Does Turning the AC On and Off Cost More? The Real Truth About Energy Efficiency
Last updated on June 8, 2025
With skyrocketing energy costs and increased demand for sustainability, many homeowners are inquiring about a popular question: Does leaving the air conditioner on and off cost more than leaving it on continuously?
It’s a legitimate question, particularly during hot summer heatwaves when your AC is your best buddy.
You may have received conflicting recommendations. Some recommend that it costs less to leave the AC at a constant temperature. Others say switching it off when leaving saves money.
What is the reality?
Let’s analyse if turning the AC on and off costs more
How Air Conditioners Consume Energy
To comprehend how having your AC turn on and off affects energy expenditure, you need to know how it operates.
Air conditioners use the most energy when they start up, when the compressor comes on to cool your room. But that start-up surge of power only lasts several seconds. Then, the machine cycles on and off, keeping the temperature stable by automatically turning on and off.
So, if you’re constantly turning it on and off during the day, it may appear to be using more power. But the truth is a little different.
Myth vs. Reality: Leaving It On or Turning It Off?
Let’s explore the two main options and their cost implications:
1. Leaving the AC On All Day
Pros:
Keeps your home consistently cool.
Prevents your system from working hard to cool down a hot house.
Cons:
Constant operation equals more electricity use overall.
You’re cooling your home even when no one’s there to enjoy it.
Leaving the AC on all day—especially when nobody is home—can lead to higher electricity bills. Even if it’s maintaining a moderate temperature, it’s still using power.
It may take longer to cool down your home when you return.
Slight discomfort while waiting for the temperature to adjust.
Unlike the popular myth, switching off the AC when you leave for hours typically saves money—even if it has to work extra to chill your home when you come back. The energy it saves when off usually compensates for the energy required to cool your space afterwards.
What the Experts Say
The U.S. Department of Energy says:
Reducing your thermostat 7°-10°F for 8 hours a day from its usual setting can save you up to 10% per year on heating and cooling.”
Energy experts concur that turning off (or raising) your AC when you leave home is among the simplest ways to reduce cooling expenses.
Smart Thermostats: The Best of Both Worlds
If you worry about stepping into a hot house upon returning home, there’s a smart remedy: programmable or smart thermostats.
These thermostats automatically adjust your AC settings according to your schedule. For instance:
Increase the temperature when you leave.
Pre-cool 30 minutes before your return.
This sounds amazing, and it saves energy while keeping you comfortable. Energy Star estimates that installing a programmable thermostat can save up to $180 a year.
Short Absences vs. Long Absences
How long you’re gone determines most.
Less than 30 minutes: It’s okay to keep the AC on. Shutting it off and on too fast can stress the system.
Several hours: Shut it off or crank up the temperature to 78–80°F (25–27°C). You’ll conserve energy and dollars.
For holidays, it’s alright to switch off the AC completely or set it to a higher temperature, such as 85°F (29°C), so that you don’t unnecessarily cool an unoccupied home.
Energy-Saving Tricks for Getting the Most from Your AC
Whether you switch it off or let it work, here are tips to get the most out of your AC:
1. Install a Programmable Thermostat
Schedule your cooling according to your daily routine. This means you’re only consuming energy when necessary.
2. Seal Leaks and Insulate
Don’t let calm air escape by sealing windows, doors, and duct gaps. Proper insulation keeps your home cooler for an extended period.
3. Close Curtains or Blinds
Direct sunlight can quickly heat indoor temperatures. Close curtains or blinds during the hottest part of the day to save on heat gain.
4. Keep Your AC System in Good Working Condition
Regular servicing and clean filters increase efficiency and lower the likelihood of breakdowns.
5. Run Ceiling Fans
Fans circulate air, making rooms feel cooler, so you can raise the thermostat a few degrees without compromising comfort.
The Cost Difference in Actual Numbers
Assume your central AC consumes 3.5 kilowatts (kW) per hour, and your rate of electricity is $0.15/kWh.
Running it all day (24 hours) will cost: 3.5 kW × 24 hours × $0.15 = $12.60 per day
If you onlyrun it for 8 hours (e.g., evenings): 3.5 kW × 8 hr × $0.15 = $4.20 per day
To save $8.40 per day, shut it off when you’re away.
In a month, that’s more than $250 saved—without a loss of comfort.
Final Verdict: Turn It Off When You Can
Does it cost more to turn the AC on and off?
No—it usually saves you money, particularly if you’re gone for the duration.
The bottom line is:
Short-term absences: Leave it on.
Long time away (more than an hour). Switch it off or turn the thermostat up.
Smart thermostat: Optimal solution for convenience and economy.
Maintenance and insulation: Get the best out of your system.
By being sensitive to how and when you operate your air conditioner, you can save money on energy and prolong the lifespan of your HVAC system.
So, Does Turning the AC On and Off Cost More? Here’s the Bottom Line
New AC units are made to cycle efficiently and can stand to be turned off and on, so don’t worry about that tactic. The trick is consistency and working smarter, not harder, with technology (such as smart thermostats).
The next time you leave for the day, crank up the thermostat or turn off the AC altogether—and reap the cool savings later.
