1. Install low-flow fixtures. Most low-flow showerheads and faucets aerate water, which means you use less energy heating it. There is often no need to replace an entire sink — the important part is the aerator (the screw-on tip of the faucet), which determines maximum flow. This simple, cheap part could save you a bundle on hot water costs. See the hot water info page on the U.S. Department of Energy (DOE) site for more on this topic.

2. Turn off lights, computers and appliances. This simple habit doesn't cost a dime and could make a big difference in your energy consumption, depending on how consistent you are. Teach children and other members of the household to follow this rule: If no one's in the room, it doesn't need to be on. In other words, shut off TVs, computers and lights before leaving a room, every single time. It's a habit that requires a bit of diligence in the beginning but will soon become second nature.

3. Swap out lightbulbs. Choose the new energy-saving incandescent bulbs for an easy change that will use 25 percent less energy than the old incandescent bulbs. To save even more energy, switch to compact fluorescent lamps (CFLs) or light-emitting diode (LED) bulbs, which use between 70 and 80 percent less energy than traditional incandescent bulbs. Be aware that CFLs do contain a small amount of mercury, which means they must be recycled rather than thrown in the trash. See the CFL info page on the U.S. Environmental Protection Agency's (EPA's) website for more information.

4. Increase insulation. The most significant source of air leaks in the home does not come from the drafts you feel, but from basements and attics, according to Energy Star. Learn how to locate and seal air leaks and improve insulation in the DIY guide available on the Energy Star website.

What is Energy Star? Energy Star is a joint program of the EPA and the DOE. Products that meet standards set by these two agencies can earn the Energy Star label.

5. Seal holes and cracks. Any deep holes or cracks in your home's walls, ceiling or floors can be a potential source of air leaks. Investing just a few dollars in caulk and weatherstripping (or foam sealant for larger gaps) is one of the easiest and least expensive ways to improve your home's energy efficiency. For more tips on sealing air leaks, visit the DOE's website.

6. Replace an outdated AC system. With the summer months approaching, now is the perfect time to assess air-conditioning systems. If you are installing or replacing central air, look for an Energy Star label with a seasonal energy-efficiency ratio (SEER) of 13 or greater, which is the new standard, though older models are still being sold. New window air conditioners are nearly twice as efficient as older ones, so springing for a new unit could cut your home cooling bill in half this summer. Look for an energy-efficiency ratio (EFR) of 10 or more for window AC units.

7. Replace (or modify) old windows. Single-pane windows are a major culprit of heat loss during the winter months. Upgrading to low-U-value, low-E windows can save you up to 25 percent of your heating bill, according to the DOE. If new windows are not in the cards, you can still improve efficiency by covering single-pane windows with storm windows in winter and white shades in summer to reflect heat away from the home.

8. Retrofit or replace your old furnace. The first step here is to check on the energy efficiency of your current furnace or boiler, which is measured by annual fuel-utilization efficiency (AFUE). Very old models had efficiencies in the 56 to 70 percent range, while the best new furnaces measure up to 97 percent efficient. It is possible to retrofit older furnaces and boilers to increase energy efficiency, though the cost should be weighed against the cost of replacement and energy bill savings.

9. Choose Energy Star–rated appliances. When you are ready to purchase a new refrigerator, dishwasher or washer, look for the Energy Star label to be sure you are getting an appliance that is up to the latest standards of energy efficiency. See more about this

10. Add a source of renewable energy. Remember, a zero-energy home must balance the energy used with energy produced. That means it's time to start producing some of your own energy! Installing photovoltaic panels (solar panels) is the best known option for homeowners today, though in some regions you can actually choose to purchase renewable energy from your local power company.

More resources:

• Check the Database of State Incentives for Renewables & Efficiency to find out if your state offers financial incentives for installing solar panels or participating in other renewable energy programs.
  
• You may also be able to take advantage of an energy-efficient mortgage or special financing for your home improvement projects; read more on this topic on the DOE website.
  
• Learn more about solar energy through the Solar Rating & Certification Corporation.