Comparative assessment of vernacular passive cooling techniques for improving indoor thermal comfort of modern terraced houses in hot-humid climate of Malaysia

Abstract

The main objectives of this study were to investigate vernacular passive cooling techniques and their potential application for improving indoor thermal comfort of naturally ventilated, modern brick terraced houses in Malaysia. Field measurement was conducted in two traditional timber Malay houses and two traditional masonry Chinese shophouses to examine their indoor thermal environments. The results of the former showed that the indoor air temperatures were higher than the outdoor air temperatures by 1 °C during daytime under open window conditions and 2 °C at night under closed window conditions on average. The emphasis was on reducing the temperature of the outdoor air before entering the lightweight house for bodily cooling by cross ventilation. The outdoor air temperature at the Malay house sites was lower than that of the terraced house site by 1.7 °C on average. The results of the latter revealed that indoor air temperatures in rooms that were adjacent to small internal courtyards were lower than the immediate outdoors by about 5 °C on average at the peak period. At night, the indoor air temperatures maintained values that were similar to the outdoors. The small courtyards were effective to cool the high thermal mass structures through nocturnal ventilative and radiative cooling. When assessed using an adaptive thermal comfort equation for hot–humid climates, the periods of indoor operative temperatures exceeding the 80% comfortable upper limit in the Malay houses, Chinese shophouses, daytime ventilated and night ventilated terraced houses were 47%, 7–8%, 91% and 42%, respectively, on fair weather days. Potential passive cooling techniques for the existing terraced houses including night ventilation, roof or ceiling insulation, window and wall shading, small courtyard concept, and microclimate modification and/or urban heat island mitigation were discussed.