There are countless ways to help the environment, from biking to work to eating locally grown foods, but if you own a house, the one place you should start is right where you live.

If every American homeowner maximized their home’s efficiency, the collective energy savings would be so great that other green efforts would just be icing on the conservation cake.

But a lot of energy improvements require research and can be expensive. Luckily, there are programs, all spelled out on the Web (isn’t everything?) to make the process easier and cheaper.

A wealth of resources on ways to save on energy improvements can be found at the Database of State Incentives for Renewables & Efficiency and at consumer sites such as Mother Earth News. But the best place to start for many may be a government program -- widely available but vastly underused -- that was revamped as part of the just-passed Housing and Economic Recovery Act: energy-efficient mortgages.

EEMs allow homebuyers (and homeowners who wish to refinance) to defray the cost of energy-efficiency improvements by rolling the cost into a mortgage. The catch is that eligible mortgages must be held by Fannie Mae or Freddie Mac or backed by the Federal Housing Authority. But if you qualify, improvement costs can total up to 5% (part of the new EMM program is that they’re dropping a previous $8,000 limit) of a home’s value. When you’re talking about $15,000 or more, this makes HUD’s EEM program well worth looking into.