Effects of Air Leakage on Buildings’ Overall Thermal Resistances Based on U.S. Climate Zones (LB-17-008)

Air-leakage through building envelopes causes significant energy losses. Air-tightness codes do not account for air-leakage due to wind-driven pressure gradients and thermal resistance codes do not consider any air-leakage effects. Air-leakage needs to be included codes to understand the effects on thermal performance. We calculated effective thermal resistances in 103 locations considering air-leakage effects, to see effects on thermal performance. Simulations showed decreased thermal resistances and increased energy losses in every climate. Varying levels of thermal performance demonstrate relative importance of air-tightness in different climates. Results imply current codes do not accurately represent thermal performance and where air-tightness matters most.