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Synthesis/Regeneration 53   (Fall 2010)

The Air-Conditioned Dream in a Warming World

by Stan Cox

The share of electric utilities' output that goes to power air-conditioning has escalated relentlessly over the past decade and a half. The resulting greenhouse emissions are expected to make the outdoor climate harsher in coming decades. More hot weather will stimulate even greater demand for air-conditioning, resulting in the combustion of even more fossil fuels and further rounds of warming.

Partly as a result, the US Global Change Research Program and the Environmental Protection Agency expect the death rate from summer heat waves to rise steeply between now and 2050. [1] Accordingly, air-conditioning is being viewed less and less as an amenity and more as a life-support system. But even though air-conditioning has helped reduce death rates during heat waves over the past half-century, it has not eliminated them. Heat remains the nation's leading cause of weather-related mortality. Meanwhile, in many ways, air-conditioning has been playing a leading role in the distortion of American society for decades.

Chilled communities

Many who die from heat stress don't have air-conditioning or cannot afford to run it, but that's only part of the story. Just as important are the generally harsh conditions under which heat-wave victims often live. They typically suffer and die in economically forgotten, concrete-rich, vegetation-free stretches of large, mostly northern cities. The nature of the surrounding community can be a matter of life and death in a heat wave. A study by the Midwestern Climate Center found that "features of neighborhoods on a relatively small geographic scale (e.g., amount of pedestrian traffic, small shops, public meeting places) affect survival rates [positively]." The researchers also suggested that in such areas, fear of crime makes already vulnerable people, especially older people, reluctant to leave doors and windows open or to go outdoors in the cooler evening hours. [2]

Christian Warren, an associate professor at Brooklyn College specializing in the history of US public health and medicine, told me he is troubled by our reliance on climate control as a remedy for ills that run much deeper: "Now you see air-conditioning pitched in the medical literature as an environmental justice issue, because it can save lives during heat waves. But they aren't asking what really kills people. What about isolation, economic stress, crime, and paranoia about crime? You can easily imagine a couple staying shut away in their air-conditioned apartment during a hot spell, uninterested in checking on their elderly next-door neighbor, who could be dying of heat stroke."

...air-conditioning has been playing a leading role in the distortion of American society for decades.

The quest for control of the summer climate took off a half century ago in the warm, muggy South. By the 1980s, air conditioning had thoroughly transformed the region's culture, leading Southern historian Raymond Arsenault to opine that "General Electric has proved a more devastating invader than General Sherman." [3]

One of the most striking changes, noted Arsenault, was a sharp decline in "human interaction with the natural environment." For evidence, he wrote, "one has only to walk down almost any Southern street on a hot summer afternoon, listen to the whir of compressors, and look in vain for open windows or human faces." In the quarter-century that followed, air conditioning spread most quickly through regions far from the Sunbelt. In New England, for example, only 41 % of homes had air conditioning in 1993, whereas more than two-thirds have it today.

An ill wind

Today, in much of the country, it's hard to imagine life before air-conditioning. The idea that our society should become less dependent on climate control can seem radical, even absurd. But the post-air-conditioned world need not be one of malaise, poor health, social turmoil, and economic collapse; besides, hazards like those have become a bit too familiar already. In fact, several lines of research indicate that turning down or even turning off the flow of chilled air could improve our quality of life.

Research in human physiology suggests that artificial cooling of the indoor environment undermines our natural heat-adaptation mechanisms. I asked Michal Horowitz, professor at the Hebrew University of Jerusalem, about her pioneering research on the biology of heat stress and acclimatization and its implications for how we live. She responded that "those who live exclusively in an air-conditioned environment endanger their ability to cope with severe heat load."

"...listen to the whir of compressors, and look in vain for open windows or human faces."

It's not only the body's heat tolerance that suffers. Studies in California, Brazil, France, the United Kingdom, Denmark, and elsewhere have shown that people employed in air-conditioned workplaces have poorer health and visit doctors and hospitals more frequently than do those who work without air-conditioning. The specific causes of these health problems are not fully understood. But a study published in 2003 in The Lancet suggested that one of the several mechanisms at work could be the growth of bacteria and fungi in air-conditioning systems of office buildings. Such contamination has resulted in outbreaks of rhinitis, humidifier fever, asthma, pneumonitis, and Pontiac fever. [4]

Houses are kept tightly sealed in summer partly to shut out dirt, pollution, seasonal allergens and disease-bearing mosquitoes, as well as to reduce the need to dust, sweep and vacuum. However, as kids lounge in cool, sterile interiors - whereas in the past they might have been in the backyard making (and maybe tasting) mud pies - they receive less exposure to friendly soil bacteria and nematodes. That, according to a growing number of scientists, may be contributing to a rise in rates of asthma and allergies. [5]

...turning down or even turning off the flow of chilled air could improve our quality of life.

Medical researchers have speculated that air-conditioning may even contribute to rising obesity rates. There are at least three mechanisms: the human body burns calories more slowly when it doesn't have to work to shed heat; we eat more when we're in a cool environment; and people, especially children, are less physically active indoors than out. [6] Thanks partly to air-conditioning, we just aren't getting outdoors as much. In my own Kansas neighborhood, a shady street on a pleasant 80 summer evening can be as free of human life as it would be on Super Bowl Sunday in the middle of a sleet storm.

The indoor life may be taking a mental as well as a physical toll. Spontaneous outdoor activity is good for more than fresh air and exercise. It has also been shown to relieve stress, spur creativity, and expand children's friendship networks. Lack of contact with the outdoors, in contrast, has been associated with behavioral problems. [7] Air-conditioning has also helped pave the way for the widespread elimination of outdoor school recess, despite research showing that recess improves attentiveness and behavior in the classroom. [8]

Cooling the mall, heating the planet

Air-conditioning is undermining the planet's health as well. It now accounts for almost 20 % of year-round electricity consumption by American homes and an equivalent share of the resulting greenhouse emissions. Energy consumption by air-conditioning in the residential, retail, and automotive sectors has doubled just since the mid-1990s. Cooling of US homes, businesses, and public buildings consumes as much electricity as is available for all purposes across the entire continent of Africa - home to almost one billion people. Air-conditioning of buildings plus vehicles in this country causes the release of greenhouse gases equivalent to almost half a billion tons of carbon dioxide annually. If those were the total carbon dioxide emissions of a separate country, that country (call it Frigistan?) would rank among the top ten nations in climate impact. [9]

If, as diverse analysts are telling us, Americans have to cut our nonrenewable energy use by 80 % or maybe much more [10], everything, including air-conditioning, must be on the table. Thorstein Veblen once noted that in a capitalist economy, invention is the mother of necessity. Air-conditioning illustrates his quip nicely; but now it should be relegated, as it once was, to the category of a luxury.

...they receive less exposure to friendly soil bacteria and nematodes.
That...may be contributing to a rise in rates of asthma and allergies.

Residential air-conditioning units in service in 2005 were an impressive 28 % more energy-efficient on average than they were in 1993. But that did not reduce energy consumption; instead, as cooled square footage of the average residence expanded and summers grew hotter, the number of kilowatts of electricity used for cooling the average household increased by 37 %. Federal standards have since tightened, requiring that new equipment be another 30 % more efficient. Should we expect energy consumption to take another leap as a result? [11]

The US Energy Information Administration reported in 2009 that improvements in overall energy efficiency of the nation's residential lighting and appliances during the past decade had been wiped out by the increased load imposed by air-conditioning. As a result, total residential electricity consumption shot up 23 %. Most of that electricity is supplied by power plants burning coal and natural gas. Output from geothermal, biomass, solar, and wind sources could expand 400 % and still not be sufficient even to run America's air conditioners, let alone serve other uses. [12]

Energy consumption by air-conditioning... has doubled just since the mid-1990s.

Low-energy cooling projects - for example, wind towers in India and solar absorption air-conditioning in Arizona - provide real-life examples of how a home or office can be kept comfortable without burning fossil fuels. Traditional hot-climate features such as high ceilings, cross-ventilated designs, awnings, shade trees, screen porches, fans, whole-house exhaust fans, evaporative coolers, reflective or planted roofs, and even the creative use of basements can improve summer comfort without heating the great outdoors.

Those technologies can't always deliver the calm, uniform, predictable environment that conventional air-conditioning does - but that's not necessarily bad. In recent years, industry experts have incorporated into their natural-ventilation standards the "adaptive model of comfort," which says that the range of temperatures we find comfortable is not fixed but depends largely on the temperatures we've been experiencing over the past few weeks. [13] In other words, we adapt mentally as well as physically to heat and cold.

The refrigerator on wheels

Taking air-conditioning on the road magnifies the damage. Per cubic foot of space to be cooled, a vehicle air conditioner is worse for the Earth's atmosphere than is a home or office air conditioning system. As a result, vehicles contribute a disproportionately large share - one-fourth - of greenhouse emissions from all forms of air conditioning in America.

Low-energy cooling projects...provide real-life examples of how a home or office can be kept comfortable.

A vehicle's cooling system can increase fuel consumption, and therefore carbon emissions, by more than 20 %. That figure, from National Renewable Energy Laboratory tests, was for passenger cars in mixed city and highway travel. [14] The tests did not include summertime traffic jams, in which car engines perform little useful work other than saving occupants from being broiled.

Air-conditioning America's vehicles will add 64 million tons of carbon dioxide to the atmosphere this year, according to the Environmental Protection Agency. But fuel combustion is just a little over half of the story. In its effect on climate, a single pound of the refrigerant most widely used in car air conditioners is as potent as 1,430 pounds of carbon dioxide. In this country alone, leaked automotive refrigerants have as much warming effect as 55 million additional tons of carbon dioxide annually. [15]

When members of the Society for American City and Regional Planning History were asked to rank "the top 10 influences on the American metropolis" between 1950 and 2000, air conditioning came in at number nine. And it helped make possible most of the other items on the list, which included Sunbelt sprawl and shopping malls as well as the historians' number-one pick, "dominance of the automobile." [16] Without the growing array of amenities that help make mobile confinement tolerable - wireless communications, sound systems, GPS, ergonomic seating and, above all, air conditioning - America's commuters would have revolted long ago against their increasingly lengthy and annoying twice-daily regimen. And in a grim rush-hour arms race, closed windows and mechanical cooling have become essential defenses against pollution and noise, even on a mild, sunny 75 day.

Although innovations like high-tech reflective windows and better refrigerants can trim emissions, they can't stop the harm being done by the unsustainable living, commuting, and working patterns that air conditioning encourages. A relatively small but outrageous contributor to those wasteful patterns is some drivers' habit of keeping engines idling at curbs and in parking lots on summer afternoons, achieving zero miles per gallon in pursuit of comfort. A ban on idling - a large share of which is done to keep cars cool - could save an estimated 7 billion gallons of fuel each year in the United States. To help further reduce fuel waste, restaurants and banks could eliminate drive-through lanes and reward customers for venturing out of their wheeled oases and crossing hot asphalt.

But our top priority should be to keep cars at home and switched off. As Don Fitz has written, "Deep green transportation means reducing the number of autos and trucks on the road - by a huge amount, not by a little bit." [17]

With our dependence on the automobile, the air conditioner, and other energy-wasters, we've gone down an ecological cul-de-sac. Backing out, difficult as it will be, is the only solution. By reducing our dependence on air-conditioning, we can not only save energy but also become more resilient human beings. And we'll need that resilience. The coming decades will test our ability to adapt and create, and we can't leave it to technology to bail us out this time.

Stan Cox is a senior scientist at The Land Institute in Salina, Kansas. His new book Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World is published by The New Press .


1. EPA, "Excessive Heat Events Guidebook," Publication No. EPA 430-B-06-005, June 2006

2. M.S. O'Neill, A. Zanobetti, and J. Schwartz, Modifiers of the Temperature and Mortality Association in Seven US Cities, American Journal of Epidemiology 157 (2003), 1074-82.

3. Raymond Arsenault, The End of the Long Hot Summer: The Air Conditioner and Southern Culture, Journal of Southern History 50 (1984), 597-628.

4. D. Menzies et al., Effect of Ultraviolet Germicidal Lights Installed in Office Ventilation Systems on Workers' Health and Wellbeing: Double-Blind Multiple Crossover Trial, Lancet 362 (2003), 1785-91.

5. Garry Hamilton, Filthy Friends, New Scientist, April 16, 2005; E.W. Gelfand, 2003. The Hygiene Hypothesis Revisited: Pros and Cons, http://www.medscape.com/viewarticle/45217; Graham Rook and Christopher Lowry, The Hygiene Hypothesis and Psychiatric Disorders, Trends in Immunology 29 (2008), 151-58; Graham Rook, Review Series on Helminths, Immune Modulation and the Hygiene Hypothesis: The Broader Implications of the Hygiene Hypothesis, Immunology 126 (2009), 3-11.

6. S.W. Keith et al., Putative Contributors to the Secular Increase in Obesity: Exploring the Roads Less Traveled, International Journal of Obesity 30 (2006), 1585-94; C.P. Herman, Effects of Heat on Appetite, in Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations, ed. B.M. Marriott, (Washington, DC: National Academy Press, 1993), 187-214; Pawel Wargocki and David Wyon, The Effects of Moderately Raised Classroom Temperatures and Classroom Ventilation Rate on the Performance of Schoolwork by Children (RP-1257), HVAC&R Research 13 (2007), 193-220; M. Kobayashi and M. Kobayashi, The Relationship Between Obesity and Seasonal Variation in Body Weight among Elementary School Children in Tokyo, Economics and Human Biology 4 (2006), 253-61.

7. Richard Louv, Last Child in the Woods: Saving Our Children from Nature-Deficit Disorder (Chapel Hill, NC: Algonquin Books, 2005); Nancy Wells and Gary Evans, Nearby Nature: A Buffer of Life Stress among Rural Children, Environment and Behavior 35 (2003), 311-330.

8. Romina Barros, Ellen Silver, and Ruth Stein, School Recess and Group Classroom Behavior, Pediatrics 123 (2009), 431-36.

9. See http://unfccc.int/2860.php, http://www.hm-treasury.gov.uk/sternreview_index.htm; George Monbiot, Heat: How to Stop the Planet from Burning (Cambridge, MA: South End Press, 2007); and Francois Marechal, Daniel Favrat, and Eberhard Jochem, Energy in the Perspective of the Sustainable Development: The 2000 W Society Challenge, Resources, Conservation and Recycling 44 (2005), 245-62; Stan Cox, Why 80%? Synthesis/Regeneration 44 (2007).

10, 11, 12. Stan Cox, Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World (And Finding New Ways to Get Through the Summer) (New York: The New Press, 2010).

13. Richard de Dear and Gail Brager, The Adaptive Model of Thermal Comfort and Energy Conservation in the Built Environment, International Journal of Biometeorology 45 (2001), 100-108.

14. R. Farrington and J. Rugh, Impact of Vehicle Air-Conditioning on Fuel Economy, Tailpipe Emissions, and Electric Vehicle Range, Earth Technologies Forum, Washington, DC, 30 October - 1 November, 2000, http://www.nrel.gov/docs/fy00osti/28960.pdf

15. http://www.epa.gov/cppd/mac/index.htm

16. Robert Fishman, The American Metropolis at Century's End: Past and Future Influences. Housing Policy Debate 11, no. 1 (2000), 199-213.

17. Don Fitz, "Deep Green Transportation," Synthesis/Regeneration 46 (2008).

[10 sep 10]

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