DIY Home Energy Audit for Summer

Air leaks are the #1 source of energy waste in most homes. Walk through your home on a windy day with an incense stick or a lit candle. Move it slowly around window frames, door edges, baseboards, electrical outlets on exterior walls, and where walls meet floors. When the smoke flickers or the flame dances, you have found a leak. Common leak locations: windows (check sash, frame, and sill), exterior doors (bottom sweep and all edges), attic hatch (the biggest single leak in many homes), recessed lights (especially non-IC-rated), plumbing and wiring penetrations through exterior walls, fireplace dampers, baseboard trim (where floor meets wall), and mail slots. Mark every leak with painter's tape and plan to seal it during your sealing session.

Check insulation levels in your attic, the most critical area for summer heat gain. Measure the depth of existing insulation—if it is less than the recommended R-value for your climate zone, add more. Check for compressed, wet, or missing insulation. Look for insulation that has settled or been disturbed. In the basement or crawlspace, check that rim joists are insulated—this is a major heat loss/gain point. Seal rim joists with rigid foam insulation and expanding foam. Check wall insulation by removing an outlet cover on an exterior wall and peeking inside with a flashlight—you should see insulation filling the cavity. For homes with uninsulated walls, blown-in cellulose or foam injection is the retrofit solution. Document all insulation gaps and prioritize them by area.

In summer, ductwork running through hot attics can lose 20–30% of cooling energy before it reaches your rooms. Inspect all accessible ductwork in the attic, basement, and crawlspace. Look for disconnected sections, tears, and crushed ducts. Feel for air escaping at joints when the system is running. Seal all joints with mastic (not duct tape, which degrades quickly). Apply mastic with a brush over wire mesh on gaps larger than ¼ inch. Wrap exposed ducts in unconditioned spaces with R-6 or higher duct insulation. Check that flex duct is properly supported—sagging sections trap air and restrict flow. Verify that all supply registers are connected and blowing air. Check return air ducts for leaks—return leaks pull hot attic air into the system.

Appliances generate heat that your AC must overcome. Check the age and efficiency of major appliances: refrigerator, dishwasher, clothes dryer, and water heater. A refrigerator from 2005 uses twice the energy of a new Energy Star model and produces more heat. Switch to LED bulbs—traditional incandescent bulbs waste 90% of energy as heat, and every 100-watt bulb in a room adds heat your AC must remove. Run heat-generating appliances (dishwasher, clothes dryer, oven) in the early morning or late evening rather than during the heat of the day. Use a microwave or toaster oven instead of the full oven when possible—they use less energy and produce less heat. Check the water heater temperature setting—120°F is sufficient and saves energy.

After completing your DIY audit, consider a professional energy audit for a complete picture. A professional uses a blower door test that depressurizes your home and measures total air leakage in cubic feet per minute at 50 Pascals (CFM50). A typical home measures 2,000–4,000 CFM50; an efficient home is under 1,000. Infrared thermography reveals insulation voids and thermal bypasses invisible to the naked eye. Professionals also test combustion safety—ensuring furnaces and water heaters are not backdrafting carbon monoxide into the home. Many utility companies offer discounted audits and rebates for recommended improvements. The $200–$500 cost is often recouped in the first year through energy savings. A professional audit provides a prioritized, quantified action plan.