The measure of a material's ability to resist heat flow (commonly applied to building insulation). The higher the R value, the less heat is transmitted throughout the material. The R-value is the reciprocal of the U-value.
The measure of a material's resistance to heat flow. The higher the R-value, the more effective its insulating property.
Measurement of a material's resistance to heat loss, most often referring to insulation products. The higher the R-Value, the slower the rate of loss.