The R-value, also known as thermal insulance, is the temperature difference per unit heat flux, at steady state, between two defined surfaces of a material or construction that induces one unit of heat flux between the surfaces. The R-value is used for comparing insulating values of different materials, for the specific thickness of the material. The higher the R-value, the greater a material's insulating properties and the slower heat flows through it. The R-value does not include the interior and exterior air film coefficients. The R-value is the reciprocal of the U-factor.

# R Value

Data Type:

Decimal

Category:

Unit of Measure:

hr-ft2-F/Btu

Source:

ASHRAE

Sector:

Commercial, Residential, Multifamily

**Term ID:**c24d66cb-8f89-4dd6-8c3b-39542499a472