EVALUATION OF THE THERMAL PERFORMANCE OF METAL ROOFING UNDER TROPICAL CLIMATIC CONDITIONS

The assessment of the thermal performance was carried out on a low cost house mainly built from waste oil
palm shell (OPS-Concrete) with galvanized steel-roof. It was noticed that reasonable thermal comfort took
place during the night for the roof without ceiling and without insulation, and during the day at a peak
temperature of a highly ventilated attic area. For such situation, it was recommended to install insulating
horizontal plated surface under the roof, which should be turned into a vertical position during the night.
Other alternatives may be creating small adjustable openings around building envelope just under the ceiling
or making an open roof-ceiling system. This technique will reduce the heat flux from insulated ceiling by the
flow of the cooling air at night, but the impact of surrounding microclimate on human thermal comfort should
be considered. The mathematical model used to predict the attic temperature for a lightweight roof system
was obtained by correlation, which can be used for a quick inspection. Insulation materials of 50 mm
fibreglass and foil-aluminium were used with sealed attic, and found the ceiling temperature reduced by
about 3 oC and 2 oC respectively. For the case of fibreglass of thickness beyond 50 mm, the reduction of
ceiling temperature was recorded less than ½ oC, really not attractive.
Keywords: thermal performance, metal roofing, attic temperature, sealed attic, ventilated attic, insulation