What Is It and How Does It Work?

There are so many different ways to improve your home's energy efficiency, it can be difficult to know where to start. The best way to figure it out is by doing a home energy audit to determine where your home leaks, what equipment needs maintenance, whether you should replace your HVAC system, whether you need better insulation, or how much money you could save by replacing incandescent lightbulbs with compact fluorescent bulbs. You can get very reliable guidance and data-based answers to these questions and others with a professional home energy audit, but you can also get a good idea about where the trouble areas are by doing an energy assessment of your own.

The Do-It-Yourself Home Energy Assessment

If you are doing a preliminary home energy assessment on your own, there are a few key things you should look for.  Some causes of inefficiency you can assess and even fix on your own, such as finding a leak around the edge of a window frame that you repair by applying caulk to the frame. Some problems are more difficult to assess and require professional installation, such as figuring out whether your wall insulation meets current standards or has settled and requires reinsulating your walls.

One of the first things to do is to identify any obvious air leaks. If you have been living in your home for a while, you may already have an idea where these are. If there are rooms in your home that feel cooler or more drafty than others, you may be able to identify a leaky window or gap along the baseboard. In general, there is an infiltration risk wherever there is an opening cut in a wall or ceiling (electrical outlets, windows, or an attic hatch, for example) or at any joint between two surfaces (where walls meet floors, for example). These are also the first places to look for leaks that can be easily repaired with weather-stripping or caulk. Also check your home’s exterior caulking, especially at windows and eaves.

There are a few steps you can take to identify where your home has adequate and properly installed insulation. The older your house is, the greater the chance that your home is poorly insulated—or maybe even not insulated at all. One easy step is to check the insulation in your attic. There should be insulation on the floor of the attic, the attic hatch should be weather-stripped and backed with insulation, and any openings into the ceiling below should be filled with caulk or expanding foam. Your attic should have vents in the eaves around the perimeter of the house to prevent moisture buildup. Check these vents to make sure they are not blocked by insulation. While it may be relatively easy to check the visible insulation in your attic, you will have some difficulty checking the insulation in your walls without a thermographic inspection. You can get a rough idea of what type of insulation you have by cutting a small hole in the wall in a hidden location, such as in a closet. However, this will not tell you whether the entire wall is insulated, whether the insulation has settled, or whether the insulation has become damp and ineffective in some locations.

As part of a DIY home energy assessment—and as a matter of regular routine maintenance—you can check your HVAC system's filters and have the equipment professionally inspected for proper refrigerant levels and airflow.

Inspect your lightbulbs for excessive wattage and consider replacing inefficient incandescent bulbs with compact fluorescent lightbulbs.

The Professional Home Energy Audit

A DIY home energy assessment is a good idea to familiarize yourself with your home's energy-efficiency issues, but the best way to get a detailed idea of how your home is costing you money is by having a professional home energy assessment done by a qualified Energy Auditor. A comprehensive home energy audit consists of a room-by-room visual assessment, a blower door test, and a thermographic scan. Some Energy Auditors also do a PFT air infiltration measurement, but it is not necessarily standard practice.

Many Energy Auditors, utility companies, and retailers of energy-efficient equipment offer free or low cost visual assessments. This type of assessment can be a good starting point and should include a consultation to determine your desires and to discuss findings from past energy bills; a visual inspection of your walls, windows, and doors; inspection of mechanical equipment and lighting; and identification of obvious moisture problems. This basic energy audit is very similar to what you can do on your own, although it can be good to have a trained auditor at your side, especially since many utility companies provide this service for free.

A blower door test is a very effective way to determine where your home is suffering from infiltration (air leaking in from the outside). The blower door fits within an exterior door of your house and includes a fan that decreases the pressure inside your house by blowing air out. As the house depressurizes, air will come in through all unsealed cracks and unintended openings. While the blower door is operating, the Energy Auditor will investigate your house for leaks using a smoke pencil and/or a thermographic scanner.

A thermographic scan can be done either with a blower door operating or on its own. The benefit of using thermography with the blower door is that the blower door will make locations of infiltration even more obvious. Thermography is useful because the scanner sees light that is in the heat spectrum, so the image on the screen indicates the different temperature of each object. Cool air flowing into a warm house will show up as black on the screen, while well-sealed interior surfaces will show up in white. Thermography will also show which areas of your walls are poorly insulated, something that is very difficult to do in a visual inspection.

The PFT air infiltration measurement technique is a different type of measurement than the thermographic scan. This measurement will not tell you the exact locations of infiltration, but it will tell you how much infiltration is occurring over time. The PFT technique is performed with two long, thin devices that are about the size of a pencil. One of these devices emits a small amount of perfluorocarbon gas, while the other device absorbs the gas. If a high concentration of the gas is absorbed, than the building is not leaking much air. However, if a lower concentration of the gas is absorbed, the building is leaky.

Why Should I Consider It?

A home energy audit is a very useful tool in determining where your money will be best spent in making your house more energy efficient. By seeking advice, consultation, and investigation by a qualified professional, you will be getting the best available data regarding all of the energy-consuming components of your home. You can then make a more informed decision regarding your next steps to reduce energy consumption in your home and lower your energy bills.

What Are the Options?

Your options for performing a home energy audit include doing a visual assessment on your own, working with your utility company, hiring an Energy Auditor to perform a visual assessment, or hiring an Energy Auditor to do a comprehensive technical audit, including a visual inspection, blower door test, and thermographic scan.

What Are the Potential Benefits?

A home energy audit is an important step in determining what you can do to save money on your energy bills. There are many ways to make your home more energy efficient, but without an inspection to deetermine where your home is inefficient, you won't have a good idea of the best steps to take. If you already have efficient windows but your walls lack adequate insulation, it won't save you money in the long run to replace your windows, but adding insulation will. Without an energy audit, you may just be guessing about the best energy-efficiency measures to take.

Are There Health and Safety Concerns?

If your energy audit includes a blower door test, remember that you will be temporarily increasing infiltration and drafts. Clean ash from your wood stove or fireplace to prevent blowing the particles into the air. Also be sure to check the pilot lights on your stove and hot water heater after the test is completed. Sometimes the added draft can extinguish them.

How Much Does It Cost?

Many utility companies offer free or discounted energy audits to help their customers conserve energy. Chances are, a free audit is a visual assessment rather than a detailed technical audit, but it still may be a useful step in determining what energy-efficiency measures you can take and whether or not you need a more comprehensive audit. Also, some contractors and product retailers offer free audits, but in many cases these are also a way for a company to market their services. This still may be a productive inspection, because you may actually need whatever products or services the company provides, but it may be best to get a second opinion.

If you can't get a reliable, low-cost visual assessment from your utility company, you should expect to pay between $150 and $300 for a basic audit from a consultant or contractor. A detailed, technical energy audit, including blower door test and thermographic scan will likely range from $300 up to $1,500. As always, be sure you solicit price quotes from several Auditors, and make sure you know what you are paying for so you can accurately compare different bids.

What Else Should I Know?

Before the Energy Auditor arrives, there are a few things you should do to prepare your home and to provide the Auditor with useful information. If you have any particular trouble spots, such as interior condensation or a tangible draft, make a list before the Auditor arrives. Also, collect your energy bills for the previous year. Be prepared to answer questions about the occupation patterns in your home, such as the times your home is occupied, which rooms are used more often than others, and the temperature you set your thermostat, and so on.

Where Do I Start?

Selecting a qualified Energy Auditor is very important. You can use Energy Star’s Partner Locator to find trusted Auditors in your area, but you should also use word-of-mouth to find out if any of your friends or neighbors have had an experience working with an Energy Auditor. It is always good to speak with a few different qualified consultants or contractors before narrowing it down to one. Some good questions to ask before selecting an Auditor include:

How many audits have you performed?
Do you have references that I can contact?
What is your BBB accreditation rating?
What certifications do you have? (Look for Home Energy Rating System [HERS] Certification)
What types of inspections and tests will you perform?
Will you create a report of your findings?

Where Can I Get More Information?

U.S. Department of Energy
U.S. Department of Energy Weatherization Assistance Program
Energy Star Partner Locator