The building envelope is the first and least expensive element to address in the design of energy efficient homes and above grade walls are where shortcuts are taken most often. A NAHB-RC study summarized below shows that two-thirds of a typical home’s heat loss is due to above grade walls when combining both conductive and convective heat lost.
Why do above grade walls add up to such heat loss? The nature of light-framed stud wall construction results in a design that is difficult to insulate sufficiently on the inside, and requires bracing from lateral loads, typically on the outside. These two factors have led to prevailing construction techniques that don’t sufficiently weigh building science basics, which are to have a building envelope that controls heat, air and moisture transport.