Passive and Active Environmental Controls in Malaysia:
Case Study Sabah

By Djamila Harimi¹, Narayanan Sambu Potty² and Chu Chi Ming³
February 2007

  1. PhD Student, Civil Engineering Program
  2. Associate Professor, Civil Engineering Program
  3. Doctor, Chemical Program

at Sekolah Kejuruteraan dan Teknologi Maklumat of Universiti Malaysia Sabah in Kota Kinabalu, Malaysia. → See also:

Abstract
Scientists have concluded that human activity, primarily the burning of fossil fuels, is the major driving factor in global warming. The air-conditioners are widespread in Malaysia not only in offices but also in residences to reduce the indoor temperature at least to an acceptable condition. The electricity generated for air conditioning in most cases requires the burning of fossil fuels in power plants which emits combustion products such as carbon dioxide. These emissions contribute to global warming which has significant implications for building energy usage. The global warming adversely affects life and vegetation which added urgency to the search for lower energy techniques. This paper focuses on passive cooling including the traditional passive cooling strategies under tropical climatic condition and explores their limitation and their sustainability in Malaysia.

Keywords: Climate, Air Conditioning, Passive cooling, Thermal Comfort

Introduction

Several states in Malaysia experienced an increase in temperature part of it is due to the huge amount of the carbon dioxide emissions. The data from Sabah meteorological station for the period 1968 to 2003 are plotted in Figure 1.

Figure 1
Figure 1 · Temperature Variation in Kota Kinabalu over the years 1968-2003

The estimated trend of the increase in the maximum temperature per decade in Kota Kinabalu, the capital of Sabah state located in east Malaysia is about 0.4°C with an average increase in outdoor temperature of 0.3°C and a coefficient of determination of 0.62. A case study was carried out by Tetsu and Supian (2005) in Johor Bahru located in West Malaysia to understand people behavior and electricity consumption. The number of respondents was 131. The survey revealed that the main reason for not purchasing air-conditioners by several occupants was cost saving (Figure. 2). This situation should be carefully considered since it has a big impact in energy consumption in the future once their living standard improves sufficiently.

Figure 2
Figure 2 · Reasons for not Intending to Purchase Air-Conditioners

Figure 3
Figure 3 · Modern Building in East Malaysia

Emerging fast-growing economies like Malaysia needs to develop alternative strategies including sustainable and bioclimatic concepts, where the buildings should be designed to optimize energy consumption and satisfy the occupant at same time. Creating a successful indoor thermal conditions as reported by (Forwood, 1995) require more than satisfying thermal design criteria but depends upon the extent to which the internal environment is considered acceptable by the occupants. Modern Malaysian buildings have generally large glazed facades and transmit rapidly the heat from outside to the inside of the building and they are always running with air conditioning. The reduction of building energy usage has a vital role in reducing the emissions of greenhouses gases and it is important to understand that the use of energy is to cool the resident in the building rather than the building (Lovedayet al., 2002, Milne, 1995).

Energy Conscious Building Design

Figure 4
Figure 4 · Ceiling Air Conditioner with Air Distribution Systems

In Malaysia, modern office buildings are generally cooled with centralised air-handing systems whish waste a considerable amount of energy before the cool air reaches the person. The model shown in Figure 4 is a typical air conditioning system used in some modern office building in Malaysia with ceiling based air distribution systems.

Such design has its limitation compared with the Task/ambient conditioning (TAC) under floor air distribution which cools only the space closer to the sitting person and thereby provide individual comfort control. The occupant could adjust the indoor environment to personnel requirement without negatively affecting other occupants. The Task/ambient conditioning (TAC) could also increase the percentage of satisfaction in a given space over 80% which is the required percentage to be thermally satisfied in thermal comfort study as suggested by Fanger formula. TAC is also very suitable for commercial building and library. The installation of TAC system is quite costly compared with ceiling based air distribution systems, whereas the main advantages are its ability to improve further thermal comfort, indoor air quality and reduce energy use. It is very interesting to highlight that it is very possible to reduce more energy consumption by gentle cooling of the most influential and sensitive body part in term of cooling instead of whole human body. A study have been conducted in Berkeley University revealed that gentle cooling of the most influential body part is the most effective way to cool people at expenditure cost (Zhang H., 2003). Further energy use could be reduced in tropical climate by adopting flexible clothing in the offices. The Japanese government through its "Kuuru-bizu campaign" permitted the use of lighter clothing during the hot months (Fritz, 2006). A total of 460000 tonnes of Carbon dioxide has been saved, equal to emissions from a million households in a month. It is also necessary for a designer to select the most appropriate passive cooling strategies under specific climatic condition before opting to a mechanical cooling.

Peoples´ Thermal Behaviour to Direct Solar Radiation

Figure 5
Figure 5
Figure 5 · People Behaviour to Direct Solar Radiation
Figure 6
Figure 6 · Bus Driver with Clothing Adjustment
Figure 7
Figure 7 · Dog Protecting Itself from Direct Solar Radiation

The people thermal behaviour is an important parameter to be considered in building design with no mechanical cooling. The adaptive thermal comfort approach is the most cost effective method in minimizing the energy consumption from air conditioning by reducing the comfort temperature to an acceptable level. Figures 5 and figure 6 are two examples of people behaviour for protecting themselves from direct solar radiation which helps in reducing the feeling of the increased temperature.

Figure 6 shows a bus driver protecting only his exposed right arm from direct solar radiation by wearing long sleeve cloths. His face is also protected from direct solar radiation by temporarily fixing cloth near the windows. The photo was taken during early morning when the sun is almost horizontal and can directly penetrate inside the mini bus.

It maybe necessary to highlight that not only people are looking for shade to protect themselves from direct solar radiation but also pets. Figure 7 shows a tired dog relaxing in a space designed for people during the peak outdoor temperature when the sun is almost perpendicular to the horizontal space, the trees seems to be quite far from this lazy dog which was sitting for a long time but moved immediately when the photo was taken.

Passive Cooling Strategies and their Limitation

Several passive cooling strategies are adopted in Malaysia to reduce the indoor temperature or/and to improve the indoor thermal comfort. Some of passive cooling strategies has their limitation under tropical humid climate and should be carefully selected or designed.

Figure 8
Figure 8 · Roll-up Clothing Shading Device in Kota Kinabalu

Roll up clothing as external shading device is useful under Malaysia climate and are commonly used for protecting shops from direct solar radiation when the wind velocity is almost still. The only inconvenience of such strategy is the dirt accumulation (Figure 8). Whereas the other advantage is to display advertisement of the product sold in the shop.

Figure 9
Figure 9 · The Effect of Rain on Balcony under Tropical Humid Condition

Well ventilated balcony surrounded the building is a very good strategy to improve the ventilation and the balcony also could be considered as a horizontal shading device as seen in Figure 9 but needs to be protected in tropical climate from the splash of rain.

Figure 10
Figure 10 · Floor Well Ventilated in Malay Traditional House

The adaptation of Malay architecture strategies to new building materials such concrete or brick walls should be carefully considered. The traditional Malay houses were usually built in stilts to protect the house from floods and the floor was usually built with organic loosely woven walls that allow the least gentle cool wind under the ground to penetrate in as seen in Figure 10.

Figure 11
Figure 11 · Malay Architecture with New building Materials

However the adaptation of such design without any consideration to the selected building material and to the microclimate of the building can lead to higher indoor temperature where the use of air conditioning becomes a necessity (Figure 11).

It is very important to highlight the importance of the selection of building material with specific time lag which could be more convenient for a specific microclimate. The lightweight building material which appears to be very suitable under tropical climate could only be acceptable when the building is located in a jungle or well surrounded by the trees.

Figure 12 shows the variation of the hourly outdoor, indoor and attic temperatures in two traditional Malay houses named Suluk and the Brunei houses. The data were recorded on 26 October 2004 at 10 a.m. to 27 October 2004 at 9 a.m . These two traditional Malay building are located in Sabah Museum. The building design and material are exactly the same as in the traditional Malay architecture and the only difference is that the buildings are situated in urban area instead of rural area.

Figure 12
Figure 12 · Hourly Temperature Variation in the Suluk and Brunei Houses

The attic and the indoor temperatures as seen in Figure 11 closely followed the curve of the outdoor temperatures. The maximum attic temperature in the Suluk house was 0.4°C bellow the maximum outdoor temperature. The indoor temperatures in the Brunei house were slightly lower than in the Suluk house.

The indoor temperatures in the Suluk house were slightly lower than the attic temperatures at night. These two houses are very hot during day time when the outdoor temperature reaches its maximum and seems to be uncomfortable when the outdoor temperature reach its maximum.

So, why do people say that traditional houses are very cool?

The microclimate in the traditional houses was really very cool and were usually located in a jungle and since light building material follows closely the outdoor temperature, the indoor temperature in the traditional Malay houses were quite acceptable with the consideration of the impact of wind velocity on thermal comfort. New building material require new architecture adapted to climate and learning from the past does not always mean to duplicate the same architecture but rather to understand the principles in building design under specific climate.

Figure 13
Figure 13 · Ventilated Walls Using Modern Building Materials

Figure 13 shows a ventilated public toilet with perforated walls, which seems to be an inspiration from Malay architecture and well designed. Such strategy can be well adapted in some buildings such wet supermarket built with concrete or brick walls.

Figure 14
Figure 14 · A Well Ventilated Wet Market in Malaysia

Figure 14 shows a well ventilated wet market in which only ceiling fans are used. However, it was very much possible to improve further the ventilation with perforated walls which could further reduce the temperature and improve the indoor thermal comfort.

Figure 15
Figure 15 · Use of Vertical Shading Device in Building

The vertical shading devices are more appropriate for use during the time of sunrise and sunset where the sun position is almost horizontal. Figure 15 shows a building with vertical and horizontal shading device and a very small opening. A cross ventilation is not ensured in this building which use air conditioners.

Conclusions and Recommendations

Acknowledgements

The author acknowledges the help of Sabah Meteorological Station for providing the climatic data of several states in Sabah and the great help of Sabah Museum for making the traditional houses available for this research.

References

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