Thermal performance of selected heritage buildings in Penang, Malaysia.
INTRODUCTIONThe thermal performance of any building is a very important aspect to be considered if sustainability and energy efficiency are to be emphasized. In hot tropical climates, buildings with poor thermal performance will easily introduce outdoor heat to the indoors, creating large energy requirements to cool the spaces; in order to achieve adequate thermally comfortable conditions. Glass or highly glazed modern buildings in the tropics are known to be energy inefficient when it has light and heat penetrating uncontrollably into its interior spaces [1]. However their popularity is increasing in urban areas like Kuala Lumpur; in line with other big cities like Singapore, Bangkok and Jakarta etc., especially with their attractive sleek and high-tech aesthetics. In contrast to that, the indigeneous 'kampung' houses in Malaysia has a few lessons to offer with good thermal performance, notably with the prescence of its extensive overhangs, large ventilation openings and highly insulated attap roofs [2], [3].
Apart from the above, Malaysia is also blessed with large numbers of historical and heritage buildings from its colonization period. These colonial buildings have heritage values and some of them are preserved and in good conditions today despite being more than 100 years old. In fact, George Town Penang has even been declared a world heritage site by UNESCO in 2008. As such, the historical documentations of numerous heritage buildings are well-archived and preserved for future reference.
The architectural style of these colonial buildings in Malaysia are typical of the buildings in Britain built during similar periods. The climates of the two countries, however, differ to quite a great extent. Therefore, the study of this paper concerns the thermal performance of these heritage buildings in the hot and humid climate of Penang. The two main characteristics normally found in colonial heritage buildings are in its massing of walls and its high ceiling [4], [5].
Methodology:
In this research, focus is given to naturally-ventilated colonial heritage buildings in George Town, Penang. After numerous visits to George Town World Heritage Incorporated for advice, a few buildings were suggested. Among them, four were found suitable for studies related to thermal performance under natural ventilation, while accommodating small, medium and large-scale buildings. They are: (1) Jabatan Hal Ehwal Agama Islam Pulau Pinang, Lebuh Pantai (JHEAIPP), (2) Balai Bomba dan Penyelamat, Lebuh Pantai, (3) Town Hall, Jalan Padang Kota Lama, and (4) George Town World Heritage Incorporated, Lebuh Acheh (GTWHI). The criteria for the selection of buildings are as listed below :
* All buildings are located within the UNESCO World Heritage Site in George Town, Penang.
* They are all documented and conserved heritage buildings with minimal renovations done.
* The buildings are also significant; most unlikely to be demolished or replaced, suggesting long-term existence, effect to the local surrounding and energy consumption.
* They possess high thermal mass with clay brick walls with lime plaster exceeding 150mm in thickness.
* The buildings have tall floor-to-ceiling height, exceeding 3 metres.
* They have large, vacant areas that are naturally-ventilated, without the interference of electric fans or air conditioning.
* The cooperation from owners and tenants were encouraging, allowing unhindered study on the buildings.
* The architectural drawings of the buildings are available.
Using callibrated data loggers with several temperature probes, the internal air temperatures (Ti) were taken simultaneously with the outdoor air temperatures (To) for comparison. The difference between Ti and To were recorded as the criteria of assessing the buildings thermal performance. To be more thorough, each building is measured for 7 consecutive days from the months of June 2011 to May 2012 and the average of all seven days are graphed below. Table 1 describes the four buildings and the investigated spaces/rooms in more detail.
RESULTS AND DISCUSSION
As seen in Fig. 1, similar patterns exist in the thermal performance assessments of all four heritage buildings. Generally, the high outdoor daytime air temperatures is filtered and delayed by the thermal massing of the walls, resulting in cooler interiors during the day. However, at night, the massing of walls may have an adverse effect by not allowing the heat generated inside to escape to the cooler outdoors. The warmer environment compared to the outdoors during the night may not be suitable for houses when thermally comfortable periods are essential for resting and sleeping. As a comparison, indigenous Malay architecture of 'kampung' houses have very thin walls with large ventilation openings. Insulation and massing of walls were not common occurrence in traditional 'kampung' houses.
Upon assessing the individual rooms' results for average indoor air temperature in Fig. 1 above, it would seem that the room in the JHEAIPP building provided the lowest figure, suggesting that it may be the room which is most likely to be able to provide its occupants with a comfortable thermal environment (via passive means). The room in the GTWHI building also diplays very large Ti-To differences, suggesting its ability to filter the temperatures outside. However, considering the importance of maintaining favourable night time temperatures as well, it would seem that the BOMBA building has outperformed both; in providing a large and favourable gap between the indoor-outdoor temperature readings during the day, as well as keeping minimal air temperature readings during the night. It shows the most favourable average for Ti-To, at -0.94[degrees]C and highest percentage of hours that Ti remains below To. This means that the difference between the indoor and outdoor temperature is most significant during the investigation in the Balai Bomba building, indicating that the its envelope surrounding the room has managed to moderate the indoor air temperature to a more comfortable level despite the influence of high outdoor temperatures.
Summary:
Generally, outdoor temperatures in the George Town World Heritage zone are highest (and relative humidity, lowest) around the hours of daylight, and the temperatures peak around noon. Due to thermal lag, the indoor air temperatures inside the heritage buildings rise and drop with a few hours' delay compared to the outside, with slow cooling processes due to large thermal mass.
Lastly, it is apparent that the room sample from the BOMBA building is the best performing, in terms of providing favourable Ti-To readings for thermal comfort. The building has an average floor-to-ceiling height of 4.2 metres, and considerably large, unpartitioned floor areas compared to the other samples. The total areas for glazed and more imporantly--openable--windows are also rather high for this building. One potentially defining difference between this building and the others--for the whole period of investigation--was its use of natural ventilation. These are factors which would have to be addressed and duly investigated further.
Massing, therefore, may not be advantageous in our tropical climate especially for its thermal performance during night time hours; but high ceilings prove to be advantageous throughout.
REFERENCES
[1] Gratia, E. and A. De Herde, 2007. Greenhouse effect in double-skin facade, Energy and Buildings, 39: 199-211.
[2] Lim, J.Y., 1987. The Malay House: Rediscovering Malaysia's Indigenous Shelter System, Institut Masyarakat, Pulau Pinang Malaysia.
[3] Abdul Rahman, A.M., M.H. Abdul Samad, A. Bahauddin and M.R. Ismail, Towards
[4] A Low-Energy Building Design for Tropical Malaysia, 2009. Penerbit Universiti Sains Malaysia, Pulau Pinang Malaysia.
[5] Mohamad Omar, N.A. and S.F. Syed Fadzil, 2011. Assessment of Passive Thermal Performance for a Penang Heritage Shop House, Procedia Engineering, 20: 203-212.
[6] Mohamad Omar, N.A. and S.F. Syed Fadzil, 2014. Analysis of Building Envelope Thermal Behaviour Using Time Sequential Thermography, 2nd Annual International Conference on Architecture & Civil Engineering (ACE 2014), 180-187.
Sharifah Fairuz Syed Fadzil and Nur Alia Mohamad Omar
School of Housing, Building and Planning, Universiti Sains Malaysia
ARTICLE INFO
Article history:
Received 12 October 2014
Received in revised form 26 December 2014
Accepted 1 January 2015
Available online 17 February 2015
Corresponding Author: Sharifah Fairuz Syed Fadzil, School of Housing, Building and Planning, Universiti Sains Malaysia
E-mail: [email protected]
Table 1: Detailed descriptions of the buildings and the
investigated rooms.
Building Approximate area Floor-ceiling Volume
height
JAIPP 38.1 [m.sup.2] 4.6 m 175.3 [m.sup.3]
Bomba 129.9 [m.sup.2] 4.2 m 545.6 [m.sup.3]
Town Hall 75 [m.sup.2] 5.4 m 405 [m.sup.3]
GTWHI 9.5 [m.sup.2] 4.2 m 39.9 [m.sup.3]
Building Average exterior Total window
wall thickness surface
JAIPP 152 mm --
Bomba 375 mm 26.6 [m.sup.2]
Town Hall 252 mm 24.8 [m.sup.2]
GTWHI 300 mm 1.8 [m.sup.2]
Building Ventilation Exterior
colour
JAIPP Closed. Still air White
Bomba Open. Natural White
Town Hall Closed. Still air Yellow
GTWHI Closed. Still air White
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| Author: | Fadzil, Sharifah Fairuz Syed; Omar, Nur Alia Mohamad |
|---|---|
| Publication: | Advances in Environmental Biology |
| Article Type: | Report |
| Geographic Code: | 9MALA |
| Date: | Mar 1, 2015 |
| Words: | 1436 |
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