Energy efficiency and the home
According to the Energy Star program, half the energy an average U.S. home consumes in a given year is devoted to heating and cooling. If your home uses older, inefficient equipment, or if your home has never undergone energy-efficiency improvements, there's probably a lot of energy -- and money -- going to waste.
The average American household spends more than $2,000 on energy bills, so any steps taken to save on energy will likely add up to monetary savings as well.
So, how do you decide where to start saving energy use in the home? Where should you start and what improvements can you afford? For many homeowners, an energy audit can help measure your home's current energy use, analyze its weaknesses and make recommendations about how to make the most effective energy-efficiency improvements.
What is an energy audit?
A home energy audit, often called a home energy assessment, is a room-by-room review of how efficiently your home uses energy. You can do a rudimentary assessment yourself just by walking around the house on a cold, windy day looking for drafty windows and places rooms tend to be cold.
When you hire a professional energy auditor, the assessment becomes much more scientific. Using diagnostics such as a blower door test, where a doorway seal and fan measure a home's air exchange rate to detect leaks, and a thermographic scan, which makes infrared energy visible and reveals over- or under-insulated areas, an energy audit can help you determine where your home is losing the most energy.
How do energy audits work?
During a blower door test, an energy audit inspector will affix a flexible, airtight door over an exterior door frame, leaving the exterior door frame open. The blower door shroud contains a powerful fan that removes the indoor air, which lowers the pressure.
All of your windows and exterior doors need to be closed, as well as the fireplace flue vent. The point is to close all normal openings and then see where air comes in anyway. It's a good idea to turn down your thermostat during the test to ensure the system doesn't start up due to a possible drop in temperatures.
Once the home has achieved sufficient negative pressure, the inspector will evaluate the home's exterior envelope, looking for sources of drafts, heat loss or air infiltration. This may be performed with something as simple as a smoke pencil, which produces a wisp of smoke used to identify air currents, or something high tech like a thermography scanner.
The Department of Energy's Energy Savers program, which provides consumer and homeowner information about increasing residential energy efficiency, notes that it's important to have a calibrated blower door test performed, not an uncalibrated one.
A calibrated blower door test will use sensors to measure the actual amount of air that's being pulled out of a home, which means you'll get a more accurate interpretation of your home's energy use. An uncalibrated blower door test won't measure the volume of air being pulled from the home, so it can only identify air leaks and not how much potential energy those leaks waste.
Thermography scan: A thermography scan may be performed in conjunction with a blower door test, or as as separate, standalone energy audit diagnostic. A thermographic scanner is typically a camera or video camera that can make the infrared spectrum visible to the human eye. Using this information, an energy inspector can visibly inspect the surface temperature of various components of the home.
Thermography is typically used indoors to measure the coverage and effectiveness of insulation. For instance, if a thermography reveals that one particular spot on an exterior-facing wall has relatively cooler temperature spot, it's likely that that area has less than adequate or missing insulation. Based on this evidence, an energy inspector may recommend adding new, more temperature resistant insulation to that area to improve the home's energy efficiency.
The DOE's Energy Savers program recommends that homeowners prepare for a thermographic scan by helping ensure accurate readings. Moving furniture away from walls and removing drapes from windows can help ensure that temperature variations are correctly attributed to the home's insulation or exterior envelope and not other conditions. Further, the DOE states that to get the best results from a thermographic scan, homeowners in the northern U.S. should have them performed during colder winter months and southern U.S. homeowners should have them performed in warmer months when the AC is typically on.
Hiring an energy auditor
Look for a highly rated energy audit or assessment company on Angie's List. Your utility or energy provider may offer consumer discounts and may also be able to provide a list of approved audit providers that can provide an audit for free or at a substantial discount.
To be included on an approved list, an auditor may have to provide proof of passing the audit experience or certification requirements as determined by the particular jurisdiction.
If your state or city considers an energy audit to be a home inspection, your auditor may be required to hold a home inspector's license.
There are many organizations that provide energy audit and inspection courses, certification and accreditation, so choosing a qualified energy auditor with the right credentials may be a confusing prospect. The Energy Star program offers a Home Energy Rater certification through its Energy Star for Homes Partners program.
As with any home improvement hiring decision, be sure to ask about the company's experience, referrals and qualifications before committing to hiring. If you become a member of Angie's List you can search for energy audit services in your area and read reviews and ratings from other Angie's List members who have hired those companies.