Best Temperature for AC in the Summer

Inspire Clean Energy

16 min read

category: Sustainable Living

Where would we be without air conditioning? There are many places in the US where life would be pretty unbearable in the summer without AC. When temperatures head toward 90℉ or over 100℉, having a good AC system in your home makes a big difference. And if that temperature is twinned with high humidity, AC is the only thing that makes doing anything more than sweating possible.

But that comes at a (literal) cost. Heating and cooling are the most power-hungry parts of running a home, so you want to get it right; throwing money away is never a good idea. So what temperature should you set on your AC to give you a comfortable temperature and not hemorrhage dollars? Also, what can you do to keep those electric costs down?

What is the best temperature for AC in summer?

Saying the best AC temperature in summer is the one that suits you may sound like a cop-out, but it carries a lot of truth. Everyone is different; what’s too warm for some is a little cool for others. The environment you live in also has a bearing. If you live in Texas, your idea of hot may be rather different from a native from Colorado. If a New Yorker visits Italy in the fall, they might feel shorts and a t-shirt are the way to go, while the Italians are wearing jackets and coats.

Even the experts disagree; one will say 72℉ is perfect, another 78℉, and a third, something in between. Only you can say with certainty what temperature feels best to you, which may change with the weather outside or even your age. However, somewhere between that range is often best.

What is the ideal temperature for AC?

Most people like to set their AC so that their house's temperature is somewhere in the 70℉-80℉ range. This is cool enough to work or relax without being so cool you feel the need for an extra layer to be comfortable. Keeping the temperature in the 70s will allow your AC to be in its sweet spot, too, though that does depend on how hot it is outside. The harder an AC system works, the more power it will use, and the more it’s going to cost you when the bill comes in.

Is 72℉ a good temperature for air conditioning?

The question is, what temperature to put ac on in summer? Often 72℉ is quoted as the ideal AC temperature setting in summer. While 72℉ is certainly a temperature that many will feel comfortable with, it might not suit you and anyone else who shares your living space.

Even if you feel good at 72℉, it might not be what you need to set on your thermostat. Other factors come into play. For instance, the US Department of Energy estimates that fans play an important part in making you feel cool. The DOE suggests that ceiling fans make about 4℉ difference in how you feel. If you use fans, you may be able to set your AC to 75℉ or 76℉, reducing energy consumption, and still enjoy a 72℉ environment.

So would 75℉ be a good temperature for air conditioning? If you want to enjoy a 72℉ living temperature and are using ceiling fans or window fans, then setting your AC at 75℉ makes sense. 75℉ is cheaper to achieve than a lower temperature, and the fans' cooling effect will give you a 72℉ environment.

Is 78℉ too hot for a house? The simple fact is that the warmer your house is in summer, the less it’s going to cost you. Many people find that a temperature approaching 80℉ is absolutely fine, so long as the humidity is kept in check. Humidity has a massive effect on how hot and uncomfortable you feel. Don’t forget that one way an AC works is by reducing humidity. If your AC system is well maintained and efficient, it will keep the humidity low, and a higher temperature will feel fine.

How cool should my house be if it’s 100℉ outside?

In many states, it’s not uncommon to see temperatures reach over 100℉ in summer for days on end. Trying to keep indoor temperatures to 72℉ or less will keep your AC working hard and consuming a lot of energy. Most AC systems are designed to reduce temperatures by around 20℉, and attempting a 30℉ reduction may be stretching its capabilities. A dehumidified 80℉ is livable for most people, and if you have to go outside, it won’t come as too big a shock.

Even running the AC at 80℉ will require it to be looked after and running at peak efficiency. Having the system serviced before the summer heat comes around is a wise precaution.

Which mode is best for AC?

AC units vary in their flexibility and the modes they offer. At the very least, apart from temperature control, they will offer different fan settings. You should select high for the most effect on a normal warm day. However, if humidity is the problem, you are better off choosing slow, which allows the AC to remove the moisture more efficiently.

For many units, the cool mode is the default setting for cooling a room and allows the fan to run continuously while the compressor turns on and off to maintain the temperature. Some systems have a fan mode which just provides air movement rather than cooling. This may be useful in some situations but not in the summer when you are looking to lower the temperature.

Some air-cons offer a dry mode where it simply operates to dry the air rather than cool it. This is of limited use in hot weather but might be employed at other times. You should remember that while an AC unit does dehumidify, it is not a replacement for a dedicated dehumidifier which has much more capacity than an AC.

Most modern ACs include an energy saver mode in their features. It is certainly a good idea to employ this mode when you can, as it offers real energy savings. However, some will find the repeated switching on and off of the fan irritating.

If your AC includes a sleep mode, it allows the temperature to rise a little during the night when your metabolism is slower, and the need for temperature reduction is not so acute.

How many hours should AC run per day?

When the outside temperature is high, you may find your AC runs pretty much 24 hours a day. However, if it does this when the weather is not terribly hot, it is probably because it doesn’t have sufficient capacity for your home or has a fault. During milder weather, you might expect an air-con to run in perhaps 12-15 minute periods a couple of times an hour.

How can I lower my AC bill?

ACs do tend to use a lot of power, but there are ways to reduce the bill:

  • Use a programmable thermostat so that the AC is used efficiently, allowing your home to be warmer when you’re not there but turning on 30 minutes before you come back so that the temperature is perfect when you arrive.
  • Set your thermostat a few degrees warmer – every degree will reduce the time the AC operates.
  • Check that the AC is running efficiently and that it’s topped up, the ducts are sealed, and the filters clean. When an AC is running optimally, it costs less to run.
  • Make sure your home is sufficiently insulated. It is far easier to maintain the temperature of a well-insulated home.

Can I run my AC 24/7?

When it is super hot, running your AC all day, every day may be the only way you can maintain a comfortable temperature. However, if it continues to operate like this even when the outside temperature drops, you should have it looked at as it is like something is amiss or that it is undersized for the area of your house.

Is 78℉ the best temperature for AC?

Both the DOE and Energy Star suggest that 78℉ is the ideal setting for an AC unit, although they advise increasing that during the day and when you are asleep. In fact, they recommend that you adjust the temperature up by as much as 7℉ during the daytime and 4℉ at night. With fans installed, that is an excellent place to start, but you may want to diverge from that figure depending on personal preference and the relative humidity. If you do live in an area that experiences high humidity, you may be wise to install dehumidifiers in addition to your AC and fans. Most of us can stand higher temperatures providing humidity remains low.

Turning on your AC and forgetting about it is not the smart option if you want to save energy and lower your electric bill. Asking what temperature should the AC be in the summer, keeping it well maintained, in the right mode, and with the thermostat set carefully will significantly reduce the amount you pay for power and reduce your carbon footprint, too.

At Inspire Clean Energy, we don’t want you to waste electricity or make those energy bills larger than they have to be. By paying attention to your AC in summer, you can minimize waste and cut those bills. If you know you can’t reduce energy consumption in the summer but also don’t want to see your carbon footprint grow significantly, switch to a green energy plan.

Our clean, renewable energy plan provides you with 100% clean, renewable energy, so you can rest assured that your energy consumption isn’t contributing to global warming and other negative environmental effects. Click here to see unlimited energy plans today or find out more.

What's the best AC temperature for energy saving?

Programmable thermostats do not always set the most energy-efficient air conditioner temperature. Modern programmable thermostats have defaults for full cooling mode, away mode, and sleep time mode. By modifying these settings, you can decrease cooling expenditures without sacrificing comfort. 

Most programmable thermostats offer four time periods: 

  • Active morning
  • Daytime away 
  • Active afternoon/evening 
  • Sleep

Default temperatures for thermostats with three settings are 78 Fahrenheit for active, 82 for asleep, and 85 for away.  The default temperature difference between full cooling and energy-saving mode is 4 or 7 degrees Fahrenheit for thermostats with distinct away and asleep settings. 

You can conserve more energy by expanding the gap between active, away, and sleep temperatures. The optimal air conditioning temperature while away is 88 to 90 degrees, providing you arrange the afternoon cycle to start long enough before your return from work. For morning activity, raise the temperature a degree a week until it is uncomfortable.

In addition, the larger the temperature difference between active and away, the longer it takes to cool your home. As you raise the temperature for your away time, you may need to move the afternoon activity time earlier to allow your home to cool down. Poorly insulated or sealed dwellings are more susceptible, and well-weatherized homes gain little heat and cool rapidly. 

Lastly, while many people prefer to keep the house temperature between 68 and 72 degrees in the summer, it's not the best option. Most air conditioners are not meant to cool a house below that temperature, and the system may freeze, causing necessary maintenance and additional costs. 

What's the best temperature for humidity control?

During the summer, keeping your residence below 80 degrees at all times will help to maintain the humidity levels. At 80 degrees, the humidity level in your home is likely to be extremely high. In the summer, keep your house warmer than normal when you are away and raise the thermostat as high as you are comfortable with when you require cooling and humidity control. 

Even at a higher temperature, operating the air conditioner removes humidity and provides some comfort. By late evening in many climates, it is chilly enough outside that the air conditioner simply keeps humidity out of the house; it is typically cooler outside than inside.

What's the best temperature for sleeping?

The optimal AC temperature for sleeping is whatever you can manage with a sheet. If you require pajamas and a comforter, the air conditioner is too low. Try between 82 and 86 degrees to begin and adjust as needed. Also, consider changing the amount of bedding on your bed (along with your sleep wardrobe) to cooler options. 

If you like to sleep at a cooler temperature in the winter, begin the temperature reduction process a few hours before you plan to go to bed. Take into account everyone's schedules in the house. It makes sense to alter the temperature if the house is uninhabited for four hours or more during the day.

What does the Department of Energy say about home temperatures?

The Department of Energy (DOE) offers many suggestions to keep your home temperature comfortable and affordable. The DOE suggests resetting your thermostat when you are asleep or away to save money without major discomfort. The DOE also suggests using a programmable thermostat, which can remember and repeat six or more daily settings that you can manually alter without affecting the daily or weekly program. 

In addition, the DOE says turning your thermostat back 7  to 10 degrees Fahrenheit for 8 hours a day can save 10 percent a year on heating and cooling. The narrower the indoor-outdoor temperature differential, the cheaper your cooling bill. Set the thermostat to 68 degrees when you are awake and reduce it when you are asleep or away. Keep the temperature differential narrow to lower your cooling bill in the summer. 

Next, avoid setting your air conditioner's thermostat to colder than usual. It will not chill your home faster and may cause excessive cooling and extra money. A popular myth about thermostats is that a furnace works harder after being set back, resulting in little or no savings. When your home's temperature dips below normal, it slowly loses energy. 

For warmer summer months, the DOE advises setting the temperature to 78 degrees in the morning, up about 7 degrees in the daytime, back to 78 in the evening, and up 4 degrees for sleep. Using ceiling fans to distribute air and window screens to reduce exposure to the sun are other options to reduce the temperature without raising prices. 

Finally, the location of your thermostat might impact its efficiency and functionality. To function correctly, a thermostat must be installed on an inside wall away from direct sunlight, drafts, doorways, skylights, and windows. Warm air rises, and cool air sinks; hence it should be placed where natural room air currents occur. Because furniture will obstruct natural airflow, avoid placing it in front of or below your thermostat and keep it within easy reach. 

Tips on AC Temperatures in the Summer:

According to the DOE,, the optimal indoor temperature for your home during the summer months is 78 degrees. However, if that temperature is too high for you, there are a few things you can do to change how your home feels without increasing your energy expenditure. Keep in mind that every degree above 72 can save you up to 3 percent on your cooling bills.

Ceiling Fan Direction in Summer

A ceiling fan will not replace your air conditioner during the summer, but it will undoubtedly enhance the efforts. A small switch is located near the bottom or side of the fan's mounting base on most versions. This switch allows you to adjust the fan's direction according to the season. 

Your ceiling fan blades should spin counterclockwise during the summer months. The fan provides a cool breeze by spinning in this direction and pushing air down. As a result, the room will feel up to 4 degrees cooler and will remain steady throughout the day. Additionally, the fan's cooldown allows you to raise the temperature of your air conditioner by 2 to 3 degrees.

Seasonal AC Maintenance

Just as you would prepare your vehicle for a long journey by double-checking that everything is in working order, you should do the same with your air conditioning. Before the summer heat arrives, perform spring maintenance on your HVAC to verify the unit is operating correctly, refrigerant levels are topped off, and the unit is cooling as efficiently as possible. Leaky air ducts, inadequate insulation, and overgrown vegetation around your air conditioner can all reduce performance.

Energy-Efficient Air Conditioning

If your air conditioner is not functioning efficiently, you may not see a reduction in your electric cost even if you raise the temperature. To save energy and keep your home comfortable, you may need to replace your HVAC system. Many homes have outdated systems that reduce effectiveness and cost more to run and maintain.

A modern Energy Star certified system with a high Seasonal Energy Efficiency Ratio (SEER), and Energy Efficiency Ratio (EER) rating can be 15 percent more energy efficient than older, less efficient versions. Newer systems, which often include two-stage cooling and a variable-speed fan, can also improve your comfort. Even on the lowest level, this type of air conditioning system will keep you cooler for longer. It also operates for longer without the energy-intensive starts and stops and eliminates twice as much humidity from the air to keep you feeling cooler.

Naturally Cool Your Home

There are simple ways to make your home cooler, in addition to raising the thermostat, utilizing ceiling fans, and scheduling AC repair during the warm months. During the day, close the shades, blinds, and drapes to keep the sun out. Blackout blinds and curtains are extremely effective in reducing the sun's effects on your home. 

To let cooler air in, open windows and switch off your air conditioner at night. Then, close the windows and curtains in the morning to keep the cool air inside. 

Keep cold air in and hot air out by weatherstripping doors and windows. Replace old windows for reduced air leaks when possible, as a small gap can increase prices and reduce the desired temperature of your home. 

Check your air filters every month and change out air filters regularly as needed. Keeping air filters clean can reduce energy consumption by up to 15 percent, as can removing clogs. Additionally, everyone in the home will breathe easier, especially those with seasonal allergies.

Use heat-generating appliances during the day to avoid scorching a hot dwelling. Appliances can increase the temperature in your home by 10 degrees. Waiting until 8 p.m. can lessen summer appliance heat. Traditional lightbulbs can fluctuate in temperature, so consider LEDs.

Request an Energy Audit

If your home is not brand-new, the chilly air inside is probably leaking out through faulty seals on doors and windows, a poorly insulated attic, and other cracks. Sign up for a home energy audit with your utility company or a local contractor to discover how well your home keeps the cold out. A qualified home energy rater or auditor will inspect your home for leaks and give recommendations for the most energy-efficient improvements. 

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