Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use

Abstract

This report presents a simulation study of the energy impact and cost effectiveness of improving envelope airtightness in U.S. commercial buildings. Despite common assumptions, measurements have shown that typical U.S. commercial buildings are not particularly airtight. Past simulation studies have shown that commercial building envelope leakage can result in significant heating and cooling loads. To evaluate the potential energy savings and cost effectiveness of an effective air barrier requirement, annual energy simulations and cost estimates were prepared for three nonresidential buildings (a two-story office building, a one-story retail building, and a four-story apartment building) in 5 U.S. cities. A coupled multizone airflow and building energy simulation tool was used to predict the energy use for the buildings at a target tightness level relative to a baseline level based on measurements in existing buildings. Predicted potential annual heating and energy cost savings ranged from 2 % to 36 % with the smallest savings occurring in the cooling-dominated climates of Phoenix and Miami.