increase annually at rates of 2, 4, 6, 8, and 10 percent,

e.g., at 7% about $200 billion over 20 years. These projections for housing are also indicitive of the scope of similar energy and cost savings potential that might be attained in other

types of building such as office buildings.

It is possible to reduce the heat loss or gain in residences by 50 percent through the use of thermal insulation in the ceilings, (6 inches) walls (3 inches) and floors (3 inches). As an example, Figure 10 was prepared to illustrate the application of four insulation requirements in terms of a heat load factor defined as Btu/(1000 ft3 of heated volume ) (degree-day) for a hypothetical residence of 1200 ft2.

In addition to conserving energy, increased insulation can save on heating furnaces (about 20 percent smaller), cooling machinery (about 10-15 percent smaller), and also smaller

lues, smaller electrical wire sizes to equipment and smaller

auct sizes.

ENERGY CONSERVATION FEATURES

FENESTRATION

General building design practice over the past decade

has called for large expanses of glass with most commercial building having between 50 and 60 percent of the exterior surface area occupied by these transparent surfaces. Historically it was for the purpose of making proper use of

natural light; however, most often today it is to provide a view of the outside, which in most instances is to cater to a real or assumed psychological need.

In contrast to the favorable characteristics of windows, they can have a significant impact on the heating and cooling loads imposed on the building. For example, figure 11 depicts a typical process occuring during the summer with solar radiation impinging on a 1/4" clear plate window and also energy being conducted across it as a result of hot outdoor 3/ air. As can been seen over 80 percent of the incident solar energy enters the space and the total energy entering is probably ten times larger than through a comparable amount of conventional wall. In the winter time, a different kind of problem exists. The ability to conduct heat of ordinary plate glass is five to ten times more than typical well insulated walls. Consequently they become a source of "heat leaks in

cold weather, being only partly compensated for by the solar energy. In addition, their high conductance results in a cool