How are R-Value’s tested?
The R-Values of insulating materials are measured in laboratories under ideal conditions and the conductive heat transfer property is the only property that is measured. However, in reality, convective heat transfer plays a big role when it comes to energy performance of a house. Icynene provides superior energy performance over air-permeable insulation because of its air barrier capability even though they both have similar R-values.
Extensive computer modeling and field data have shown that the energy performance of Icynene at much lower R-values almost always outperforms fiberglass insulation in the field due to its superior air-sealing ability. Hence, although we usually recommend lower R-values than fiberglass, Icynene's thermal performance in the field is superior in terms of the energy efficiency of a building.