Energy Academy
Envelope Design & Heat Loss1 / 13

Fabric Performance & U-Values

How building elements lose heat; U-value targets for new and retrofit; cost-benefit.

11 min read ยท Jacob Willis, Net Zero Lead


The building fabric - walls, roof, floor, and windows - determines how much heat escapes in winter and enters in summer. Controlling losses at the fabric is almost always cheaper than oversizing the heating and cooling plant to compensate.