Photos: Green buildings for the rest of us

Another green retrofit is a compost pile. Toss in your yard waste, flowers, or banana peels, and it will turn into fertilizer. One challenge is that it takes months for things to decompose. To get around that, you can buy a standalone composter that you turn easily (pitchforks work for heaps like I've got). You can also speed up the process by amending the compost pile with a garden store mix. Either way, you're cutting down on municipal waste.

Some cities, including San Francisco, have added composting to their waste collection programs.