National University of Singapore

Department of Building

School of Design and Environment

PF2302: Construction Technology

Report on Integrating Solar Panels on Building Facade in Singapore

Submitted to

Professor Chew Yit Lin Michael

Submitted by

Choong Choy Teng(U086742U)

Cui Tingting (U086791M)

Do Thi Hong Van(U086749Y)

Goh Siok Lee (U086725L)

Le Nguyen Hanh Phuong (U086745A)

Nguyen Dinh Song Anh(U077897B)

Tan Jia Ling Esther (U077924R)

Tran Phuong Quynh (U086748M)

Woon Shi Yun (U087787E)

Yang Kailin (U086774E)

October 2009

Integrating Solar Panels on Building Façade in Singapore

Executive Summary

This report studies the feasibility of incorporating solar panels onto building facades and makes recommendations to overcome the limitations. Research findings include web-based literature reviews and articles, site visits and interviews with the relevant professionals.

The Earth is experiencing gradual depletion of fossil fuels and other non-renewable energy sources. Countries worldwide are worrying about the world coming to an end when all the natural resources have been fully utilized. In recent years, they came up with an alternative source of energy – renewable energy. Renewable energy includes hydropower, wind energy and solar energy. In this paper, we would be discussing the use of solar panels to convert solar power into usable energy for consumption within a building.

Major findings indicate that while solar panels perform better on roofs than on facades, we see its potential in Singapore because buildings here are tall and slender with larger areas of facades being exposed to sunlight. The limitations of façade solar panels discussed in this paper includes the positioning of solar panels, shading & shadowing of surrounding buildings, thermal heat transfer during the conversion of energy, and the cost of solar panels.

This report also includes the methods of overcoming the limitations mentioned above, primarily by improving the system efficiency of façade solar panels and encouraging government and consumer support for the technology. Given our strategic location, we are in position to make use of the abundant solar energy to ensure that Singapore can be a self-sustainable nation. Therefore, our team feels that we should have large-scale implementation of solar panels across the nation.

ContentsExecutive Summary21.Introduction51.1 Background51.2 Purpose51.3 Scope61.4 Methods of Investigations62.Theory72.1 Solar Panel72.1.1 Definition72.1.2 Function72.1.3 Types82.1.4 Importance112.2 Facades122.2.1 Multifunctionality of PV modules on the façade122.3 Building Integrated Photovoltaic (BIPV)143.Literature Review173.1 Case Study (1) ZICER BUILDING - University of East Anglia173.1.1 General background173.1.2 Solar panels on ZICER building183.1.3 Construction213.1.4 Monitoring system223.1.5 Performance study243.2 Inference for the Case Study 1303.3 Case Study (2) William Farrell Telus Building343.3.1 General Background343.3.2 Goals353.3.3 Special Features353.3.4 System Details363.3.5 Design413.3.6 System Performance423.3.7 Economic Analysis423.4 Inference for the Case Study 2434.Findings464.1 Interview464.1.1 Grenzone Company464.1.2 National University of Singapore514.2 Site Visits554.2.1 Biopolis Helio Building554.2.2 Building Construction Authority (BCA) Academy585.Feasibility Results645.1 Prospect of Solar Panels in Singapore645.1.1 Current Situation regarding solar energy globally645.1.2 Increasing usage of solar panels in Singapore665.1.3 Increased funding for solar energy research685.2 Benefits715.3 Installation of solar panels on building facades745.3.1 Overview of installation of solar panels745.3.2 Application of BIPV technology on building façade755.4 Limitations805.4.1 Position of Solar Panels805.4.2 Design of the buildings825.4.3 Distances between buildings825.4.4 Thermal heat transfer835.4.5 Cost of solar panels845.5 Overcome the limitations (simulation)865.5.1 Position and angle of the solar panels865.5.2 Design and surrounding of the buildings905.5.4 Costs of solar panels936. Conclusion97Reference98List of Figures101List of Tables102Appendix A103Appendix B120

Integrating Solar Panels on Building Façades in Singapore

1. Introduction1.1 Background

With the gradual depletion of fossil fuels and increased occurrence of natural disasters worldwide, using renewable energy seems to be the trend now, with the invention of solar vehicles, construction of green buildings and so on. This is especially important in Singapore, because we depend on other countries for natural resources. However, if we could make use of what nature has granted us – the advantage of having a large amount of sunlight throughout the year, we could come up with ways to supply ourselves with renewable solar energy from the sun.

At present, there are some projects in Singapore installing solar panels on the roofs to generate energy for the buildings. However, due to the nature of high-rise buildings being tall and slim, the energy generated, based on the limited area of solar panels that can be placed on the roof, might only be sufficient to provide for energy consumption of one storey of the building. Hence, placing solar panels on the building façade will be more practical in countries like Singapore, because the area of the building façade is much bigger than that of the roof and is able allow for the absorption of more solar energy and the production of more electrical energy.

1.2 Purpose

The purpose of this report is to study the feasibility of integrating solar panels on building façades in Singapore and to make recommendations on overcoming the limitations faced.

1.3 Scope

This report is limited to the study of the integration of solar panels on the façade of high-rise buildings in Singapore. It will focus on the prospects of solar panels on building facades, its benefits, methods of installation, limitations and solutions.

1.4 Methods of Investigations

Interviews were conducted with professionals in energy management and in solar panels application to gather information on the issues involved in integrating solar panels on the façade. They are Associate Professor Lee Siew Eang of National University of Singapore (NUS), Department of Building and Mr Teo Boon Teck, the Application Manager of Grenzone Pte Ltd respectively. Observations were also made during site visits to existing buildings integrated with BIPV technology on their facades – Building Construction Authority Academy, Zero-Energy Building (BCA ZEB) and Biopolis Helio Building North. Further research was obtained from internet like, journals, articles and newspapers.

2. Theory 2.1 Solar Panel2.1.1 Definition

Solar panels are a form of active solar power, a term that describes how solar panel makes use of the sun’s energy. Solar panels harvest sunlight and convert the energy into electricity or into heat energy to heat up water.[footnoteRef:1] [1: Solar Panel Information. (n.d.). What are solar panels? Retrieved October 24, 2009, from Solar Panel Information: http://www.solarpanelinfo.com/solar-panels/what-are-solar-panels.php]

There are actually two types of solar panels. One type uses the solar energy, the sun's rays, to heat up water. The other type uses sunlight to create electricity directly.

The term solar panels usually refers to panels that use the sun rays to heat up water. A system that creates electricity is referred to a solar cell, or a photovoltaic panel ("PV panel" for short).

This report will focus only on the system used to create electricity, since the aim of our project is to find a solution to increase the energy efficiency for tall buildings’ façade. Hence, whenever the term “solar panels” is used in this report, it is in reference to the “PV panel”.[footnoteRef:2] [2: Solar Power. (2009). The Difference Types of Solar Panels . Retrieved October 24, 2009, from Solar Power. Product. Information. Guides. News.: http://www.findportablesolarpower.com/solarenergy/solarpanels.html]

2.1.2 Function

Solar panels take advantage of the solar energy by converting solar energy directly into electrical energy. A solar panel comprises of solar cells that act as the basic component on the panel itself. Materials called “semiconductors” are used. The usability and efficiency of a solar cell largely depend on the kind of semiconductor materials the solar cell is made of, which is normally silicon. When sunlight hits the solar panels, the semi-conducting materials absorb photons in the sunlight.[footnoteRef:3] One side of the material becomes negatively charged while the other side becomes positively charged, thus creating an electrical flow similar to that of a small battery. This is the photovoltaic effect. [3: Wikipedia The Free Encyclopedia. (2009, October 23). Solar Cell . Retrieved October 24, 2009, from Wikipedia The Free Encyclopedia: http://en.wikipedia.org/wiki/Solar_cell#Simple_explanation]

The basic unit in a photovoltaic (PV) system is a solar cell. A solar cell consists if a small piece of semi-conducting material ranging from 1 – 15 centimeters in size, depending on the application. One single cell does not create a lot of electricity, which is why normally several cells are arranged and connected together forming what is known as a “module”, or more commonly known as “solar panel”. The amount of electricity produced, depends on the number of cells in the module or panel. If more electricity is needed, several modules can be connected to one another, thus creating a “solar array”.[footnoteRef:4] [4: Solar Power. (2009). The Difference Types of Solar Panels . Retrieved October 24, 2009, from Solar Power. Product. Information. Guides. News.: http://www.findportablesolarpower.com/solarenergy/solarpanels.html]

2.1.3 Types

Solar cells are classified into three generations, according to the order in which each one became important. Currently, further research is being done for all three generations, with the first being the most highly represented in commercial production, accounting for 89.6% of 2007 production.

First generation

The first generation of solar cells refers to monocrystalline and polycrystalline silicon cells.

(a) Monocrystalline Solar Cell

Monocrystalline solar cells are currently the most productive among the three types of solar cells with efficiencies of up to 17%. They are widely used for integration into the building’s elements and have the oldest history of application. They are made from thin wafers of silicon, sliced from large crystals that have been developed under strictly controlled conditions. The cells are laid on the panel with a few inches between each other like a grid pattern. The main advantage of this solar cell is that it has a minimum lifespan of 25 years or more, which makes it more worthwhile consumers to invest. Besides, it is also more suitable to be used when space is an issue due to its high efficiency. On the other hand, the disadvantage is the vulnerability to high temperature and exceptional fragility. Therefore, a rigidly mounted installation is required to deal with monocrystalline solar cells.

(b) Polycrystalline Solar Panel

Polycrystalline solar panels are the cheapest among the mentioned solar cells and it is also the most common type of panel in the market. They are made from a block of silicon that has multiple crystals which makes the appearance look like a mosaic. In the polycrystalline process, the cooling of silicon melt took an especially long time, under controlled conditions. The silicon block produced from this process contains crystalline regions in it and were separated by grain boundaries. In this way a number of interlocking silicon crystals grew together. This system is generally known to be less efficient than the monocrystalline solar system with efficiencies of up to 12%. Despite all the disadvantages, they are still widely accepted by the users due to their low production costs and ease of manufacture. The durability is quite compatible to monocystalline solar system although it is less productive.

Second generation

The second generation of solar cells refers to amorphous silicon cells.

In amorphous silicon cells, the silicon atoms are not arranged in an ordered formation in a crystal lattice. It involves a complex method of production and differs from the crystalline cells, as the silicon is deposited in a very thin layer or backing substrate. To add on, several layers of silicon doped in slightly different ways to respond to different wavelengths of light are stack on top of one another to improve the efficiency. The advantage of the very thin layers allows for the flexibility of the panels. It enables the solar panel to be installed on the curved surfaces on a roof. It also produces relatively low cost per Watt of power. Amorphous solar panel can be seen as a practical alternative to the crystalline panels. However, its efficiency is very much lesser compared to those made from individual solar cells and they need twice as much space to generate the same amount of energy. Hence, they are very suitable to be integrated in large and high buildings. Moreover, for a given power rating they do perform better at low light levels than crystalline panels, making them worthwhile to have during wintery or cloudy days with little sunlight.

Third generation

The third generation is a “departure from the first and second generation, which are silicon-based technologies, promising a new approach currently under commercial development” (BCA Academy of Built Environment, 2009). They are dye-sensitized cells which are both opaque and semi-transparent. It aims to enhance the poor electrical performance of the second generation at the same time maintaining the production costs low. There are a few approaches to achieving these high efficiencies including the use of multijunction photovoltaic cells, concentration of the incident spectrum, the use of thermal generation by UV light to enhance voltage or carrier collection, or the use of the infrared spectrum for nighttime operation.[footnoteRef:5] [5: Wikipedia The Free Encyclopedia. (2009, October 23). Solar Cell . Retrieved October 24, 2009, from Wikipedia The Free Encyclopedia: http://en.wikipedia.org/wiki/Solar_cell#Simple_explanation]

2.1.4 Importance

Nature has offered us an unlimited source of energy and that is solar energy. It is freely available, it can be replenished as long as the sun shines; but most importantly, it is a natural resource, and thus, will not burden our planet earth. Solar energy could be used to power electricity, to heat water, to warm the house or to power a vehicle. It could be used for almost anything, and it only costs a small fraction of what we are currently paying for. At present, households have been making use of solar energy to power solar water heaters and solar cookers to cook and dry foods, which on the whole reduce reliance on firewood or other fuels. This reduces smoke emissions and conserves our fossil fuel sources.

The solar panels used to collect solar energy can come in different shape and sizes, to fit the desired surfaces. This means more flexibility and choice in incorporating these solar panels onto the surfaces of the building facades. To some extent, it might even be possible to cover the entire building’s east and west surfaces (corresponding with Singapore’s angles of sunlight exposure) with solar panels. In Singapore, where sunlight is almost constant, this implies high energy absorption and thus, a large amount of solar energy can be utilized as an alternative energy source to fossil fuels.

The disadvantage of the current technology level of solar panels (current solar panel technology remains at the second generation cells) is that it requires a large amount of space. This can easily be reconciled with the judicious usage of the large available spaces on Singapore’s buildings and facades. In the event that a new breakthrough in the third generation solar cells is made, this would spell even more energy savings because the third generation would be building on the strengths of the second generation cells, making them both malleable and efficient converters of solar energy.

2.2 Facades

A facade or façade generally refers to one side of the exterior of a building, especially the front, but sometimes it could also refer to the sides and rear of the building. In architecture, the façade is one of the most important parts from a design point of view, because it sets the tone of the building.

2.2.1 Multifunctionality of PV modules on the façade

In this way, the multifunctionality of PV modules widens the spectrum of market approaches when energy generation is no longer in the foreground. Figure 12.9 illustrates the functions of a PV facade element as a substitute for conventional elements.

Basic functions of the external covering of the building: weatherproofness

Physical functions: Thermal insulation, soundproofing, damp proofing, fire protection

Energy conversion

Sun and visibility protection, light deflection,

electromagnetic design

Figure 1 multifunctionality of pv façade (Ingrid Lützkendorf, IFF Weimar)

The PV module must assume the basic functions of the external covering of the building; these functions include weatherproofing, protection against mechanical impacts (e.g. hailstones), optical impression, and so forth. Alongside these basic functions, a number of physical functions must be given. Thermal protection and damp proofing are essential to the energy use, fireproofing is a safety consideration, and soundproofing heightens the quality of life. In locations close to airports, and particularly in the case of tall buildings, it may be important to consider electromagnetic damping properties in order to reduce radar radiation. Contemporary PV modules are not designed for the above-mentioned functionalities. For more than 20 years now, form and structure have been dictated by the need to obtain maximum yields from minimal space. All the same, such modules are being deployed as facade elements after undergoing slight alterations.

2.3 Building Integrated Photovoltaic (BIPV)

Figure 2 Coloured solar panels

The building façade (envelop) provides a number of possibilities for the integration of a solar panel system. Roofing material, curtain wall, construction glass and shading structure on the external fabric of the building are potential areas for incorporating solar cells.

A Building Integrated Photovoltaics (BIPV) system which integrates photovoltaics modules into the building envelope as part of the building structure is introduced to maximize the amount of active surface area of building exposed to solar radiation. BIPV systems are considered to be multi functional building materials; therefore, they are usually designed to serve more than one function. Basically, the PV modules serve the dual function of building skin by replacing conventional building envelope materials and acting as power generator. Nowadays, this system is not only getting more efficient, it also becomes more attractive and adaptable.

There is a rising trend to shift from conventional PV systems to BIPV as more and more architects and building owners begin to understand the great potential of BIPV. The flexibility of BIPV is such that it can meet the architect’s imagination and result in a building that is both attractive and environmentally friendly.

A successful BIPV solution requires interaction between building design and PV system design. In order to be effective, BIPV products are designed to be flexible in matching dimensions, structural properties, qualities, and life expectancy of the materials they display. Many people also consider them more visually appealing as compared to the solar panels which are not always pleasing to the eye due to their obtrusive appearance. Most of the time, BIPV can be naturally blended to the building design, creating a harmonious architecture.

Architecturally, the size of the BIPV system physically depends on the dimensions of the building’s available surface area. The type of PV technology to be adopted is partially determined by the balance between the electricity requirements and the size of surface area available. When the available surface area is large, amorphous silicon can be the most suitable type of solar cell as it costs less than the solar panel system made of crystalline solar cells.

BIPV systems consist of BIPV construction materials and balance-of-system (BOS) hardware. The BOS hardware is composed of cabling, wiring, and structural elements which hold the modules in place, as well as grid-metered connections, fault protectors, a power conditioning unit (inverter), and an energy storage system, as needed.

In order to maximize the performance of the BIPV system, both environmental and structural factors should be taken into consideration. Some of the key considerations for these kinds of systems are system orientation and tilt, electrical characteristics, and system sizing and shading.

3. Literature Review3.1 Case Study (1) ZICER BUILDING - University of East Anglia

Figure 3 Zicer building

3.1.1 General background

Site background

University of East Anglia (UEA), established in 1963, is a public research university in Norwich, England. Since 1990, the university has implemented the policy to attain energy efficiency in new buildings. In 2003, the Zuckerman Institute for Connective Environmental Research (ZICER), a new building for the School of Environmental Sciences, was built as a big step towards fulfilling the aims of this policy. The building has five floors and occupies a space of 2,860 m2.

Goals

The goals of the ZICER building design are to focus on the technical aspects of constructing a low-energy building; to incorporate renewable energy; and to adopt a good energy management system. Another objective is to demonstrate the use of solar panels on the facade as well as on the sloped roof.

3.1.2 Solar panels on ZICER building

Figure 4 Solar panels on zicer building

Solar panels are incorporated on the top levels of the façade and on the roof of the building. Energy generated from the system is either used within the building itself or exported to other buildings on the UEA campus.

The glass PV is fitted to the ‘atrium’-like arrangement on the top floor, which was designed to maximise the potential for demonstrating PV: both on vertical and gently sloped roof surfaces.

Glass/glass laminates were selected to give semi- transparent glazing. The area behind which the solar panels are installed is naturally ventilated, with air entering at low levels, passing over the PV panels to remove heat, and leaving again through louvres at high levels. The roof shape was also designed to draw warm air up over the PV panels in the roof, and away from the occupied area.

On the flip side, with a space constraint of only one surface of one storey façade, an isolation limit for vertical surface and the low efficiency of polycrystalline cells, it is predicted that the façade arrays can hardly achieve the estimated output.

Initially, the plan was to use thin film (amorphous silicon) arrays in the vertical glazing. Although its efficiency is lower than that of polycrystalline panels and twice as much space is needed to generate the same amount of energy, they are able to attract direct sunlight and diffused sunlight such that they can be operative even when the modules are partially shaded.

However, due to manufacturing difficulties with the double-glazing unit, thin film was replaced by square crystalline cells: polycrystalline cells on the façade, and monocrystalline cells on the roof. Square cells are more expensive than the usual octagonal cells because they need to be cut from circular cells, so there is more wastage. They were chosen here purely for aesthetic reasons. The solar-panelled façade consists of 3360 polycrystalline cells. The solar-panelled roof consists of 12,320 monocrystalline cells. Thirteen Fronius IG 20 inverters are used for the conversion of energy generated by the solar panels on the roof.

The solar cells are spaced to provide 15% transparency to allow visibility of the outside and at the same time provide adequate shading from the sun.

Module type

BP Solar glass laminates

Module power rating

194 W p (roof) and 80 W p (façade)

Module area

1.87 m2 (roof) and 1.00 m2 (façade)

Sub array arrangement

140 (roof) and 84 laminates (façade)

Sub array size

27.16 kWp (roof), 6.4 kWp (facade)

Array orientation

10° East of South

Array inclination

15° pitch on roof, and vertical façade

Total modules

224

Total area

350 m2

Total system size

33.88 kWp

Table 1 Technical specifications of solar panels

PV laminates

£169,580

Inverters and wiring

£36,061

Roof

· Frame

· Glazing (labour)

· Gutters/flashing

£40,471

£7,831

£4,390

Façade

· Frame

· Glazing (labour)

· Gutters/flashing

£17,595

£3,205

£3,074

Table 2 system cost

The BIPV system was funded through the DTI Major PV Demonstration Programme and the EU Framework 5. The project’s total cost is £5 million. The total cost of the BIPV system, excluding monitoring cost, is £323,847, which is about 6.5% of the project cost. The system cost will be analysed later in the part of performance study.

3.1.3 Construction

Design

Figure 5 Design of ZICER building

One big challenge encountered was that the funding for the BIPV system was secured only after the construction had started on site, which means that the design team had to cater for maximum flexibility. This actually caused a lot of troubles because the solar panels must be incorporated into the building and the designs of other members are dependable on the PV system design.

For the façade PV system transparency is very important. This value of 15% transparency is decided by the spacing between modules as well as by the array arrangement. In the case of ZICER building, the arrays on the façade are not placed next to each other so that there can be a band of clear gap at the eye level to improve the view from the top floors.

The cleaning gantry for the façade glazing was carefully designed so that there would be no shading of the PV arrays.

Installation stages

(a) A steel frame structure was constructed between the reinforced concrete stair tower;

(b) The mechanical ventilation system for the building was installed;

(c) Curtain walling system installed on the roof and south façade;

(d) Passive ventilation grills and framework were installed;

(e) The glass/glass laminates were installed on the roof and the façade;

(f) Glazing trims, trims, flashing, and cover trips were installed;

(g) The cleaning gantry was installed and tested, and the glazing cleaned; and

(h) The inverters and monitoring equipments were installed.

3.1.4 Monitoring system

The monitoring system consists of:

· A solar irradiance sensor that measures how much the amount of sunlight falling onto the arrays

· Temperature sensors that monitor both ambient temperature as well as the PV module temperature

· AC and DC monitoring

· Trend Building Management System

Data from different sources are all gathered in the Building Management System control centre. This system reviews the way how energy is being used and identifies possible improvements that can be made to save more energy. Therefore, if the system is optimized, significant energy savings can be made. One important thing is that the energy reduction programme needs to be measured and monitored. A typical Building Management System can control 60-80% of a building’s energy usage.

Problems

Solutions

· Two inverters discovered not to be working.

· Cell temperature equipments not working.

· Insolation meters to measure had not been installed.

· No import/export meter had been installed.

· Independent PV meter for electricity output gives incorrect reading.

· Installer contacted inverters operational on 27 February 2004.

· Cell temperature equipment corrected and commissioned on August 2004.

· After they were fitted there were problems with the readings. Light sensors were sent to the manufacturer for repair.

· Meter installed in February 2004, but both had failed by April 2004. New meter were installed in May 2004.

· A 40 A current transformer was installed in place of the incorrectly sized 400 A CT.

· Fronius foftware not working due to a fault with the data connection.

· Communication cards/cables had not been installed correctly. Two new communication cards fitted on 19 May 2004.

· A fault with on inverter due to it not being configured for the UK.

· Inverter fault corrected on 6 April 2004.

· External temperature sensor not calibrated correctly.

· New meter installed on 19 August 2004, and calibrated correctly.

· Cell temperature sensors stopped working.

· Cable had been cut by a contractor – rectified November 2004.

· Inverter off line.

· Problem traced to a loose connection on printed circuit Board.

· No data recorded by the Building Management System.

· Problem still not resolved at completion of monitoring.

· A number of roof modules show significant delimitation.

· The manufacturer replaced them at their own cost.

Table 3 Maintenance log

3.1.5 Performance study

Total PV system output

22,650 kWh/year

Roof array

730 kWh/kWp

Façade array

415 kWh/kWp

Power used in building

249,760 kWh/year

Power imported into building

227,500 kWh/year

Power exported to grid

390 kWh/year

Table 4 Energy summary results (2005)

During the first year of generation, a total of 22,650 kWh was provided to the building, slightly below the predicted output of 28,400 kWh. The roof array performed better than the façade, which was expected.

System efficiency

When sizing the PV system and calculating predicted system output, module efficiency and inverter efficiency must be carefully considered so that the output will not be overestimated and the unit energy costs and the energy payback time underestimated.

Figure 6 Effect of average hourly solar radiation on (a) Monocrystalline and (b) polycrystalline cell efficiencies

The module efficiencies were derived from the inverters and also backed up by more accurate independent monitoring. Correction was made to the readings from the inverters as they were shown to have underestimated the D.C. power by 7-9%. From the scatter in figure 6, it is shown that module efficiency is affected by the cell temperature. For each one degree variation in temperature the efficiency changes by about 0.4%. The temperature in the standard test condition is 25 o C, but the solar cell temperature can be up to 70 o C. It means that the potential reduction in efficiency is 18%. The monitoring data shows that for monocrystalline PVs the maximum hourly apparent module efficiency is approximately 14.0% but the overall annual average module efficiency of PV electricity generated is only 11.1%. For polycrystalline PVs the two values are 9.5% and 7.5% respectively. So we can see that although applying BIPV to the façade has the disadvantage of shading and less insolation, the module temperature of the panel on the façade will be lower than that on the roof and the system efficiency will not be as much reduced.

Figure 7 Conversion efficiency of two PV inverters from d.c. to a.c. electricity. The measurements were supported by independent metering: (a) efficiency with input power; (b) efficiency as a function of input power to power rating of inverter. The inverter has sizing ratios of 1.24 and 1.5 respectively

The annual average inverter efficiencies are 89.7% and 91% from the arrays on the façade and roof respectively. The inverter efficiency depends very much on the sizing ratio of PV array output to the inverter capacity.

The average overall system efficiency taking into account both module and inverter efficiencies for the monocrystalline PVs is 10.1% with the maximum actual value of approximately 12.7%. The average system efficiency compares favourably with corresponding efficiencies for other systems reported in the UK. (Table 5)

Location

Monitoring period

System efficiency %

Northumberland building, University of

Northumbria, Newcastle-upon-Tyne, UK

1995-1997

8.1

Solar office, Doxford International,

Sunderland, UK

Mar 1998-May 2000

7.5-8.0

Jubilee Energy House, Nottingham

University, Nottingham, UK

Sept 2000-Aug 2001

8

Eco Energy House, Nottingham

University, Nottingham, UK

Sept 2000-May 2002

3.6

Gaia Energy Centre, Delabole,

Cornwall, UK

Jan 2003-June 2003

9-10

PV domestic installation, UK

(average of six systems)

12-25 months

8.2 (6.5-10.4)

Ecos Millennium Environmental Centre,

Ballymena, Northern Ireland

Dec 2000-Dec 2003

7.7

Table 5 Actual recorded crystalline PV system efficiencies in the UK

Performance prediction

The predicted average annual electricity generation of the ZICER building is 2860 kWh (427 kWh/kWp) for the façade array and 22,300 kWh (820 kWh/kWp) for the roof array. The figure 8 on the next page shows the predicted monthly output.

Figure 8 Monthly average predicted ZICER PV electricity generation

There are some reasons why the predicted output did not turn out to be very accurate but the most significant reason is due to the two assumptions: no shading and no downtime. Let us see how the predicted output can be corrected by taking into account the assumptions.

Shading from other neighbouring buildings theoretically reduces output by 4.0%, which means the predicted output is reduced from 2860 to 2770 kWh. However, in reality the reduction should be much more than that because the cells are connected in horizontal arrays. If one cell in an array is shaded and cannot generate current the whole module output will drop to zero. This effect further reduces the predicted output to 2660kWh.

During downtime such as having bad weathers, the PV arrays often trip. The problem is that the automatic reset function is not installed, so it often takes several days to rectify if the trip happens over weekends or holiday periods. Monitoring data shows that during the study period there were more than 26 days when the electricity generation was zero. Those incidents lead to further loss of the output of about 100 kWh/year and the final predicted become 2570, which is very near to the mean actual electricity generated of 2570 kWh.

Applying the same correction method, the roof array predicted output is reduced from 22,300 kWh/year to 20,280 kWh/year, which is quite comparable to the actual value of 19,600 kWh/year.

For output prediction, the azimuth and tilt angle of the arrays are significant. Table 6 shows that with different combinations of tilt angle and orientation, the proportion of maximum electricity generation achieved can range from 100% at South-30° to only 45% at East-90°.

Orientation

Proportion of maximum electricity generation %

Tilt angle

0°

15°

30°

45°

60°

75°

90°

East

87

84

80

73

65

55

45

South-east

87

92

93

90

83

72

58

South

87

96

100

98

91

80

63

South-west

87

94

97

95

89

78

64

West

87

87

84

79

73

64

53

Table 6 Percentage output of maximum electricity generation of PV arrays with different tilt angles and azimuth

Economic Analysis

The viability of a PV system can be determined comparing its unit cost with the unit cost of other electricity generation sources. There are two components of the unit cost, the regular maintenance cost and the payback of the initial capital costs each year, taking into account the discount factor and the annual degradation of the solar cells.

In this study, different economic scenarios are applied when calculating the unit cost. Therefore there are a range of cost scenarios shown in table 7, where a discount factor of 5% is applied.

Scenario

Description

Net capital cost of PV system (£)

Capital cost per peak Watt (£)

A

Actual Zicer PV cost including installation, ancillary equipment and design fee.

482,350

14.20

B

Sinilar to ‘A’ but include fundings from UK government and European grants totaling £172,200 towards the cost of the ZICER PV installation

310,150

9.15

C

Including “avoided cost”

209,000

6.12

D

Similar to ‘C’ including actual PV grant towards the ZICER PV installation

36,800

1.09

E

Average European cost of PV power in 2006 including installation/design fee

Not applicable

8.00

F

Similar to ‘E’ including a 50% governmental PV grant

4.00

Table 7 Scenarios used in the analyses

The PV system has no moving parts hence the maintenance costs of the arrays are minimal. The maintenance cost considered in this study only includes the replacement of inverters which is estimated at 0.4% of the total capital cost.

The avoided cost mentioned in scenario C is the cost saved as a result of applying BIPV instead of the traditional standard glazing unit.

Table 8 summaries the key information for each of the scenario for three different discount factors (3%, 5%, 7%) and for three different solar radiation values.

Discount factor

Solar radiation

(kWh/m2 per year)

Cost (£/kWh)

Scenario

A

B

C

D

E

F

3%

800

1.75

1.16

0.76

0.17

0.98

0.52

1000

1.37

0.91

0.59

0.14

0.77

0.41

1200

1.13

0.75

0.49

0.11

0.63

0.34

5%

800

2.13

1.14

0.92

0.20

1.20

0.63

1000

1.67

1.11

0.72

0.16

0.94

0.50

1200

1.38

0.91

0.60

0.13

0.77

0.41

7%

800

2.55

1.68

1.11

0.24

1.44

0.75

1000

2.00

1.32

0.87

0.18

1.13

0.59

1200

1.65

1.09

0.72

0.15

0.93

0.48

Table 8 Unit costs of energy generated by PV for different discount factors, solar radiation and scenario

Even when grants and avoided costs are considered during analysis, the unit cost of installing solar panels is still higher than the conventional generation costs on electricity bills. It means that it would be difficult to promote solar energy as a competitive souce of renewable energy due to cost being one discouraging factor.

3.2 Inference for the Case Study 1

1. It could be a possibility to use fan-assisted systems to cool down the PV panel and as a result limit the reduction of efficiency in solar cells due to high cell temperature. We may think about the possibility of combining the use of stand-alone systems and grid-connected systems for buildings in Singapore. Energy generated from the stand-alone system can be used to operate the fan system, while energy from the grid-connected system can be used to operate other loads in the building.

2. Good inverters can help to make sure the panels operate at their peak efficiency.

3. It is important to decide on the optimal size of the PV system.

a. We must identify the purpose of the system and calculate the total daily energy consumption of the loads that will use energy from the PV system.

b. We must notice that PV modules only operate at the peak watt when they receive 1000 watt per square meter of exposure to the sun. therefore, we must determine the daily amount of sunlight available in the local region in order to identify the yearly average of the daily watt-hrs of electricity for each peak watt that a PV module is rated. This value should be calculated in all the months in the year from which the lowest value will be taken.

c. We must calculate the needed peak watt of the module given the inverter efficiency and safety factor.

4. PV systems in Singapore also encounter the same problem of shading and downtime, the prediction method discussed in the study based on the monitoring data in 2005 would be a good method to apply for buildings in Singapore.

5. We should customize the cell spacing of the PV modules, if possible, because it decides the transparency level of the façade and affects the indoor environment significantly.

6. Façade array arrangement must be designed carefully so as to make full use of the façade area for PV system. At the same time, we must maintain a suitable transparency level that allows for reasonable view from the inside and also satisfy the indoor environment requirement.

7. A lot of problems occurred during the construction phase because the system design could not be finalized soon enough and the contractor in charge of the PV system did not seem to be suitable for the job. Applying BIPV technology means that the PV modules are integrated as part of the structural members of the building. For the system to work well, everything must be designed together, as a whole unit, so that all the system components can operate as planned.

8. Heat would be generated in the process of energy conversion, it is advisable to place solar panels in opened areas to allow dissipation of the heat released.

9. The angle of tilt of solar panels is very important in ensuring maximum efficiency. If placed at an inappropriate angle, there would be a 50% reduction in the system efficient. Much effort needs to be done to investigate the condition of the region in which you plan to install the solar panels.

10. Solar panels are reliable because it is shown that the percentage of system efficiency in the different countries is about the same. Even though different types of solar cells or arrays are used, they are all able to generate a considerably fair amount of energy. There is no wide range of the types of solar panels that we can distinguish the good from the bad. Each type of solar cells or panels are used to suit different purposes of the building, aesthtic purposes, research purposes and so on.

11. Government fundings and grants can help to reduce the cost of installation for up to 70%. Since costs is the most crucial factor that is stalling people from using solar panels to generate renewable energy, the government has to step in to at least introduce the use of solar panels. This can be done through giving incentives to private or public organisations, as a form of showing support and determination from the governmental sector in using clean energy.

3.3 Case Study (2) William Farrell Telus Building3.3.1 General Background

Figure 9 Overview of the William Farrell Telus Building

General Description:

8 story office building

Gross/Net Floor Area:

12,193 m2/8,654m2

Typical Building Population:

500 persons

Table 9 Specification of the building

William Farrell Telus Building is located in Vancouver, British Columbia, at the latitude of 49.11 N and longitude of 123.10 W. The altitude in Vancouver is 3 meters above sea level. The mean monthly temperature ranges between 3 to 17 degrees Celsius. William Farrell Telus Building is skewed at nearly 45 degrees off the north south axis.

William Farrell Telus building is the headquarter of Telux, one of the Canada’s largest telecommunications companies. The building was built in 1947 for housing telecommunication equipment together with technical and administrative staff. In 2000, due to the plan of raising company’s profile and the change in building space requirement, Telux building must be changed. Being a community leader in working towards environment sustainability[footnoteRef:6], the company decided to renovate the existing building instead of demolish it and build a new one, which would result in a lot of unnecessary waste. [6: Boyes, A. & Henderson, K. & Krejcik, A. & Sibbald, B. Telus William Farrell Building,Vancouver BC. 3A Environmental Design.]

3.3.2 Goals

The project aimed to renovate the building in order to provide more work space that was safe, efficient and healthy. Green strategies were applied for both interior and exterior renovations to reduce as much as possible waste during construction process and to establish an environmental friendly and energy efficient building.

3.3.3 Special Features

· A new second skin of double glazing was added to the existing façade to form a triple skin façade, which is the one in Canada. The new façade plays a very important role in the building energy efficiency and indoor environment quality including air quality, lighting.

· The renovated building has natural ventilation and natural day lighting. Operable windows provide the buildings users with a certain level of indoor air quality control. BIPV arrays are installed on the North West and South West façade, and the generated electricity is used for a fan assisted ventilation system which provides natural ventilation for the building. Interior light shelves promote natural lighting by providing diffused sunlight farther to the indoor areas.

· Heat recovery system is applied, which is an important part in the green strategies of the project. This system reuses heat emitted from the building occupants and electrical appliances and assists to reduce CO2 emission of the building.

3.3.4 System Details

The new innovative triple-skin façade:

The new double glazing layer is suspended from the existing façade about 90 cm, which creates an air space called plenum in between. This plenum has different functions in different weather. In summer, it is ventilated to cool down the temperature of the façade and at the same time reduce the heat radiated from the façade into indoor space. Dampers together with PV-powered fans are installed to naturally ventilate the plenum. The air is ventilated from the bottom and goes out of the façade through louvers at the top of the façade. In winter, the dampers and louvers are closed and the plenum becomes a very effective insulator of the whole building. Moreover with the air gap between the two layers, the façade can absorb much more solar energy in the form of heat then re-radiate the heat into the building. Electronic temperature sensors are used to control the ventilation system and maintain the air space temperature at an optimum level. With such functions, the new triple-skin façade helps to reduce a significant amount of energy in ventilation and heating system.

Figure 10 Schematic diagrams showing characteristics of the interstitial space during summer and winter day conditions

(BC Buildings Corporation , 2000)

Figure 11 Ventilation themes in summer and spring/autumn

(Boake, Chatham, Harrison, & Lum, 2003)

Apart from the special feature of plenum, the façade has a graduated fritted pattern on the exterior glazing that acts as a solar shade. The fritted pattern is designed with much consideration to ensure that it can provide shading especially during the sunniest times of the year and also ensure comfortable view from inside.

BIPV arrays:

System Type:

· New Construction – BIPV Curtain Wall – Polycrystalline- Grid Tie

Solar production:

· 2.5 kW Solar Array

Supplier of Solar Panels:

· Soltek Powersource Ltd. (SPS Energy Solutions)

Engineering:

· Soltek Powersource Ltd., BC

Figure 12 BIPV system

The photovoltaic array is designed to operate a fan system that ventilates the air gap between the new and old exteriors. Carmanah supplied the 2.5 kW array to the project, which benefited from a National Research Council grant. The array is comprised of twenty 125 watt custom designed solar modules. The Southern and Western façades have 10 each of the modules arranged horizontally across the top of the building. [footnoteRef:7] [7: Carmanah Technologies Corporation. Solar Grid Tie Project References.

]

The special feature about the BIPV system in the case of Telux building is that the generated energy is only used for the fan assisted ventilation system. The advantage is that the system can be simply designed because there is no inverter needed. The DC generated from the two arrays can be used directly to operate the fans located right inside the façade. As a result, the cost for the solar system is not very high but its effect in reducing energy consumption is significant. . There was one problem with the BIPV system which is due to the system size. The power generated from the system is not enough to generate the fans at requirement system.

Heating and ventilation system:

One distinctive feature of the heating and ventilation system of Telux building lies in the special triple-skinned façade with air space. Apart from that, the heat recovery system is also a major innovation in the effort towards an energy efficient building. The heat recovery system that replaces the traditional stem-heat system uses waste heat from the process cooling in an adjacent Telux building. The surprising thing is that by reusing only waste heat, this system can provide 85 percent of the building heat and as a result dramatically reduce the building’s emission.

Taking advantage of the high floor-to-ceiling height and the fact that no ceiling was installed for the original building, engineers installed underfloor pressurized plenum with a raised-access floor. The underfloor plenum is used to provide conditioned air to diffusers in the occupied areas of the building. The diffusers allow occupants to have individual control of the conditioned air flow and therefore help to improve thermal comfort, air quality and energy efficiency. The fan energy consumption of this system is also lower than the traditional overhead ducted air distribution system as the static pressure requirements are lower. Moreover the underfloor plenum structural mass can act as heat storage member, which slowly releases heat and helps to reduce peak cooling load.

Figure 13 Ventilation system

Natural and artificial lighting:

Figure 14 Natural and artificial lighting

1. Interstitial space- seasonal climate buffer zone

2. Daylight reflector and sunshade

3. Aluminum framed glazing curtain wall

4. Solar shade glass panel- ceramic frit glass panel reduces solar heat gain

5. Operable windows-existing restored

6. Operable windows- new mechanized

7. Existing exterior wall- exposed concrete

8. Curtain wall hangers

9. Steel reinforcing for curtain wall frame

10. Raised office floor

11. Air plenum in raised floor

12. Air diffusers

13. Natural ventilation possible in moderate Temperatures

3.3.5 Design

Plenum Height:0.46m (18 in.)

Diffuser Types:Krantz swirl diffusers are used for all interior and perimeter areas.

Raised Floor:0.61m (24 in.) wood-core panels using a stringer-less post mounting system were supplied by APS Access Floors.

Supply Temperature:Air Nominal 17°C (63°F), varies with load

UFAD Types:System Constant air volume – variable temperature (CAV-VT) for delivery to the space; variable air volume (VAV) at air handler

3.3.6 System Performance

With the installation of the building’s new skin and the innovative heating and ventilation system, the facility uses 30% less energy than one built to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard. The energy consumption level is also about 35% more efficient than levels stipulated by Vancouver’s energy by laws.

The amount of energy saved signifies that the company’s expense on energy is reduced and the amount of CO2 emission is reduced. The result of the completed building saves 15,600 tonnes of greenhouse emissions (CO2). The new building system operations is expected to save 520 tonnes of greenhouse emission per year for an estimated 75 years lifespan. The project will thus save in total 54,600 tonnes of greenhouse emissions.

3.3.7 Economic Analysis

As compared to traditional cladding systems in North America, double skin systems may cost up to four or five times in price. This increase in price is due to additional engineering costs, and increase in material (special glass) and labour costs due to unfamiliarity among the trades, as well as generally higher maintenance costs. If the initial cost can significantly reduce the overall ongoing operating cost of the building than the initial capital investment can be justified. Telus put forth an up-front financial commitment that will pay for itself over time. Their primary motivation was a dedication to environmental sustainability and a healthy workplace. This impact was immediate: emission of green house gases was reduced significantly in the first year.

Telus proves through their environment policies and beliefs that they are a responsible company dedicated to the well being of their employees and the environment. This building was successful in many ways, the environment and people benefited greatly from Telus' environmental goals. In the past, there had been health-related complaints by some employees, which were perceived to be the result of "sick building syndrome". These employees have stated that as a result of this renovation they feel much better and healthy in the updated William Farrell Building. Overall, the environmental considerations for the building were received with great success.

3.4 Inference for the Case Study 2

1. First of all, this case study shows that renovating the building when installing or updating solar panel systems in a building is more cost effective. During a building’s lifespan, there might be times when new requirements or needs with regards to the solar panel system (or any other system for that matter) are raised. And it has been a traditional practice to replace the old building entirely with a new one without considering renovating it. It has been proven that renovating existing building, although requires extra effort, can really save a huge amount of materials while ensuring that the new needs are met.

2. With an air space, fritted glass, and light shelves, the façade has multiple functions, such as ventilation, thermal insulation, noise reduction and daylighting. The façade can promote many passive methods to improve indoor environment quality and therefore make significant impact in reducing energy consumption of the building. Apart from that, the application of BIPV system to the facade to operate the fan assisted ventilation system is also a very wise use of solar energy. While using only simple and not too costly BIPV system without inverters, the PV-powered fans really plays an important role in the building’s ventilation system and energy efficiency. However, the problem is that due to the small size of the PV system, the fans sometimes cannot operate at the required speed. Therefore, while applying this technology, the size of PV arrays should be carefully considered. In the Singapore context, applying the concept of triple-skinned has a big advantage which is the clean outdoor air of Singapore. As the outdoor air is clean, it can be used for circulating the façade plenum and effectively improve the indoor air quality.

3. The existing building owned by Telus, which was of solid masonry exterior wall construction with “punched” double hung wood windows was cleaned, retained, and clad with a new exterior fully glazed skin. The use of the double skin allowed for the salvaging of the existing structure and the upgrading of the quality of the interior environment. Lower operational costs are also expected.

4. The triple skinned facade can be modified to double skinned, which keeps the same thermal cavity idea for controlling the temperature of building. Instead of using the heat generated from the adjacent building, some building may have different type of machines operating for specific industry, that heat can be retrieved and recycled. The new heating and ventilation systems of Telus building are usually installed in a large scale, and require a large capital investment. They are more suitable for commercial buildings rather than residential. Moreover before installation takes place, engineers should conduct a thorough study of the building structure and the site condition in order to achieve optimum energy performance. However some smaller devices, like fritted glass, light shelving, and natural ventilation idea can be used in any building of any size.

5. Control of sunlight and solar heat (by the use of fritted glass for solar shading, the use of light-shelves to increase daylight penetration, and the use of the concrete structure as a heat sink) can be incorporated into many designs to increase energy-efficiency.

4. Findings4.1 Interview4.1.1 Grenzone Company

This interview was conducted on 30 September 2009, 3.00pm, at Grenzone Private Limited. It is located at Woodland Spectrum 1, Woodland Sector 1 #05-14. Grenzone is an innovative company that designs and manufactures energy and energy efficient products. Their portfolio in Singapore includes Building Construction Authority Zero Emission Building (BCA Academy ZEB) and 313 Orchard Shopping. The company has several projects being carried out in ASEAN countries like Timor Leste and Australia.

Brief description of the interviewees

(a) Dr Toh Pen Seng (Director of Grenszone Pte Ltd)

He obtained his B.Eng degree in Electrical and Electronic Engineering from Nanyang Technological University in 1987, and Ph.D degree from Imperial College of Science and Technology, United Kingdom in 1991.

His working experience includes technical, management and academic positions with Axiom Innovations (UK), Nanyang Technology University, Vital Technology, Hewlett Packard and Agilent. He is presently the managing director of Grenzone Pte Ltd., a company founded in 2002 to focus on renewable energy and energy efficient appliances. Dr. Toh has published more than 50 technical papers in journals and conferences. He has at least 25 patents in the areas of machine vision automated optical inspection and environmental technology.

(b) Mr Teo Boon Teck (Application Manager of Grenzone Pte Ltd)

He is a Project Manager with Grenzone Pte Ltd. He is in charge of the Singapore and ASEAN renewable energy market. He holds a B.Sc. degree in Computer Science from The Open University and also a Diploma in Manufacturing Engineering from Singapore Polytechnic.

He has worked as an Industrial/Production Engineer for six years in the manufacturing industry and three years as a Technical Engineer in machine inspection. He is an experienced speaker on Photovoltaic technology and he has participated actively on solar system seminars and educational solar projects, organized by local universities and polytechnics.

Summary of interview

Mr Teo began the interview with a brief description of how solar panel technology works in theory: For grid connection systems, the energy is not stored in a battery. The solar panels absorb sunlight and convert it into electrical energy (DC). The DC energy is then sent through an inverter which converts it into AC energy. The actual generated power (AC) is then linked to the electrical switch board. Grid and solar generated energy run in parallel to each other, such that when the solar generated energy is insufficient for the building’s energy needs, grid power is there to back up the supply. If there is an excess in supply, the energy will flow out and supply neighbouring buildings. Export and import figure of kilowatt/hour (kwh) meters are used to record the energy consumption of the building.

According to Mr Teo, his understanding of the Singapore solar panel technology is that the main disadvantage is the cost. There is a long payback period of 25 years, without any subsidies provided. To address these concerns, Grenzone offers a 25-years warranty for their solar panels to ease the need to spend on the maintenance works. This will prevent the client from bearing extra costs, thus encouraging more people to use energy efficient equipment. The Singapore government has also introduced a scheme to subsidise industrial building managements and other developers. This can further reduce the payback period.

The method of installation for the solar panels depends on the types of roofs. He mentions three types of roofs namely, concrete flat roofs, roof tiles and metal roofs. The common method of installation is the clamping method. This is to prevent voiding the warranty of the building elements, particularly the roof. As compared with installation on a roof, installation on a façade is more difficult. This is because there is nothing behind the façade. The heat emitted from the solar panels as the solar energy is converted into electricity invariably heats up the building, thereby resulting in either increased costs in terms of building cooling devices such as air conditioners, as is the case of the Buona Vista Biopolis solar panels. The heat had effectively raised the temperature of the building, thereby forcing the air conditioners to work harder and to consume more energy, thereby negating any energy savings that might have resulted from solar panel use. Thus Mr Teo recommended that the best installation method for solar panels on façades involves the use of double grazing glass, because another layer of glass is present behind the solar panel in order to reflect the heat away.

Mr Teo repeatedly mentioned that it may not be worthwhile to invest on façade when the energy harnessed is low whereas the same amount of money invest on the roof can obtain higher energy harnessed. This is due to the limitation of the sun path in Singapore. The sun path is always directly upright, +/- degree only. He emphasised that solar panels are more applicable on roof in Singapore.

In a solar panel company’s perspective, Mr Teo said that their main concern is the efficiency of the solar panel when installed onto the building elements. He believed that if the efficiency is too low, the amount spent on the solar panel is considered a waste. This is because there is no gain or benefits for installing a solar panel when only little energy is collected.

When asked about the prospect of solar panel technology in Singapore, Mr Teo was upbeat. “Singapore in the future will have more solar panels. This is due to the introduction of the Green Mark Scheme by the BCA.” Under this scheme, new buildings are required to obtain a minimum of a Gold under their Green Mark Award standards. According to a 120 point standard judging buildings on energy and water usage efficiency, 20 points are devoted to renewable energy like solar generated energy. In order to gain the full 20 points, a renewable source of energy like solar panel technology must replace 5% of the building’s energy consumption. He added, “Other than academies and schools, housing development boards are also participating in this scheme.”

Inference of the interview

We can conclude that costs of the installation and the positioning of the buildings are the main limitation faced by solar panel installations, and there are several disincentives from placing solar panels on façades. If we can overcome the limitations, more developers and clients will turn to green technology like energy and energy efficient equipment.

We can infer that the installation of solar panels integrated with façades is also similar to the installation of curtain walls because the solar modules can be incorporate into the glass panel. This suggests that it is likely that there may be an increase in the popularity of solar modules integrated into the building because it can be accomplished at current technological levels, but it will need to be aided by a breakthrough in solar cells technology. These breakthroughs will have to address the problems that solar panels face in terms of heat emission, solar light absorption efficiency and aesthetic properties.

We can infer that professionals like Mr Teo still have doubt about installing solar panels on the façade due to the limitations in Singapore. However, currently researchers are still looking for a way to enable the solar panels to absorb solar energy or diffused light energy because Singapore buildings’ façade has more surface area as compared to the roof. Should the breakthrough occur, it is likely that with more people adopting solar panel technology, and that will drive costs down.

4.1.2 National University of Singapore

This interview was conducted on 06 October 2009, 2.30pm, at National University of Singapore; School of Environment. It is located at 4 Architecture Drive.

Brief description of the interviewees

(a) Professor Lee Siew Eang

He trained as a building engineer, is the Director of the Centre for Total Building Performance, a joint research centre between the Building and Construction Authority of Singapore and the National University of Singapore. The Centre undertakes R&D work relating to building performance with particular reference to climatically responsive buildings in the Tropic.

Dr. Lee also heads the Energy Sustainability Unit (ESU). The Unit is a fully industry sponsored energy research unit. Major sponsors include the Economic Development Board of Singapore, National Environment Agency, the Energy Market Authority and companies from Singapore and Europe. Current major research programmes of Dr. Lee include energy performance benchmarking of buildings, development of energy labeling systems, baseline models development, and the development of Zero Energy Building in the tropics.

Summary of interview

Our interview with Professor Lee focused mainly on two issues. They are, firstly, the use of solar panels in Singapore from an energy management perspective and secondly, the need to start developing the use of solar energy to prepare for the future.

As an expert on building energy management, he emphasized on the importance of the façade design’s ability to control the solar heat transfer into the interior of the building, as it is an important limitation that could get in the way of energy savings. One way to reduce heat transfer is to provide a cavity between the building façade and solar cells. Ventilation of air inside the cavity can help cool down the heat gained. Other than that, some technologies can be adopted to bring water to the back of solar panel to cool it down; after which the warm water can be recycled for other purposes. He highlighted that, if the solar heat gain is not carefully dealt with, it can even consume more energy for air-conditioning the interior space. Therefore, he suggested, the building, either new or existing, must be designed to be energy efficient first before adopting solar panels as solar energy is expensive to invest in. He further emphasized the importance of proper design of building envelope.

Another issue raised was the difficulties of investment in solar façades. The first difficulty mentioned was the cost, because up till now, photovoltaic technology is still a lot more expensive when compared to buying conventional electricity. But there may come a day when energy prices are so high, especially when oil prices continue to increase. That will force solar energy costs lower or even to a level that is on par with conventional electricity, thereby making the return of investment much shorter compared to current prices. Right now, the return of investment for solar panels is, depending on the construction and where it is put, about 25-30 years. Hence, in reality, the developers who are going for solar panels are obviously going into the technology more because of the environmental issues rather than on pure economic motivations. Most of them receive subsidies and incentives from the government schemes.

The second difficulty is the lack of technical and design experts. The most important concern when adopting solar panels is that Singapore must have a competent designer and technician team. Solar panel design must integrate well with the main system, so that we can switch between the use of solar energy and electricity. Nowadays, almost all buildings that use solar panels also use other forms of electricity because solar panels alone are currently not enough. When solar energy can provide enough power, we can then use 100% solar energy to power our buildings. In case solar energy is not enough, we can use, for example, 80% solar energy and top up with 20% electricity from the Grid.

As a result, given these difficulties, the use of photovoltaic technology has been increasingly popular in Singapore because Singapore has seen the pressing necessity of developing alternative energy sources. This is due to its inability to produce electricity and the rapid increase in oil prices recently. As we do not know whether fossil fuels like oil will run out in the long term, we may need to rely on solar energy. Moreover, solar energy is also a clean source of energy, which suits the current trend in the official policy towards sustainable (environmentally friendly) development in Singapore.

Therefore, what we are doing now in Singapore, Prof Lee emphasized, is to prepare ourselves for that impending future, the world without fossil fuels. Government subsidies to researchers and test-bed projects increase Singapore contractors’ confidence in adopting the use of solar panels. Once they become more knowledgeable, get a better understanding on how to design as well as install solar panels, and get better coordination among the industry, the cost of solar panel and installation will come down. Professor Lee emphasized, “If Singapore does not start to prepare now, in 30 years’ time, let’s say, oil runs out, everybody will be panicking. By then if we want to get solar panels, nobody knows how to install. So the industry has to be prepared for it. Singapore has the need to prepare for it for the future.”

Inference of the interview

From the information we collected during the interview with Professor Lee, there are obvious links to our other findings.

The need to reduce solar heat gain in the process of working of solar panels was also highlighted in our interview with Greenzone Company. Hence, from that, attention must be drawn on how to overcome the heat transfer, which will be discussed further in the later part of this report.

The rapid increase in oil prices and the energy consumption of Singapore in recent years further emphasizes the need to start investing in the solar energy industry.

The following is the energy consumption chart of Singapore and the international oil price charts in recent years. The total energy consumption has been increasing dramatically, as has international oil prices.

4.2 Site Visits4.2.1 Biopolis Helio Building

Location Map

Special glass modules (solar cells) are installed on the façade of Visitor Center at the highest floor

Figure 15 Biopolis Helio Building

The site visit was carried out at Biopolis – Helios Building on Saturday 17 October 2009, 1pm. It is located at One-North, 11 Biopolis Way. Biopolis is a unique work-live-learn-play development by JTC Corporation.

From observation and research, the following were established:

1. Biopolis buildings used different environmentally features to develop a sustainable building.

2. Biopolis developers hope to encourage the building industry to move toward greener and sustainable buildings.

3. Building-integrated Photovoltaic (BIPV) is installed at the highest level of the building on the glass façade and roof to absorb solar energy. We can infer that there is an opportunity to absorb solar energy on the façade despite the limitations in Singapore.

4. The BIPV does not cover the whole surface of the glass façade. We can infer that the solar cells are only installed on the area that has maximum exposure to direct solar energy.

5. The design of BIPV in Helio Building adopted architectural special glass modules on the façade instead of having the whole solid black solar panel on the façade to improve the aesthetics of the building. This implies that aesthetics can be achieved even if solar panels are installed as a façade. Moreover, it also shows that the clients, developers and architects are concerned about the external appearance of the building.

6. The entire system has 10kWp BIPV glass facades at the Visitor Centre and 10kWp conventional multicrystalline PV system on the building rooftop.

7. The renewable electricity generated by the BIPV is used to provide the energy needs of the Visitor Center on that day.

4.2.2 Building Construction Authority (BCA) Academy

Location Map

Overview of Zero-Energy Building (ZEB)

Thin solar stickers (Amorphous Silicon – Uni-solar PVL29) are placed on the sunshade to absorb solar energy

ZEB’s Sunshade

3 Generations of solar panels are installed onto the façade to absorb solar energy and function as a curtain wall. Solar panels’ cables are placed inside the red steel casing and connected to a battery to store the electrical energy.

Overview of Staircase Facade

Solar cells are assembled and placed inside the glass panel. The solar cells are connected with thin cable (silver line on panel) which allows the energy to travel from the cell to the battery for storage.

Surface of the Solar Panel on Façade (Front View)

Sensors are installed on solar panels to continuously monitor solar irradiation and module temperature. The result allows the possibility to calculate the expected output of the PV array for comparison to the actual power output of the inverters.

Sunny SensorBox

The solar cells are connected with thin cable (silver line on panel) which all the energy to travel from the cell to the battery for storage. The thin cables run through the black tubes and then into the red metal casing where direct cables are hidden.

Surface of the Solar Panel on Façade (Back View)

Reflectors are installed together with the solar panel to improve the absorption of solar energy

Overview of Solar Panel on Corridor Railing

Special glass with modules are installed onto the railing to absorb solar panel

Surface of Solar Panel on Corridor Railing (Front and Back View)

Solar Panel on the Roof of Staircase

Figure 16 Zero energy building

The site visit was carried out at the Building Construction Authority (BCA) Academy of the Built Environment on Monday 19 October 2009, 4pm. It is located at 200 Braddell Road. An existing building in this premise has been retrofitted into a Zero-Energy Building (ZEB). ZEB is oriented on a north-south axis with the main façade facing the east and west. Grenzone was awarded the installation of the BiPV system for ZEB.

From observation and research, the following were established:

1. Three generations of photovoltaic systems are installed onto the staircase façade to harness solar energy to generate electricity supply and store inside the battery instead of grid system. This implies that the amount of converted energy by the façade is low and the efficiency of the panels for façade is poor. Mr Teo from Grenzone also commented that the energy harnessed from the façade is only 8 to 10%. In the ZEB, the energy is only sufficient to charge mobile phones.

2. Sun Sensors are installed onto the solar panel to monitor the solar irradiation and module temperature. This indicates that the researchers are studying the feasibility of incorporating the solar panel on the façade through monitoring. It also implies that there is a possibility for the technology to overcome the limitation faced by solar panels on façades in Singapore, for instance, like the angle of the sun path.

3. The third generation of photovoltaic system is used to integrate the solar panels into the building façade and skylight of the ZEB building. This type of system improves the aesthetic purpose of the façade as compared with the first generation. This implies that there is a possibility for solar panel to have dual function by incorporating the functions of the curtain wall and solar panel. We can infer that clients, developments and architects today are still very concerned about the external aesthetic of the buildings. Therefore, if the appearance of the solar panels can beautify the exterior of the buildings, more professionals will integrate them with the building (excluding the cost issue).

4. Reflectors are installed to reflect sunlight to the modules at the railing. This implies that reflectors can be use to attract more sunlight and increase the efficiency of the modules.

5. The low height of the ZEB façade and the location of the building have affected the harnessing of energy form sun. In the ZEB premises, an existing tree and a low-rise building have blocked the sunlight from reaching the solar panel of the facade. This should be the reason for the low amount of energy being harnessed. We can infer that surrounding environment, location, building’s design, orientation, and building’s height should be taken into consideration before the installation of solar panels.

5. Feasibility Results5.1 Prospect of Solar Panels in Singapore

While other countries in the world such as Germany, Japan, and Hong Kong have adopted Building Integrated Photovoltaic (BIPV), Singapore can also begin to utilize this fast-growing technology.

In 1992, when Singapore launched its Green Plan to become an environmental tech hub, the idea of this sunny island plugging into solar power was raised, discussed but ultimately dismissed.

Today, however, Singapore wants to become one of the world's centres for clean energy. Funds amounting to $350 million have been set aside for the strategy, which the EDB says will be a 'full government effort' involving agencies including the Housing Board and research institutes, among others.

5.1.1 Current Situation regarding solar energy globally

The price of solar power is falling by 5% a year, and this is what will cause demand to increase tremendously worldwide (Tay, 2007).

Nevertheless, sceptics of Singapore's clean energy push point out that Germany and Japan, two of the world's leading users of solar power, are a long way ahead in the game. Through strong government subsidies, the two nations have the highest number of solar installations worldwide.

How then will Singapore compete? For one, when the cost of solar power falls to a point where it can compete with fossil fuel energy without subsidies, urban demand is expected to increase globally.

This presents an added bonus for Singapore if this demand materialises would be the fresh lease of life given to the semiconductor manufacturing sector, as the materials and technology for making silicon solar panels are similar to those used in electronic chips.

Suitability of using solar panels in Singapore

Singapore is located close to the Equator, hence is able to receive optimum sunlight in day time. Singapore’s solar radiation is 50% more than in Germany, a country which successfully adopted the use of solar panel in renewing energy. Moreover, solar radiation in Singapore is regular throughout the year while other countries have little provision of radiation in winter and excess provision in summer. Solar radiation in Singapore also has the predominant diffuse nature, which enables vertical surfaces to receive high amounts of solar radiation in all orientations.

“High amount, constant and even provision and the predominately diffuse nature of solar radiation are key advantages for grid-connected BIPV” (Wittkopf, 2004).

Suitability of using solar panels on building facades

The current designs and construction methodology of Singapore’s buildings makes it suitable to install solar panels on building facades. Singapore has a large number of tall and slim buildings and skyscrapers, which means that the area of facades is larger than the area of roofs. Hence, solar panels could be installed on the larger area of façades to receive greater amounts of radiation as compared to those received on the roof. In addition, due to the buildings having close proximity to one another, solar panels on facades can also be used to receive reflective light from the surroundings.

5.1.2 Increasing usage of solar panels in Singapore

As Singapore has to cope with very limited resources, utilizing solar energy will be a viable way to save costs and maximize efficiency. For example, land constraints in Singapore make it practically impractical to construct solar power plants to produce solar energy. Hence, it gives great support to the idea of integrating solar panel into building facades which not only saves land, but greatly make use of existing facilities. Furthermore, with the lack of natural resources, Singapore has to import all of its fuel. Thus, these make solar power even more attractive.

Currently, Singapore government is very supportive of transforming Singapore into a “living laboratory for solar energy”.

Solar Capability Scheme (SCS)

The Singapore Clean Energy Programme Office (CEPO) has initiated a programme known as the Solar Capability Scheme (SCS) which is applicable for private sector projects. Launched in 2008, the S$20 million SCS aims to encourage the integration of solar panels into green building by subsidizing up to 40% of the project costs. Some projects under this scheme have adopted solar panels into building facades, such as the City Developments Limited’s Tampines Grande, Robert Bosch’s Regional Headquarters for Research and Advance Engineering. The Tampines Grande is the first commercial building in Singapore that has thin film BIPV facades. Forty customized amorphous silicon panels form part of the facades cladding, replacing the conventional glass that would otherwise have been used. The rated system power generated by the façade is 6 kWp.

Figure 17 City Developments Limited’s Tampines Grande façade with BIPV panels

Essentially, through this SCS, the payback period of costs spend on solar panels will be reduced from 25 years to 12 or 14 years. If there is an inflation of oil prices, it will further shorten the payback period to around 7 or 8 years. This means that on the 9th year onwards the consumption of energy in the building is free.

BCA’s Green Mark Scheme

Also, since the introduction of Green Mark Scheme by BCA, there have been more developers adopting the use of solar panels as part of their building design. The Green Mark scheme, launched in 2005, is a green building rating system to evaluate a building for its environmental impact and performance based on five key criteria: Energy Efficiency, Water Efficiency, Environmental Protection, Indoor Environmental Quality, Other Green Features.

New buildings must be certified with minimum Green Mark Gold rating by the BCA. In this scheme, the developer needs to achieve a total of 120 points based on the 5 criteria stated above, mainly focusing on energy efficiency and water efficiency. Out of the 120 points, there is a section of 20 points on using renewable energy, mainly solar power. Developers can choose to utilise wind or hydropower but, in Singapore, solar power is most applicable. 20 points would be awarded on solar applications. In addition, if the developer installs solar panels on the building and the power generated by the solar panels is able replace 1% of the building power consumption, 4 points will be awarded. If the developer is able to size up a solar power system good enough to replace 5% of the energy power consumption of the building, 20 points will be awarded to the project. Thus, it is worthwhile for developers to go into this scheme using solar panels.

Recently, the government announced in the Sustainable Singapore blueprint that it has set a target for 80% of the existing building stock to achieve at least Green Mark Certified rating by 2030. A $100 million Green Mark Incentive Scheme for Existing Buildings (GMIS-EB) was set up to encourage private building owners of existing buildings to undertake improvements in energy efficiency. The scheme provides a cash incentive that co-funds up to 35% of the costs for energy efficiency improvement.

5.1.3 Increased funding for solar energy research

In early 2007, the National Research Foundation (NRF) identified the field of Clean Energy, with emphasis on solar technology, as a key growth area, as part of the broader Environmental & Water Technologies programme. A total of S$170 million has been dedicated by NRF to develop and build R&D and manpower competencies in Clean Energy over the next five years. Together with funding from other government agencies, the total public funding available for Clean Energy is S$350 million. Singapore aims to grow the Clean Energy industry to generate a total of S$1.7 billion in value-added and 7,000 jobs by 2015, across a broad range of areas, including solar power, fuel cells, wind power, energy efficiency and carbon services.

MND Research Fund for the Built Environment

The MND Research Fund for the Built Environment is a $50 million funding initiative by the Ministry of National Development (MND) and managed by BCA. The objective of the fund is to encourage and support applied Research &Development (R&D) that will raise the quality of life and make Singapore a distinctive global city

Under the MND Research Fund, some key focus areas include sustainable development projects such as integrating solar technologies into building facades. The fund covers 30% to 75% of the qualifying cost of the project, subject to a cap of $2 million.

Clean Energy Research and Test-bedding (CERT)

The other programme is the Clean Energy Research and Test-bedding (CERT) which is applied for public sector projects. Launched in 2007, S$17 millions CERT aims to provide supports for companies to develop clean solar energy applications using government buildings and facilities. Some test-bedding projects under this scheme include Singapore polytechnic, BCA’s ZEB and the EDB’s Eco-Precinct @ Punggol.

These numerous funding projects reflect a strong push by the Singapore government in encouraging green technology which includes the integration of solar panels in buildings.

5.2 Benefits

Environmental friendly or green buildings will inevitably become part of the mainstream architectural world in the near future. Natural resources will be conserved and renewable forms of energy – especially solar energy – will be used as extensively as possible. In the context of Singapore, its rapid economic growth has spurred the rise in energy demand. In order to achieve energy savings and a decrease in emissions, Singapore is at the beginning stage of developing renewable technologies such as BIPV to be an alternative that can meet economic needs while at the same time protecting the environment against pollution from fossil fuel consumption.

The idea of a building façade as a power plant by itself can be promoted to the building owners, decision makers and users as a viable green building strategy with low capital cost. Therefore, it is essential that we have a better grasp of the benefits of embracing this innovative technology of integrating the solar panel on the bui