A field monitoring study was implemented to measure the impacts and benefits of membrane colour (white, grey and black) and insulation strategy on the performance of conventional roofing assemblies. The same roof membrane cap sheet type with three different surface granule colours was placed over three different conventional insulation strategies, creating a total of nine unique roofing assemblies on the same building. The thicknesses of the different insulation products were varied to achieve approximately the same R-value for each of the nine roof assemblies. Sensors were installed to measure temperature, relative humidity, moisture content, and heat flux at various points within each of the roof assemblies. Displacement sensors were also installed within the insulation boards to measure the dimensional stability of the different insulation products, and solar radiation sensors were installed above the cap sheet to document the long-term reflectivity and soiling of the roofing membranes. In conjunction with the sensors, webcam photos were captured to study the impact of night sky cooling, wetting/frost, and other differences between the assemblies. To complement the field study, supplemental laboratory testing of the insulation products was performed to measure the installed insulation R-values and whole building energy simulations were performed to apply the calibrated results from the study to other building types and climate zones across North America.
Presented in this paper are findings from the study which highlight the impact of both roof membrane colour and insulation strategy on the thermal behaviour and energy gains/losses through conventional roofing assemblies. Whole building energy modeling is used to synthesize the study findings and demonstrate how whole building heating and cooling energy consumption is affected by different roof membrane colours and insulation types/strategies across Canada.
This paper was presented at the 2014 Canadian Conference on Building Science and Technology.