How to save money on ac in summer
How to save money on ac in summer
The biggest savings come first and cost the least. Raise the thermostat, block the sun, use fans, and keep the filter and outdoor unit clean. Sealing air leaks and ducts comes next. Big projects like new windows or a new AC come last, because they take years to pay back.
| What to do | Cost | Typical impact |
| Raise the thermostat on a schedule | Free | About 3% per degree, per the Department of Energy |
| Ceiling fans and closed blinds | Free to low | A fan can let you set the thermostat about 4°F higher |
| Eco mode (window and portable units) | Free | EPA estimates about 10% less energy than regular cool mode |
| Clean filter, clear outdoor unit | A few dollars | Keeps airflow and efficiency up |
| Annual tune-up | One service call | Catches small problems before they get expensive |
| Seal air leaks, insulate the attic | Low to moderate | EPA estimates 15% of heating and cooling costs on average |
| Seal and insulate ducts | Moderate | Leaky ducts can cut efficiency by as much as 20% |
| New windows, cool roof, new AC | High | Long payback. Do the rest first |
1. Set the Thermostat on a Schedule (Free)
78°F when you’re home, 82°F while you sleep, and 85°F when you’re away is the ENERGY STAR schedule. See what temperature to set your AC in summer for how to adjust it for sleep and humidity.
Setting it lower won’t cool the house faster. It only keeps the system running longer. For short absences, a small setback works better than shutting the AC off (turning your AC on and off vs. leaving it on).
2. Block the Sun and Use Fans (Free to Low)
- Close blinds and curtains on sunny windows during the hottest hours. Awnings, trees, and window film cut heat further.
- Use ceiling fans. They cool you, not the room, so turn them off when you leave. Run them counterclockwise in summer.
- Avoid heat-producing activities in the hottest hours: the oven, the dryer, and a lot of lighting.
3. Use Eco Mode the Right Way
Eco or Energy Saver mode on a window or portable unit lets the fan shut off when the compressor does. EPA estimates it uses about 10% less energy than regular cool mode. It removes less humidity, since the unit cycles off. On a very hot day, run it in normal cooling until the room cools, then switch to eco.
Most central AC systems don’t have a button called Eco. A thermostat schedule gives you the same benefit.
4. Do the Basic Maintenance
- Replace the filter monthly during heavy use (how often to replace it). A dirty filter makes the system work harder.
- Keep 2 feet of clearance around the outdoor unit, and clear leaves and debris.
- Have the coils cleaned (how to clean an AC coil).
- Schedule an annual tune-up before cooling season (how often to service your HVAC).
5. Seal Air Leaks, Insulate, and Fix Ducts
EPA estimates that sealing air leaks and adding insulation saves an average of 15% on heating and cooling costs combined, so your summer saving may be smaller. Start with caulk or weatherstripping around windows and doors, then add attic insulation.
Ducts are the hidden cost. In many homes, about 20 to 30% of the air moving through the ducts is lost to leaks. Leaky ducts can reduce a system’s efficiency by as much as 20%. Sealing and insulating them often pays for itself. Ask a contractor to inspect your ductwork.
6. Bigger Projects (Long Payback)
- Energy-efficient windows, window film, awnings, and a reflective roof reduce heat gain, but they cost the most and take years to pay back.
- A new AC saves money mainly when your old one is failing or oversized. Don’t replace a working unit only for efficiency (how long central AC lasts). For central systems, compare SEER2 ratings. For window units, compare CEER (repair or replace a window AC).
- Check your utility for rebates before you buy.
When Timing Matters
Running the AC at a particular time only saves money if your plan has time-of-use rates. Check your bill or ask your utility. If you’re on a flat rate, the price per kWh is the same at any hour, and the best lever is the thermostat.
Mistakes That Cost Money
- Setting the thermostat very low to “cool faster”
- Leaving fans running in empty rooms
- An oversized AC, which shuts off before removing humidity (how long an AC can run)
- A dirty filter or blocked outdoor unit
- Skipping the annual tune-up until something breaks
Common Questions
Does eco mode save money?
Usually, a little. On window and portable units it cuts about 10% by cycling the fan with the compressor. It works best in moderate weather.
Does turning up the AC save money?
Yes. About 3% per degree, so moving from 72°F to 78°F saves more than most other free changes.
What’s the cheapest way to cool a house?
Fans, closed blinds, and a thermostat set as high as is comfortable. These cost nothing.
How much does a window AC cost to run?
See how much it costs to run a window AC.
If you’re in the Philadelphia area and want your AC and ductwork checked, Cool Aid Co. can help.