Over the holidays, the most e-mailed story published by the New York Times was almost devoid of news, but it was arguably one of the most important things the paper could have run. It's an account of an old and simple idea: saving money by ensuring that your house is well insulated.

Thick walls and insulation, insulated windows placed on the side of the house where the sun shines, eaves that shade these windows during the summer, a ventilation system that uses an old technology called a heat exchanger--all make it possible to heat a house in the winter with a hair dryer and cool it in the summer with a small window air conditioner. And that's only on the most extreme days, when temperatures are very low or very high. Most of the time, no heating or air conditioning is needed at all. Amory Lovins, founder of the Rocky Mountain Institute, an organization that promotes energy efficiency, has built such a home for himself in the mountains of Colorado. It features a tropical indoor garden. He says he enjoys coming in from the blowing snow and bitter cold and eating a freshly picked banana.

These so-called passive houses have been around for decades. If designed and built properly, they don't even cost more than a conventional house (the extra money for better windows can be offset by the savings from not installing a furnace, for example). So why haven't more been built? Judging from the response to the New York Times article, not many people know about them. And builders (I used to work for a number of them) suffer from inertia. They'd rather go on building the same buildings they're used to.

Paul Torcellini, a researcher at the National Renewable Energy Laboratory, says that the cheapest way to reduce carbon emissions is to use less energy. NREL recommends that people not turn to solar panels and wind turbines to power their homes and businesses until they have adopted passive measures, such as better insulation, which can reduce energy consumption by about 75 percent.

President-elect Obama apparently got the word. He plans to create tens of thousands of jobs by weatherizing one million homes.