If your heating and cooling bills have begun to spiral out of control, it may be time for a home energy audit. Assessing your home’s energy consumption is the first step toward figuring out what you can do to increase your home’s energy efficiency.

The point of an energy audit is to identify the areas of your home that are losing energy. These areas include your home’s heating and cooling system, hot water heater, and electrical. Correcting problems in these areas will not only reduce your carbon footprint but also reduce your energy bills significantly over time.

Any homeowner can conduct a simple energy audit, but for more detailed results you can call in a professional. A thorough energy audit utilizes blower door tests, thermography, and other techniques to detect areas of air infiltration and missing or insufficient insulation.

A professional audit includes a list of action steps for how you can reduce the energy expenditure in your home while improving its comfort level. A full analysis should include:

• How much you currently spend on energy.

• Where your greatest energy losses are.

• How long it will take for new energy-efficient products and appliances to pay for themselves in energy-cost savings.

• What additional benefits you may garner from your energy-saving measures, such as increased comfort from better insulated walls.

Now ask yourself these important questions:

• How long do I plan on staying in my home?

• Which energy-saving measures will significantly increase the value of my home?

• How much of the work can I do myself and what jobs will I need to contract out?

• How much ready money and time do I have to accomplish the measures recommended?

Based on the results of the home energy audit and your answers to these questions, you will be able to set priorities for maximizing your home’s energy efficiency while spending the least amount of money to save you the most amount.

Locating Air Leaks

The first step in assessing your home’s energy efficiency is to determine which parts of your house are consuming the most energy. A professional home energy audit will pinpoint those areas for you, but you can conduct a reasonably thorough inspection yourself.

Start by walking through every room of your house and taking note of any obvious air leaks. Drafts alone can add 5%–30% to your energy bill and generally make a house less comfortable.

Areas to check for air leaks include gaps in the baseboards or where the flooring meets the wall and the wall meets the ceiling, as well as around electrical outlets and switch plates, window and door frames, attic hatches and air conditioners, pipes and wires.

Check to see if all weatherstripping and caulking have been applied properly and are in good condition. If you can rattle a window or door or see daylight around a window or doorframe, you have air leakage.

If you are having trouble identifying the location of leaks, you may want to conduct a pressurization test. First, shut all windows, exterior doors, and fireplace flues and turn off the furnace and water heater. Then, turn on every exhaust fan in the bathrooms and kitchen or set up a large window fan; the idea is to suck as much air out of the house as you can.

Once you have done this, air will begin to leak back into the house faster. To locate the leaks, you can use an incense stick—the smoke will waver at the source of the leaks—or just lightly dampen your hand, which will feel cool at the source of a leak.

When you have finished inspecting the inside of your house, check the outside. Look everywhere two different building materials meet, such as roofing and chimneys, siding and the foundation. Also inspect around any penetrations such as pipes, electrical outlets, and hose bibbs to see if they have been properly caulked. Next check around doors and windows to make sure they have been properly caulked and that they seal tightly.

Once you have identified all the areas of leakage, take care in how you seal them. A house that is too airtight can present a real health hazard. If the various combustion appliances and exhaust fans compete for air—called “backdrafting”—combustion gases can actually be pulled back into the home. If your home is heated by natural gas, fuel oil, propane, or wood, have your local utility come out to make sure the heating appliance has an adequate air supply—1 square inch of vent opening for each 1,000 BTUs of input heat.

Blower Door Tests

Blower door tests are performed by professional energy auditors to discover how airtight a home is. Reducing energy consumption and increasing the comfort level of the home are important, but determining moisture condensation problems and assessing how contaminated the indoor air is are critical to health issues.

The auditor will first mount the blower door—a large, powerful fan—into the frame of your front door or other exterior door. Much like a vacuum, the fan sucks the air out of the house, reducing the indoor air pressure. Because the outside air pressure is higher, air then flows inside through any cracks or other openings.

Blower doors come in calibrated and uncalibrated models. Make sure your auditor uses a calibrated door because it has gauges to measure the amount of air pulled out of the house as well as the amount of air that re-enters. Once measures have been taken to seal any areas of leakage, a calibrated blower door can then measure how effective the job was.

Before an auditor begins the test, make sure that all windows and interior doors are closed, all thermostats are turned off, and all fireplace dampers and doors are shut.

Thermography

Thermography—or infrared scanning—is another technique used by energy auditors to detect air leaks in a home. With thermography, infrared video and still cameras measure light in the heat spectrum, from white for warm to black for cool. The images reflect where insulation is needed or where insulation was not correctly installed.

A thermographic inspection can be done of either the interior or exterior of a home. Interior surveys are generally more reliable because the air inside a structure is much stiller than outdoor air. With an exterior survey, the origin of heat loss from a certain area of the home might be deceptive due to air movement on the outside.

Thermographic scans are often conducted along with a blower door test. Air leaks appear as black streaks in the infrared camera’s viewfinder.

An energy auditor may also use any of several infrared sensing devices in an inspection, though none are as accurate as a thermal imaging camera. A spot radiometer, or point radiometer, measures and notes radiant temperature one spot at a time. A thermal line scanner measures and notes radiant temperature along a line. A thermogram superimposes the line over a picture of the panned area to show temperature variations along the line.

Thermographic surveys yield the best results when the indoor and outdoor temperatures differ by at least 20 degrees Fahrenheit. Therefore, in cold weather climates, thermographic scans are usually done in winter, and in warm weather states they are conducted in summer with the air conditioner on. 

Inspecting Home Insulation

If the insulation in your home does not meet minimum levels, this could account for a huge amount of your energy loss. If you own an older home, it is likely that your insulation is insufficient, even though it may have met recommendations at the time it was installed.

Start your inspection from the top down. First, make sure the attic hatch closes tightly and is weatherstripped. In the attic, make sure penetrations for pipes, ductwork, and chimneys are sealed with expanding foam caulk and that electrical boxes for any light fixtures below are sealed with a flexible caulk.

Next, check the insulation itself to see if there is a vapor barrier. It could be tarpaper, plastic, or kraft paper. If there does not appear to be a vapor barrier, you can replace the insulation or paint the ceiling with vapor barrier paint. A vapor barrier or vapor barrier paint inhibits moisture from passing through the ceiling, thereby preventing moisture damage and retaining the integrity of the insulation.

Last but not least, make sure that the insulation is not blocking the attic vents.

To check your walls’ insulation levels, do one wall at a time, turning off the electrical power to any outlets along that wall. Once you are certain the power is off (test the outlets to make sure they are not “hot”), remove a cover plate and gently insert a screwdriver inside the wall. If you meet with some resistance, you have insulation in that wall.

To check an unheated basement, look for insulation under the flooring above. If it is a heated basement, check the walls as you did with the upper floor.

Inspecting Your Heating & Cooling Equipment

On an annual basis (or as recommended by the manufacturer), have your heating and cooling equipment inspected and cleaned by a professional. If your furnace is forced-air, check the filters on a monthly basis; during high-usage periods, you will probably replace them that frequently.

As part of your inspection, also check the ductwork. If you see dirt streaks, particularly around the seams, you have air leaks; seal them with duct mastic. Also, insulate any exposed ducts with insulation that has an R-value of least 6.

If you’ve had the same furnace for more than 15 years, consider replacing it with a new, energy-efficient unit, which will reduce your energy consumption and your energy bill.

Inspecting Lighting

About 10% of a residential energy bill is used to power lighting. To make sure you are using only what you need, look at the lightbulbs in your house to see how much wattage they use. Could you do with 60 or 75 watts where you have 100-watt bulbs? Could you use fluorescent lighting where you now use incandescent bulbs—especially in areas where lamps are on for a large portion of the day? If you don’t like the quality of light cast by fluorescent bulbs, you can still reduce your lighting energy use by putting certain lights on dimmers, timers, or occupancy sensors.