The economic forces acting on the air-conditioning and heating equipment market have changed and continue to change in response to energy technology, supply, and cost, as well as construction trends. During the 1970s, substantial heat-actuated cooling R&D was focused on the useful conversion of solar energy--a heating technology contender--for air-conditioning.

Today’s energy market forces are responsible for the renewed interest in the direct conversion of fuels in place of premium-priced electricity for the production of cooling. A number of mature equipmentechnologies, such as absorption cycle refrigeration, are available for this market but are limited in application to water-cooled, chilled water systems. Other circumstances--such as construction trends swinging to low-rise structures and the ensuing rapid increase of unitary air-conditioning products, the growth of speculative construction, and the shift of electric charges to peak-use sensitivity--have identified the market for broad-based, adaptive nonelectric cooling products.