What is a U-Factor?

Resolution:

The U-Factor, R-Value and K-Thermal Rating are measurements of thermal transmission through building products.

U-Factor: Overall co-efficient of heat transmission passage through a built-up panel section. Technically, it is heat transmission in BTU per hour per square foot per degree Fahrenheit of temperature difference from air to air for a complete panel sectional.

• The lower the U-factor, the better the insulation).

R-Value: Thermal resistance is a measure of ability to retard heat flow. R is an expression of the total resistance to heat flow through a complete panel section or construction assembly. “R” represents a value of the thermal resistance, per hour per square foot of a typical panel section. The R-Factor is the numerical reciprocal of the U-factor.

• The higher the R, the higher the insulating value.

K-Thermal Rating: Conductivity (K) is the amount of heat that passes through a homogenous material one inch thick and one square foot in area per hour. Values of K are expressed in BTU per hour (the lower the K, the higher the insulating value). The K unit is for a single component material one inch thick and one square foot in area. Therefore, it does not apply to a 1-3⁄4” thick door panel consisting of several materials. (Conductivity is not a method of measuring heat transmission through built up panels.)