How to Conduct a Home Energy Audit and Save Money

What Is a Home Energy Audit?

A home energy audit is a systematic assessment of how your home uses energy and where it wastes it. The goal is to identify specific improvements that will reduce your energy consumption and lower your utility bills. Think of it as a diagnostic checkup for your home, similar to a car inspection but focused on energy efficiency.

The average American home wastes 25-40% of the energy it consumes. Most of this waste comes from air leaks, inadequate insulation, outdated HVAC equipment, and inefficient appliances. A thorough audit identifies these problems and quantifies how much each one costs you, so you can prioritize the fixes that deliver the best return on investment.

You can perform a basic audit yourself using a checklist and simple tools, or hire a professional energy auditor ($200-$500) who uses specialized equipment like blower doors, infrared cameras, and combustion analyzers. Either way, the information you gather will guide smart investment decisions that pay for themselves through lower energy bills. Use our Home Energy Audit Tool to track your findings and calculate potential savings.

Before You Start: Gather Your Data

Before walking through your home, collect information that will help you understand your current energy usage patterns and costs.

Collect 12 Months of Utility Bills

Pull up your electricity and gas bills for the past 12 months. Most utilities provide this data online. Note the monthly kilowatt-hour (kWh) usage and natural gas therms. Look for seasonal patterns — high summer bills indicate cooling inefficiency, while high winter bills suggest heating problems. The average U.S. household uses approximately 10,500 kWh of electricity per year and 500 therms of natural gas.

Note Your Home Details

Record your home square footage, year built, number of stories, foundation type (slab, crawlspace, or basement), and the age of major systems (HVAC, water heater, windows). Older homes (pre-1980) typically have significantly more air leaks and less insulation than modern homes. Use our Electricity Cost Calculator to establish your baseline energy costs before starting improvements.

Tools You Will Need

• Incense stick or thin tissue paper (for detecting air leaks)
• Flashlight (for inspecting attic, crawlspace, and behind appliances)
• Tape measure (for measuring insulation depth)
• Notepad or phone for recording findings
• Kill-a-Watt meter or smart plug (optional, for measuring appliance usage)
• Infrared thermometer (optional, $20-$40, for detecting temperature differences)

Step 1: Find Air Leaks

Air leaks are the single largest source of energy waste in most homes, responsible for 25-40% of heating and cooling costs. Sealing air leaks is also one of the cheapest and easiest fixes, often costing less than $200 in materials.

Where to Check for Air Leaks

Systematically inspect every potential leak point in your home. Light an incense stick and slowly move it along edges and seams. When the smoke wavers or gets sucked in a direction, you have found a leak. Alternatively, hold a thin tissue near suspected leak areas on a windy day.

• Windows and doors: Check all edges, especially at the bottom of exterior doors. A gap of just 1/8 inch under a 36-inch door is equivalent to a 4.5-square-inch hole in your wall.
• Electrical outlets and switch plates: Remove cover plates on exterior walls and feel for drafts. Foam gaskets ($0.25 each) eliminate these leaks instantly.
• Plumbing and wiring penetrations: Every pipe, wire, and cable that passes through an exterior wall or ceiling is a potential leak. Check under sinks, behind washers and dryers, and around cable TV and internet entry points.
• Attic access: The attic hatch or pull-down stairs is often the biggest single leak in a home. Weatherstrip the edges and add an insulated cover.
• Recessed lights: Can lights in insulated ceilings leak significant amounts of air. Replace with IC-rated, airtight models or cover them from the attic side.
• Fireplace damper: Even when closed, fireplace dampers leak. Inflatable chimney balloons ($30-$50) seal the flue when not in use.
• Dryer vent: Ensure the exterior vent flap closes properly and is not stuck open.

How to Seal Air Leaks

Most air leaks can be sealed with inexpensive materials. Use caulk ($3-$5/tube) for fixed joints around window frames, door frames, and where walls meet floors or ceilings. Use weatherstripping ($5-$15/door) for movable joints like doors and operable windows. Use expanding foam ($5-$8/can) for larger gaps around plumbing and wiring penetrations. For very large gaps (more than 1 inch), stuff with backer rod before applying foam or caulk. Total cost for sealing a typical home: $50-$200 in materials for a savings of $200-$400 per year.

Step 2: Check Insulation Levels

After air sealing, insulation is the second most impactful energy upgrade. Insulation slows heat transfer through walls, ceilings, and floors, keeping your home cooler in summer and warmer in winter.

Attic Insulation

The attic is the most critical area to insulate because heat rises and escapes through the roof. Climb into your attic with a flashlight and tape measure. If you can see the tops of the ceiling joists, you do not have enough insulation. For most U.S. climates, the Department of Energy recommends R-38 to R-60 in the attic, which translates to 10-16 inches of fiberglass batts or 10-14 inches of blown cellulose.

Adding attic insulation is the most cost-effective insulation upgrade, typically paying for itself in 2-4 years. Blown-in cellulose or fiberglass is the fastest and cheapest method for existing attics, and many homeowners can do it themselves with rental equipment from home improvement stores ($50-$100/day).

Step 3: Evaluate Your HVAC System

Heating and cooling account for approximately 50% of a typical home energy bill. An aging or poorly maintained HVAC system can waste 30-40% more energy than a modern, well-maintained one.

System Age and Efficiency

Check the data plate on your furnace, air conditioner, or heat pump for the model number and manufacture date. If your system is more than 15 years old, it is likely operating well below modern efficiency standards. A furnace from 2010 may be 80% AFUE, compared to 96-98% for current models. An air conditioner from 2010 may be SEER 13, compared to SEER 18-22 for new units. Upgrading to a modern heat pump can reduce heating and cooling costs by 30-50%.

Use our Heat Pump Calculator to estimate savings from upgrading your HVAC system, and read our Heat Pump vs Furnace Guide for a detailed comparison of your options.

Ductwork Inspection

Leaky ducts waste 20-30% of the air flowing through them. In the attic, crawlspace, or basement, visually inspect exposed ductwork for disconnected joints, holes, or crushed sections. Feel for air escaping at joints while the system is running. Professional duct sealing costs $1,000-$3,000 and typically reduces energy bills by 10-20%. DIY sealing with mastic or metallic tape (not standard duct tape, which fails over time) can address accessible leaks for under $100.

Thermostat Settings

If you do not have a programmable or smart thermostat, you are leaving easy savings on the table. Setting back your thermostat by 7-10 degrees for 8 hours per day (while sleeping or at work) can save 10% per year on heating and cooling costs. A smart thermostat ($100-$250 installed) learns your schedule and optimizes automatically. Many utilities offer rebates of $25-$100 on smart thermostats.

Step 4: Audit Your Appliances

Appliances account for approximately 20% of a typical home energy bill. Older appliances can use 2-3 times more energy than modern Energy Star models.

Check the Energy Guide Labels

Look at the yellow EnergyGuide label on each major appliance (refrigerator, washer, dryer, dishwasher, water heater). This label shows the estimated annual energy cost and how the appliance compares to similar models. If you cannot find the label, search for the model number online to find its energy specifications.

High-Impact Appliances to Audit

• Refrigerator: Runs 24/7 and is the third-largest energy user in most homes. A refrigerator from 2005 uses 500-700 kWh/year versus 400-450 kWh/year for a new Energy Star model. If yours is over 15 years old, replacing it saves $50-$100/year.
• Clothes dryer: One of the most energy-intensive appliances at 2,500-5,000 watts. A heat pump dryer uses 50% less energy than a conventional electric dryer. Line drying costs nothing.
• Water heater: The second-largest energy user in most homes (14-18% of total). Check the temperature setting — every 10 degrees you lower it saves 3-5% on water heating costs. 120 degrees Fahrenheit is ideal.
• Washer: Modern HE washers use 25% less energy and 45% less water than standard top-loading models.

Use our Appliance Calculator to calculate exactly how much each appliance costs to operate and compare it to newer, more efficient models.

Step 5: Assess Lighting and Electronics

Lighting accounts for 10-15% of a home electricity bill. Electronics and phantom loads (devices that draw power when turned off) add another 5-10%.

Lighting Audit

Walk through your home and count every light bulb. Note which are incandescent, CFL, or LED. Each 60-watt incandescent bulb you replace with a 9-watt LED equivalent saves about $7 per year (at $0.13/kWh, 3 hours/day). If you still have 20 incandescent bulbs, switching to LED saves $140 per year. LED bulbs cost $1-$3 each and last 15-25 years. This is the single fastest payback upgrade in any home. Visit our LED Savings Calculator for a bulb-by-bulb cost analysis.

Phantom Loads

Devices like TV cable boxes, game consoles, computer monitors, printers, and phone chargers draw 5-25 watts even when turned off or in standby mode. These phantom loads can total 50-100 watts continuously, costing $50-$100 per year. Use power strips with switches to cut phantom loads completely. Smart power strips ($25-$40) automatically cut power to peripheral devices when the main device is turned off.

Step 6: Inspect Water Heating

Water heating consumes 14-18% of a home energy budget, making it the second-largest energy expense after HVAC. Several simple checks can reveal significant savings opportunities.

Tank Temperature

Check your water heater thermostat. Many are factory-set to 140 degrees Fahrenheit, but 120 degrees is sufficient for most households and reduces energy consumption by 6-10%. The temperature dial is usually located near the bottom of the tank on gas models or behind an access panel on electric models.

Tank Insulation

Touch your water heater tank. If it feels warm, it is losing heat through its walls. An insulating blanket ($20-$40) reduces standby heat loss by 25-45% and saves $20-$50 per year. This is particularly impactful for tanks in unconditioned spaces like garages or basements. Also insulate the first 6 feet of hot water pipes leaving the tank ($10-$15 in pipe insulation).

System Age and Type

Standard tank water heaters last 8-12 years. If yours is approaching that age, plan for a replacement before it fails. Heat pump water heaters use 60-70% less energy than conventional electric tanks and qualify for a $2,000 federal tax credit. They cost $1,200-$2,800 installed (versus $800-$1,500 for a standard electric tank) but save $300-$500 per year. Read our Electric vs Gas Water Heater Guide for a detailed comparison.

Prioritizing Improvements by ROI

After completing your audit, prioritize improvements based on cost, savings, and payback period. Here is a typical ranking from fastest to slowest payback.

Start with the no-cost and low-cost items (thermostat adjustment, LED bulbs, air sealing) and work your way toward larger investments. The first three items on this list can save $300-$600 per year for under $300 total. Track your progress with our Electric Bill Estimator to see how each improvement reduces your monthly costs.

When to Hire a Professional

A professional energy audit costs $200-$500 and provides capabilities beyond a DIY inspection.

What a Professional Audit Includes

• Blower door test: Depressurizes your home to measure total air leakage and pinpoint leak locations. Costs $150-$300 standalone.
• Infrared thermal imaging: Shows exactly where heat is escaping through walls, ceilings, and around windows. Reveals insulation gaps invisible to the naked eye.
• Duct blaster test: Measures duct leakage separately from the rest of the building envelope.
• Combustion safety testing: Verifies that gas appliances (furnace, water heater, stove) are venting properly and not producing dangerous levels of carbon monoxide.
• Detailed report: Provides a prioritized list of improvements with estimated costs and savings, often required for rebate programs.

Consider hiring a professional if your home was built before 1980, if your energy bills seem unusually high compared to similar homes, if you are planning major renovations, or if you need documentation for utility rebate or weatherization assistance programs. Many utilities offer free or subsidized professional audits for their customers. Check with your utility company before paying out of pocket.

Frequently Asked Questions