The Best Practice specifications for extending dwellings

This guide covers two related insulation specifications:

• the Best Practice specification for new buildings

• the Best Practice refurbishment specification

The level of insulation required to satisfy the specification is expressed in terms of U-values for the main structural elements of the building, such as the walls, roof, etc. U-values measure the rate of energy loss through these elements.This rate can be slowed (and the U-value reduced) by incorporating more insulation within the respective elements.