Development of an indoor solar simulator for the evaluation of the thermal roof performance for commercial buildings in Malaysia

Past researchers have expressed the difficulty in assessing the empirical thermal performance of an entire roof assembly in terms of thermal resistance (RSI value) under hot conditions. This research discussed the development of an indoor solar simulator to assess the thermal performance of commercial building roofs under steady-state conditions. The indoor solar simulator has 40 halogen lamps to simulate solar radiation. Thermocouples and heat flux transducers are mounted at various points across the roof assembly to measure the heat transfer through the roof assembly. From the error analysis, the RSI values obtained experimentally using the indoor solar simulator and ASHRAE Standard agree with a MAPE value of 6.13%. This paper compares the thermal performance of radiant barriers, bubble foil reflective insulation, polyurethane (PU) foam, and mineral glass wool in a roof assembly. The measurement results showed that the radiant barrier and bubble foil reflective insulation has high RSI values ranging from 1.22 m2K/W to 2.19 m2K/W for enclosed air gap thicknesses from 25 mm to 125 mm. In contrast, the metal deck roof with PU metal resulted in RSI values from 0.55 m2K/W to 1.62 m2K/W for PU thicknesses from 20 mm to 50 mm. The combination of radiant barrier and glass mineral wool of 50 mm and 100 mm resulted in RSI values of 0.83 m2K/W and 1.60 m2K/W, respectively. The results from this research can be used to identify the optimum insulation for different roof configurations commonly used in the Malaysian building industry.