The inevitable pro-air-conditioning backlash has come from Slate in the form of an article by Daniel Engber. His chief arguments are that heating in the US uses more total energy than does air-conditioning, and that air-conditioning can protect health in severe heat waves. Those are points that I make in Losing Our Cool as well, and they don’t amount to a justification of air-conditioning.
Heating may still use more energy than cooling even with today’s hotter summers, but air-conditioning creates more greenhouse emissions. Here’s why. Air-c0nditioners are powered almost totally by electricity (for buildings) and liquid fossil fuels (for cars) and always requires climate-unfriendly refrigerants. Most heating is done by burning fuels directly. The inefficiencies of electricity generation and transmission and the fact that it is done largely with coal and fuel oil means higher emissions. If you count only energy use and only buildings, A/C is responsible for under 300 million metric tons of CO2 emissions annually versus more than 400 for heating. But add in vehicle A/C and the greenhouse impact of refrigerants, and the total climate impact of air-conditioning is almost 450 million metric tons CO2 equivalent, versus 415 for heating.
But the much more important point is that most of that heating is necessary (even if the energy could be used more efficiently) whereas most of that air-conditioning is not (or is what we might call a “created necessity” because of the way we have constructed buildings and cities and arranged our transportation system.) So the factors that have decreased demand for heating, including the great southward migration and global warming, represent a missed opportunity to save energy. All of the emissions–and then some–that could have been spared because of lower heating demand have been replaced by cooling emissions.
I have dealt with the heat wave argument many times. The use of air-conditioning to protect people of advanced age or poor health against deadly heat waves accounts for a tiny percentage of total A/C use; by far the greatest use is of a completely different kind, in situations that do not warrant a refrigerated environment. I noted recently, for example, that “keeping vulnerable members of our communities alive during heat emergencies is one thing; using that as an excuse for neglecting horrible urban living conditions while at the same time tolerating the routine, lavish deployment of chilled air throughout much of the rest of society is another.”