A DIY home energy audit is a simple walk-through of your home to find where energy (and money) is leaking out: drafts, thin insulation, tired heating and cooling equipment, and power-hungry appliances. You don’t need special tools — a flashlight, an incense stick, and your last 12 months of bills get you most of the way. The U.S. Department of Energy’s own guidance says a careful DIY assessment can reveal many problems, while noting a professional assessment (typically about $100–$500) can find things you’ll miss.

Quick answer

Step	What you check	Tools	Time
1. Bills	12 months of kWh and gas use	Past bills / utility app	20 min
2. Air leaks	Windows, doors, outlets, attic hatch, pipes	Incense stick, flashlight	45 min
3. Insulation	Attic depth, walls, basement/crawlspace	Tape measure, gloves	30 min
4. Heating & cooling	Filter, ducts, thermostat	Flashlight	20 min
5. Water heating	Temperature setting, pipe insulation	Thermometer	10 min
6. Lighting & appliances	Bulb types, old fridges, standby loads	Notepad, plug-in meter (optional)	30 min
7. Action plan	Rank fixes by cost and impact	This article	15 min

Before you start: read your bills

Pull 12 months of electric and gas bills and note the kWh and therms (or CCF) each month. Your lowest months show your “base load” — lighting, fridge, water heating, electronics. The jump above that in winter and summer is mostly heating and cooling.

To put a dollar figure on things, use roughly $0.18 per kWh, close to the U.S. average residential price for 2026 according to the U.S. EIA (your own rate is printed on your bill; see how to read your electric bill). For gas, EIA data put the 2025 residential average at about $15.40 per thousand cubic feet — roughly $1.49 per therm.

Example: if your lowest month is 600 kWh and your peak winter month is 1,400 kWh, about 800 kWh of that winter month is likely heating: 800 kWh × $0.18 = $144 for one month.

Step 1: Hunt for air leaks

The DOE notes that all the small, invisible cracks in a typical home can add up to the equivalent of an open window. Check these spots, as listed in DOE’s assessment guidance:

• Around electrical outlets and switch plates on exterior walls
• Window and door frames, and baseboards
• The attic hatch or pull-down stairs
• Wall or window AC units
• Where pipes, cables and wires enter the house (gas line, cable/phone lines, dryer vent)
• Vents and exhaust fans, and where the foundation meets the walls
• Around the chimney and where different materials meet

The incense (smoke) test

1. Pick a cool, windy day.
2. Close all windows, exterior doors and fireplace dampers.
3. Turn off combustion appliances (furnace, gas water heater) so you don’t draw exhaust back in.
4. Turn on bathroom and kitchen exhaust fans to slightly depressurize the house.
5. Slowly move a lit incense stick around each suspect spot. Where the smoke wavers or gets sucked in or blown away, you’ve found a leak.
6. Turn combustion appliances back on when you finish.

Other quick checks: if you can see daylight around a closed door, or a window rattles in its frame, it’s leaking. Mark each leak with painter’s tape so you can fix them in one go.

Typical fixes: caulk for small gaps around stationary frames, weatherstripping for doors and operable windows, foam gaskets behind outlet covers, and expanding foam for bigger gaps around pipes.

Step 2: Check your insulation

Attic

With gloves and a mask, look at the attic floor. Can you see the tops of the ceiling joists? If so, insulation is likely thin. Measure the depth in a few spots. Also look for:

• Gaps or compressed patches
• Uninsulated or unsealed attic hatch
• Holes around light fixtures, pipes and chimneys (seal these before adding insulation)

Walls

Turn off power to an outlet on an exterior wall, remove the cover plate and shine a flashlight into the gap (don’t poke metal tools in). You may see insulation — or nothing.

Basement or crawlspace

Check whether the rim joists (the top of the foundation walls) are insulated, and whether heating ducts or pipes run through unheated space bare.

For what to tackle first, see home insulation: where to start.

Step 3: Heating and cooling

Heating and cooling are usually the biggest chunk of a home’s energy use — DOE’s home energy checklist notes that heating alone can be almost half of a family’s winter energy bill.

• Filter: pull it out and hold it to the light. If you can’t see through it, replace it. Most are changed every 1–3 months during heavy use; follow your system’s instructions.
• Ducts: look for disconnected sections, gaps at joints, or ducts running through the attic or crawlspace uninsulated. Seal with mastic or foil-backed tape (not ordinary cloth duct tape).
• Thermostat: is it programmed? A setback while you sleep or are away is free money — see smart thermostat savings.
• Age of equipment: note the furnace, heat pump or AC age from its label. Older systems are worth a professional tune-up and planning a replacement before it fails.

Step 4: Water heating

DOE’s checklist puts water heating at roughly 14–25% of home energy use.

• Check the setting. DOE suggests 120°F (49°C) for most homes. Run hot water at the tap nearest the heater for a minute and check with a kitchen thermometer.
• Insulate the first few feet of hot water pipe from the tank.
• Look for drips at faucets and showerheads — hot water leaks cost both water and energy.

Step 5: Lighting, appliances and standby power

• Lighting: count remaining incandescent or halogen bulbs, starting with those on most hours a day. A 60 W incandescent swapped for a 9 W LED used 3 hours a day saves 51 W × 3 h × 365 ÷ 1,000 = 55.8 kWh × $0.18 = about $10 a year per bulb.
• Second fridge or freezer: old units in garages often use far more than modern ones. A plug-in meter shows actual kWh.
• Standby loads: game consoles, cable boxes and old chargers draw power 24/7. Use the “all lights off” trick: with everything you’d normally leave on, read your smart meter or the meter dial — that’s your always-on load.

Step 6: Build your action plan

Rank what you found:

Priority	Fix	Typical DIY cost	Why
1	Change filter, set thermostat schedule	$0–$30	Free or nearly free
2	Weatherstrip doors, caulk windows, outlet gaskets	$20–$100	Cheap, fast payback
3	LED bulbs in high-use fixtures	A few dollars per bulb	Low cost
4	Seal and insulate accessible ducts and attic hatch	$50–$200	Moderate effort
5	Add attic insulation	Varies widely	Bigger job — may be worth a pro
6	Replace old appliances or HVAC	Hundreds to thousands	Plan for when they wear out

About tax credits: the federal energy-efficiency home improvement credit (25C), which had covered part of the cost of a home energy audit and insulation, ended for expenditures made after December 31, 2025 under the 2025 federal budget law. Don’t count on a federal credit for work done now — but check your utility and state energy office, as many still offer free or discounted audits and rebates.

DIY vs. professional audit

	DIY audit	Professional assessment
Cost	Free–$50	About $100–$500 (DOE estimate), sometimes subsidized by utilities
Finds obvious drafts	Yes	Yes
Measures total air leakage	No	Yes (blower door test)
Sees hidden insulation gaps	Limited	Yes (infrared camera)
Safety checks on gas appliances	No	Often included

A DIY audit is a great first pass. If your bills are still high after the easy fixes, a professional blower-door test tells you exactly how leaky the house is.

Frequently Asked Questions

How long does a DIY home energy audit take?

Most homes can be done in two to three hours, including reviewing bills. Spread it over a weekend if you’re also doing fixes.

What’s the best time of year to do it?

A cold, windy day makes air leaks easiest to feel and see with the incense test. Attic checks are more comfortable in spring or fall.

Is the incense test safe?

Yes, if you turn off combustion appliances (furnace, gas water heater) during the test and keep the flame away from curtains and insulation. Turn appliances back on afterward.

Can renters do a DIY energy audit?

Yes. Renters can check bills, use removable weatherstripping and draft stoppers, swap bulbs, and report bigger problems (insulation, HVAC) to the landlord.

Is a federal tax credit still available for home energy audits?

Not for audits done in 2026. The 25C credit ended for expenditures after December 31, 2025. Check your utility and state for local programs instead.

The bottom line

A DIY home energy audit costs almost nothing and turns a vague “our bills are high” into a ranked to-do list. Start with bills, air leaks and the HVAC filter, knock out the cheap fixes first, and save bigger upgrades for when they make sense. Savings vary by climate, home and rates — but you can’t fix what you haven’t found, and this afternoon’s walk-through is the fastest way to find it.

Figures in this guide are estimates based on typical US prices at the time of writing. Savings vary by home, climate and utility rates — check your own bill before making a purchase.