The capacity utilisation figures of Ylläs show that, when built, the passive house would not beoccupied continuously. When the house is occupied, the indoor air temperature has been set torange from 17°C to 22°C, depending on the spaces. The temperature should be lowered duringunoccupied times in order to not use energy to heat empty spaces. In the simulations, 10°C hasbeen set to the indoor temperature of an unoccupied house. During unoccupied times, the houseconsumes approximately half of the heating than when occupied
Yearly climatic data also effects the calculation of heating energy consumption. The heating energyconsumption of a house with radiator heating is 27.9 kWh/m²a when calculated with 2004 climaticdata, while being 31.6 kWh/m²a when calculated with 1979 data. With the ongoing climate change,years are likely to resemble the 2004 weather more than that of 1979. However, the use of the1979 data is justified in order to design the systems for temperature extremities.
Both technical and architectural solutions need to support the energy efficiency objective andprovide adequate thermal comfort. Design choices, such as window area, orientation and buildingshape, have a direct impact on the energy consumption and indoor air temperature. Summertimeoverheating can and should be prevented nonmechanically, by adding window blinds andoperable windows. They can also form a distinctive part of the aesthetics of a passive house.
It is essential for architects to understand the effects that their design choices have on the energyefficiency of a building, yet the information is not yet easily available. Because the energyefficiency topic has only recently entered public discussion, the design practice has not yetprioritised its principles. There is also a considerable need for informative material on the affectsthat individual design choices have on the overall energy consumption of the building.
Being a highly ambitious target, planning a passive house for a cold climate location like Ylläsrequires expertise from its designers. Moreover, a new level of cooperation between architects andenergy engineers is needed to ensure energy efficiency, optimal thermal performance and a highquality of building.
Wooden passive holiday house for Lapland. Design principles andenergy simulation
Iina ValkeisenmäkiResearch AssistantAalto University,School of Science andTechnology,Department ofArchitectureFinland
iina.valkeisenmaki@tkk.fi
Minna JokirantaResearch AssistantAalto University,School of Science andTechnology,Department of EnergyTechnologyFinland
minna.jokiranta@optiplan.fi
Summary
This research examines the possibilities to reach the passive house standard for a holiday home inthe extremely cold arctic climate of the Finnish Lapland. In order to reach the passive house target,architectural and technical solutions were investigated and applied to a model passive housebuilding, which was located in the ski resort of Ylläs. Thermal comfort was examined throughsimulating the maximum summertime temperature, in order to define whether overheating is achallenge for passive houses in Lapland. The impacts of structural solutions such as window blindsand awnings on controlling the indoor temperature were also investigated .
After the development of the concept, the design of the model house was simulated by using theyearly climatic data of Ylläs. The tools used were the dynamic simulation tool Ida Ice and thecalculation method D5 of the Finnish building code. As for the passive house target, a localdefinition made by the Finnish Association of Civil Engineers was used. Other local definitions arealso discussed and the results are compared in this paper.
The results of this research project prove that it is possible to build passive houses in a ski resort inLapland, according to the RIL definition for passive houses, although the requirements areextremely demanding. The results and the success to reach the target demand greatly on technicalsolutions, which should be optimised in order to reach the results. Therefore it is extremelyimportant that energy engineers and architects work closely together already in a draft phase of theproject.
Keywords: passive house, energy efficiency, energy simulation, Lapland, cold climate, tourismdestination, overheating prevention, building service solutions
1. Introduction
To increase the energy efficiency of a society and to fight the climate change, improving the energyefficiency of buildings offers significant opportunities. In Finland, The Government foresight reporton climate and energy policy sets the target to improve the efficiency of energy use in buildings sothat consumption is at least 30 per cent lower in 2030, 45 per cent lower in 2040 and 60 per centlower in 2050 than in 2009 [1]. Ministry of the Environment has demanded all new buildings thatwill be built by the state administration to be passive houses in 2015 [2]. In addition to the officialpolicies, the market value of passive houses has also been noticed and several companies selling
prefabricated passive houses are starting to emerge.
This research examines the possibilities to reach the passive house standard for a holiday home inthe extremely cold arctic climate of the Finnish Lapland. It is part of a research project “SustainableTourism Destinations – Land Use, Architecture and Energy (MATKA)”, which investigatessustainable solutions for Nordic tourism destinations in terms of land use planning, energy systemsand architecture.
In addition to analysing energy efficiency objective, this paper investigates what kind of impact thefollowing design choices have on the energy consumption of the model building:
Shape of the building Orientation of the building Window size Heating system choice
In order to reach the passive house target, architectural and technical solutions were investigatedand applied to a model passive house building, which was located in the ski resort of Ylläs.Thermal comfort was examined through simulating the maximum summertime temperature, todefine whether overheating is a challenge for passive houses in Lapland. It was also investigatedwhat kind of impacts structural solutions such as window blinds and awnings have on controllingthe indoor temperature.
After the development of the concept, the design of the model house was simulated by using theyearly climatic data of nearby Sodankylä. The tools used were dynamic simulation tool Ida Ice andthe calculation method D5 of the Finnish building code. As for the passive house target, a localdefinition made by the Finnish Association of Civil Engineers was used. [3] Other local definitionsare also discussed and the results are compared together.
Simulation with climatic data from different years is compared to define what kind of impacts thewarming climate have on the energy simulation results. User’s role in controlling the indoortemperature is discussed in conjunction with the role of the buildings in holiday resorts. The yearlycapacity utilisation was also analysed in order to define the optimal heating system and heatenergy consumption.
2. Local Passive house solutions
Up to present date, there is very little research and education on passive houses in Finland. Thecountry lacks an official local standard for passive houses, and different variations and opinionscan be found. Expertise on building them is extremely rare, and only a handful of architects andengineers have received any education on how to plan them.
Nieminen et al have concluded that the Central European definition for a passive house is notviable, nor are the experiences of building passive houses in Central Europe directly applicable toNordic climates. The concepts demonstrated in Central Europe do not fulfil the heating energydemand in Finland. Therefore, both a local definition and local solutions are needed. [4]
There are currently two overlapping and competing definitions. The first definition was published bythe Technical Research Centre of Finland VTT and was created as a part of the Promotion ofPassive Houses in Europe PEP Project. Its requirement for the heating energy demand is 2030kWh/m2a, depending on the location of the house. Primary energy demand should be within 120140 kWh/m2a. Requirement for air tightness n50 is the same as in the original Passivhaus, 0.6 1/h.[5]
Another local definition for passive houses has been described in a low energy building guide bythe Finnish Association of Civil Engineers “RIL”. It gives passive houses a requirement for theirheating energy demand, whereas other values are given as recommendations. The heating energydemand also varies by the location of the house and is converted by given conversion factors. The
basic heating energy demand 25 kWh/m2a is given for Central Finland, with conversion factors of0.9 for South Finland and 1.33 for North Finland. [3]
The question of selecting the appropriate passive house definition is not simple. Nieminen et alcriticise the Finnish Association of Civil Engineers definition by claiming that it "tries to flatten thedefinition as one class of the energy certificate and forgets two other criteria, which have addedessential demands of energy and quality of construction".[6] However, the use of primary energy isvery problematic at the moment; Finland is one of the only countries in Europe where officialprimary energy factors have not been defined yet. Some conversion factors have been calculated,for example the energy factors of the ongoing “KesEn Sustainable Energy” research project,conducted by Aalto University, School of Science and Technology in 20082010 [7 ]. Theseconversion factors have been used in this research to unofficially estimate the primary energydemand.
The two main definitions of passive houses in Finland have slightly different values for passivehouses in Northern Finland. They both divide the country to three different areas based on theirclimate, and allow a higher heating energy demand for the Northern parts of the country. The VTTdefinition gives a maximum heating energy demand of 30 kWh/m2a, [5] whereas the RIL guide hasan upper limit of 33.25 kWh/m2a. [3]
Thus, the process of developing the passive house concept in Finland is ongoing. This researchhas decided to use the definition of RIL, as it is the latest framework for low energy building inFinland. The publication of their guide also involved a large group of professionals and is thereforewidely supported in the field. [3]
2.1 Local climatic solutions
Currently, experiences of building passive houses in a climate as cold as that in Ylläs areextremely limited. The first passive house to be built above the Arctic Circle is about to be finishedin Rovaniemi, but due to the recent building, there are no user experiences of the building.
The Technical Research Centre of Finland VTT has conducted research on passive houses byusing two pilot projects: one in Vantaa and one in Valkeakoski. Its results show that it is possible toreach the Finnish passive house standard developed by VTT. The RIL definition is slightly lessstrict than that of VTT and is therefore also fulfilled.
However, the location of Ylläs is much further north than those of Vantaa and Valkeakoski. Thedimensioning temperatures for heating energy demands are 26 °C for South Finland, 29 … 32°C for Central Finland and 38 °C for Lapland [8]. Therefore, aiming at a passive house in Laplandis a much higher standard than in South Finland and can meet different specific challenges due tothe extremely cold climate.
In Finland, the building code requires using the climatic data of 1979 in the energy calculations,and the data of Sodankylä is applied to buildings in Northern Finland. In addition to the 1979 data,this research has analysed the data from years 2001 to 2008 in order to compare the calculationsto warming climate. The average year based on the analysis was 2004, which has thus beencompared to the 1979 climate.
In addition to the demands for the insulation, the location of the house sets some demands for thearchitectural design of the house. Throughout the year, sun shines from the low elevations ofmaximum of 46 degrees. Being above the Arctic Circle, Ylläs experiences a vast contrast ofdaylight conditions that range from the darkness of midwinter, when the sun does not rise abovethe horizon, to the abundance of daylight of midsummer, when the sun does not set for weeks. Thesun also shines from the north in summer, which gives special demands for the orientation.
When houses in Lapland are designed for passive heating gains and overheat prevention, thisdifference of climate and solar angles must be taken into account. Orientation of windows and the
Fig. 1 The capacity utilisation of commercial rooms inYlläs, years 20012009. Different months areindicated with numbers. Average yearly utilisation isshown with the black line. (Image source: RegionalCouncil of Lapland)
use of shading need to be adjusted to local conditions. The benefit of passive heating gains bysouth facing windows is questionable, as the sun does not rise at all during peak heating demand.One can argue that large windows can cause more challenges than benefits; there may be moreheat losses than heat gains and, together with extreme insulation adapted for the arctic climate,large window area is a probable cause to severe overheating challenges during summer.
2.2 User's role in holiday housing
The topic of building passive houses in a holiday resort raises some specific questions andchallenges. How can the user's role in operating a passive holiday house be minimized, yetoffering adequate control of thermal conditions? Is it recommendable to build massive fireplaces,even at the risk of misuse and overheating?
Approximately 30 % of visitors to Ylläs are from overseas [9]. Part of the leisure homes of Ylläs areprivately owned and used by the same owners, while several are commercially rented on a weeklyor nightly base. Hotel owners have reported problems from the use of fireplaces; yet the customerswish to have them in the holiday apartments. [10] The thermal comfort and operation, controlledfrom the inside of the apartment, should be mistakeproof. Technical facilities should be accessedfrom the outside of the apartment, leaving the control to the maintenance crew.
In addition to the challenges inoperating the house appliances, thecapacity utilisation of holiday homesgives a special characteristic to theleisure homes of tourist destinations. InYlläs, the capacity utilisation variesgreatly by the season. The busiestseasons are around Easter, Christmasand the period of autumn colours inSeptember, whereas the quietest times
of the year are May and October. (Fig. 1)The vast differences in capacityutilisation have a major impact on theyearly heating energy demand of abuilding, but yet the Finnish buildingcode suggests that a leisure buildingused year round is treated as a normal
single family house in the heating energy demand calculation. This research calculates the heatingenergy demand according to the building code.
Despite the obvious shortcomings of energy calculations according to the building code, thecharacteristics of capacity utilisation should be taken into account when designing buildings for use.
3. Model Passive House
The Model passive house wasdeveloped from an existing holidayhouse, which gave this project thefloor plan and sizes for different roomspaces. It was then adjusted in orderto become more energy efficient
The model house is a semidetachedhouse that has two identicalapartments, both the size of 100 m²for their floor space. Living room,
Fig. 2 The U values of the buildingelements in the model passive house
kitchen, bathroom and sauna are situated downstairs, whereas three bedrooms are locatedupstairs.
The model house is placed in Ylläs, a ski resort located in the municipality of Kolari in the FinnishLapland and the pilot area for the MATKA Project. It is located approximately 100 kilometres Northof the Arctic Circle and 820 kilometres North of Helsinki. I
4. Design Solutions
Several architectural design choices contribute to building’s energy efficiency. These includebuilding orientation, building shape, roof type and inclination, area of glazed façade. In addition toenergy efficiency, architectural design should aim at thermal comfort and a pleasant microclimateboth inside and outside the house.
It has been stated that, as regards the heating energy needs of a building, the most significantfactors are the building’s glazed façade area, which had the considerably highest contribution toenergy consumption, and building shape, which had a smaller but yet an important contribution.[11]
The building was developed in order to reach the passive house standard of RIL, the FinnishAssociation of Civil Engineers. The structural, technical and architectural design solutions aimed atmaximising energy efficiency and thermal comfort of the house. After these adjustments, the housewas simulated using yearly climatic data of Ylläs.
4.1 Building and structural solutions
The compactness of the reference building was evaluated with its shape coefficient Cf, calculatedas the ratio between the outside surface area of building construction and the external volume ofheated space in the building.
There has been scientific proof that there is a linear correlation relating the energy consumption tothe shape coefficient Cf, which is emphasised in places with a cold climate [12]. The shape of themodel building was consists of two full floors, with an angled roof. Its shape coefficient is 0,81.
With regard to structural solutions, the modelpassive house of this research project usesstructures of an existing passive house in Finland,in order for the results to be comparable withexisting passive houses. The structures wereobtained from passive house “Paroc Lupaus”,designed by architect Kimmo Lylykangas, whichwas completed in Valkeakoski in 2009 (House
website at http://www.energiaviisastalo.fi/?cat=Pilottikohteet&id=101).
4.2 Internal heat gains
Internal heat gains have been decided to be located so that the most intensive ones will be in themiddle of the building. This provides even distribution of heat, avoiding excess heating. Free airspace in front of the fireplace has been maximised to even out the heat load.
The fireplace should be as massive as possible, so that it will distribute heat evenly. A lightfireplace or a stove gives too high thermal peak for a passive house, which raises the indoortemperature to be too high. [13]
In addition to the fireplace, internal heat gains consist of lighting, electrical equipment and
Building element Heat transfer coefficient,U value [W/m²K]
External wall 0.09Roof 0.07Floor 0.06Window 0.70Door 0.60
Fig. 3 Monthly heating energy demand in the modelpassive house, depending on the orientation of thehouse. Left paragraph displays the house with southfacing windows, while the right paragraph displays thehouse with northfacing windows
Fig. 4 The model passive house with blinds preventingsummertime overheating.
occupants of the house. The internal heat gains of occupants have been defined according to thenumber of occupants, which is derived from the number of bedrooms in each apartment andadding one extra person. Thus, the occupant number for the model passive house is eightoccupants per building [3]. 60 % of the energy used in equipment is transferred as heat gains tothe space [8]. This research assumes that the household equipment installed in a passive housemust be energy efficient and therefore the energy uses have been estimated from a recentlycompleted research project. [14 ] The heat gains from lighting are estimated to be 8 W/m²,multiplied with the capacity utilisation rate of 0.1 [15].
4.3 Size and orientation of windows, passive solar heat gains and overheating prevention
Special attention to the size and orientation of windows has been paid in the planning of thepassive house. As the U value is substantially worse in windows than in other building parts, therole of windows in the total heating energy demand of the building is significant. Therefore the sizeof windows needs to be moderate in relation to the floor size; in the model building it is 15 %.
Architectural form of the passivehouse should respond to twoopposing design challenges. In theheating period, maximum solarirradiation is needed to lower thesupplementary heating load,whereas overheating poses a threatto extremely insulated houses in thesummertime. Adjusting theorientation and size of windows area main tool in addressing thesechallenges; windows permit solarirradiation to enter the buildingduring the underheated period butalso cause the overheatingchallenges. This emphasizes thecritical role of windows.
During the heating period, peakdemand occurs when the sun hardlyrises in Ylläs. Therefore theorientation of the house only impactsthe supplementary heating load inspring and autumn, when the sunshines from higher elevations andheating energy is still needed. (Fig. 3)Southfacing windows are beneficialduring the months of February,March, April, September andOctober. Therefore orienting thehouse to face south can berecommended even in the North,given that the summertimeoverheating can be adequatelysolved.
Overheating is a serious problem that occurs especially in houses that are extremely well insulated.The Finnish building code recommends the use of structural means in preventing summertimeoverheating. Canopies, awnings, window blinds, solar control glazing and avoiding large windowsurfaces are mentioned. In addition, the building code recommends using thermal mass and nighttime ventilation whenever possible. [16]
Fig. 5 Section of the passive house, displaying thecontrolled passive heat gains.
The south facing façade of the modelpassive house was fitted withawnings, which prevent the steepangle of the summertime solarirradiation from entering the building,while allowing the low angle of springand autumn sun to enter (Fig 5).External, operable blinds wereinstalled on the east and west facingfacades. During the winter months,they can be drawn permanently onthe side as all solar irradiation iswanted to reduce the supplementaryheating load. During the summer, theblinds are an efficient way to controlthe thermal comfort and preventoverheating. (Fig 4)
In addition to the structural means inoverheating prevention, one must not
forget the importance of ventilation through opening and closing of windows, which is probable thesingle most efficient way for thermal comfort. Temperature limits only apply when the thermalconditions in the spaces at hand are regulated primarily by the occupants, through opening andclosing of the windows. [17]
4.4 Air tightness
The air tightness specification n50 is used to portray air tightness of a building. It describes theamount of air leaking from the house in an hour, compared to the house volume, when there is anunder or over pressure of 50 Pa. The air tightness of a building has a significant impact on theenergy demand. When the air tightness specification n50 grows by one unit, the energy use forheating and air conditioning of a twostorey building increases by 7 % while the total energy useincreases by 4%. [18]
The Finnish building code gives a limit of 4.0 1/h for n50. In present small buildings, 1.0 1/h is anexcellent value, while 3.0 1/h is a normal and 8.0 1/h a weak value [19]. The original definition of apassive house requires the air tightness specification to be less than 0,6 1/h. In the Finnish passivehouse definitions, the same demand can be found in the VTT definition, while the RIL guide onlygives it as a recommendation. In this research, n50 value of 0,6 1/h is used in the calculations andsimulations.
4.5 Technical systems
Building service solutions, heating systems, hot water use and air conditioning have a significantimpact on the heating energy consumption. The parameters of air conditioning have a large impacton the energy efficiency, and attention should be paid to the air flow, supply and exhaust air ratio,annual operating efficiency of air heat recovery and the specific fan power of air conditioning.
When designing a building, it is especially important to pay attention to the sizing an airconditioning system. By planning the air conditioning thoughtfully, one can affect the building’senergy consumption significantly [3]. Air change of 0.35 dm³/s. m² is mainly used for buildings.Outside the utilisation time, when air flow is not needed to for example control humidity, control ofair conditioning can be assigned to reduce the air flow of the apartment to 60 % of utilisation timelevel [20]. In order for the reduction of airflow to be possible, apartments need to be installed withtheir own control of air conditioning. The air conditioning of the passive house was planned to
Fig. 6 The left paragraph displays the energy class andenergy efficiency number of different heating systemsaccording to the Finnish building code. Right paragraphdisplays the total energy use, converted with the energyfactors. 1979 Jyväskylä weather used.
contain an air changes per hour of 0.53 1/h.
According to the Finnish Indoor Climate Classification 2008, exhaust air flows of an apartmentshould be fitted to be 10 % larger than supply air flows [15]. The RIL Guide for low energy buildingsstates that the proportion can be smaller than usual in low energy buildings. Good air tightness ofthe outside surface area enables a reduction of low pressure compared to a normal building, whenthe supply and exhaust air ratio is between 9598 %. [3] With the planned air flows, the supply andexhaust air ratio of the passive house is 98 %.
The effectiveness of heat recovery varies with every building, planning of ventilation and qualitiesof the air handling unit. In North Finland, cold climate presents a challenge to the heat recovery byreducing the effectiveness of heat recovery of air handling unit. In addition, the deicingtemperature needs to be as low as possible. With the air flows planned for the passive house ofthis research, the effectiveness of heat recovery is 75 %.
The specific fan power of mechanical supply and exhaust air system is usually allowed to be amaximum of 2.5 kW/(m²/s), while the specific fan power of mechanical exhaust air system isallowed to be a maximum of 1.0 kW/(m²/s) [20]. A specific fan power of 1.56 kW/(m²/s) is used forthe passive house, which is obtained from the sizing tool for air handling unit, with designedairflows.
5. Results
5.1 Energy efficiency
The energy efficiency of the model passive house has been calculated with both the calculationmethod D5, according to the Finnish building code, and with the dynamic simulation tool Ida Ice.D5 calculation methods were used to determine the energy class of the building, together with the
energy efficiency rating, whichwas then further calculated withthe energy conversion factorsdefined in the KesEn researchproject. (Fig. 6)
The energy efficiency number,when calculated according to thepresent Finnish building code,varies slightly with differentheating systems, while the energyfactors have a significant impacton energy efficiency (Fig. 6)
The primary energy conversionfactors have an impact especiallyon the energy classes of electricheating solutions. Defined by theKesEn research project, theconversion factor for electricheating is 2.0. It has beenassumed that the water heatingsystems are heated with districtheating, whose conversion factoris 0.7. [7]
Heating system Code EnergyFactor
Electric radiator heatingEnergy efficiency number kWh/brm²,a 61 121Energy class A C
Water radiator heatingEnergy efficiency number kWh/brm²,a 60 56Energy class A A
Water floor heatingEnergy efficiency number kWh/brm²,a 67 61Energy class A A
Air heating (electric)Energy efficiency number kWh/brm²,a 66 132Energy class A C
Electric floor heatingEnergy efficiency number kWh/brm²,a 66 132Energy class A C
Fig. 7 Results of the energy efficiency calculations,space heating energy demand with different heatingsystems
Fig. 8 Results of the energy efficiency, depending onclimate and indoor air temperature
The capacity utilisation figures of Ylläs show that, when built, the passive house would not beoccupied continuously. When the house is occupied, the indoor air temperature has been set torange from 17 °C to 22 °C, depending on the spaces. The temperature should be lowered duringunoccupied times in order to not use energy to heat empty spaces. In the simulations, 10 °C hasbeen set to the indoor temperature of an unoccupied house. During unoccupied times, the houseconsumes approximately half of the heating than when occupied (Fig. 8, fourth row).
The impact of the heating system wasinvestigated with the help of the D5calculation method; however, the systemlosses were set to a standard leveldepending on the heating system. Basedon the analysis of the energy factors andheating systems (Fig. 7), water radiatorheating was selected for further research.
The more specific space heatingdemands, calculated in Fig. 8, differslightly from each other depending on thecalculation method. The dynamicsimulation method Ida Ice was used toexamine the impact that the climate hason the results. Heating energyconsumption of a house with radiatorheating is 27.9 kWh/m²a when calculatedwith 2004 climatic data, while being 31.6kWh/m²a when calculated with 1979 data.
In addition to indoor temperature, yearlyclimatic data also effects the calculationof heating energy consumption. Thewarming climate reduces the heatingenergy demand, which is clearly visiblewhen comparing the results of 1979 and2004 together (Fig. 8). [21]
The choice of heating system also has some affect on the calculation results. Distribution losseswere not taken into account in the simulation tool, while they are added to the calculationsaccording to the building code D5 calculation tool. Therefore the results from these two differenttools differ slightly from each other; those of D5 being generally higher. The climatic data ofSodankylä is used for these calculations.
5.2 Thermal comfort and overheating prevention
If there are no window blinds, awnings or possibility for occupants to open the windows, indoortemperature can rise to uncomfortable levels during summer. However, when window blinds areadded and the occupants open the windows, the summertime indoor thermal conditions remainpleasant.
With the help of window blinds and opening of the windows, the maximum temperature of thehouse is 26.4 °C, while without them the maximum temperature is 31 °C.
ParametersYear Weather 1979Indoor air temperature (°C) 21Calculation method Code D5
Heating system kWh/m²,aElectric radiator heating 28.0Water radiator heating 32.8Water floor heating 38.2Air heating (electric) 33.2Electric floor heating 32.6
Parameters ResultsYear Weather, Indoor airtemperature (°C),Calculation method
Water radiatorheating, kWh/m²,a
1979, 21 °C, Code D5 32.81979, 1722 °C, Ida Ice 31.62004, 1722 °C, Ida Ice 27.92004, 10 °C, Ida Ice 14.0
Fig. 8 Maximum summertimetemperature downstairs without anyoverheat prevention
Fig. 9 Maximum summertimetemperature downstairs withwindow blinds, awnings andopening of windows.
Fig. 10 The energy efficiencynumber of different heatingsystems, converted with theenergy factor. 1979 Sodankyläweather was used.
5.3 Passive house according to the VTT definition
The results of the passive house simulation fulfil the primary energy demand defined by VTT, whenradiator heating is used as a heating system. However, the VTT definition for the heating energydemand 30 kWh/m2a could not be reached. (Fig. 10)
6. Conclusions
The results of this research project prove that it is possible to build passive houses in a ski resort inLapland, according to the RIL definition, although the requirements are extremely demanding. Theresults and the success to reach the target demand greatly on technical solutions, which should beoptimised in order to reach the results.
In addition to the different definitions, the choice of year for climatic data used in the calculationsmay have a definitive impact on the result. With the ongoing climate change, years are likely toresemble the 2004 weather more than that of 1979. However, the use of the 1979 data is justifiedin order to design the systems for temperature extremities.
In addition to the technical solutions, architectural solutions need to both support the energyefficiency objective and provide adequate thermal comfort. Design choices, such as window area,
orientation and building shape, have a direct impact onthe energy consumption and indoor air temperature.Summertime overheating can and should be preventednonmechanically, by adding window blinds and operablewindows. They can also form a distinctive part of theaesthetics of a passive house.
It is essential for architects to understand the effects thattheir design choices have on the energy efficiency of abuilding, yet the information is not yet easily available.Because the energy efficiency topic has only recentlyentered public discussion, the design practice has not yet
prioritised its principles. There is also a considerable needfor informative material on the affects that individualdesign choices have on the overall energy consumption ofthe building.
Heating systemEnergy
efficiencynumber
kWh/brm²,aElectric radiatorheating 139Water radiatorheating 63Water floor heating 66Air heating (electric) 155Electric floor heating 148
Being a highly ambitious target, planning a passive house for a cold climate like Ylläs requiresexpertise from its designers. Moreover, a new level of cooperation between architects and energyengineers is needed to ensure energy efficiency, optimal thermal performance and a high quality ofbuilding. Perhaps this aim takes us back to the origins of architecture as a shelter and a provider ofa pleasant microclimate.
[1] Government Foresight Report on Longterm Climate and Energy Policy: Towards aLowcarbon Finland, Government of Finland, 2009
[2] Kestävät julkiset hankinnat, Ministry of the Environment 2009[3] “Matalenergiarakentaminen, asuinrakennukset”, RIL 2492009, Finnish Association of Civil
Engineers, Helsinki, 2009[4] NIEMINEN J, HOLOPAINEN R, LYLYKANGAS K, ”Passive house for a cold climate”,
Nordic Symposium on Building Physics, Conference Proceedings, Copenhagen, 2008[5] NIEMINEN J, “Mikä on passiivitalo”, Technical Research Centre of Finland VTT , (Online),
Available from, http://passiivitalo.vtt.fi/files/mika%20on%20passiivitalo.pdf (Accessed April29 2010)
[6] NIEMINEN J, LYLYKANGAS K, “Mikä on passiivitalo”, (Online), Available from:http://www.passiivi.info/download/passiivitalon_maaritelma.pdf, (Accessed April 29 2010),2009
[7] KURNITSKI J, “Rakennusten energiatehokkuuden osoittaminen kiinteistöveron porrstustavarten”Helsinki University og Technology, Espoo, 2009
[8] “D5 Suomen rakentamismääräyskokoelma. Rakennuksen energiankulutuksen ja lämmitystehontarpeen laskenta”, Ohjeet 2007, Ministry for the Environment, Department of housingand building, Annex 1
[9] Matkailutilastot, (Online), Available from: www.lapinliitto.fi/julkaisut_ja_tilastot/matkailu,Regional Council of Lapland
[10] Interview of Pertti Yliniemi, owner of Lapland Hotels, during hotel visit in Muonio, January27 2010
[11] CAPOZZOLI A, MECHRI H E, CORRADO V, “Impacts of architecturaldesign choices on building energy performance. Applications of uncertainty and sensitivitytechniques”, Conference Proceedings, Eleventh International IBPSA Conference, Glasgow,2009
[12] DEPECKER P, MENEZO C, VIRGONE J, LEPERS S, “Design of buildings shape andenergetic consumption”, Building and Environment, No. 36, 2001, pp. 627635
[13] SAARI M, “Energiatehokkaan talon lämmitysratkaisut. PEP – Promotion of EuropeanPassive Houses”, Conference Proceedings, Intelligent Energy Europe Seminar, Espoo,2006
[14] Kotitalouksien sähkönkäyttö 2006, Tutkimusraportti 2.10.2008, Adato Energia Oy, 2008[15] “Sisäilmastoluokitus 2008” LVI 0510400, Rakennustietosäätiö RTS 2008[16] “D3 Suomen rakentamismääräyskokoelma. Rakennuksen energiatehokkuus”, Määräykset
ja ohjeet 2007, Ministry for the Environment, Department of built environment[17] “Indoor environmental input parameters for design and assessment of energy performance
of buildings addressing indoor air quality, thermal environment, lighting and acoustics”,SFSEN 15251, Suomen Standardisoimisliitto SFS, 2007
[18] VINHA J, “Asuinrakennusten ilmanpitävyys, sisäilmasto ja energiatalous”, TampereenUniversity of Technology, 2009
[19] “Teollisesti valmistettujen asuinrakennusten ilmanpitävyyden laadunvarmistusohje”, RT 8010974, Rakennustieto Oy
[20] “D2 Suomen rakentamismääräyskokoelma. Rakennusten sisäilmasto ja ilmanvaihto”, Määräykset ja ohjeet 2010, Department of built environment