A field monitoring study was implemented to measure the impacts and benefits of membrane color (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 colors was placed over three different conventional insulation strategies, creating a total of nine unique roofing assemblies (16 square in size) on the same building. The thicknesses of the different insulation products were varied to achieve approximately the same R-value for each of the 9 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 to measure the dimensional stability of the insulation. In addition, webcam photos were captured to study the impact of night sky cooling, wetting/frost, and other differences between the assemblies. To complement the field investigation of this study, the effective R-values of the insulation products were measured in the laboratory following ASTM C518 protocols.
Presented in this paper are findings from the study and the highlights of the impacts of the insulation strategy on the thermal behaviour, dimensional movement, and moisture movement for these conventional roofing assemblies. In-situ R-values and net energy transfer for each of the roofing assemblies are discussed in combination with comfort and performance implications. The study also provides insight into the performance of various insulation and mixed insulation assemblies, which take advantage of optimum temperatures, and highlights the potential benefits of each assembly.
This paper was presented at the 2013 RCI Building Envelope Symposium.