Cool Roofs, Cool Roofing Explained : how cool vinyl roofing surface membranes save money and the environment


	Cool Roofing: A Solution to National Energy and Environmental Challenges Self-guided presentation (HSW and SD credits). A detailed overview of the performance characteristics and benefits of cool roofing systems using reflective white vinyl roofing. Green roofing, energy saving programs, environmental challenges and solutions are also reviewed. For instant access to the course, click here »

COOL ROOFING PROGRAMS

Also known as albedo, a measure of a material’s ability to reflect sunlight (including the visible, infrared and ultraviolet wavelengths), expressed either as a decimal fraction or a percentage. A value of 0 indicates the surface absorbs all solar radiation, and a value of 1 represents total reflectivity.
The ability of a material to release absorbed (non-reflected) heat, expressed either as a decimal fraction or a percentage.
A value that incorporates both solar reflectance and emittance in a single value to represent a material's temperature in the sun. SRI quantifies how hot a surface would get relative to standard black and standard white surfaces. It is defined such that a standard black (reflectance 0.05, emittance 0.90) is 0 and a standard white (reflectance 0.80, emittance 0.90) is 100.
A roof surface having a maximum slope of 2 inches rise for 12 inches run.
Three years’ exposure.
Requirement for conditioned spaces only.
Roughly equivalent to, for example, 0.65 reflectance and 0.90 thermal emittance, although a number of different combinations of reflectance and emittance can achieve this value.
Effective August 1, 2009; call (800) 772-3300 or (916) 654-5106 for detailed understanding of this provision's implementation
Effective August 1, 2009; may not apply in every climate zone

Characteristics of Common Roofing Systems¹	Solar Reflectance	Emittance	Solar Reflectance Index
Black EPDM	0.06	0.86	-1
Smooth Bitumen	0.06	0.86	-1
White Granular Surface Bitumen	0.26	0.92	28
Dark Gravel on BUR	0.12	0.9	9
Light Gravel on BUR	0.34	0.9	37
White Thermoplastic (Vinyl)	0.83	0.92	104

(1) Lawrence Berkeley National Laboratory Cool Roofing Materials Database