One of the easiest ways to be green is the regular replacement of your home's air filter. It certainly falls in the out-of-sight-out-of-mind category, but a clogged air filter can cost you extra energy dollars every month. As your filter works to trap dust and debris, over time it loses efficiency as it fills up. The more full the filter the harder the blower motor must work to pull air through it to keep your home conditioned. And the harder it works, the more electricity it uses...thus the higher power bill. Check the MERV rating on the filters you purchase. The higher the better. But, also note that the better the filter, the faster it will clog, but that means better indoor air quality. Change your filter regularly and keep the filter factor in your favor.