Definitions for "R value"
Keywords:  batt, insulation, heat, resist, higher
A measure of insulation, or more specifically, a measure of a material's resistance to the passage of heat; the higher the R value, the better it insulates (e.g., the walls of a typical new home are usually insulated with 4" of batt insulation with an R value of R-13, and a ceiling insulation of R-30)
This measures a materials resistance to the ability of heat to flow through it. A high number here is superior. To read more on R Value.
A measure of the overall resistance to heat transmission due only to the difference in air temperature on either side of the material.