Natural ventilation performance of air welled single storey terrace house

Abstract

Terraced housing in Malaysia hardly provides its occupants with thermal comfort. More often than not, the occupants need to rely on mechanical cooling, which contributes to outdoor heat dissipation that leads to urban heat island effect. Alternatively, encouraging natural ventilation can eliminate heat from indoor environment. Unfortunately, with static outdoor air condition and lack of windows at terraced houses, the conventional ventilation technique does not work well, even for houses with an air well. Hence, this research investigates ways to maximize natural ventilation in terraced housing by exploring the air well and louvre’s passive design. By adopting an existing single storey house with air well in Kuching, Sarawak, the existing indoor environmental conditions and thermal performance was monitored using scientific equipment, namely HOBO U12 air temperature and air humidity, HOBO U12 anemometer and Delta Ohm HD32.3 Wet Bulb Globe Temperature meter for six-month duration. The collected data was used as background study and benchmark for simulation. In this case, a simulation software – DesignBuilder® was utilised. The field study illustrated that there is a need to improve indoor thermal environment. Thus, the study further proposed improvement strategies to the existing case study house. The proposition is to turn the existing air well into solar chimney to take advantages of constant and available solar radiation for stack ventilation. The study also considers the effect of louvre windows to further accelerate the wind movement. The results suggest that the enhanced air well with proposed louvres were able to improve the indoor room air velocity and reduce air temperature. The enhanced air well with 3.5m height, 1.0m air gap width, 2.0m length with 45° tilted room opening louvres with 167mm slate gap were able to induce higher air velocity. During the highest air temperature hour, the indoor air velocity in existing test room increased from 0.02m/s in the existing condition to the range of 0.15 to 0.40m/s in the hottest month while during the lowest temperature month, the air velocity could be increased to the range of 0.25 to 0.53m/s. Installation of louvres at test room with solar chimney increases the percentage average air velocity of 16.5% and reduce percentage average air temperature to 1.1% compared to test room with solar chimney only. For indoor room temperature, the greatest mean air temperature could be reduced by up to 1.8°C compared to the outdoor air temperature during the hottest day. The findings revealed that the proposed air well and louvres could enhance the thermal and ventilation performance under Malaysia tropical climate.