The R-value is a measure of thermal resistance, indicating how well a material resists the conductive flow of heat. A higher R-value means better insulating effectiveness.
There are two ways to measure R-value: nominal and effective. Here's how the two concepts differ and why they both matter.
Read more: USGBC Seminar for Architects
Nominal R-Value
The nominal R-value represents the stated insulation value of a specific material under steady-state, laboratory conditions. This is the R-value that is generally printed on the insulation packaging and is used in marketing and sales of insulation products.
An architect would use the nominal R-values in initial design phases to compare different insulating materials and to calculate an initial estimate of the overall thermal resistance of various building components.
