How to lower your summer electric bill

Last updated 2026-10-21

Air conditioning is usually the largest summer load. A central AC can use about 945 kWh a month in hot weather, around $170 at the U.S. average 17.99¢/kWh. These are the fixes ranked from free to expensive.

1. Savings at a glance

Action	Typical saving	Cost
Raise the thermostat to 78°F when home	3% to 5% of cooling per degree; 4°F ≈ $27/mo	Free
Set back 7 to 10°F while away or asleep	Up to about 10% of cooling	Free; smart thermostat $100 to $250
Replace or clean the air filter	5% to 15% if the filter was clogged	$5 to $40
Use ceiling fans and raise setpoint 2 to 4°F	Fan costs $1.73/mo; saves 6% to 16% of cooling	Free if installed
Close blinds on sun-facing windows	Cuts solar heat gain through windows by up to about half (reflective/cellular shades)	$0 to $100/window
Clean the outdoor condenser coil; get a tune-up	5% to 15% on a neglected system	$0 DIY; $100 to $200 service
Seal and insulate ducts in the attic	10% to 20% of HVAC energy when ducts are leaky	$300 to $2,000
Seal attic air leaks and add insulation	10% to 15% of heating and cooling	$500 to $2,500
Replace single-speed pool pump with variable-speed	About $45/mo in season	$800 to $1,500 installed
Replace an old AC (SEER 10 or less) with a SEER2 15+ heat pump	30% to 40% of cooling	$6,000 to $15,000; rebates often available

Ranges from DOE and ENERGY STAR guidance and typical field results; your results depend on climate, house and equipment. Dollar figures use 17.99¢/kWh.

2. Thermostat settings

Home and awake: 78°F.
Asleep: 80 to 82°F with a fan, or as warm as you can sleep.
Away 4+ hours: 85°F. Do not turn the system off entirely in humid climates; indoor humidity and mold risk rise.
Each degree warmer saves roughly 3% to 5% of cooling energy. Going from 72°F to 78°F can cut cooling use by a fifth or more.
Setting the thermostat lower does not cool the house faster; it just runs longer.
Keep lamps, TVs and heat-producing appliances away from the thermostat.

3. Fans

A ceiling fan uses 15 to 75 W, about $1.73 a month at 8 hours a day for a 40 W fan. Central AC uses 3,000 to 4,000 W. A fan lets you raise the setpoint about 4°F with the same comfort.

Fans cool people, not rooms. Turn them off in empty rooms.
Summer direction: counterclockwise, viewed from below.
In dry climates or cool nights, a whole-house fan can replace AC in the evening for a fraction of the power.
Box and pedestal fans work too: see box fan costs.

4. Pre-cooling on time-of-use

If your plan charges more from, say, 4 to 9 p.m., cool the house to 73 to 75°F by 3:30 p.m., then raise the setpoint to 78 to 80°F during peak. The house coasts on stored cooling. Smart thermostats can do this automatically, and many utilities pay $25 to $100 a year for letting them adjust your thermostat on peak days. See time-of-use rates and the TOU savings calculator.

5. Maintenance

Filter: check monthly in summer; replace every 1 to 3 months. A clogged filter cuts airflow and efficiency.
Outdoor coil: turn off power at the disconnect, clear debris, and rinse the fins from the inside out with a garden hose (no pressure washer). Keep 2 feet of clearance around the unit.
Condensate drain: flush with a cup of vinegar to prevent clogs and shutdowns.
Professional tune-up every 1 to 2 years: refrigerant charge, coil cleaning, electrical checks. Low refrigerant means a leak; topping off without a repair is a recurring cost.
Supply vents: keep them open and unblocked. Closing vents in unused rooms raises duct pressure and leakage in most systems.

6. Keep heat out

Shades and blinds: close them on east windows in the morning and west windows in the afternoon. Exterior shades, awnings and solar screens block more heat than interior blinds.
Window film: low-e or solar control film on west and south glass. $5 to $15 per square foot installed.
Ducts: in many homes ducts run through a 120 to 140°F attic. Leaky ducts can lose 20% to 30% of the air moving through them. Seal joints with mastic or foil tape (not cloth duct tape) and insulate.
Attic: seal top-plate gaps and penetrations, then insulate to R-38 or more in most climates.
Cooking and laundry: use the microwave, air fryer or grill outdoors; run the dryer at night. Each kWh of heat added indoors must be removed by the AC.

7. Upgrades

Right size: oversized AC short-cycles, removes less humidity and wastes energy. Ask any installer for a Manual J load calculation, not a rule of thumb.
Heat pump instead of AC: a modern heat pump cools as efficiently as the best AC and also replaces resistance or fuel heating. Federal and utility rebates vary; check your utility.
Room units: in homes without central air, an ENERGY STAR window AC or a mini-split cooling one or two rooms costs far less than cooling the whole house. Portable units are the least efficient.

Compare running costs: central AC, window AC, portable AC, or side by side on compare appliances.

8. Pools, dehumidifiers and other summer loads

Pool pump: a single-speed 1.5 kW pump running 8 hours costs about $65 a month. A variable-speed pump on low for 12 hours costs about $19. Even without replacing it, cut runtime to the minimum that keeps water clear (often 6 hours) and run it off-peak.
Dehumidifier: 300 to 700 W. Set to 50% humidity, not lower, and empty or drain it so it does not run against a full bucket. ENERGY STAR models use noticeably less energy per pint.
Second fridge in a hot garage: can use twice its rated energy. Unplug it if you do not need it (garage fridge costs).
Electric water heater: 120°F is enough for most homes.

Find your biggest loads with the home energy audit. Estimate your bill with the bill calculator. More: how to cut your electric bill and the winter guide.

Frequently asked questions

What temperature should I set my AC to in summer?

78°F when home and awake is the common efficiency recommendation; 82°F or higher when away. Each degree higher saves roughly 3% to 5% of cooling energy. With ceiling fans running, most people are comfortable at 78 to 80°F.

Is it cheaper to leave the AC on all day?

No. Raising the setpoint while you are away uses less energy than holding it steady, because a warmer house loses less cooling to the outdoors. The exception is a time-of-use plan, where it can pay to pre-cool before peak hours and let the house drift up during them.

Do ceiling fans cool a room?

No, they cool people by moving air across skin, which feels about 4°F cooler. Turn them off when you leave the room. Set them to run counterclockwise (viewed from below) in summer.

Why is my summer bill so high?

Cooling. A central AC drawing about 3.5 kW for 9 hours a day uses about 945 kWh a month, roughly $170 at the U.S. average of 17.99¢/kWh. Check that the system is sized correctly, the filter is clean, and the outdoor unit is not blocked.