one third of the energy required annually for space conditioning can be saved.¹⁹

More comprehensive energy-saving measures, such as community-based utility systems,²⁰ are economically feasible but impractical today for a variety of reasons, including environmental restrictions, the difficulty of making connections with utilities, and developers’ reluctance to assume the burden of resolving technical complexities. Concentrated efforts to remove or reduce these institutional barriers could result in substantial additional energy savings in the buildings sector.

Economic considerations are likely to weigh more heavily than others in the decision to improve thermal integrity²¹ in buildings. But because many homeowners move frequently, and because the consumer who pays the bills for operating and maintaining a building does not usually make the design and construction decisions, any decision to improve efficiency must be encouraged by building code standards, financial incentives, and information campaigns. Builders have inadequate incentives to minimize life cycle costs; in fact, they tend to favor low initial costs instead. (Of the 1,455,000 single-family homes built in 1977, 904,000 were erected by developers for sale on the open market.)²²

Retrofitting an existing structure for greater efficiency in energy use will not appear wise to many consumers, even as energy prices rise. Existing buildings offer less scope for energy conservation than do new ones, but some retrofit measures are generally economical. Caulking, increasing attic insulation to 6 in. and wall insulation to 3 1/2 in., adding foil insulation in the floor, and installing storm doors and windows are the best energy conservation investments. Together, they can reduce heating requirements by as much as 50 percent; savings on air conditioning would be somewhat less. Figure 2–1 illustrates the energy savings possible in new and retrofitted single-family residences as a function of incremental capital costs.

The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) developed a new building code in 1975, setting out construction guidelines for energy-efficient buildings (ASHRAE-90–75). The Energy Policy and Conservation Act of 1975 (Public Law 94–163) requires that states adopt ASHRAE-90–75 or similar standards to be eligible for federal funding of state energy conservation plans. More stringent standards, based on performance, are being prepared and discussed.

High on the list of priorities in any program to accelerate improvements in existing buildings is accurate information for lending institutions, homeowners, and homebuyers on the advantages of retrofitting. Readily available loans, subsidies, and tax incentives can also stimulate retrofitting. A justification for such measures is that the whole society benefits from