As we discuss in detail in our section on how to save energy at home, making simple repairs or improvements and changing wasteful habits will yield enormous energy savings for most families.

Before spending thousands of dollars on new windows, a furnace, or solar energy system, take basic steps toward fixing common sources of waste. For most buildings, heating costs are by far the biggest source of home-energy expense, so the best place to start is by assessing how your home passively wastes energy by looking for areas in outside walls, windows, and doors that allow conditioned indoor air to escape.

Energy auditors can help identify problem areas and suggest solutions, plus provide advice on other changes you can make to go green at home.

You can do much of this work yourself. Enter characteristics of your home into the U.S. Department of Energy's excellent Home Energy Saver tool and it will calculate for you recommended cost-effective improvements. And our advice on saving energy at home identifies 32 changes that will minimize your home's energy use—and many of these tasks require little or no spend.

The benefit from hiring a professional auditor is that they can use equipment to identify leaks and other problems you might not find yourself and, of course, likely have more expertise than you do.

Most auditors offer quick assessments and full inspections. Utility companies often help pay for the quickies—typically, your share of the cost is $100 or even nothing.

If you’re paying for a full inspection, you may as well hire one certified by the nonprofit Residential Energy Services Network. Certified raters must complete RESNET’s training program, pass an exam, and complete five inspections under supervision by an approved supervisor. Certified home energy raters must attend a conference or complete ongoing training to recertify every three years.

A comprehensive audit typically costs $400 to $600, but you’ll get a lot more info out of it. The inspector will examine all features of your residence and evaluate your utility spending for the last year. For a full audit, the company should use a calibrated blower door to measure the overall air leakage of your home and perform a thermographic inspection using an infrared camera. Confirm in advance that it will do these tasks; if they’re not included, don’t do it.

Most homes have holes, cracks, and gaps that let cold air in and warm air out in the winter—and do the reverse in the summer. One little leak might not seem like much, but the cumulative effect of several can add up to the equivalent of leaving open a small window. Finding and plugging leaks costs very little money yet yields significant savings.

You can sleuth out major leaks on your own. If you feel drafts in the winter, that’s an obvious sign of leaks. If you consistently feel chilled between furnace cycles, that’s another sign.

Turn off your furnace on a cool, very windy day; shut all windows and doors, turn on all exhaust fans that blow air outside, such as bathroom fans or stove vents; light an incense stick and move around your house, watching where smoke is blown to identify drafts.

Most leaks occur where different building materials meet—brick and wood siding, foundation and walls, and between the chimney and siding. Other common problem areas are around windows and doors; mail slots; points of entry for electrical and gas lines, cable/internet wiring, and phone lines; outdoor water faucets; where vents pass through walls; cracks or gaps in siding, stucco, masonry, and all foundation materials; and around window air-conditioning units.

Use caulk to seal any cracks or gaps measuring less than ¼ inch wide and polyurethane foam sealant for larger ones.

To minimize leakage around doors and windows, install weatherstripping. Open-cell foams are inexpensive and relatively inefficient but easy to apply and suitable for low-traffic areas. Vinyl is more expensive and lasts longer. Metals last for years and provide a decorative element for older homes. Also add sweeps to the bottoms of all exterior doors to seal gaps there.

Prevent drafts around outlets and light switches located inside exterior walls by adding insulating receptacle gaskets, which cost less than $5 each.

If you have window A/C units, remove them during the winter, or insulate them from the outside with an A/C cover ($20-$60). During summer, install units so they fit tightly within windows.

Combined, these measures can save five to 20 percent of your heating and cooling costs.

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