EPDM Roof for Every Climate
Today's construction climate places a heavy emphasis on green, sustainable building practices. But there's more to being green than black or white. Many experts agree that light-colored reflective surfaces are most appropriate in warm southern climates while dark, heat absorbing surfaces are best in the north. EPDM is the only roofing material that offers solutions for ALL climates without the need for additional coatings or modifications.
With the emphasis on optimizing energy performance, the table below is based on insulation R-values (shown in second column) published in ASHRAE 90.1 Addendum F, which was approved in June 2010. For white and black membranes, the table outlines the necessary adjustments in R-values to maintain a roof assembly’s energy performance. For example, while optimum performance using a black membrane, the assembly must utilize insulation with an R-value of 29. Quite the contrary in colder regions (ASHRAE Zones 4 through 8). For example, while optimum performance can be achieved with a black membrane combined with R-35 in Zones 7, an assembly with a white membrane will require an increase in the insulation levels to R-38 in order for the assembly to deliver the same energy performance.
Traditional ballasted EPDM roof assemblies can deliver superior energy performance to cool roofs in Zones 4 and above. With an increase in coverage, ballasted roofs equal the performance of cool roofs in Zones 3 and below.
For more information, this article from "Choosing the Right Membrane" may be of particular interest.
As research on reflective roofs and their impact on energy efficiency and climate change is always evolving, this recent study by Stanford University researchers may also be of interest. This study found that reflective roofs do not have the same impact on reducing the urban heat island as others have asserted.
|Insulation Levels Without Equivalent Load Values|
|Fully Adhered & Mechanically Fastened|
|ASHRAE Zone||R-Value||White EPDM||Black EPDM||Ballasted EPDM|
Figure 1., * = 17 #/SF Ballast, ** = 10 #/SF Ballast