Daily Score Blog

Salon.com has a great article that discusses the environmental impacts of building larger and larger houses. Apparently, even super-efficient, high-tech houses that use the latest in "green" construction techniques use more energy than smaller but less efficient homes. For example, a 1998 Environmental Building News article found that...

a 1,500-square-foot home with low energy performance standards will use less energy for heating and cooling than a 3,000-square-foot house with high energy performance standards.

And the long-term trends on house size are telling:

Fifty years ago, the average house size was 1,100 square feet, and the average household size was 4.2 people. Today, the average house size has increased to 2,150 square feet, while the average household size has declined to 2.3 people.

That means that, person for person, we have about three and a half times as much house as our grandparents did. To some extent, that's a good thing, since older houses would probably feel cramped to many families today. But our love of elbow room carries an environmental toll: it means that our technology has to be three and a half times as efficient as our grandparents' to provide the same level of comfort without increasing our energy consumption.

The trend towards ever-larger houses, packed with the latest in environmentally-friendly materials and super-efficient appliances, produces the most cogent line in the article:

"Give Americans sustainable technology, and we'll super-size it beyond recognition."

I always thought that heating with electricity was supposed to be a bad idea. Yes, electric resistance heaters--which operate like the element on an electric stove--are pretty efficient at turning electricity into heat. But turning fossil fuels into electricity is incredibly inefficient. In a typical coal-fired power plant, only about a third of the energy content of coal is actually turned into electricity; the rest is wasted. The newest types of gas-fired power plants are more efficient, but still waste about 45 percent of the energy content of the natural gas they burn. Then, transmitting electricity to your home wastes additional energy.

So all things considered, it makes far more environmental sense to heat your home with gas directly than it does to burn the gas to produce electricity, transport the electricity to your home, and then use it to power a baseboard electric heater.

But electric-powered heat pumps--which work sort of like refrigerators in reverse--are making me change my thinking about using electricity for home heating. Unlike resistance heaters, heat pumps don't actually convert electricity into heat. Instead, they move heat from place to place, which is much more efficient: one kilowatt-hour of electricity in a heat pump may produce two to three kilowatt-hours of usable heat. (And no, this doesn't actually defy the laws of physics: heat isn't being created, it's just being moved around.)