Historically, state energy codes have focused on conductive heat transfer through prescriptive R-value and U-values for building enclosure systems. Lesser focus has been place on air leakage control and air barrier requirements.

But codes requiring air barriers are starting to be adopted on a state by state basis, although they are not currently required in most states. With recent changes in energy codes, continuous insulation is now required for frame construction in at least six out of eight U.S. climate zones—while there are continuous air barrier requirements in five out of eight climate zones. But does this make sense from a building science perspective. Let's look at the energy conservation benefits of continuous air barrier systems, relative to the benefits of increased insulation.

Energy Codes

Rising energy costs and environmental concerns have driven changes in energy codes and in construction practices, which are aimed at reducing energy consumption. Rising energy costs have also resulted in an increased focus on retrofit of existing buildings to reduce energy consumption.

Controlling conductive heat transfer through exterior walls and controlling air leakage through the building enclosure are two key aspects to reducing energy consumption.

Current U.S. energy codes require continuous insulation for frame construction in at least six of the eight climate zones, and there are continuous air barrier requirements in five of the eight climate zones.

The first modern North American quantitative code requirement for air barrier materials was implemented in the National Building Code of Canada in the mid 1980’s. In 2001, Massachusetts became the first state to incorporate a quantitative air barrier code requirement, Wisconsin, Michigan, Rhode Island, Georgia, Minnesota and Florida have since included air barrier requirements in their state codes.

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