The United States currently uses more energy for air conditioning than all other countries combined. But as economic conditions improve in other large and hot countries, an increase in the use of air conditioning may put an unprecedented demand on the global energy supply, according to a researcher from the University of Michigan.
In his paper, published in the current issue of "American Scientist", Michael Sivak projects that eight countries may exceed America's use of air conditioning, due to a combination of their large populations and hot climates. In the city of Mumbai alone, Sivak estimates that there is the potential for an energy demand for cooling that is about a quarter of the current demand for all of the United States.
"The U.S. is using air conditioning a lot, and currently, developing countries are not because they don't have means to do that yet," Sivak told U.S. News. "But some are getting richer by the day and will be able to afford air conditioning on a much wider scale than they do now."
Sivak calculated the degree of different countries' climates based on "cooling degree days," which give an indication of the energy needed to cool indoor spaces. One cooling day occurs for every degree the average temperature is above 65 degrees Fahrenheit. For example, if on a given day the average temperature is 70 degrees, the result would be five cooling days.
To calculate annual cooling days, Sivak used the same calculation for the entire year. He used this index to show what the energy usage would be in each country if the use of air conditioning became as prevalent as it is in America.
And several countries are already on track to do so. In China, for example, the percentage of households with an air conditioner grew from less than 1 percent in 1990 to 62 percent in 2003. In India, though only 2 percent of households had air conditioning units in 2007, sales for the cooling units are growing by 20 percent each year, Sivak wrote in his report.
Sivak says the potential implications are quite serious. If other countries use air conditioning at the same rate as the United States, it could cause the world consumption of energy to skyrocket.
By Sivak's calculations, India would use about 14 times as much energy for cooling as the United States. China and Indonesia would surpass America's energy usage by factors of about 5 and 3, respectively.
"If all countries were to adopt our style of cooling, the potential is there for a 50-fold [increase in the] consumption of energy compared to the United States," Sivak says. "This is unlikely to happen anytime soon, but the potential is there."
Sivak says other factors such as humidity, cloud coverage and tolerance for hot weather need to be considered to paint a more accurate picture. Still, he says, it is clear that the energy demand for cooling will grow substantially and that there is a need to accelerate progress in creating more energy-efficient air conditioners and changing housing design and urban planning.
"This trend will put an additional strain not only on global energy resources but also on the environmental prospects of a warming planet," Sivak says.