“Take a 3,000-square-foot house on a summer day — only about 3 percent of the cooling power from the central air conditioning is going for people cooling.”
The quote comes from Stan Cox, author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World (and Finding New Ways to Get Through the Summer), in a Salon.com Q&A. Continuing his thought, Cox explains:
That is to say, 3 percent is being used to help remove heat from people’s bodies. The other 97 percent is going to cool the structure of the house, all the tens of thousands of cubic feet of air that aren’t even coming in contact with these people. So all that energy is not being focused where it’s needed, and this is assuming that people are home all of this time, when really they’re probably out working for most of the day. But the air conditioning stays on because it would be too difficult if they turned it off and then came back in the evening and turned it on.