R-value is the measure of resistance a material has to heat flow. The higher the R-value, the greater the resistance. As explained in the section “Why Insulate?”, resisting heat flow is the primary purpose of insulation which in turn lowers energy costs.
The chart below shows the recommended levels of insulation for different parts of the United States:
Note: These values can be achieved in new home construction but may not be able to be reached in existing homes. These recommendations are design to provide the best opportunities for energy savings.