With some of the fastest-growing nations situated in some of the world's hottest climates, the use of air conditioning is expected to skyrocket in coming decades.
It's good news for public health and economic productivity, but there are concerns about the large amount of energy needed to meet that demand, especially in countries that still rely predominantly on the most polluting sources of electricity.
"Should the world eventually adapt the US level of need for cooling, energy demand for air conditioning would be equal to about 50 times the current demand for cooling in the US," said Michael Sivak, a researcher at the University of Michigan and author of a study of global air conditioning use published in the September-October 2013 issue of American Scientist.
In India, for example, only 2 percent of households had air conditioning in 2007, according to the European Council for an Energy Efficient Economy. But sales of air-conditioning units in India are growing by about 20 percent a year. If the country of more than 1 billion people eventually adopts American cooling habits, Mr. Sivak estimates India's energy demand for cooling will be 14 times the US demand for cooling.
Nobody knows if the explosive rate of growth seen in places like India and China will continue, and emerging economies still have a long way to go before matching the US.
About 87 percent of US homes have air conditioning, according to the US Energy Information Administration, and together they consume roughly 185 billion kilowatt hours of electricity each year. Air conditioning accounts for 14 percent of all electricity consumed in the US. The nation uses more energy for air conditioning than all other countries combined, according to Stan Cox, author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World.
"I grew up in Georgia, and throughout my childhood A/C was taking off there," Mr. Cox said in a telephone interview. "It seemed almost like magic at the time, but gradually ... I started thinking about the feedback loop. A/C is burning so much fossil fuel, especially coal, which is helping to ensure the greater need for air conditioning in the future."
Air conditioners also rely on refrigerants that can damage the ozone layer and are hundreds to thousands more heat-trapping than carbon dioxide. In June, President Obama signed a deal with Chinese President Xi Jinping to phase out the use of a hydrofluorocarbons, a common refrigerant.
There are benefits to the spread of air conditioning, of course. Heat-related fatalities are down dramatically from 100 years ago, and studies repeatedly show people are more productive when working in cooler environments.
"The South would not be home to so many white-collar industries and manufacturing jobs if it weren’t for air conditioning," Cox said. "So it has helped [initiate] a big shift in where our economy has thrived and where it hasn’t."
But some question whether the US has gone overboard in its race to beat the heat – using lavishly what is ultimately a creature comfort.
"A major complaint of people working in office buildings today is that they’re wearing sweaters in the summer," Cox said.
There's hope that better designed air conditioners, homes, and cities can stem a widespread ballooning of cooling-related energy use, Mr. Sivak said in a telephone interview.
Future air conditioners could be between 20 and 70 percent more efficient, according to the National Renewable Energy Laboratory, but there's some concern increased efficiency will simply encourage more net use. Better use of reflective paint, windows, trees, and other more design elements in urban construction could also mitigate the need for air conditioning.