Most know R-value as a simple rating system for building insulation products, but what exactly is an R-Value? (see sidebar) This is a great question, and one that is not asked often enough in today’s environmentally conscious society. However, an even better question is whether R-value is still a valid unit of measurement for the performance of insulation products. If not, then why is it still being utilized as the predominate gauge to compare these products? To answer these questions it is important to discuss how R-value came to be and how it is used today.
In the past, when energy was cheap, little thought went into energy efficient building design, and there were even fewer associated products; people did the best they could with what was available. Then, as energy prices rose, heating and cooling costs became an issue. (see sidebar) The Federal Trade Commission recognized the importance of energy expenditures on housing to homeowners and other consumers, and in 1979, it promulgated the R-value Rule, 16 CFR Part 460. The R-value Rule requires that, “thermal insulation manufacturers, among others, disclose the thermal performance of their products, based on uniform testing procedures adopted by the thermal insulation industry.”