An energy auditor is a professional who inspects buildings to find where energy is being wasted and recommends fixes to lower utility bills. Sometimes called energy raters or energy consultants, these specialists use diagnostic tools and on-site testing to pinpoint problems like air leaks, poor insulation, and inefficient heating or cooling systems. The end result is a detailed report that tells a building owner exactly where money is going out the window, often literally, and what to do about it.
What an Energy Auditor Actually Does
The job starts before anyone sets foot in your building. An auditor begins by reviewing your utility bills, sometimes going back a full year or more, to spot patterns in energy use and identify seasonal spikes. This billing history gives them a baseline: how much energy you’re consuming, when you’re consuming the most, and where the biggest opportunities for savings likely are.
The bulk of the work happens during an on-site inspection. The auditor walks through the building with the owner, checking for drafts around windows and doors, inspecting insulation in attics and walls, examining ductwork for leaks, and evaluating heating and cooling equipment. They’ll look at lighting, appliances, and ventilation systems too. For homes with gas-burning appliances like furnaces and water heaters, auditors also perform combustion safety testing, checking for dangerous carbon monoxide levels and making sure exhaust vents are working properly.
After the inspection, the auditor produces a detailed report covering every test result, problem area, and recommended upgrade. They’ll typically walk you through the findings in person, pointing out specific spots where air is escaping or insulation is thin, and help you prioritize fixes based on cost and impact.
Tools That Reveal Hidden Problems
Energy auditors rely on specialized equipment that can detect problems invisible to the naked eye. Two tools form the backbone of most professional audits.
A blower door is a powerful fan mounted in an exterior doorframe that depressurizes the entire building. By pulling air out, it forces outside air in through every crack, gap, and unsealed penetration, making leaks much easier to locate and measure. Think of it as turning every tiny draft into something you can actually feel and quantify.
Infrared cameras (also called thermal imaging cameras) detect temperature differences across surfaces. Warm areas show up as white or light-colored on the screen, while cool areas appear dark. This lets an auditor instantly see where insulation is missing inside a wall, where cold air is streaming in around a window frame, or where a hot water pipe is losing heat. When an infrared camera is used while the blower door is running, air leaks show up as dramatic black streaks in the viewfinder, making them unmistakable.
Auditors also use simpler devices like spot radiometers, which measure the temperature of a single point at a time and are useful for quick comparisons between surfaces. For example, aiming one at different sections of an exterior wall can quickly reveal which areas are insulated and which aren’t.
Residential vs. Commercial Audits
Home energy audits tend to follow a fairly standard process: review bills, run a blower door test, scan with an infrared camera, check insulation and equipment, and deliver a report with prioritized recommendations. The Department of Energy also offers a Home Energy Score, a simple 1-to-10 rating where 10 represents the most efficient homes and 5 is average. An assessor enters roughly 50 data points into a scoring tool, covering things like insulation levels, heating equipment efficiency, and home size. The score is based solely on the physical characteristics of the house, not on how you use it, so thermostat habits and appliance choices don’t factor in. Larger homes generally score lower than smaller ones with similar features, since the score reflects total energy use rather than energy per square foot.
Commercial building audits are more complex and follow a tiered system established by ASHRAE, the main professional body for building engineers. There are three levels. A Level 1 audit is a walk-through survey, a relatively quick assessment that identifies low-cost improvements and ballpark savings. A Level 2 audit goes deeper with a full energy survey and engineering analysis, modeling how specific upgrades would perform. A Level 3 audit is the most intensive, involving detailed analysis of capital-intensive modifications like replacing an entire HVAC system or overhauling a building envelope. Each level requires progressively more data collection, more sophisticated modeling, and more investment, but also produces more precise savings estimates.
How Energy Auditors Get Certified
There’s no single license required to work as an energy auditor, but two industry certifications carry the most weight. RESNET (the Residential Energy Services Network) certifies Home Energy Raters through a structured process: candidates attend accredited training classes, then pass a national rater exam along with simulation tests for combustion safety and practical rating skills. After passing, new raters complete five supervised probationary ratings under an accredited provider before earning full certification. The entire process, from exams to probationary ratings, must be finished within 15 months.
The Building Performance Institute (BPI) offers a parallel certification path focused on whole-building performance, covering not just energy efficiency but also health and safety factors like indoor air quality and moisture management. Many auditors hold credentials from both organizations, and some states or utility rebate programs require one or the other before they’ll accept audit results.
What Happens After the Audit
The real value of an energy audit is the prioritized action plan. A good auditor won’t just hand you a list of problems. They’ll help you figure out which upgrades deliver the fastest payback, which ones improve comfort beyond just saving money, and which ones make sense given how long you plan to stay in the building.
Common recommendations include sealing air leaks around pipes, outlets, and window frames with caulk or weatherstripping; adding insulation in attics, crawlspaces, or walls; replacing inefficient lighting with LEDs; sealing leaky ductwork; and upgrading older heating or cooling equipment. Some of these fixes cost very little and pay for themselves within a season. Others, like replacing a furnace or adding wall insulation, are bigger investments that take several years to recoup but can significantly reduce monthly bills.
Many utility companies offer rebates or incentives tied to professional energy audits, and some will subsidize the cost of the audit itself. The audit report often serves as the documentation you need to qualify for those programs, making it worth checking with your local utility before you schedule one.