If you think your car is an environmental monster, then be afraid, very afraid, of your house. I was covering a major home building conference last February when I heard an incredible factoid: your house leaves a bigger carbon footprint than your car. Why? Because, unlike your car, it is ALWAYS running.

So I went home to my hundred-year-old wood and stucco house in DC and started to re-evaluate. Green building is one thing, but the bulk of houses in America are old, so the best we can do is what those in the enviro-industry call "retro-fit" our homes.