A home energy audit can help you save money while you help save the planet. But how do you find a certified home energy professional, and what do they do?
What is a home energy audit?
A home energy audit or assessment done by a certified professional from the Residential Energy Services Network (RESNET) will evaluate your home’s energy usage and efficiency and can generate a Home Energy Rating System (HERS) Index Score. (Energy auditors can also be certified by the Building Performance Institute.)
RESNET-certified examiners can perform three levels of assessment.
Home Energy Survey
This is a visual inspection of the home’s “envelope.” The HERS raters look for air leaks, moisture problems, and health and safety issues and evaluate appliances, lighting, HVAC equipment, utility bills and homeowner complaints about comfort. This type of home energy audit does not include the use of diagnostic equipment.
Building Performance Audit
The HERS Building Performance Audit combines all elements of the Home Energy Survey with the performance of diagnostic tests. One of the most basic is the blower door test. A strong fan placed in an exterior doorway draws air out of the house, creating a slight negative air pressure condition in the home. The resulting stronger outside pressure will force air into the house through any leaks in the home’s energy envelope, which allows the auditor to identify leaks that need to be fixed.
The Building Performance Auditor also uses other diagnostic tests to examine insulation for effectiveness, heating and air ducts for leaks, and combustion devices (furnaces and other heaters) for efficiency and potential safety problems.
After a Building Performance Audit, which takes three to four hours, the auditor will prepare a report for the homeowner that prioritizes needs and recommends fixes.
Comprehensive HERS Rating
This takes the Building Performance Assessment to the next level, adding a computer-generated simulation to calculate a HERS score for the home. This evaluation will produce a cost-benefit analysis of recommended repairs as well as information on your expected return on investment in certain repairs. In calculating your home’s HERS rating, the HERS rater will evaluate:
- the amount and location of air leaks, including the amount of leakage from HVAC distribution ducts
- the effectiveness of wall and ceiling insulation as well as HVAC systems
- the efficiency of your water heating system
- the state of attics, foundations, crawl spaces and floors over spaces that aren’t air-conditioned
- the condition of windows, doors, vents, and ductwork
What can you do on your own?
Homeowners can conduct a broadly simplified home energy audit, called a Home Energy Yardstick, on their own. Your energy efficiency is calculated using your home’s location, square footage, number of occupants, energy bills and a list of the fuels you use in a year. This audit rates your home against similar ones across the country compares the energy you are using for home comfort systems versus your energy usage on other items and provides information on how to lower your energy bills and your home’s carbon emissions.
Helpful energy improvements
Often the most cost-efficient improvement you can make is to add more insulation, especially in the attic. Next would be replacing old caulking and weather stripping around windows and doors where air leaks in. Replacing old, energy-inefficient windows is expensive at purchase, but savings add up over time. Updating appliances also involves costly investment, but newer technology uses less energy. Purchase both appliances and windows that are Energy Star-rated by the U.S. Department of Energy.