This methodology is applicable to weatherizing existing buildings, replacing mobile homes and impletmenting individual energy efficiency measures within existing dwellings. Applicable interventions that result in emission reductions fall into one of the following categories: all energy retrofit, which includes improving the building envelope, improving the efficiency of the central heating or cooling system and reducing energy consumption of appliances; efficiency enhancement of the building envelope and central heating and cooling system only; replacement of appliances currently in use; or replacing mobile homes currently occupied with energy efficient mobile homes.

Emission reductions are achieved by implementing measures that reduce the energy load, heat load or cooling load, or appliance plug load of the existing building, which reduces the amount of fossil fuel or electricity consumed to operate the building.