Ammoniacal copper arsenate. One of several varieties of toxic pesticides used in pressure-treated wood; see also CCA (chromated copper arsenate).

ACH stands for Air Changes per Hour. This is a metric of house air tightness. ACH is often expressed as ACH50, which is the air changes per hour when the house is depressurized to -50 pascals during a [..]

ACQ is a water-based wood preservative alternative to CCA for preserving wood that prevents decay from fungi and insects. There are four standardized ACQ formulations, Types A, B, C, and D. The differ [..]

House-framing techniques in which lumber use is optimized, saving material and improving the energy performance of the building envelope.

A U.S. Environmental Protection Agency (EPA) program to promote the construction of "better than Energy Star" homes.

A proposed U.S. Environmental Protection Agency (EPA) program to promote the construction of “better than Energy Star” homes. The proposal calls for builders to comply with a “Builder Option Package” [..]

Annual Fuel Utilization Efficiency. Widely-used measure of the fuel efficiency of a heating system that accounts for start-up, cool-down, and other operating losses that occur during real-life operati [..]

Building assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the i [..]

Heat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps.

In terms of solar energy, the angle that the sun's rays make with an imaginary line perpendicular to a surface. The angle of incidence determines the intensity of the energy that any surface “see [..]