Rapid U-Values

The rate of thermal transmittance through individual building elements contributes significantly to the overall energy efficiency of a building. The lower the U-value of an element of a building’s fabric, the more slowly heat is able to transmit through it, and so the better it performs as an insulator.

Regardless of the construction method used, the in-situ U-value of a floor, wall or roof element can vary significantly from a calculated value. Influencing factors include inhomogeneous materials, variations in the level of moisture content of materials, exposure of an element to wind and rain, inconsistencies in building practices and workmanship and also inaccuracies embedded in material libraries used for running calculations.