Replace old appliances. Lowering your utility bills also conserves energy, making it a win-win for your finances and the environment. In fact, a number of utility companies offer customers rebates for saving energy. When Diane MacEachern, author of "Big Green Purse: Use Your Spending Power to Create a Cleaner, Greener World," bought an energy-efficient refrigerator, she received $100 from Pepco, and the utility company gave her $50 for recycling her old refrigerator.
EnergyStar.gov provides information on what appliances are the most energy-efficient.
Lease solar panels. While solar panels are the gold standard, most consumers simply can't afford the technology. For a typical three-bedroom home, installing a medium-sized 4-kilowatt system can cost upwards of $25,000 to $30,000, based on 2012 data from GTM Research and the Solar Energy Industries Association.
However, there are a number of national solar leasing companies such as SolarCity.com, Sungevity.com and SunRunHome.com. "A homeowner can get the benefit of solar panels and lower utility bills immediately without having to lay out all that capital," Loux says. For the average three-bedroom home, leasing solar panels costs around $100 to $300 a month. (Many companies don't charge a down payment.) According to SolarCity.com, for a typical three-bedroom home with a current electricity bill of $200 per month, installing a 4-kilowatt solar system will generate enough electricity to reduce the bill to an estimated $60 per month.
Patch minor damage. A poorly insulated home requires more air conditioning in the summer and, naturally, more heat in the winter. Loux says this can be a major problem in older homes that are less energy-efficient than homes built in the last 10 to 20 years.
[Read: 10 Ways to Save by Going Green]
Two of the biggest culprits are gaps and cracks, which expand over time. Low-cost calks, sealants and repairs can make your home more insulated and save you hundreds in utility costs each month.
Control your home's temperature. Another way to reduce energy costs is by installing a programmable thermostat, which costs as low as $40. You can program the device so, say, the in-house temperature is higher when you're at work, then cools down when you're at home. Some devices let you set different temperatures for specific rooms.
Change the lights. Installing energy-efficient lighting like LED bulbs throughout your home is also a way to save money. "I have [energy-efficient] light bulbs in my house that I haven't changed in 10 years," MacEachern says. "It's a no-brainer." LED bulbs last up to 10 times as long as compact fluorescents and significantly longer than typical incandescents. They also only use 2 to 17 watts of electricity – a fraction of what incandescents or CFLs need – meaning with LEDs, you save money on both energy and replacement costs.
Pinpoint areas in your home for improvement. For specific tips on how to make your home more eco-friendly, consider getting an energy audit. You can pay an energy professional to inspect your home and identify ways to make the property more energy-efficient. (Some utility companies offer free home energy audits.)
Reuse materials. When doing home renovations, you can often recycle old materials. If you're doing a kitchen remodel and replacing the cabinetry, for example, rather than disposing of the old cabinets, consider installing them in your garage for extra storage space. If you're putting new tile in the laundry room, use the old tiles as a walkway outside.
Homeowners planning to renovate can visit their local Habitat for Humanity ReStore, a nonprofit store and donation center that sells new and gently used building materials at a fraction of the retail price. You can find your nearest ReStore outlet at habitat.org/restores.