Solar Powered Intelligent Building Services System

Solar Powered Intelligent Building Services System

POOK, Yik Wan 14077627d 2017/18 FYP_78

The Hong Kong Polytechnic University

Department of Electrical Engineering


by

POOK, Yik Wan

14077627d

FYP_78

Formal Project Report

Bachelor of Engineering (Honours)

in

Electrical

of

Department of Electrical Engineering

The Hong Kong Polytechnic University

Supervisor: Dr. K.C. WONG Date: 17 MAR 2018


POOK, Yik Wan 14077627d 2017/18 FYP_78

Abstract

Smart building is the World’s trend that develops sustainable and smart city in a society. In

Hong Kong, BEAM Plus scheme provides instructions and awards to registered building.

Based on that idea, the proposed integrated building system aims to earn BEAM Plus scores

by applying Building-integrated photovoltaics cell (BIPV1

) technology with intelligent

building system control over lighting and shading devices. 90% of electricity consumption in

Hong Kong is due to human activities in buildings, of which 60% accounts for commercial

buildings. Based on this fact, this project focus on the methods of reducing electricity usage

in commercial office buildings.

Applying green building strategy in commercial office buildings, two axis sun tacking solar

panels on rooftop are suitable in densely Hong Kong buildings. The second proposed method

is using BIPV as shading fins to power LED lighting system at perimeter zone. The proposed

system dims the light in perimeter zones under the sufficient daylight2 conditions to reduces

energy consumption of lighting load. When temperature near window rises due to sun

irradiation at noon, the system operates shading devices automatically and bright up light to

reduce OTTV3 and consequently reduces energy consumption of air conditioning load.

Integrate IoT to the project, the data detected by sensors such as humidity, temperature and

light levels are sent to webserver via Wi-Fi so that user can monitor the temperature and light

condition near window. To demonstrate the ideas, a small-scale building model were built

and software simulation model were done.

1 Building-integrated photovoltaics are PV to replace traditional building material in building envelop.

2 Combination of direct and indirect sunlight including diffuse sky radiation and reflection by other buildings

3 Overall Thermal Transfer Value indicates average rate of heat transfer into a room


POOK, Yik Wan 14077627d 2017/18 FYP_78

Acknowledgements

The author is pleased to acknowledge the final year project supervisor Dr. Chan Ka Chung at

the Hong Kong Polytechnic University who contributed in stimulating suggestions, guiding,

helped and encouraged to coordinate the project especially in building services information.

I would like to express my deepest appreciation to all those who provided me the possibility

to complete this final year project report and I am grateful to have funding from Electrical

Engineering department in the Hong Kong Polytechnic University.


POOK, Yik Wan 14077627d 2017/18 FYP_78

Table of Contents

I. Introduction ................................................................................................................................1

1. BEAM Plus Scheme ............................................................................................................ 1

2. Renewable Energy .............................................................................................................. 2

3. Daylight vs Cooling Load ................................................................................................... 3

II. Literature Review .....................................................................................................................5

1. Solar Energy ...................................................................................................................5

2. Lighting Technology .....................................................................................................11

3. Intelligent Lighting Services ........................................................................................12

III. Assumption and Background ...............................................................................................14

IV. Methodology ...........................................................................................................................18

I. Hardware ..............................................................................................................19

1. Sun Tracking Solar Panel on Roof ..................................................................19

2. Solar Panel Circuit ...........................................................................................20

3. Intelligent Lighting System ..............................................................................23

4. Condition Monitoring and Webserver ............................................................28

II. Software.................................................................................................................29

1. AutoCad and PVCad ........................................................................................29

2. AutoCad and Dialux .........................................................................................30

3. Arduino Programming .....................................................................................36

V. Analysis and Result .................................................................................................................38

VI. Conclusion and Further Development ................................................................................55

VII. References .............................................................................................................................56

VIII. Appendixes ..........................................................................................................................57


POOK, Yik Wan 14077627d FYP 1

I. Introduction

1. BEAM Plus Scheme

Sustainable building is designed in a resource-efficient manner to achieve certain objectives

in BEAM Plus4 (Building Environmental Assessment Method) system such as wisely using

energy, water, and other resources more efficiently as well as reducing the overall impact to

the environment. BEAM Plus system is to score the performance of a building and concerns

the environment and energy usage which can rise the building reputation when score is high

and get the certificate that driving future developers to build more sustainable buildings in

the future [1]. This project is mainly focus on the energy saving aspect in new commercial

office buildings in Hong Kong.

Figure 1 - Beam Plus Scheme

Over 1,000 out of 4,561 buildings have already certified as green building by HKGBC (Hong

Kong Green Building Council) in 2014. Total saving of BEAM Plus assessed projects



compare to baseline has estimated annual electricity reduction of 446,280MWh equals to

312,000 tons carbon footprint saving [1]. The HKGBC predicted this scheme will lead to

reduction in energy intensity by 40% in Hong Kong by 2025. The 2018-19 Budget proposed

an enhanced tax incentive for energy efficient and renewable energy building installation

which owner can enjoy tax deduction upon achievement of certain BEAM Plus rating. This is

the reason why this project exists.

2. Renewable Energy

In addition, Zero-energy designed school building was constructed in Singapore which even

produces more than its own energy with 1200 PV solar panels on the roof and adapts daylight

and natural ventilation whenever possible [2]. Large scale over sailing roof provides shade from

direct sunlight to reduce cooling load. Solar powered building system becomes an architectural

trend over the world and it can also be applied in Hong Kong. For innovative design, the

proposed system will apply sun tracking solar panel operation and BIPV technology such as

sunshade type and skylight type so as to maximize the system efficiency.

Figure 2 - Different types of BIPV

4 BEAM Plus assessment is to offer independent assessment of building sustainability performance in Hong Kong. The

assessment covers site aspects, materials aspects, energy use, water use, indoor environmental quality and innovations.



Figure 3 - BIPV in the Hong Kong Polytechnic University

An example of thin film PV cells installed in the Hong Kong Polytechnic University is shown

as above. The thin film PV cell connects with inverter and battery is suppling corridor’s lighting

system which is standalone system. This also shows that BIPV is gradually accepted by

community and used in building since recent years. The reasons are that the price of PV cell is

reduced, whilst the technology and the efficiency of PV panel is developed and improved.

Moreover, society begins to aware of environment protection and also government sectors and

power companies are promoting the renewable energy that consequently attracts construction

developers to start up renewable projects in Hong Kong.

3. Daylight vs Cooling Load

Use of daylight is one of the themes in the project. Many modern interior spaces always make

good use of natural light due to its high CRI5 which enhance user comfort and reduce the use of

energy for lighting. However, radiant absorption of daylight into indoor is always conflict to the

cooling load in MVAC system. The project will wisely use daylight when sun light has not

shined onto indoor and has not heated up the surrounding air meanwhile the artificial light will

be dimmed to reduce energy consumption; when surrounding temperature rise, shading fin

outside window will close to minimize the effect of radiant energy of sun and therefore reduce

cooling load than traditional practices meanwhile the system will bright up the artificial light to

5 Colour Rendering Index increases with human eye comfort.



provide sufficient lux is based on BEC6 requirements.

Figure 4 - Solar irradiation heat up indoor air and furniture

Figure 5 – Lighting in perimeter zone is turned OFF when daylight strike into the room

6 Building Energy Code



II. Literature Review

1. Solar Energy

The growth of development of solar power in roof is a trend over the world. PV in building

today does not require extra land region and be installed in densely populated area as it provides

both power and shelter on envelop like Building-integrated photovoltaics (BIPV). Not only PV

can provide electricity during peak times, but also reduce transmission and distribution loss and

delivery requirements. With wise use of the building envelop in Hong Kong, not additional land

is used for development renewable energy as well as land cost.

“PV modules are technically well proven with an expected service time of at least 30 years.” [3]

Solar power technology in nowadays is reliable enough to be applied in building services with

sufficient maintenance and cleaning works. PV modules are no longer expensive which are

affordable for developer to consider renewable energy in building. The reducing investment of

photovoltaics panel would then in turn create an expanding market of new affordable PV

solutions. The efficiency of PV cell becomes higher under developing of R&D on renewable

energy. Below table shows efficiency of different types of PV cell.

Types of PV cell Efficiency at 25⁰C (%)

Silicon – Monocrystalline (MSC) 18 – 25

Silicon – Polycrystalline 13 – 16

Silicon – Amorphous 6 – 9

Gallium Arsenide (GaAs) 30 – 40

CIGS (Copper Indium – Gallium Selenide) 10 -14



Types of PV cell Properties Advantages Disadvantages

Silicon

Monocrystalline

(MSC)

- Made of one crystal

- Low electrical

resistance

-High efficiency -Expensive process to

make crystal structure

Silicon

Polycrystalline

- Multiple grains -Less cost than MSC -Less efficiency than

MSC

Silicon Amorphous -2nd

Generation -Very Cheap -Less efficiency

Gallium Arsenide

(GaAs)

-Made of Gallium -Very high efficiency -Very expensive

CIGS (Copper

Indium Gallium

Selenide)

-Thin film

-2nd

Generation

-High efficiency for

thin film application

-Able to automate all

manufacturing

process

-Expensive

For PV cells installed at the building envelop, thin film solar cells are usually used. Although

thin film cell has lower efficiency than other silicon PV cell, its mass production is

comparatively simple which lead to cheaper manufacturing and more flexible. High

temperature to the cell has less impact to its performance and also its size and weight is small

with more appealing appearance which is more suitable to be installed as shading fin outside

building structure.



Figure 6 - Polycrystalline PV (left) and Monocrystalline PV (right)

Although Gallium Arsenide (GaAs) PV cell has the highest efficiency of 40%, it is much more

expensive, it is rarely used in commercial size and installed on rooftop. Comparing

polycrystalline and monocrystalline PV cells, monocrystalline has higher efficiency since it is

made of highest grade silicon and it is space efficient that this kind of solar panel can yields

higher power output in limited space. However, monocrystalline PV cell is more expensive than

polycrystalline cell and tends to be more efficient in warm condition. Many of commercial

sized PV plants are using polycrystalline due to its cost efficiency with just slightly lower

output efficiency.

PV cells consist of polycrystalline silicon with efficiency around 13 to 16% which can be

connected in series or parallel and generate several kW of nominal power. PV systems can be

connected to the public grid that requires inverters for the transformation of the PV-generated

DC electricity to the grid AC electricity at the level of the grid voltage. A solar cell module is

made of 36 cells connected in series to produce peak power of 50W typically. In grid

connection system, several thousand kW of PV system will be built with 613Vdc system

voltage [3].



Assuming roof areas can be used for PV solar panels installation of 20% efficiency facing at the

Hong Kong optimal orientation (Maximum daily direct solar radiation obtained in a year: 120⁰

from north) and tilting angle (40⁰ from horizon) in Hong Kong7 , the annual total solar radiation

energy that can be obtained will be about around 4.3 MJ/m2/day which is 5.4% of the total

Hong Kong electricity consumption [4]. The monthly mean daily direct radiation is about 8 to

8.7 MJ/m2 or 2.4 kWh/m2/day recorded by HK Observatory [5, Figure7]. For a residential flat

with a full height glass window of 3 m x 3 m at south without obstruction, if a 10% efficiency

window-based thin film PV cells (Amorphous) are installed, around 2.4 MJ/day or 20

kWh/month of electricity can be generated that can reduce household electricity bill by about

HK$20 a month [4, Figure 8].

Figure 7 - Direct solar radiation levels (MJ/m2) at the King’s Park Meteorological Station (KP) and Kau Sai Chau (KSC)

from 2009 to 2012 [5]

7 HK latitude: 22.3⁰ ; longitude: -114.2⁰



Figure 8 - Electricity generated by 1 m2 10% efficiency vertical window solar cell facing south without obstruction [4]

“A sun tracking design will maximize the solar radiation energy collected …” [4, Figure 8]

The data had shown that sun tracking pyrheliometer obtained more radiation energy at any time

and even doubled productivity than the fix orientated one. Thus, sun tracking design is

encouraging to apply to system on rooftop to generate maximum possible electricity. Although

sun tracking system is slightly more expensive than stationary tilted system and require more

maintenance, advantages of tracking module overcome its drawbacks. Technology and

reliability in mechanics and electronics are advanced recently which decreases long term

maintenance concerns and make it more favourable to be applied in city.



Figure 9 – 2009 Solar radiation levels recorded at King’s Park Meteorological Station by HKO

Blue line: sun tracking daily solar radiation level (MJ/m2)

Red line: fixed surface mounted daily solar radiation level (MJ/m2) at 120⁰ orientation and 40⁰ tilting angle [4]

The above figure shows an example of solar radiation levels recorded at King’s Park

Meteorological Station researched by the Hong Kong Observatory. The blue line indicates daily

direct radiation obtained using sun tracking solar panel, while the red line represents the fixed

detector on roof. The result indicated that using sun tracking devices can absorb more radiation

though out the day where it can receive higher radiation quantity at all time than the fixed solar

panel. The maximum different of solar radiation obtained by sun tracking method over fixed

method according to the data is about 10MJ/m2 and even the minimum different of solar

radiation obtained is 1MJ/m2 more. There, it is encouraging to install sun tracking device to

solar panel to rise its output supply.



2. Lighting Technology

LED is the best choice to be design inside green building system that is beneficial over

nowadays technology includes high energy efficacy, high functionality and high freedom of

design [6]. A case study of Business Environment Council Office was done, and the result was

shown as below that the project replaces T8 fluorescent tubes with LED panels which save 54%

power annually. Furthermore, LED lighting technology offers digitalization design which is

programmable under different scenes, activities and venue. By adjusting colour Rendering

Index (CRI), Corrected Color Temperature (CCT) and Color Quality Scale (CQI) to suit with

different situations, the lighting system will be optical efficient, energy saving and flexible.

Other than the advantages about energy efficiency, health benefits also are the attraction items

such as longer lifetime, mercury free, no UV or IR and instant on or off or dimming for human

eye comfort.

Figure 10 - Case study of Business Environment Council Office



3. Intelligent Lighting Services

With the indoor lighting control system, we can dim the light in perimeter zones under right

daylight level and so reduce energy consumption. The photo sensor was placed near the

window in perimeter zone as the example of Hysan Development Company Limited [6] which

utilise exterior lighting for meeting rooms and natural light from glass window throughout

office.

Figure 11 - Position of photo sensor in Hysan Development Company Limited

With cooperation of shading/glare control, the cooling load at the window in the perimeter zone

is lowered. Additionally, well designed solar control system with shading devices can gradually

reduce building peak OTTV, heat gain and cooling requirements as well as improving the

lighting quality of interior building environment. In the long run, the approach also decreases

the number of light fittings and initial capital cost and operational costs.



Figure 12 - Case study of shading control in Hysan Place

The glare shading control above offers reduction of 5-15% energy consumption in Hysan Place

[6]. To install sheer screens on the lower parts on curtain wall and black-out screens on the

upper parts on the curtain wall, it allows flexible use the shading in different daylight conditions

for different purposes of occupants. For normal situation, when daylight is in the acceptable

level, 2 screens are open to allow light penetration and reflect into deep office area to reduce

power consumption of artificial light. For Glare control situation, a sheer screen on the lower

parts on curtain wall is rolled down automatically to block out excessive sunlight for occupants’

comfort when perimeter zonal temperature rises to certain level. It also reduces the cooling load

in perimeter zone and power consumption in MVAC system whenever occupants are existing

or not. It can decrease start up cooling load when occupants just use in the room at afternoon or

evening. Moreover, in the proposed system, not only PV penal can be placed on the roof, but

also shading fin on the curtain wall can be made of PV panel to provide power to sense near the

window.



III. Assumption and Background

The proposed system can be applied to commercial and office new building in Hong Kong

which consumes electricity of about 8000kWh/month and supplied by CLP Power. Assume the

working hour for the office is from 9:00am to 6:00pm and the major activities for the office are

a combination of both paper and computer work.

To develop energy saving system for building applicants such as lighting system, window

shading system and ventilation control. The system will generate electricity through sun

trackable photo voltaic solar panels on the roof with is standalone type and direct use type of

BIPV system on curtain walls and building envelops which also incorporate various energy

saving features such as cooling system that use temperature monitoring and automated

switching of artificial light. The active shading system prevents excessive radiation shines onto

indoor furniture, floor and walls and hence reduces OTTV and cooling load of MVAC system.

The mechanism can reduce overall building cooling as well as peak cooling load of a day. Since

the greatest building electricity consumption is air conditioning system, it will also reduce peak

electrical demand. BIPV system does not only reduce the total electricity energy, but also

decreases the peak kVA demand electrical power and minimise transmission and distribution

loss.

The proposed building system demonstrates and promotes citizens or developers how important

and possible it is to construct green and sustainable design in Hong Kong. With energy-efficient

technology, new buildings may follow the trend of this model’s sustainable design and

encourage developers to imitate this system to build BEAM Plus Platinum Class Building on

the ground to win the highest awards in the scheme [7]. Moreover, some rebates can be earned

due to renewable project according to the CLP’s new policy of Feed-in-Tariff.



This proposed building services system has few objectives including earning BEAM Plus

scores of 47 marks, reduction in carbon footprint and electricity bill saving. The below tables

show some proposed objective in terms of BEAM Plus marks about commercial office building.

1. Energy Saving

System Saving BEAM Plus score [4]

Solar energy

0.5% - 2.5% building energy consumption covered [Eu6] 5

Provision of external shading devices [Eu13] 1

Lighting &

MVAC

14% overall annual energy reduction [Eu1] 6

Reduction of CO2 Emissions,

Peak Electricity Demand Reduction

Energy Efficient Building Layout

Daylight design [Eu1]

20

15% reduction in peak demand [Eu2] 1

Demonstrate OTTV of habitable spaces ≤30W/m2 [Eu13] 1

At least 80% of the floor area in all normally occupied spaces

is adequately lit with an average daylight factor of 1% [IEQ18]

1

Providing automatic control of artificial lighting such as

daylight sensors at perimeter zone and/or occupancy sensor

[IEQ17]

1



2. Carbon Footprint

# 0.7 kg CO2 per kWh electricity consumed

System Carbon footprint BEAM Plus score [4]

Solar energy 20% - 100% building footprint covered 5

Lighting & MVAC 14% annual 6

3. Electricity Bill Saving

As a result, the proposed system can earn maximum of 47 scores in Energy Efficient aspect in

BEAM Plus scheme and a reduction of around HKD 10,000 electricity bill monthly.

Electricity bill rate (HK$/Unit) Electricity Saving Bill saving

1.020 for Each of the first 5,000 units

1.012 for Each unit over 5,000

15% overall annual energy

~8154kWh/month

HK$ 10,004/month



For easily illustration, the concept of the whole proposed building system is shown as below

block diagram:



IV. Methodology

Since a complete solar powered intelligent building service system is too large to build and

require large place to carry out testing, therefore, the proposed building system is demonstrated

by a model that several PV cells (PV panel) on the roof in the model with sun tracker will be

connected to the below LED circuit (Lighting system in building) in perimeter zone at the same

circuit that supply by battery (Normal power supply). This involves switching between PV cell

(Renewable energy) and battery (Normal power) which is programmed by Arduino board. The

electricity generated by rooftop PV cell arrays can be calculated and simulated by AutoCad and

PVCad while inputting location details, type of PV panel, invertor and tracker. This step is to

ensure the proposed system is reliable with reasonable power generated when sun tracking PV

panel locates in rooftop of a building in Hong Kong. On the other hand, the simulation of

lighting system in example office also ensures the satisfactory light perimeters (illuminance,

glare, uniformity, etc.) in the room using proposed building that does not affect the visual

comfort of people refers to the regulation in Hong Kong. And, the software like AutoCad and

Dialux can help to create a professional digital model for demonstration purpose.

In the intelligent energy saving system, for normal condition, we prefer daylight to be a light

source for normal activities and reduce energy consumption for lighting service so shading

device (reflective roller blind) is open for access of daylight and better-quality view as well

as dimming the artificial light. But, when temperature sensor/ lux meter near window detect

excessive light, it will trigger the shading device to close and reduce cooling load of MVAC

system, meanwhile, LED near window will be turned on for sufficient illuminance. For the

intelligent system on each floor, shading fins made of PV cells outside certain wall provide

electricity for the sensing system and motor action of the shading device (roller blind). Those



actions are performed in the model using MCU programming.

I. Hardware

There are four main hardware parts in the proposed system, which are sun tracking solar

Panel on building roof, solar direct supply circuit, intelligent building system and data

monitoring system. After some software simulation, hardware parts will be built as a

demonstration model to exhibit the operation of whole system.

1. SUN TRACKING SOLAR PANEL ON ROOF

The sun tracking motion is completed by coupling stepper motor to the solar PV cell so that

PV panel can be ensured its top surface always facing perpendicular to the Sun/ light source

to generate maximum energy. This can be done by using a programmable microcontroller to

generate stepped periodical pulses with PWM inputs for the stepper motor to rotate the

mounted PV cell as desired of digital signal. Two servo motors, light sensors (4* LDRs with

4* 100kΩ resistors), and Arduino are used to achieve the function. 2 servo motors are fixed

on the base structure and hold the PV cell. 4* LDRs are located in N, E, S and W direction.

Arduino programs the action and is uploaded to the microcontroller such that when one of

LDRs receives more light, the servo will move in that direction and PV cell will face

perpendicular to light source (Sun). The process is achieved by comparing the analogy values

between 2 bottom LDRs and 2 top LDRs and vertical servo will rotate in that tilt if one set of

LDRs detect more light. Same ideas that it compares the analogy values between 2 right

LDRs and 2 left LDRs and horizontal servo will rotate in that orientation if one set of LDRs

detect more light.



Figure 13 - Circuit layout of Solar Tracking System

2. SOLAR PANEL CIRCUIT

Photovoltaic system on rooftop is proposed to be connected in the utility grid system which

involves inverter for transformation from generated DC electricity to ac grid voltage, connect to

sensors to monitor in PC and synchronise the frequencies. Isolation transformer should be

installed after the solar panel and before the grid connection in order to avoid spurious noise

transfer and can convert inverter output voltage to the grid. Metering is essential to record

power generated and consumed between stand-alone system and the grid connection. For open

circuit voltage greater than 20V, PV bypass diode is installed to offer a current path around the

PV module and prevent backward current flow for protection. If PV output current is less than

the output current of other modules in same string, bypass diode will bypass the current of the

associated module. Blocking diode at the string end can stop any internal circulation current

between strings if output voltages of string are not the same. Fuse eliminates overcurrent

damage. For this project model, diode and fuse are not present in the demonstration due to its

small scale and low voltage circuit.



Figure 14 - Schematic layout of Grid Connected Rooftop PV system designed by AutoCad

This photovoltaic system not only can be connected to the grid, but also can be used

independently supplying power to DC building load likes computer loads, lighting loads and

AV entertainment. The later method requires battery storage which immediately store energy.

The below diagram shows the circuit of PV supply to DC grid and ac grid, where the supply

circuit near the source needs battery and battery charger with DC-DC converter to provide

efficient distribution voltage.

Figure 15 - PV DC supply circuit



When solar energy is not sufficient, the charged battery supplies power to the load. The circuit

requires sufficient number of battery storages and a good battery charger. This circuit design

changes normal AC distribution system to DC direct supply system can reduce size of

renewable energy system about 40% with power input reduction of around 5%. It is because

rectifiers and inverters to convert DC supply to AC grid and AC grid to DC load are avoided.

DC distribution is easily connected to renewable energy storage with higher efficiency and it is

easily connect different DC sources and building load together.

Figure 16 - PV plant supply to DC link



3. INTELLIGENT LIGHTING SYSTEM

Figure 17 - BIPV acts as shading fin and reflect sun light to indoor

By wisely use of BIPV on the shading element on the structure of the building, the power

generated by polycrystalline PV cells is supplied to automatic window roller shutter motor. The

polycrystalline PV shading fin is proposed to install only at the south facing window above

10/F for higher efficiency of solar irradiation obtained by the system where PV at lower floor is

low efficiency or even shaded by other obstacle is based on Hong Kong condition. Temperature

sensors at window are connected to roller shutter and LED light at perimeter zone.

The proposed intelligent system can be demonstrated by building an interior model using solar

panel, LED and programmed Arduino. Energy efficiency of lighting system can be simulated

and calculated by Dialux.



Photo sensor controller connects to dimming device and links to LED panel in order to response

to daylight from window. Controller is installed to convert signal from photo sensor into

command to dimming device and time delay function is to avoid rapid on off switching of light.

Figure 18 - Circuit layout of sensors and controller designed by AutoCad



The system mechanism is shown as below:

Figure 19 - Block diagram of intelligent building system operation



Temperature sensor detects high temperature near window → Close shade device + Turn on light

BIPV panel acts as external shading fin and directly supply electricity to motors of roller

shutters, internal shading devices and sensors in the system.

During daytime in Summer, temperature sensor near window detects temperature higher than

30⁰C, the signal is sent to controller and two actions are triggered: Roller shutter/ low U8

shading device rolls down to prevent excessive radiation casts onto indoor furniture and hence

reduce OTTV and cooling load of MVAC system; Dimming unit in lighting system bright up

indoor lights to acceptable illuminance level and the timer starts counting. After 30 minutes,

temperature sensor detects temperature again and sends to controller to carry out further action

or stay in the previous status.

Temperature sensor detects normal temperature near window → Open shade device + Turn off

light

If surrounding temperature is below 30⁰C, roller shutter will roll up to allow daylight to be one

of the light source and the diming unit will also operate to dim down the light to reduce energy

consumption. Same as above, timer will also count another 30 minutes to carry out the

action.

8 U value is thermal transmittance which is the rate of heat transfer through a material. Low U value means better

insulation of a structure.



The proposed intelligent shading system and lighting system was built as a model for

demonstration. This system is proposed to be put near window facing south for solar powering,

lux and temperature sensing as well as operating shading device like blind and roller shutter.

The total price of this system is cheap of about a hundred Hong Kong dollars and the materials

needed are easy to purchase.

This system is standalone system that solar energy connected by PV cell is first converted into

electrical energy and stores energy in rechargeable battery via charging module. The charging

unit should be properly sized according to the PV cell rated output and the model uses around

4.5V to 5.5V as normal input. The electricity supplied to the system passes to DC-DC booster

in between so that the voltage supplied to Arduino and the smart system is maintained in 5V

constantly for enough operating power. Controlling for voltage and current is important that to

operate the system stably. Temperature and light sensors are connected to Arduino to send

analogue signal to the microprocessor. Servo motor controlling blind position with a continuous

current of around 13 mA, so it requires to add a PNP transistor where Emitter pin goes to DC-

Dc booster, Base pin goes to Arduino board for controlling signal and Collector pin goes to

servo motor. Servo motor signal pin is connected to Arduino board for PWM signal as

programmed. The circuit for the model shown below is using Fritzing software to design.

Figure 20 - Designed intelligent shading system and lighting system powered by solar cell



4. CONDITION MONITORING AND WEBSERVER

The last part of the hardware in the intelligent building system is to monitor the condition in the

perimeter zone where the smart shading system located. Data sensed by temperature meter,

humidity meter (DHT11) and lux meter (LDR) are uploaded via ESP-12E module (Wi-Fi

module) to the web server. Data of temperature and humidity are digital input while data of

illuminance is analogue input to the Wi-Fi module. The Wi-Fi module is programmed using

Arduino WeMos D1 Mini for proper operation while baud rate of the board used in this project

is 115200, 2.4G Hz with constant voltage is needed to supply for stable data transmission.

Voltage regulator of 3.3V is used with the supply of 9V battery in the building model. Every 20

seconds, the module will send the current light, temperature and humidity values to the database

in web server by refreshing the web. User can use the default IP address to access the web

server user interface such as 192.168.4.1.

A new account and new channel is created at Thingspeak.com before three new fields of data

are created. API key is generated, and it is put into the code in Arduino programme to pair up

the web server or cloud server and data sending from Wi-Fi module. User can login to the

Thingspeak account to have a live channel view of data in continuous practice. The data can be

recorded in private view or public view by setting up in the web server.

The circuit diagram of Wi-Fi module with sensors is shown as below.

Figure 21 - Circuit design of Wi-Fi ESP-12E module with sensors



II. Software

There are two main software parts, which are simulation of the building system using AutoCad,

PVCad and Dialux, and the other part is programming in Arduino IDE software and Webserver

to building model for demonstration using MCU such as Arduino UNO, Mini and ESP-12E

Wi-Fi module.

1. AUTOCAD AND PVCAD

The rooftop PV powered system can be simulated using AutoCad and PVCad which the

software provides convenience and practical way to design and calculate the electricity

generated in kWh and some technical details such as system voltage, current, inverter properties

and string characteristics etc. First, floorplan of the target building is drawn with proper

parameter and scale. Secondly, .dwg file is imported to PVCad and geometric detail of the

building location is inputted like country, aptitude, latitude, evaluation, roof height and

obstacles. Then, details about types, manufacturer and number of string of PV etc. can be

designed and circuit layout can be drawn using the software.

Figure 22 - Planning type, size and circuit of PV panel on roof



2. AUTOCAD AND DIALUX

Similar as pervious, floor plan is required to import to simulation software Dialux. Lighting

layout and luminaire selection is done using this software to obtain the summary of calculation

of illuminance, uniformity and glare effect etc. to ensure the lighting fixture layout of the

proposed system satisfies Hong Kong standards as well as BEC [8] and BEAM Plus

requirements. DIALux 4.12 was used to simulate the lighting design result for references.

There are servals assumptions have to be made before doing the Dialux simulation which the

assumptions are according to the usual practices in Hong Kong’s industry and the value is

common in most of the office building in Hong Kong. According to the SLL Lighting

Handbook [9], the optimal ceiling height should be in the range from 2.5m to 3.5m, in order to

make good use for the indirect lighting from floor, furniture and wall. Hence, it is assumed that

the ceiling to floor height of the building is 3m. Task height is usually 0.8m for human.

Reflections of ceiling, wall and floor are assumed to be 0.8, 0.5 and 0.2 respectively. For

daylight, it is assumed to be CIE9 overcast sky [10] and no obstruction like another building

near the design building.

Requirements in Hong Kong [11]:

Location Illuminance E

(lux)

Glare UGR Lighting Power density

LPD (W/m2)

Uniformity Uo

Office area ≥500 for screen

based work;

≥300 for paper

based work

≤19 ≥13 for internal floor

area ≤ 15m2;

≥12 for internal floor

area > 15m2

≥0.6

By setting different scenes of daylight condition and shading condition, the proposed system

can be proofed as qualified design and can be simulated accurately because this software is also

widely used in building services industry to carry out lighting design. The Dialux’s detail report

9 The International Commission on Illumination, CIE is called for its French name, is the international authority

about illumination, light and colour.



shows calculation results of illuminance of each working plane, uniformity, lighting power

density (LPD) and glare factor (UGR) etc.

The software is user friendly that can produce simple, effective and professional light planning.

To start a new project, it is first needed to set up the dimensions in the imported AutoCAD floor

plan and change room properties and scale.

Windows and doors were added by using “Insert windows and doors”. Furniture was added by

using “Place Object” in the guide on right hand side. To select luminaires, I downloaded

catalogues or choose from online catalogues such as Thron, Philips and OSAM. The luminaire

files describe the information of light distribution, lux and power which can be shown in

DIALux’s screen and can be selected. In the window of Luminaire arrangement, it can arrange

luminaires with recommended lux level depending on the predefined photometric requirements.

Also, it can edit the mounting level and other properties. Then, by ticking the calculator icon on

the tool bar, calculation and results can be shown in the summary report. Glare index can be

predicted by adding glare surface with task height. After try and error processes, satisfied result

and lighting layout plan can be obtained.

Different light scenes (Daytime-shading device ON, Daytime-shading device OFF and Night-

time) were added by clicking “Insert light scene” in the project tree of Project Manager.

Luminaires were added to different control groups by clicking “Add to control group”.

Different groups were added to corresponding scenes by clicking “Add to light scene. For night,

daylight was not into account during calculation and the dimming value of different groups was

kept being 100%. For daytime, daylight was into account during calculation was ticked and the

simulation period was input. The dimming values of different groups were set to achieve the

simulations.



Dialux Report of a room in scene 1 - Daytime:



Dialux Report of a room in scene 2 – Night-time:



3. ARDUINO PROGRAMMING

Arduino UNO R3 board is used for the PV system model operation. For examples, Solar

Tracking System on building rooftop involves two axis rotational motions to track the brightest

point so as to receive the largest irradiation and generate the greatest electricity. 4 LDRs sense

the brightness and compare the value produced by LDR’s current. Then, Arduino programmed

microcontroller will run the logic and actuate the correlated horizontal and vertical servo motors.

Loop and if…else etc. functions are commanded to carry out the tracking action.

Figure 23 - Arduino programs for PV sun tracking operation and intelligent smart blind

Arduino Mini board is used for the intelligent building device locate at the window. The

operational device is supposed to be powered by solar energy right on the window shading

(Sunshade type BIPV) near the device such that it is energy effective that the system is not

consuming power when no use which is at night or cloudy day, while it is needed most when

sun shines to indoor and BIPV so the device detects and operate. The program reads signals

from LM35 as a temperature sensor and LDR as a lux meter near window. Then, compute and

determine whether the smart blind closing action should be taken according to light level and

temperature level with setting rotating direction of servo motor.



On the other hand, ESP8266 Wi-Fi board is used with Arduino board for data recording and

condition monitoring. Temperature, humidity and light data are uploaded to the web server by

programming chip ESP-12E. The HTML page hosted on the web server provides user interface

of analogue and digital data from sensors and it also allows to control LED remotely via Wi-Fi.

Figure 24 - Block diagram of WiFi Web-Server uploading

The new channel is created at Thingspeak.com with three new fields where API key is

generated. In the code, Wi-Fi ID and password of router is needed to input for data transfer to

the web at corresponding IP address. It will check the network connection and sensor detection

and continue to upload the data to the internet. User can login to the Thingspeak account to

have a live channel view of data in continuous practice. The data can be recorded in private

view or public view by setting up in the web server.



Figure 25 - Temperature, Humidity and lux data uploaded in Thinkspeak.com

V. Analysis and Result

As the schedule planned in proposal, project review on the topic was done where no change

was made to the project contents and aims. Also, it is successfully to run in progress that major

hardware and software materials were purchased, shipped and received, after that, testing on the

purchased items was also been done. However, model building progress was left behind. Hence,

an updated schedule about the time for model building and testing is prolonged to the end of

January in 2018. Finally, the building model is done at the end of February in 2018.

By learning the function of PVCad, simulation of the rooftop two axis PV arrays was done

where setting the location at the Hong Kong Polytechnic University (the red point below,

22.30342, 114.17986) such that the simulation data is according to PolyU’s direction, spectral

distribution of solar irradiation and irradiance profile to estimate the output characteristics with

respect to the designed PV circuit. Energy generated according to my example design is

calculated in excel file with some assumptions. Moreover, a digital building model was drawn

in AutoCad and Dialux for simulation and demonstration.



Figure 26 – Setting up the location and basic information in AutoCad and PVCad software simulation of PV panel

Figure 27 - AutoCad and PVCad software simulation of Rooftop PV panel 2D building modelling



Figure 28 - AutoCad and PVCad software simulation of PV panel has been done with 3D building modelling

Figure 29 - Dialux software simulation of PV panel has been done with 3D building modelling



Figure 30 - Dialux software simulation of lighting system has been done with 3D building modelling

Dialux Simulation of lighting system was done with expected result of meeting the

requirements in Hong Kong according to the SLL Code for lighting, CIBSE code for lighting,

EMSD COP 2015 version and task lighting design guideline. Illuminance level, uniformity

level, light power density, Unified Glare Rating (UGR) and other lighting parameters can meet

the requirements within certain limits. Therefore, it can be concluded that lighting dimming

control can be applied to the designed building to minimize the lighting load when daylight is

available.



PVCad Simulation of the rooftop PV module simulation was done with the result of estimated

monthly kWh energy generation as shown as below. The maximum estimated monthly AC

output is about 4000kWh with 40% efficiency. The summary of the calculation results are

shown as below:

Figure 31 - Monthly AC system output calculated using PVCad

Figure 32 - Result calculated using Excel



This project has three major model parts which are two axis sun tracking solar PV model, the

intelligent building model control smart blind and perimeter zone lighting is based on the signal

from temperature and lux sensor, and the third part is condition monitor via Wi-Fi to web server.

Figure 33 - Models with Arduino programs

Figure 34 - Rooftop PV sun tracking model

Sun tracking PV model

Smart blind model with temperature sensor and lux meter



There are two servo motors in sun tracking device which the horizontal servo and vertical servo

are limited to rotate within the range of 60~100 degree and 0~20 degree in the Arduino

program.

Figure 35 - PV powered intelligent building model

The smart blind system in intelligent building model is completed and tested. During morning,

the servo is set at 85 degrees so that daylight can enter to room. When temperature sensor

detects 30degree near window, smart blind rotates down where servo at 165 degrees. The

circuit connects LM35, PNP transistor, LDR, 5V DC-DC booster, Lithium battery charger

module, PV cell, servo motor as well as Arduino mini. Data is recorded using Arduino IDE.

Figure 36 - Data monitored and shown the expected operation



After testing the circuits, elements like sensors, PV cells and wires are inserted into building

model for demonstration. The model is built as show below.

Figure 37 - Building model

Temperature sensor (LM35) Light sensor on

working plane (LRD)

Servo motor for shading blind

WiFi to Webserver circuit Intelligent building system circuit



A function of condition monitoring is also introduced into the system. Office’s perimeter zone

condition is monitored, and data is uploaded to a web server like Thingspeak.com via Wi-Fi

module ESP8266/ESP-12E/D1R2 and Arduino programming, which the data contains

temperature, humidity and illuminance level. Users can observe the surrounding condition near

window as well as control the lighting ON/OFF via the web server. As a result, the system

fulfills the concept of intelligent building system and involves IoT technology. This function

also provides flexibility to users if they do not want to operate the smart system and it is user

friendly to control using web with the help of smart phone.

During the model building processes, two different MCUs were tested and programmed

because some connection stability and driver updating problems occurred in the board of

ESP8266. Finally, D1R2 and Wemos D1 mini were tested and functioned stably where Wemos

D1 mini (the second photo) is smaller with enough pins for this project. Thus, D1R2 was

chosen and put into the building model.

Figure 38 - D1R2 & Wemos D1 mini



Below photos show the testing result in Arduino IDE, web-server and circuiting:

Figure 39 - Serial Monitor in Arduino IDE indicates proper connection

Figure 40 - Testing two different MCUs (D1R2 and Wemos D1 mini)

Humidity Sensor Temperature Sensor

Light sensor

5V Supply



Figure 41 - Data recorded are uploaded to Web Server via WiFi

Figure 42 - Web Server that user can view


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Assume the proposed system is applied in 20 storeys commercial office building located in CLP

supplied network such as Hong Kong Polytechnic University, Hung Hom. The following is

calculation to the cost and saving of the proposed system under assumed condition for cost

benefit analysis of this project design.

According to tariff to commercial building supplied by CLP Power company, the electricity bill

calculation of office building is categorized as non-residential tariff which is consisted of

energy charge, fuel cost adjustment and energy saving rebate. The tariff of non-residential

customer is based on monthly meter readings. Each of the first 5000 units of electricity rates at

104.3 cents per unit and each of the unit over 5000 units rates at 103.5 cents per unit. It is

decreasing block tariff.

Figure 43 - Energy charge rate in CLP website

The second part of tariff is fuel cost adjustment. This year, the fuel cost adjustment is 22.0 cents

per unit. If the actual cost of fuel is less or more than $700 per 44 GJ, it should be credited or

debited to fuel clause recovery account by CLP tariff policy.


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Figure 44 - Energy Saving Rebate in CLP website

By the supply rule and CLP commitment to return to customers, an adjustment to the block size

of tariff under paragraph of energy charge and energy saving rebate rules of the respective

applicable energy charge tariff rate and energy saving rebate tariff rate will be made when the

period between two successive meter-readings is outside the 25 to 35 days range.

The calculation is shown as follows:

Applicable block units = Normal block units x N / 30

N = Number of days between two successive meter-readings

The calculation of the proposed project generates and consumes electricity in the related system

includes rooftop PV panel generation, BIPV shading panel generation, lighting electricity

consumption and HVAC consumption. The estimated electricity tariff saving, or billing are

calculated as below.


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1. Rooftop PV panel:

2. PV shading cell:

3. Lighting electricity:


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4. HVAC electricity:

Other than electricity saving is concerned in the project, carbon footprint reduction is also one

of the main objective for this building system design and earning scores in BEAM Plus scheme.

Using the 2016 data of U.S. national weighted average CO2 marginal emission rate, assuming

every MWh energy reduction can lead to deceasing of 1640.7 lbs CO2 emission by power

company. This calculation does not include any greenhouse gases except carbon dioxide and

line losses. With the fact that 4.536* 10-4

metric tons/lb of carbon reduction in relation to CO2,

the greenhouse gas equivalencies calculation equation is shown as below:

Emission Factor

= 1640.7 lbs CO2/MWh*(4.536 *10-4

metric tons/lb)*0.001 MWh/kWh

= 7.44*10-4

metric tons CO2/kWh


53

Overall estimated purchasing cost of this system: [12]

Items Quantity Expense (HKD)

Rooftop PV panel

(Efficiency is around

40%)

Two axis PV panels

(USD$4.85/W)

Inverters (USD $0.6/W)

Connectors

Rooftop $12,000/module * 50

=$ 600,000

PV shading cell Polycrystalline PV shading fin

(USD $0.35/W)

Batteries (HKD 240/unit)

Voltage Regulators

10 floors $10,000/module *10

=$ 100,000

Intelligent building system MCUs

Sensors

Servo motors

10 floors $500/floor *10

$5,000

Wi-Fi Web Server Wi-Fi modules 1 system $2,000

Annual saving of this system:

Energy generated (+)

/Reduction (-)

Electricity

Bill saved

[13] (HKD)

Carbon foot print

Reduction [14]

Rooftop PV panel +48,000 kWh $59,752 39.4 Tons = 35,722kg

PV shading cell +10 floor*1,000 kWh $12,480 8.2 Tons = 7,442kg

Lighting electricity -10 floor*5%*18,500 kWh $11,547 7.6 Tons = 6,884kg

HVAC electricity -5%*73,000 kWh $4,600 3 Tons = 2,716kg


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As above result, overall estimated minimum purchasing cost is HKD 707,000 per project and

estimated maximum annual saving is around HKD 89,000. The energy generated by PV cell

can cover parts of the electricity load in building with pay-back period of around 8 years and

meet objectives in BEAM Plus scheme of earning 47 marks in Energy Efficient aspect.

After analysing the result of proposed system, there are some limitations and difficulties are

appeared. The first limitation in this project is that many technologies are integrated into one

single system using modelling, however, there is no solid solution for a large and real system

for a building. For example, the model use MCU to operate the switch over action between

lighting and shading device, but no switching between battery and PV panel system to supply

the system when it is cloudy day or may not store enough energy in battery for the system

during night time because it was assumed the office time is 6:00pm.

The second limitation is that the simulation using different software can just estimate the

approximate value for reference only due to measuring large building system or obtaining data

from one reference commercial building is impossible for a university degree project with no

relevance people supporting this project. Therefore, the simulation data can only be shown as a

reference data. Further to this limitation, this project can perform better when really apply to

one specific building and this proposal is better to transform as a case design. The reasons are

that the efficiency of solar energy and sun light energy are greatly depended on the location and

orientation of a building. If the location is changed (not at the Hong Kong Polytechnic

University), all the design is needed to be re-simulated, re-calculated and re-designed.

As a result, this proposed system can only demonstrate the idea and concept of using renewable

energy and natural resources. If it is proposed to install in a new construction project, further

assessments are needed to carry out to determine whether the system is suitable on that site

based on the efficiency of the system.


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VI. Conclusion and Further Development

There is possible high potential of solar energy in Hong Kong and it is known that solar energy

is abundant in Hong Kong. Solar power has potential for widespread development in Hong

Kong buildings by the application of PV panels. BEAM Plus certificates the use of renewable

energy in building and the projects involve energy saving also scores some marks on the

scheme and thus encourage developers to consider the proposed building services system.

Besides, the proposed system only expects to be applied in commercial and office building in

Hong Kong. Hence, a further advanced design can be made for residential building with the

improvement of economic benefit in small scale system.

Real time monitoring of the energy saving can be introduced. Energy generated data and

illuminance can be uploaded to internet for monitoring and develop user interface for personal

setup in website such that user can control the On / Off and dimming profile depend on personal

practices. The Wi-Fi monitoring and control system though web server can be improved since

the privacy security has not been introduced and there should be some recognitions of access

like passwords to different floor or zone for user’s login.

For prospection, such kinds of intelligent and renewable energy related system can be promoted

and being considered in developer vision because the proposed system can indeed help

construction developer to earn an award in BEAM Plus scheme as well as electricity bill saving

in buildings. BIM10

technology can be introduced into this system so as to have more

completely insight to building services system and efficient maintenance preparation. Whilst, it

is the world’s trend to provide BIM technology in every building system.

10 Building Information modelling


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VII. References

[1] HKGBC. (2016, October). Hong Kong: Green Building in ACTION.

[2] Peter, G., “Solar Power in Building Design: The Engineer’s Complete Design

Resource”, SOLAR POWER SYSTEM PHYSICS, Chapter (McGraw-Hill Professional,

2008), AccessEngineering

[3] Friedrich, S. & Thomas, E., “PHOTOVOLTAICS IN BUILDINGS: A Design Handbook

for Architects and Engineers”, IEA Solar Heating and Cooling Programme.

[4] B.Y. Lee & H.Y. Mok., “Potential of wind and solar energy in Hong Kong(28 May

2010)”, Hong Kong Observator

[5] T.C. Lee, C.M. Shun & S.M. Lee. (24 May 2013). Grasping our Climate Resources for

Sustainable Development. Hong Kong Observatory

[6] HKGBC. (2016). Hong Kong Green Office Guide. Construction Industry Council

[7] Achievement rate of credit of BEAM Plus New Building (V1.2)

[8] Code of Practice for Energy Efficiency of Building Services Installation (2015)

[9] The SLL Code for Lighting, CIBSE 2012 code for lighting.

[10] Calculation and Presentation of the Standard CIE UGR Table for Indoor Lighting Luminaires

[11] EMSD Code of Practice for the Electricity (Wiring) Regulations, Task Lighting Design.

[12] Friedrich, S., “A Design Handbook for Architects and Engineers”, International Energy

Agency, Paris

[13] CLP. (2018). Non-Residential Tariff Calculator. [online] Services.clp.com.hk. Available

: https://services.clp.com.hk/en/TariffCalculation/nonResidentialTariff.aspx [Accessed 11 Feb. 2018].

[14] US EPA. (2018). Greenhouse Gas Equivalencies Calculator | US EPA. [online]

Available at: https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator

[Accessed 11 Feb. 2018].


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VIII. Appendixes

BEAM Plus New Buildings Version 1.2 (2012.07) - 1.5 Summary of Credits - 4 Energy Use

(Eu)


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59

BEAM Plus New Buildings Version 1.2 (2012.07) - 1.5 Summary of Credits - 6 Indoor

Environmental Quality (IEQ)


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Dialux 3D modelling:


61


62


63

PV Cad simulation:


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Monthly kWh of Rooftop PV plant:

Hourly kWh of Rooftop PV plant:


65


66

Non-Residential Tariff Calculation:


67

Carbon footprint calculation:

Solar Powered Intelligent Building Services System

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