Heating and cooling account for nearly half of residential energy use in the US—and a large fraction of that energy is lost through leaks, inefficient behavior, or equipment running when it doesn’t need to. The good news is that most of the highest-impact improvements require no major renovation and cost very little. Here’s where to start.
Air Sealing: The Highest ROI Fix
Before upgrading any equipment, seal the leaks. Heated and cooled air escapes through gaps around windows and doors, pipe penetrations, attic hatches, electrical outlets on exterior walls, and anywhere different building materials meet. The US Department of Energy estimates that air sealing plus adding adequate insulation can reduce heating and cooling costs by 10–20%.
Do it yourself: A $6 tube of caulk and a $4 can of expanding foam spray handle most gaps. Caulk goes around window and door frames, pipe penetrations through walls, and gaps where the foundation meets the house. Expanding foam goes in larger gaps (around pipes entering from outside, gaps in attic areas). Weatherstripping on doors takes 30 minutes and costs under $20 per door.
Find the leaks: Light a stick of incense or a smoke pen near suspected gaps on a windy day—the smoke will move toward leaks. The DOE’s home energy audit tool (energy.gov) has a room-by-room checklist. Or pay for a professional blower door test, which pressurizes your home to reveal every air leak—typically $300–500 but often subsidized by utilities.
Thermostat Habits: Low Cost, Measurable Impact
The standard guidance: set heating to 68°F when awake and home, lower when sleeping or away. For cooling: 78°F when home and awake, 85°F or off when away. These aren’t arbitrary—the EPA estimates that programming your thermostat to these setbacks saves about 10% annually on heating and cooling costs.
A programmable thermostat ($25–50) automates the setbacks so you don’t have to think about it. A smart thermostat (Nest, Ecobee, $150–250) goes further by learning your schedule and adjusting automatically, plus allowing remote control via phone. The payback period for a smart thermostat is typically 1–2 years in saved energy costs.
One specific high-impact habit: raise your AC setpoint by 2°F. The DOE estimates that 2°F higher in summer saves about 6% on cooling costs. Most people don’t notice 2°F if the humidity is managed.
Humidity Management
How hot or cold you feel is as much about humidity as temperature. In summer, a dehumidifier running in a humid basement can make the whole house feel 5°F cooler at the same thermostat setting, because low humidity dramatically increases the body’s ability to cool itself through evaporation. In winter, humidity above 40–45% makes air feel warmer and reduces static electricity.
A standalone dehumidifier in a problem area costs $150–250 and uses about 300–700W. If it lets you raise the AC setpoint by a few degrees, the net energy effect can be positive.
HVAC Maintenance
A dirty air filter increases the energy consumption of your HVAC system by 5–15% as the blower works harder to move air through restricted flow. Change it every 60–90 days (monthly if you have pets). A standard 1-inch filter costs $3–8; upgrade to MERV 8 for better particulate capture without excessive restriction.
Have your furnace and AC serviced annually by an HVAC technician. Cleaning coils, checking refrigerant charge, and tuning combustion efficiency can recover 5–10% efficiency that degrades gradually between services.
Window Treatments
Closing blinds or curtains on south- and west-facing windows during summer afternoons significantly reduces solar heat gain—free cooling load reduction with no hardware. In winter, opening south-facing curtains during daylight hours lets passive solar gain supplement your heating. The effect is more meaningful than most people expect; south-facing windows can contribute meaningfully to daytime heating in sunny climates.
Thermal curtains (insulated cellular shades or heavy curtains with thermal lining) add another layer of insulation on cold nights. The R-value added isn’t huge, but it reduces heat loss through glass on the coldest nights and improves comfort near windows.
✏️ This article was researched and edited by the HappyHippie team, sometimes with the help of AI writing tools. See our content disclosure.
