In 1960, only 12 percent of U.S. households had air conditioning. Today it’s close to 90 percent. During the same time, the average new house has roughly tripled in size. As a result, air conditioners now consume an estimated five percent of all electricity that’s produced.
Affordable air conditioning has prompted builders to skip some features that once helped cool homes naturally, such as porches, transom windows, and ceiling fans.
Air conditioning has made desert cities like Phoenix and Las Vegas livable and prosperous, but one unintended consequence is that these places have become even hotter—and more polluted.
Running air conditioners and power plants throws more heat and greenhouse gas into the atmosphere. Along with more asphalt, we have the so-called “heat island” effect. Some cities are now up to 22 degrees warmer than nearby non-urban areas.
A recent Arizona State University study estimates use of air conditioning has raised average nighttime temperatures in Phoenix as many as 3 degrees. Before 1970, overnight lows never stayed above 90 degrees. Now, that’s relatively common during summers.
We can try to tolerate warmer temperatures, opening the windows when temperatures reach into the 70s instead of turning on the cooler.
Better public transportation and more shade trees will help too, say experts. Energy-efficient building design is another big step—we’ll hear more about that in next week’s Earth Note.