Weatherization
Improving a building envelope through air sealing, insulation, window upgrades, and duct sealing to reduce energy waste. The most cost-effective first step before any clean energy investment.
Why It Matters
The cheapest kilowatt-hour is the one you never use. Weatherization reduces the size (and cost) of solar and HVAC systems needed, and the WAP provides free weatherization for qualifying households.
Related Tools
Related Terms
Air Sealing
The process of identifying and sealing unintentional air leaks in a building envelope — including gaps around pipes, wires, ducts, windows, and the attic hatch.
R-Value
A measure of thermal resistance — how well a material resists heat flow. Higher R-values mean better insulation. Recommended attic R-values range from R-38 to R-60 depending on climate zone.
Blower Door Test
A diagnostic test that uses a calibrated fan mounted in an exterior doorway to depressurize the house and measure the total air leakage rate, expressed in CFM50 or ACH50.
WAP (Weatherization Assistance Program)
A federal program that provides free energy efficiency improvements to low-income homes, including insulation, air sealing, and heating system upgrades.