The Earth Advantage Institute and Energy Trust of Oregon teamed up to develop the Energy Performance Score (EPS), which rates a home’s efficiency and measures it against similar-sized dwellings in the region. A third-party verifier develops a unique scorecard for each home, which includes estimates of monthly energy costs, annual energy consumption (measured in millions of Btu) and carbon emissions (measured in tons of carbon dioxide). The lower the score, the more efficient the home. Though voluntary, EPS is available throughout Oregon; pilot programs incorporating EPS have been launched in several other states.
A blower door test is part of the EPS scoring. This test, which measures a building’s airtightness and identifies leaks, is one of a home energy auditor’s best tools. A flexible panel is fitted into the frame of an exterior door; a fan mounted into the panel sucks air out of the home, creating a pressure differential between inside and outside, which is measured. Seeking lower pressure, outside air flows in through unsealed cracks and openings. The auditor can also measure the rate of air exchange and determine whether a home needs mechanical ventilation to improve indoor air quality or, conversely, leak mitigation to reduce heat loss or unwanted heat gain.