Courtesy Lennox Corporation

Courtesy ©Ewing Galloway

Architect John Eberson designed the fanciful Olympia Theatre in Miami, Fla., with air conditioning c. 1920.
Courtesy Carrier Corporation

Courtesy Carrier Corporation

This 1954 advertisement for central air conditioning glamorizes the modern ranch house, heat-transmitting picture windows, and sliding glass doors.
Courtesy Lennox Corporation

Hot America
Before air conditioning American life followed seasonal cycles determined by weather. Workers' productivity declined in direct proportion to the heat and humidity outside--on the hottest days employees left work early and businesses shut their doors. Stores and theaters also closed down, unable to comfortably accommodate large groups of people in stifling interiors. Cities emptied in summers as people fled the city for mountain and seaside resorts. Low-tech solutions helped people cope with the heat. Fans evolved from hand-held to electrically powered devices that could produce air movement, but could not control humidity. Houses and office buildings were designed to enhance natural cooling, and people spent summer days and evenings on porches or fire escapes. They cooled off by getting wet--opening up fire hydrants, going to the beach, or diving into swimming holes.

Leisure Land
Air conditioning in America has followed two tracks: "process air conditioning" for manufacturing and "comfort air conditioning" for people. Although factories installed mechanical cooling systems as early as 1888, it wasn't until the 1920s that the general public encountered "man-made weather" in movie theaters around the country. Before air conditioning, however, early 20th-century storefront nickleodeons caused public officials and reformers concern about the healthfulness of movie theaters and "unwashed masses" crowding together in poorly ventilated spaces. In summer months the heat and odors accumulating over multiple performances became unbearable and most theaters closed for the season. Instead, people went to outdoor amusement parks, amphitheaters, and ballparks to be entertained. In order to maintain their business year-round, theater owners sponsored early experiments in "comfort air conditioning" and played a pioneering role in introducing the new technology to the public in the 1920s. Mechanical cooling allowed theater owners to provide a comfortable, luxurious, and often exotic environment far from the real world outside. Air conditioning itself became an attraction, as people flocked to movie theaters to experience the new way to stay cool. Movie theaters inaugurated a tradition of mechanically cooled recreational environments. Indoor shopping malls, sports arenas, theme park rides, casinos--none of these facilities would exist without air conditioning. Engineered air not only made these facilities possible, but also enhanced their sense of fantasy by creating sealed, windowless environments isolated from the real world outside. People started going to malls, movies, and indoor sports events to cool off on hot summer days, and interior recreation became a year-round activity.

Home Conditioning
Not until after World War II did air conditioning enter the home of the average American. Engineered air was marketed to the public as an essential component of modern living. Manufacturers claimed that it promoted better sleeping and eating, healthier air quality, cleaner interiors free from pollen and dust, and the enjoyment of nature through glass window walls without the discomforts of summer heat and humidity. With its steadily decreasing costs, air conditioning was touted as a technology "for the millions, not just for millionaires." The refrigerator provided the model for early residential air conditioners. As domestic interest grew in the late 1920s, refrigerator manufacturers were among the first to develop air conditioners due to their technical expertise with small-scale refrigeration units, automatic controls and mass-production. During the Depression power companies, manufacturers, and retailers advocated self-contained home units as industrial use waned. Residential units evolved from bulky cabinets in living areas with basement condensing units into small-scale central systems with ductwork or the popular, economical window air conditioners. Domestic air conditioning meant that traditional architectural features--wide eaves, deep porches, thick walls, high ceilings, attics, and cross ventilation--were no longer needed to promote natural cooling. Also irrelevant was siting or landscaping a house that maximized summer shade and breezes, since mechanical equipment was able to maintain perfect indoor conditions independent of design. Builders found they could pay for the costs of central cooling systems by deleting elements made unnecessary by the new technology. As air conditioning replaced traditional features, the design of the modern house became fully integrated with--and dependent on--air conditioning. It allowed postwar architects and builders to achieve a new "ranch house" aesthetic of glass picture windows, sliding doors, and rectangular forms.

Cool Works
The needs of business spurred many of the earliest developments in air conditioning. Manufacturers of products susceptible to heat and humidity--tobacco, pasta, textiles, chocolate, and color printing--commissioned many pioneering experiments in mechanical cooling. Since the early 20th century, industry has demanded increasingly sophisticated technology to provide cool, clean, stable environments for manufacturing their products. Facilitating important developments in high-tech manufacturing, science, medicine, and consumer products, air conditioning ushered in the Age of Information.

Manufacturing Facilities
Before air conditioning cotton threads broke, cigarette machines jammed, bread grew mold, film attracted dust, pasta lost its shape, and chocolate turned gray when temperatures and humidity fluctuated. By filtering air and stabilizing temperature and humidity, mechanical systems improved the environment for products as well as workers. The technology of air conditioning developed concurrently with the invention of more sophisticated products that required increasingly precise temperature, humidity, and filtration controls. Today many consumer products such as computer chips and CDs must be manufactured in "clean rooms," which provide a pristine dust-free environment

Office Buildings
Beginning with the New York Stock Exchange in 1901, office buildings served as important laboratories for air conditioning advances. After World War II mechanical cooling allowed the development of the modern glass-walled skyscraper--the symbol of freedom from traditional construction systems as well as heating and cooling methods. Before mechanical cooling systems were common in office buildings, most were based on T, H, or L-shaped floor plans that allowed the maximum number of windows to provide natural light and ventilation. After World War II the development of large-scale air conditioning systems for office buildings altered their traditional footprint, interior layout, and exterior appearance. Glass-walled skyscrapers such as the United Nations (1952) linked the development of modern architecture with the new technology. Mechanical cooling freed designers from conventional methods of siting office buildings in relation to the sun or ventilating them with operable windows, while making them dependent on air conditioning systems to function. Many of today's real estate developers, builders, engineers, architects, manufacturers, and clients are going "green." Since the energy crisis of the 1970s, interest has returned to a "green-er" architecture that relies less on fossil fuels and more on natural principles. Using both new technology--air-pollutant filtration and sensor systems, floor-level air distribution, off-peak energy storage--and traditional methods--increased fresh air supply to the mechanical system, architectural sunshades, natural ventilation, contemporary engineers are designing buildings that are healthier and more energy efficient than their predecessors. Buildings also are becoming more environmentally friendly, as they are designed to consume fewer fossil fuels and emit fewer ozone-depleting agents. Today's green architecture is the latest in a century of air conditioning experiments that shape contemporary building and improve modern life.