It's July and I'm sitting at my desk in a sweater

It's ninety-four degrees out there. In here I've got a cardigan on and my hands under my legs. — Office worker, 1998

Offices here are often cooler in summer than in winter, say Berkeley's building researchers. A 2009 study of American office buildings backs it up: winter temperatures landed all over the range experts recommend, while summer ones mostly landed below it. The glass towers of the 1950s had windows that didn't open, so air conditioning became the only air there was. Nobody has told it when to stop since. OSHA has no rule on office temperature either. So you wear a sweater in the hottest month of the year. The thermostat is somebody else's.

For now: warm your feet with a small heated mat if your building allows one.

The full file

The cold is a habit. The Berkeley center that studies office comfort has collected more than 38,000 survey answers from 435 office buildings in North America, and it puts the cost of the overcooling at about $10 billion a year in extra electricity. That's its estimate. It's a big number for a cardigan.

Part of it is the machinery. A Berkeley professor told Popular Science that air conditioners are often oversized and don't handle humidity well, so they overcool the room.

The same researchers built an office chair with small heating elements and low-power fans that the person in it controls. They say warming a person's feet is one of the best ways to make that person comfortable. They also figure that letting people stay comfortable across a wider range of temperatures could cut a building's energy use by 5 to 15 percent.

Warm your feet. That's as far as the research has got.