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A whole-house energy audit is a comprehensive assessment of your home’s energy efficiency. It identifies areas in which you’re losing energy and makes recommendations about where you can make improvements. This can save you money and make your house more comfortable. Read our guide below to learn how to perform a whole-house energy audit.
Understanding Energy Audits
Energy audits show homeowners where their homes are losing energy. Audits also offer recommendations about how homeowners can become more energy efficient.
Types of Energy Audits
There are three main types of energy audits. Read more about each below.
- Comprehensive audits: In-depth evaluations that use advanced diagnostic tools
- General audits: Detailed assessments that may include some diagnostic testing
- Preliminary audits: Quick, visual inspections that provide general overviews
Benefits of Professional Energy Audits
DIY energy assessments can be helpful, but professional audits offer several advantages. Read more about these below.
- Access to specialized equipment such as blower doors and infrared cameras
- Detailed reports with prioritized recommendations
- Expertise in identifying less obvious energy loss areas
- Potential access to subsidized remediation work through utility companies
Preparing for an Energy Audit
There are several steps you can take to prepare for the audit before it begins. Read more below.
Gather Utility Bills
Collect at least a year’s worth of utility bills. These will help the auditor to understand your energy consumption patterns and identify potential areas for improvement.
Make a List of Concerns
Make note of any specific issues you’ve noticed, such as drafty rooms or inconsistent temperatures. This information can guide the auditor’s focus during the assessment.
Make All Areas Available
Clear paths to attics, crawl spaces, and other areas of your home that you don’t frequent. The auditor will need to inspect these spaces thoroughly.
The Energy Audit Process
A comprehensive energy audit involves several steps. Each evaluates a different part of your home’s energy efficiency.
Appliance and Lighting Assessment
The audit begins with an evaluation of your home’s appliances and lighting fixtures. Energy-efficient lighting such as CFLs and ENERGY STAR-rated appliances are positive findings in a home energy audit.
Pro Tip: Jennifer Thorne Amann, senior associate at the American Council for an Energy-Efficient Economy, advises: “The easy way to know if an appliance is efficient is just to look for the Energy Star label.” But she adds that consumers who want to dig deeper should compare product specifications on the Energy Star website, since appliances within the same Energy Star category can vary significantly in actual energy consumption.
Heating System Evaluation
The heating system is an important component of the energy audit. It includes the following steps:
- Inspecting the water heater for leaks, rust, or lack of insulation
- Evaluating the age and efficiency of the boiler or furnace
- Conducting a combustion safety test
Blower Door Test
A blower door test involves depressurizing the house to exaggerate air leakage points. It also helps you to identify where conditioned air escapes, and provides a baseline for comparing the effectiveness of air-sealing efforts.
Pro Tip: On a recent This Old House project, energy auditor Jordan explained the results of a blower door test to Richard Trethewey: “We just completed our test, and we’re at 3.8 ACH50.” As Richard clarified, ACH stands for air changes per hour—a measure of how much air leaks out of the building under pressure. Jordan noted that poorly sealed homes can score as high as the 20s, and that even a reading of 3.8 is “the equivalent to probably this window being open about five inches or so” under pressure.
Infrared Camera Inspection
An infrared camera is a powerful tool that allows the auditor to visualize temperature differences in walls, ceilings, and floors. It also identifies areas that don’t have adequate insulation, and detects air leaks around windows, doors, and other openings.
Attic Inspections
The attic is usually a significant source of energy loss in homes. The auditor will inspect the attic by performing the following tasks:
- Measuring the depth and condition of the existing insulation
- Checking for air leaks, especially around chimneys and other penetrations
- Evaluating the effectiveness of attic ventilation
Common Energy Loss Areas
Energy audits reveal areas from which homes lose energy. Addressing these issues can lead to significant improvements in energy efficiency.
Air Leaks
Air leaks can occur in various places throughout the home, including the following:
- Around chimneys and vents
- Around windows and doors
- In the basement, especially around the rim joist
- Through gaps in the attic floor
Inadequate Insulation
Energy audits frequently uncover insufficient or degraded insulation. Pay special attention to the areas below.
- Around ductwork in unconditioned spaces
- Attic floors
- Basements and crawl spaces
- Exterior walls
Inefficient HVAC Systems
Older heating and cooling systems can cause issues such as leaky ductwork and low-efficiency equipment.
Recommended Energy-Saving Improvements
An audit may reveal several ways in which homeowners can make their properties more energy efficient.
Air Sealing
Homeowners can usually make their homes more energy efficient by caulking and weatherstripping around windows and doors and installing foam gaskets behind outlet covers on exterior walls. They can also seal gaps around penetrations in the building envelope.
Insulation Upgrades
Homeowners can make their homes more energy efficient by improving insulation systems. Common upgrades include adding insulation to attic floors, insulating exterior walls, and insulating basements and crawl spaces.
HVAC System Improvements
Improving your heating and cooling systems can lead to substantial energy savings. Options include installing a programmable or smart thermostat, upgrading to a high-efficiency furnace or boiler, or sealing and insulating ductwork.
DIY Energy Audit Tips
Professional audits are comprehensive, but there are several steps homeowners can take to assess their own home’s energy efficiency:
- Check for visible air leaks around windows, doors, and other openings
- Evaluate the age and condition of major appliances and HVAC equipment
- Inspect insulation levels in accessible areas such as the attic
- Review energy bills and look for unusual spikes or patterns in consumption
Using the Infrared Camera
Homeowners can use infrared cameras to identify temperature differences in their walls and ceilings. This can pinpoint specific areas in which insulation or air sealing would be especially effective.
Assessing Appliance Efficiency
You can use a watt meter to measure how much energy your appliances consume. Plug each appliance into the meter to see how much energy it consumes, and compare it with energy-efficient models. You can then evaluate potential savings.
Pro Tip: Paul, an energy efficiency expert who has worked with This Old House, recommends using a switched power strip to manage phantom loads: “One of my favorite tips for these types of things is to use the switch to power strip, very easy to plug in all your equipment here and make that switch accessible so that you can easily turn it off when you’re done watching your movie. One switch, everything goes down.” During testing on a This Old House project, a home entertainment system in the off position was still drawing about 115 watts continuously — adding up to nearly 1,000 kilowatt hours per year, almost as much as a refrigerator.
Optimizing Water Heaters
To optimize your water heater, simply set its temperature to 120 degrees Fahrenheit. This adjustment can save energy and reduce your utility bills without compromising your comfort.
To make the adjustment, find the temperature dial on the side of the tank and unscrew its cover. Use a flathead screwdriver to set the dial to 120 degrees. For every 10 degrees the temperature is lowered, you can expect to save up to 5 percent in energy costs. If you plan to be away from home for more than three days, turn the water heater off or set the thermostat to its lowest setting.
