How to Cut Your Cooling Bill During a Heatwave: 6 Moves Backed by Data

The heatwave is coming for your bill, not just your street

Air conditioning is one of the largest electricity expenses in most American homes, and a heatwave turns it from a background cost into a visible one. The U.S. Energy Information Administration's Residential Energy Consumption Survey puts space cooling among the top household electricity uses, with the heaviest cooling concentrated in Houston, Phoenix, and Las Vegas.

The useful news is that most of the savings available to you are boring, cheap, and quantified by federal agencies that have no product to sell. Here are six moves worth making, with the arithmetic attached.

1. Stop renegotiating with the thermostat and set it to 78°F

What to do: Set the thermostat to 78°F when you are home, 82°F when asleep, and 85°F when the house is empty. That is the Department of Energy's published guidance, not a heuristic invented by a utility press office.

Why it works: Your compressor does not know what temperature you find pleasant; it only knows the gap between indoor and outdoor air. Each degree you raise the setpoint shortens compressor runtime.

What it saves: The DOE estimates 1% to 3% off cooling costs for each degree the setpoint is raised for eight hours. The EIA puts the average residential electricity bill at roughly $137 a month in 2022, and cooling is the part of that bill a heatwave pushes hardest.

Interpretation: This is the highest-effort-free item on the list. A programmable or smart thermostat is not required, though it helps you stick to the schedule when you forget at 9 a.m.

2. Run ceiling fans counterclockwise so you can raise the setpoint 4 degrees

What to do: Set ceiling fans to counterclockwise in summer, run them only in occupied rooms, and switch them off when you leave. The DOE's fan guidance is explicit on direction: counterclockwise creates a wind-chill effect, and the reverse setting is for winter.

Why it works: Moving air evaporates moisture from skin, which makes an 80°F room feel like 76°F without changing the air temperature. Fans cool people, not rooms, which is why an empty room with a running fan is just a small heater.

What it saves: The DOE states that a ceiling fan lets you raise the thermostat about 4°F with no reduction in comfort, and puts the operating cost of a typical ceiling fan at around 1 cent per hour. A 4-degree setback worth up to 12% on the cooling portion of the bill dwarfs that cent.

3. Close blinds on south and west windows before 2 p.m.

What to do: Close or lower blinds and curtains on south- and west-facing glass, and keep them closed through the afternoon. East-facing windows matter in the morning, but the afternoon load is what breaks grids.

Why it works: Lawrence Berkeley National Lab's researchers have spent decades measuring solar heat gain through glazing, and their work on window film and shading shows that most single-pane and older double-pane windows admit far more infrared energy than occupants assume. Blocking sunlight before it enters beats scrubbing it out with an air conditioner afterward, because the compressor pays an efficiency penalty as outdoor temperatures peak.

What it saves: The DOE estimates that tight, lined curtains and similar window treatments can cut cooling loads meaningfully on sun-exposed glass; Berkeley Lab's window-film retrofits have shown single-digit percentage reductions in cooling energy in hot climates. The treatment cost is under $30 per window, so a payback inside one cooling season is realistic for west-facing rooms.

4. Move laundry, dishwashing, and cooking out of the 4 p.m. to 9 p.m. window

What to do: Run the washer, dishwasher, and dryer before midday or late at night. Check whether your utility bills time-of-use rates; the EIA reports a growing share of residential customers now face them, and California's peak window under PG&E's standard summer schedule runs 4 p.m. to 9 p.m.

Why it works: Two reasons stack. First, time-of-use rates make each kilowatt-hour two to three times more expensive during the peak. Second, every appliance with a heating element adds heat to the house, and the air conditioner then has to remove it.

What it saves: The DOE reports that about 90% of the energy a clothes washer uses goes to heating water, so a cold wash cuts that appliance's electricity close to zero. Pairing cold washes with off-peak scheduling is the cheapest laundry change available, and it costs nothing but a habit.

5. Replace the HVAC filter; it is a $12 lever with a measurable return

What to do: Check the filter monthly during cooling season and replace it when it looks dirty, typically every 1 to 3 months. The DOE's homeowner guidance recommends this specifically as an energy measure, not only an equipment-longevity one.

Why it works: A clogged filter restricts airflow across the evaporator coil, which drops system efficiency and, in bad cases, freezes the coil and turns a cooling problem into a service call.

What it saves: The DOE estimates that a dirty filter can raise cooling energy use by 5% to 15%. Standard filters run $5 to $15 each, so this is one of the few household maintenance items where the annual return is a clean multiple of the cost.

6. Do not use the oven; use the microwave or cook outside

What to do: During a heatwave, swap oven meals for microwave, stovetop, slow-cooker, or outdoor-grill cooking. The stovetop still adds heat, just less than a 450°F cavity radiating into the kitchen.

Why it works: Every oven kilowatt-hour becomes indoor heat that your air conditioner then removes. It is the only appliance on this list whose running cost is doubled by the act of using it.

What it saves: The DOE puts microwave cooking at roughly 75% less energy than a conventional oven for comparable tasks. On the EIA's 2023 average residential rate of about 16 cents per kilowatt-hour, an oven cycle drawing 2 to 3 kilowatts is real money, plus the cooling load on top.

What the data says, and what it does not

Fact: The six items above are all sourced from the Department of Energy, the EIA, or Berkeley Lab. None require new hardware, and the two that do cost money return it quickly. None of them will keep a poorly insulated house comfortable at 2 p.m. during a record-setting afternoon.

Interpretation: Federal guidance assumes cooperation between occupant and machine. When heat arrives with a failing AC unit and a west-facing second story, behavior change becomes a mopping-up exercise. That is the honest limit of a list like this one, and the reason the overnight side of a heatwave needs separate treatment. See hot nights, deep sleep, and the heart for what happens when the temperature never drops after dark.

Prediction: Time-of-use pricing will spread, because peak demand is the expensive problem and utilities have few other levers. Households that automate these shifts now, before rates force the issue, should see their bills barely move when the structure changes. The monitoring side of that shift is already here, and not always benignly: the smart meter as auditor covers what your meter now knows about your habits. The storage side is treated in why four-hour batteries now beat gas peakers on cost.

No single move here is transformative. Six of them, applied every summer week between June and September, are a real line item returned to your bank account and a smaller spike on the local feeder when the grid is already straining.