Home Energy Audit Checklist: 15 Steps to Cut Your Bills

Before walking your home, establish your baseline. Pull 12 months of electricity (and gas, if applicable) bills and plot your usage month by month. Calculate your average monthly kWh, your peak month, and your effective rate (total bill ÷ kWh consumed). Note unusual spikes — a single high month often points to a specific equipment failure (HVAC running continuously, refrigerator going bad, water heater element failing).

Attic heat loss accounts for 25–30% of total heating and cooling loss in a typical pre-2000 home, according to DOE data. Bring a flashlight, a ruler, and a moisture meter if available. Measure insulation depth in multiple locations — near the eaves, at center, and near any penetrations (light fixtures, HVAC boots, exhaust fans). DOE recommends R-49 to R-60 for most U.S. climate zones (roughly 15–19 inches of blown fiberglass or cellulose).

The stack effect in a two-story or multi-level home creates constant pressure driving warm air out through every gap at the top of the building. Common attic air leak locations: around recessed light fixtures (code-required air-tight IC-rated fixtures in newer homes, often missing in older homes), at top plates where interior walls meet the attic floor, around HVAC supply and return boots, around plumbing and electrical penetrations, and at attic access hatches. Use a can of low-expansion spray foam ($6–$8) for gaps under 3 inches and rigid foam board plus tape for larger openings.

On a windy day or cold day (best results with a 20°F+ temperature differential), light an incense stick and slowly move it around every potential air leak location in each room. Watch for the smoke to bend or be drawn to a leak. Systematic locations to check: all exterior electrical outlets and switches (use foam gasket inserts — $8 for a 12-pack), baseboards along exterior walls, around window and door frames (not the glass — the frame/drywall junction), fireplace dampers in the closed position, whole-house fan louvers, and recessed lighting on exterior ceilings.

Windows are the most visible and emotionally satisfying thing to upgrade, but they also have the worst financial return of any energy improvement. According to NREL research, replacing single-pane windows with double-pane low-E windows saves $100–$200/year in an average climate — but the windows cost $5,000–$15,000, giving a 25–75 year payback. Your time is much better spent sealing around existing windows than replacing them. Check for: failed glazing compound (crumbling caulk around glass panes), gaps between frame and rough opening, deteriorated weatherstripping on operable sashes and doors, and non-functioning storm windows.

Pull your HVAC air filter and hold it to the light. A clogged filter — one you can no longer see through — is adding 5–15% to your cooling costs as the system works harder to move air through the restriction. Replace it immediately. Per EIA's 2022 RECS data, heating and cooling represent 51% of residential energy consumption, making HVAC the single highest-leverage system in your audit. Note the unit age: central air conditioners and heat pumps older than 15 years have SEER ratings of 10–13; current minimum-efficiency units run 14–15 SEER, while high-efficiency units reach 18–26 SEER. A 10-SEER unit replaced with a 20-SEER system cuts cooling costs in half.

Leaky ductwork is one of the most underappreciated sources of energy waste. The average U.S. home loses 20–30% of conditioned air through duct leaks, per DOE data. Inspect accessible ducts in your attic, crawlspace, and garage. Look for: disconnected sections (this happens more than you would think — a HVAC tech bumps a duct and it stays disconnected for years), visible gaps at junctions, and uninsulated ducts running through unconditioned spaces. Seal accessible leaks with mastic sealant ($8–$15/quart) or foil tape — never use standard cloth duct tape, which delaminates within 2–5 years.

Water heating accounts for 19% of residential energy use per EIA 2022 RECS data — making it the second-largest energy consumer in most homes. Check the age (stamped on the nameplate or encoded in the serial number), the type (electric resistance vs. gas vs. heat pump), and the tank insulation (older tanks feel warm to the touch because heat is constantly escaping through uninsulated walls). Electric resistance water heaters (old coil-type units) are the least efficient technology still widely installed — efficiency factor around 0.9. Heat pump water heaters achieve 3.5–4.0 efficiency factor, using 75% less electricity for the same hot water output.

Walk every room and identify any remaining incandescent (old warm-white with visible filament), halogen (bright white, very hot to the touch), or compact fluorescent (CFL, tube-in-bulb shape) fixtures. LEDs use 75–90% less electricity than incandescents and last 15,000–25,000 hours vs. 1,000 hours. At the current national average of 18.05¢/kWh, a single 60W incandescent burning 4 hours/day costs about $15.74/year in electricity alone. The LED equivalent (9W) costs $2.37/year — saving $13.37/year per bulb, paying back a $2 LED bulb in 7 weeks. Per ENERGY STAR data, lighting accounts for about 5% of home energy use — significant if you have many non-LED bulbs.

Plug a Kill-a-Watt meter (P3 Kill A Watt P4400, $25–$35 on Amazon) into each outlet before plugging in a device. Measure: active wattage (running), standby wattage (plugged in but "off"), and kWh consumed over 24 hours for always-on devices. Typical phantom load culprits: cable/satellite boxes (15–25W continuously = $23–$39/year), older game consoles left in standby (up to 150W in quick-start mode), desktop computers with enabled wake-on-LAN, and older plasma TVs. A $6 smart power strip eliminates phantom loads from home theater equipment automatically.

Your refrigerator is the only appliance that runs 24/7/365 with no off switch. Check the door seals by placing a piece of paper between the door and the gasket, closing the door, and pulling — you should feel significant resistance. A leaking seal means the compressor runs more often to compensate. Check the condenser coils (typically on the back or underneath) — dusty coils reduce efficiency by 10–15% and are cleaned in 10 minutes with a condenser coil brush ($8–$12). Check the temperature settings: refrigerators should run at 35–38°F and freezers at 0–5°F. Every 10°F colder than needed increases energy use by about 5%.

A properly programmed smart thermostat saves an average of $50–$180/year, per ENERGY STAR data, primarily by automatically setting back temperature 7–10°F during sleeping hours and away hours. If you still have a non-programmable thermostat — common in homes where the original builder-grade thermostat was never upgraded — replacing it with a Google Nest (4th gen, $130), Ecobee SmartThermostat ($200), or Honeywell T6 Pro ($50) is one of the most straightforward efficiency investments. If you already have a smart thermostat, check that it is actually programmed for setback (many homeowners install them and leave them in manual mode) and that the learning mode has had at least 2 weeks to adapt.

Check the first 6 feet of hot and cold water pipes connected to your water heater — these should be insulated (pipe insulation sleeves cost $1–$3/foot at any hardware store). Uninsulated pipes allow heat to dissipate into unconditioned spaces, meaning you run the tap longer to get hot water at the fixture (wasting both water and the energy to heat it). Also check your water heater temperature setting: DOE recommends 120°F for households without immunocompromised members. Every 10°F reduction in water heater temperature saves 3–5% on water heating costs. A water heater set at 140°F (a common factory default) wastes $40–$80/year vs. a 120°F setting.

Log into your utility portal and review what rate plan you are on. Many utilities now offer time-of-use (TOU) plans where off-peak rates (typically nights and weekends) are 30–60% cheaper than peak rates. If you own an EV, a smart charger, or a programmable water heater, you can likely shift significant load to off-peak hours and realize meaningful savings. In deregulated electricity markets (Texas, Illinois, Pennsylvania, New York, New Jersey, and others), you may also be able to switch suppliers for a lower rate. Use a rate comparison tool — your utility should offer one, or check PowerToChoose.org (Texas) or your state's public utility commission website.

A home energy audit is only valuable if it produces action. Using your findings from steps 1–14, create a prioritized list organized by payback period — not by size of savings or by cost. The goal is to execute the fastest-payback improvements first, generating savings that fund the more expensive upgrades. Typical hierarchy: (1) Behavior changes — free; (2) Air sealing materials — $50–$200; (3) Lighting — $20–$80; (4) Smart thermostat — $50–$200 net of rebates; (5) Attic insulation — $1,000–$2,500; (6) HVAC tune-up/duct sealing — $150–$500; (7) Water heater upgrade — $200–$800 net of rebates; (8) Major equipment (HVAC replacement, windows) — only after all else is done.