The U.S. Department of Energy's (DOE) Weatherization Assistance Program (WAP) differs in many ways from what is commonly referred to as "weatherizing your home." The latter involves low-cost improvements, such as adding weatherstripping to doors and windows, to save energy. WAP takes the "whole house weatherization” approach that analyzes all of the building systems—the building envelope, heating and cooling systems, electrical system, and electric baseload appliances—through the completion of an energy audit, as shown in Figure 1.

Another distinguishing feature of WAP is the attention to the overall health and safety of the clients being served and the weatherization providers. Many dwellings receiving attention are old and in need of repair.

Weatherization providers check the exterior of the building, known as the building envelope, and major energy systems to ensure there are no occupant health or safety concerns before installing any energy efficiency measures.

At its core, WAP is an energy efficiency program. The Program is largely measured in terms of energy saved. WAP recognizes homes and buildings work as a system of interrelated parts and follows the “House as a System” methodology to the assess and treat the homes.

WAP understands it is not effective to insulate an attic if the roof leaks and will degrade the insulation’s performance. Therefore, either the roof is repaired before the insulation is installed or the home is deferred until repairs can be made. When a home is deferred, it does not mean assistance will never be available, but that work must be postponed until the issues can be resolved and the home is ready for weatherization.

To help with moving homes off the deferral waiting list, many WAP local providers combine other federal, state, and local program funding to address the home or building problems so they can be weatherized.