Advancing Sustainability in the Tropics – The International School of Kuala Lumpur

Abstract

This is a case study about designing a holistically sustainable school in a tropical climate. The school described here is the proposed new International School of Kuala Lumpur (ISKL) located in the heart of the city, Kuala Lumpur, Malaysia. A building is only truly sustainable when all design areas meet sustainable goals. ISKL is designed to be that building, attempting to be sustainable from all design angles. This includes energy efficiency, indoor environmental quality, daylight harvesting, transportation energy, water efficiency, renewable energy, solid waste reduction and permaculture. Design goals and methodology of each strategy are described in this paper.

1 Introduction

The construction of large buildings is an essential part of any major city’s development. With more and more of the world’s population migrating from rural to urban areas, it is almost certain that cities will grow in size and density. According to the World Bank, urban population in Malaysia has increased from 67 % in 2007 to 73 % in 2013 and it continues to be on the uptrend (The World Bank 2015). The growth in urban population spurs the demand of more buildings in the city. However, the construction of buildings has an adverse effect on the natural environment. The built environment is a major consumer of raw materials, generates waste, consumes energy and emits greenhouse gases. That is why sustainable construction and green buildings have become an important part of the construction industry in Kuala Lumpur over the past few years.

The proposed new International School of Kuala Lumpur (ISKL) is designed to achieve sustainability in all aspects of design. This article presents how sustainability can be achieved by providing a methodology and design goals in the areas of energy efficiency, water efficiency, indoor environmental quality, daylight harvesting, transportation energy, renewable energy, solid waste reduction and permaculture. The design of ISKL approaches sustainability in a holistic manner.

ISKL is a proposed international school located at the heart of Kuala Lumpur city in Malaysia. Construction of the building is targeted to be completed in August 2018. The school will have a capacity for 2500 students and includes early years, elementary, middle, and high schools. The whole campus consist of clusters of low rise buildings. This includes a five storey administrative building with library, sports, and academic facilities and a cafeteria. There are also five teaching blocks with three or four storeys each, a gym and a performing arts center.

The following sections outline sustainability goals and methodology for achieving the targets for ISKL.

2 Energy Efficiency

In Malaysia, the Building Energy Intensity (BEI) value is widely used to measure and rate a building’s energy consumption. The unit for BEI is kWh/(m².year). It is calculated according to the following formula.

$$ \begin{array}{l}\ BEI=[\left(\mathrm{TBEC}-\mathrm{CPEC}-\mathrm{DCEC}\right)/( GFA\ (\mathrm{excluding}\ car\ \mathrm{park})- DCA- GLA* FVR)]\hfill \\ {}\ *\left[52/ WOH\right]\hfill \end{array} $$

Where:

• TBEC: Total Building Energy Consumption (kWh/year)

• CPEC: Car park Energy Consumption (kWh/year)

• DCEC: Data Centre Energy Consumption (kWh/year)

• GFA (excluding car park): Gross Floor Area exclusive of car park area (m²)

• DCA: Data Centre Area (m²)

• GLA: Gross Lettable Area (m²)

• FVR: Weighted Floor Vacancy Rate of GLA (%)

• 52: Typical weekly operating hours of office buildings in KL/Malaysia (hours/wk)

• WOH: Weighted Weekly Operating Hours of GLA exclusive of DCA (hours/wk)

In simple terms, BEI is the total energy consumed per year over the gross floor area of the building. ISKL’s BEI target is 35 kWh/(m².year). The international average for schools in tropical/sub-tropical climates is 120 kWh/(m².year) as published in Benchmarking Energy Use in Schools by Sharp (1998). Therefore ISKL aims to consume about 70 % less energy than the international average.

This BEI value has to be achieved by making improvements at every design opportunity available. The simulation software; IES VE, is used to accurately simulate each design improvement and its impact in reducing energy consumption. The list of design improvements are shown below.

2.1 Daylight Implementation

Harnessing natural daylight indoors to reduce consumption of energy from artificial electrical lights. This is presented in greater detail in Sect. 5 below.

2.2 Roof Insulation

Specify 50 mm polystyrene roof insulation with U-value 0.5 W/m² K. This reduces heating load on the air conditioning system thus reducing energy consumed.

2.3 Wall Insulation

Specify autoclaved aerated concrete blocks for all external walls for better insulation properties. U-value is 0.9 W/m² K. This reduces heating load on the air conditioning system thus reducing energy consumed.

2.4 Glazing Properties

Single glazed low-E glazing is used for all external glazing, with SHGC of 0.34 and U-value of 3.8 W/m² K. This reduces heating load on the air conditioning system thus reducing energy consumed.

2.5 Air Tightness

Infiltration introduces both sensible and latent heat into a building in the Malaysian climate. This has significant impact on the energy efficiency and indoor environment quality of the building. Although unwanted infiltration cannot be eliminated entirely, ISKL seeks to reduce it significantly. This is achieved by providing air tightness details and specifications for all external doors and windows. The aim is to reduce infiltration to 0.1 Air Change per Hour (ACH) (Ezzuddin and Tang 2010).

2.6 Lighting Power Density

Lighting power is another major source of energy consumption. Light fittings not only consume energy when turned on, lightig also loads the air conditioning system with heat. Lighting power density targets are shown below:

• (a) Classrooms and teaching areas: 9 W/m2

• (b) Walkways: 7 W/m²

• (c) Administration areas: 9 W/m²

• (d) Toilets: 7 W/m²

• (e) Staircase: 3 W/m²

2.7 Air Conditioning Air Side

A variable air volume (VAV) system is specified. Hence supply air flow can be regulated according to the cooling needs of the zone thus improving efficiency at part loads. Moreover duct design is optimized by reducing bends, tees, transitions, dampers and any others that will add to the AHU fan static pressure. This reduces duct static pressure thus reduces fan power. Total duct static pressure is targeted to be 650 Pa. Fan power is further reduced by using high efficiency filters thus reducing total static pressure to 580 Pa. Overall fan power is reduced by using air foil type fans and IE3 motors. Total fan efficiency is 71.8 %.

A carbon dioxide (CO₂) sensor and control system is also used on the fresh air intake (ASHRAE 2013, Appendix B). CO₂ sensors regulate fresh air intake into the system based on the occupants’ need for fresh air. Fresh air although necessary, when drawn into the building is hot and humid, which loads the air conditioning system. The CO₂ sensor is set to 900 parts per million.

A heat recovery system with 50 % efficiency for latent and sensible load is also specified for all teaching blocks. The system recovers energy rejected by the toilet exhaust system and transfers it to the outdoor air intake system located on the roof.

2.8 Air Conditioning Water Side

A high chilled water delta-T is specified for both chilled water and condenser water systems. Delta-T is 16 °F for chilled water and 12 °F for condenser water. Moreover pump pressure is also reduced by optimizing pipe size and reducing bends, tees, transitions and any others that will add to the pump pressure. Chilled and condenser water pump pressure is set at 20 m head. The chilled water pumps also use a variable speed motor to vary flow rate according to demand and heat load.

A high efficiency chiller is specified with COP of 6.6. To further improve the chiller performance, a variable speed drive was specified on the chiller. VSD chillers have a variable speed compressor hence have better part load efficiency. Cooling tower efficiency is also improved to 0.0275 kW/HRT.

2.9 Radiant Chilled Slab System

A radiant chilled slab system is used for all classrooms/teaching spaces in the teaching blocks. A radiant cooling system utilizes the floors and ceilings as sources of radiant cooling. Rooms are cooled by circulating water through embedded cross linked polyethylene (PEX) plastic pipes. Such a system is more energy efficient in removing heat from a space because it is using water as the main medium of heat removal as opposed to a conventional air-based system. Water has a thermal capacity of 4.2 kJ/kg.K, it has four times more thermal heat capacity than air which has a thermal capacity of 1.0 kJ/kg.K. Therefore, to provide the same amount of cooling, water requires four times less mass flow rate compared to air.

The chilled slab system is operated in conjunction with the AHU (air handling unit) system. The chilled slab system cannot be used independently because it cannot remove moisture from the air. An AHU system is required to dry the air in the classrooms to prevent risk of condensation on the cold surfaces of these chilled floor slabs. Moreover, the AHU system is required to deliver fresh air to all the classrooms. Approximately 50 % of the cooling will be provided by these AHU units, while the chilled floor slab provides the other 50 % of the cooling requirement.

The cooling of the chilled slabs is done during night time, operating from 1.30 am to 7.30 am. The concrete slabs have high thermal mass, therefore cooling of the system is not immediate. Chilled water that runs through the PEX pipe cools the concrete slabs down to 18 °C. Then the AHU system kicks in at 8 am and runs throughout the day as the building is occupied. The high thermal mass of the concrete slabs allows radiant cooling to take place throughout the day, even though the slabs are not being actively cooled with chilled water during the occupancy period. Simulation results show that the average chilled slab sensible load is 103 W/m². Figure 16.1 shows supply air flow rate results simulated for a typical floor. The orange line depicts flow rate for a conventional VAV system, while the red line shows the flow rate for a VAV system coupled with a chilled slab radiant system, which is approximately 50 % of the conventional system.

Fig. 16.1

Simulation results showing flow rate of a conventional VAV system in orange compared to a chilled slab/VAV system in red

It is advantageous to charge the chilled slabs at night because commercial electricity tariffs are cheaper. The peak cooling load of the building is reduced because the load is divided into night and day, which will reduce the size of the chiller and all other equipment. Moreover, since both AHU and chilled slab systems operate at similar cooling loads, both can operate using the same chiller, pumps and cooling tower. No additional major equipment is needed.

3 Renewable Energy

Renewable energy is provided by photovoltaic solar panels. An expected BEI of 35 kWh/(m².year) equates to about 1930 MWh of energy per year. The PV panels will be placed on the roof of the spine block. Available roof space is 5000 m², therefore PV panels with a capacity of 250 kWp can be placed on the roof. This array can generate up to 300 MWh of energy per year. Therefore, 15 % of ISKL’s energy is currently planned to be provided by renewable energy from photovoltaic panels. If all roof space of ISKL is used, it would be able to provide 100 % of the school energy consumption at ISKL’s BEI target of 35 kWh/(m².year).

4 Water Efficiency

A number of water efficiency strategies are used to decrease water consumption in ISKL. These strategies are water efficient fittings, rainwater harvesting, grey water recovery, and condensate water recovery. The baseline water demand was estimated for ISKL and shown in Table 16.1. There are four main contributors to water consumption in the school. Combined baseline consumption is estimated to be 92,883 m³ per year. With the strategies described below, total water demand is reduced by 47 % to 49,489m³ per year.

Table 16.1 ISKL’s baseline and design water demand

4.1 Water Efficient Fittings

The use of high efficiency plumbing fittings is a good method of greatly reducing potable water demand. Water efficient fittings have much lower flow rates compared to conventional fittings while are still able to accomplish their sanitary purposes. Table 16.2 shows annual consumption with conventional fittings (baseline) while Table 16.3 shows annual predicted consumption with efficient fittings. These are fittings labelled under the Water Efficiency Labelling Scheme (WELS) from Singapore or equivalent (Water Efficiency Labelling Scheme 2014). As seen in Table 16.3, all fittings have a much lower flow rate compared to conventional fittings. Consumption from water fittings reduces from 21,838 m³/year to 9009 m³/year, a reduction of 59 %.

Table 16.2 Baseline water fittings demand with conventional fittings

Table 16.3 Design case water fittings demand with water efficient fittings

4.2 Rainwater Harvesting

Rainwater harvesting is an effective method to reduce potable water usage in a building. Malaysia sees rainfall consistently throughout the year, hence it is good to harness this benefit for ISKL. Harvested rainwater is used for the high landscape irrigation demand. In-house rainwater harvesting simulation software was used to calculate the rainwater tank size. The calculation is done using hourly rainfall data from Meteonorm (Meteotest 2015). Tank size is estimated by measuring hourly rainfall data against daily irrigation needs. For ISKL, rainwater is collected from the roof area only. Rain collected from the roof is diverted via gutters to rainwater downpipes. Rainwater downpipes then divert rain water to the harvesting tank. The rainwater catchment area is 17,893 m². A run-off coefficient of 90 % is assumed. This means only 90 % of the rainwater collected is channelled to the tank, the other 10 % is assumed to be splashed out of the building or remains at the catchment area. A first flush system is also used. The first flush system diverts the initial surface rainfall collection. Initial surface rainfall contains a high level of pollutant content. Furthermore, leaves and other debris are often collected from surfaces during the initial stage of rain. Therefore the first 1 mm of rainfall is diverted away from the rainwater tank using the first flush system. This amounts to 16.1 m³ of initial rainwater being discharged into the storm water drain. All rainfall after that will be channelled into the rainwater harvesting tank.

Figure 16.2 shows the results of the rainwater harvesting software calculations. The chart shows two patterns. Firstly, rainwater collected in a year and secondly, percentage savings of overall irrigation water demand achieved by using collected rainwater. From the chart, we can see that if a tank of 250 m³ is used, 52 % of the landscape irrigation needs will be met by non-potable rainwater, which is equivalent to a saving of almost 24,439 m³ of water a year.

Fig. 16.2

Rainwater harvesting tank chart

4.3 Grey Water Recycling

Grey water is collected from all wash basins. This wastewater shall be collected in a tank at the basement and pumped back to serve water closets in the building. Referring to Table 16.3, water collected from all basin faucets amounts to 20.15 m³ per day. With a recovery ratio of 90 %, total grey water recycled is 18.14 m³ per day, which is equivalent to 3264 m³ per year. Therefore a grey water tank of 20 m³ would reduce yearly wastewater from 9009 m³ to 5745 m³, a reduction of 36 %. Recovered grey water will be used to serve all water closets in the building. This further reduces water fittings demand to 5745 m³ per year.

4.4 Condensate Water Recovery

Condensate water is the water collected from the cooling coils of all AHUs in the building. A typical building would discard this condensate water as waste water. ISKL aims to recover all condensate water as a supplement for the cooling tower make-up water. The calculation below shows how condensate water is estimated.

$$ \mathrm{Average}\;\mathrm{Cooling}\;\mathrm{Coil}\;\mathrm{Latent}\;\mathrm{Load},\mathrm{Q}=680\ kJ/\mathrm{s} $$

$$ \mathrm{Average}\;\mathrm{Cooling}\;\mathrm{Coil}\;\mathrm{Latent}\;\mathrm{Load},\mathrm{Q}=2,448,000\ kJ/\mathrm{h} $$

$$ \mathrm{Latent}\;\mathrm{Heat}\;\mathrm{of}\;\mathrm{Vaporization},\mathrm{h}=2446\ kJ/ kg $$

$$ \mathrm{Condensate}\;\mathrm{Water}=\frac{\mathrm{Q}}{\mathrm{h}} $$

$$ \mathrm{Condensate}\;\mathrm{Water}=\frac{2,448,000}{2446} $$

$$ \mathrm{Condensate}\;\mathrm{Water}=993\ kg/\mathrm{h} $$

$$ \mathrm{Condensate}\;\mathrm{Water}=0.99\ \mathrm{m}3/\mathrm{h} $$

$$ \mathrm{Condensate}\;\mathrm{Water}=15.9\kern0.5em \mathrm{m}3/ day $$

Therefore it is estimated that 15.9 m³ of condensate water is collected per day. The average condensate water collected in a year is 2862 m³ which reduces cooling tower water demand by 17 % to 13,391 m³ per year.

5 Daylight Harvesting

Artificial lighting in a building both consumes electricity and is also a source of heat gain on the air conditioning system. Therefore it is worthwhile to harness natural daylight wherever possible. A daylight harvesting strategy was implemented as part of the design. This includes daylight sensors at the building perimeter of each floor, and a window design to draw daylight deeper into the office area while preventing glare. The window design consists of horizontal venetian blinds and light shelves as shown in Fig. 16.3.

Fig. 16.3

Cross section of the window design for classrooms

Quality of natural indoor daylight is measured by Daylight Factor (DF). Daylight Factor is a measure of a reference point of the available daylight indoors versus the available daylight outdoors during an overcast sky condition. DF criteria used for ISKL are in the range of 0.5–3.5 % for classrooms (Tang and Chin 2013). The daylight simulation software Radiance is used to simulate indoor daylight conditions. Due to the space limitation, it is not possible to present here all results from the simulation but results from one teaching block are shown in Fig. 16.4. This chart shows that for Level 4, natural daylight can light up to 7 m of the classroom from the perimeter of the building. This is nearly the whole width of the room. Therefore artificial electric lights is not needed. For Level 3, up to 6 m is available, for Level 2, 4.5 m and for Level 1, 3 m. Hence about 65 % of the classroom’s artificial electrical lights can be switched off.

Fig. 16.4

Daylight Factor results for a teaching block

6 Indoor Environmental Quality

ISKL is designed to meet the requirements of ASHRAE 55 and ASHRAE 62.1. These standards provide guidelines for thermal and environmental conditions for human occupancy and also acceptable indoor air quality. Moreover, with the use of daylight simulation, ISKL is able to provide a more conducive indoor environment with natural daylight without glare.

7 Transportation Energy

A holistic approach to sustainability includes consideration of transportation energy consumed by occupants of ISKL. Hence a methodology to calculate the transportation carbon emissions should be clearly defined and documented. This methodology shall also provide a transportation carbon emission performance indicator to specify the carbon emission per student based on the type of transportation used. The performance indicator provides a measurable way to show how well the school is doing in managing transportation energy and provide a way forward to for corrections and improvements.

Below is an outline of the methodology to measure and specify transportation energy in ISKL. The method should be simple and practical to be applied during the operation of the school. The performance indicator shall be given by TCEI (School Transportation Carbon Emission Index per year per student served). This formula provides the transportation carbon emission per student served per year for a school. Ideally, this number should be as close to zero as possible for a school to be truly sustainable. This can be achieved by reducing the carbon emission of individual private vehicles, buses and public transportation and/or by increasing the number of students served by each vehicle travelling to a school.

$$ TCEI=\frac{{\displaystyle \sum } P. Vehicle+{\displaystyle \sum } S. Bus+{\displaystyle \sum } P. Transportation\ }{StY} $$

Where,

• TCEI = School Transportation Carbon Emission Index per year per student served.

• P.Vehicle = Carbon Emission per year of Private Vehicles.

• S.Bus = Carbon Emission per year of School Buses.

• P.Transportation = Carbon Emission per year of Public Transportation.

• StY=Average number of students per year

The design team will work with the school to implement a system to collect necessary data during operation of the school. Data of carbon emitted from private vehicles will be collected from those that travel to the school using private vehicles. The data shall include type of vehicle, distance travelled, trips per week and the rated CO₂ emission of the vehicle. Similarly, this data will also be collected for school buses. However, there is not much data provided by the Malaysian transport authority regarding CO₂ emission for public transport vehicles. Therefore the design team shall be working on gathering this data before the school is completed.

8 Solid Waste Reduction

ISKL’s goal is to reduce waste to landfills by 90 % (The International School of Kuala Lumpur 2015). Waste such as paper, plastic, aluminium, glass and used cooking oil can be easily segregated and recycled, as there are facilities in Kuala Lumpur to collect and recycle these items. Recycling bins shall be provided at strategic locations on the campus to encourage occupants to segregate waste accordingly. However, organic waste from the kitchen and landscape would still be required to be discarded to the landfills as Kuala Lumpur lacks the facilities to recycle such waste today. Therefore ISKL will include an anaerobic digester system to treat organic waste. These strategies will be applied to achieve the goal of 90 % waste reduction. Moreover, the anaerobic digester serves as an educational demonstration tool to students in the school. The anaerobic digester is basically a system with microorganisms that break down organic waste in the absence of oxygen. The process then produces a biogas containing methane, carbon dioxide and traces of other gases that can be used as fuel. Another by-product of the process is a nutrient rich digestate that can be used as fertilizer.

Figure 16.5 shows a concept schematic of the anaerobic digester. The components are as follows:

Fig. 16.5

Concept schematic of the anaerobic digester in ISKL

Kitchen Sink and Food Waste Dispenser

Organic food waste from the kitchen is disposed into the food waste dispenser (grinder) and flushed down with rain water or grey water, as a slurry mix into a holding tank below the sink.

Holding Tank, Pump and Check Valve

The holding tank, pump and check valve can be omitted if the kitchen sink is located higher than the anaerobic digester tank. If it is not possible, the holding tank will collect the dispensed food waste for a temporary period before pumping the slurry into the anaerobic digester tank.

Anaerobic Digester Tank

The tank is a standard polyethylene septic tank (UV resistant) that is air-tight, low-maintenance and low-cost. The slurry from the holding tank is piped into the bottom of the anaerobic tank. The tank is sized to allow 20–30 days of digestion period. The maximum gas pressure in the tank is estimated to be less than 2000 Pa (200 mm of water). The top of the tank is fitted with a gas pipe to route the accumulated gas to a biogas balloon. Digested sludge will be discharged from the top of the tank and piped to a sand filter system.

Biogas Balloon

The biogas storage balloon is fabricated out of high tenacity polyamide fabric matrix, impregnated with compatible polymer on the inside for the biogas stored and on the outside with Hypolon (or equivalent) for weather and UV resistance. These balloons are collapsible, light weight and can be suspended from the ceiling or walls or placed on the floor.

Below are the advantages for having an anaerobic digester:

• (a) Recycles all organic waste generated by ISKL.

• (b) Generates methane gas to be used in the kitchen. However the quantum of generation is quite small compared to overall kitchen needs. It is estimated that the system provides 1–3 % of total kitchen needs.

• (c) After a digestion period of 30 days, the system will produce about 150–200 kg of digestate a day at steady state operation. This digestate is high quality, nutrition rich top soil that can be used within the landscape area of the school, or bagged up and sold to nearby orchards.

9 Urban Farm and Permaculture

There are many benefits to urban farming (Mobbs 2002). In a school like ISKL, it can be used as a tool to educate students about local food sources, the science of plants, and the process of farming. Moreover, urban farms are a great solution to reduce the cost of transportation of foodstuffs, hence reducing the carbon footprint associated with food production. In the case of ISKL, urban farms within the campus may not produce enough food to supply the needs of the whole campus. But the goal is to introduce the concept of urban farming to the students and community.

Permaculture on the other hand is a concept of “ecological” design that blends various eco-systems together in a sustainable manner, forming an urban farm modelled after a natural ecosystem. The following are plans to be implemented in ISKL.

• (a) Vegetable garden on the rooftop with soil depth of approximately 0.5 m depth to maintain a healthy vegetable garden.

• (b) Introducing sting-less bees. Bees are one of nature’s most important pollinators. Many food plants such as soursop, celery, papaya, cabbage, cauliflower, cucumber etc. require bees to help with pollination. However, to ensure that the bees remain at the campus, flowering plants with high nectar content are required to be planted to keep them at the site. The bee hives in wooden or clay boxes should be kept at a high position out of reach from school children. Harvesting of honey from the hives can be done via a ladder by the farmer at regular intervals.

• (c) Fruit trees such as soursop, rambutan, papaya, or chiku trees will serve as ideal perimeter trees around the campus. When the fruit trees start to fruit, it will create an interesting learning opportunity about tropical fruit trees for the students in the school

• (d) Flowering plants shall be planted between the fruit trees as a food source for the bees to ensure that they stay within the campus to help with the pollination.

• (e) A variety of crops will be planted each season, with crop rotation constantly conducted to maintain the quality of the soil.

10 Conclusion

The new ISKL campus strives to be a holistically sustainable school. A summary of the design goals and methodology of this holistic approach to meet the important sustainability targets is presented below:

• 1. By making small improvements at every design opportunity, the building can be made very efficient. The BEI design target is 35 kWh/(m².year), about 70 % less energy than the international average.

• 2. Photovoltaic solar panels with a capacity of 250 kWp will provide 15 % of the annual energy consumption.

• 3. With the use of water efficient fittings, and implementing rainwater harvesting, grey water and condensate recovery systems, water consumption is reduced by 47 % from a baseline of 92,883 m³/year to 49,488m³/year.

• 4. Daylight harvesting system provides excellent indoor daylight. Up to 65 % of artificial lights can be switched off.

• 5. A transportation energy plan is developed to provide a measurable way of showing how well the school is doing in managing transportation energy and provide a way forward for corrections and improvements.

• 6. With a recycling program and an anaerobic digester, a target of 90 % of solid waste shall be recycled.

• 7. Urban farming and permaculture shall be designed as part of the school as an education tool and a proof of concept for agriculture in the city.

As the project continues from design to construction and then to operation, it is important the design intent continues as well. Strategies will be put in place to ensure all sustainability targets are met throughout the development of the school.