"Air-conditioning's huge machinery and enormous expense, both heavily publicized, lent prestige and glamour to the establishments capable of installing it."

A look at the history of air conditioning from a historical and sociological perspective is found in a new book, "Cool Comfort: America's Romance With Air Conditioning," published by the Smithsonian Institution Press.

Author Marsha Ackermann isn't an engineer, nor does she work for a manufacturer. Instead, she lectures in history at Eastern Michigan University in Ypsilanti, Mich. This book isn't about the nuts and bolts of early attempts at air conditioning, although there is some of that in there, too. She recounts, "Before 1920, air-conditioning was used almost entirely in factories where its role was to produce not human comfort but manufacturing consistency."

The 214-page book explores the impact of air conditioning on Americans' daily lives. For example, early on Ackermann describes life at the turn of the century in big city tenement high rises, where tenants routinely would sleep on fire escape balconies and the roofs of buildings in the heat of summer in order to catch even the most trifling of cooling breezes.

A caste system which saw renters who paid more money for the lower floors was reversed when temperatures rose; upper floor dwellers jealously staked out the more selective rooftop sleeping pads they felt they were entitled to.

A climate of change

Cooling the interior environment was a part of America growing up, Ackermann writes. It didn't spread initially exactly according to need or plan. Rather, "air conditioning expressed a city's influence and affluence, its aspirations to modernity and ability to control its domain¿ Implicit class and gender expectations shaped the decision to install air conditioning, the choice of where and how to use it, and the manner in which it was advertised. Older institutions catering to the rich were slower to embrace the air-conditioned future."

Such status symbols were especially attractive to the burgeoning middle class of the 1950s. A number of new home builders, including New Jersey tract home developer William Levitt, put central air conditioning in hundreds of homes he constructed during the 1950s.

As Ackermann traces this move from luxury to necessity, she explains how the power-hungry systems became a political issue in the 1970s as blackouts, brownouts and energy crises gripped the country. She writes: "Although air conditioning consumed less than three percent of the nation's total energy derived from all sources in 1978, according to the U.S. Department of Energy, it made extremely intense demands on electrical power supplies."

The book's later chapters delve into social and environmental issues some experts blame in part on air conditioning, such as Americans' tendency today to stay indoors, isolated from neighbors, and the effects of global warming and greenhouse gasses on the Earth.

("Cool Comfort" is available from Smithsonian Institution Press, P.O. Box 960, Herndon, VA 20172-0960; call 800/782-4612. The book is also available as a special order item from many booksellers or online stores such as www.Amazon.com.)