Energy Code Measures to Assure the Effectiveness of Thermal Insulation Installed in Buildings

Several common residential construction details are detrimental to the performance of installed thermal insulation. Degradation of insulation performance is caused by air exfiltration (convective losses and moisture gain in insulated cavities) and wind wash (the passage of outdoor air through insulation).

Existing model energy codes in the United States address the exfiltration issue, although enforcement appears to be only partially effective. U.S. model energy codes do not address wind wash. New provisions of the Minnesota Energy Code for residential buildings are intended to require construction details that would reduce exfiltration and wind wash. The language addressing these construction details is generally more prescriptive than in existing model energy codes.

The inclusion of language in residential energy codes to improve the performance of thermal insulation follows the lead of special programs' building standards for energy efficient construction.