Weatherization as defined by the Weatherization Assistance Program (WAP) differs in many ways from what is commonly called "weatherizing your home." The latter involves low-cost improvements like adding weatherstripping to doors and windows to save energy. These measures made up the services WAP provided in its early years and are likely responsible for the program's name.
Today, WAP's weatherization services consist of cost-effective energy efficiency measures for existing residential and multifamily housing with low-income residents. Under this definition, it includes a wide variety of energy efficiency measures that encompass the building envelope, its heating and cooling systems, its electrical system, and electricity consuming appliances.
The benefits of weatherization begin with reducing the energy bills of recipients for a long period of time. Some measures, such as insulating walls or roofs, for example, can provide savings for the lifetime of a house—30 years or more. Other measures, such as making heating or cooling equipment more efficient, will provide savings for 10–15 years. On average, the value of the weatherization improvements is 2.2 times greater than the cost.
WAP serves low-income families free of charge and limits the amount of money that can be spent on any single residence as determined by federal rules. (The average expenditure is $6,500.) As a result, only the most cost-effective measures are included in the upgrade of a particular home. This constant pressure for low-cost energy savings has become the trademark of weatherization and distinguishes it from the larger home retrofit industry.
Another distinguishing feature of weatherization is attention to an all-around safety check. Many buildings receiving attention are old and in need of repair. Weatherization service providers check major energy systems to ensure occupant safety.
Increasingly, weatherization service providers look at the house as a system under the concept of "whole-house weatherization." In recent years, weatherization providers in many states have begun to combine resources from other programs to address other needs of their clients. This expanded approach is referred to as Weatherization Plus.
Weatherization today comprises a comprehensive series of energy efficiency measures that are based on sophisticated analyses of individual homes. These analyses take the whole-house approach, which maximizes energy and dollar savings. Because of this rigorous approach and analyses backing it up, weatherization has become a leader in advancing home energy science and in helping spawn a new industry providing home energy efficiency services to the wider public.