Should You Turn Off Your AC When You Leave The House?


Most of us want to keep our home as comfortable as possible at a cost that is as low as possible. Running your air conditioner all summer long can get expensive, so you might be wondering whether you should turn your air conditioner off when you leave your house. Basically, if you are going to be gone for a short time, it is best to leave it on, and if you are going to be gone a long time, it is best to turn it off.

What a long or short time is, can be subjective. If you are gone a whole day and turn your air conditioner off, it will make your unit work harder to cool the house down again. You may save a little on electricity but lose a little on wear and tear. Being gone a whole week would be different, but even then, you could set it at a very high level so it will not run much.

In all reality, for most homes and apartments, the difference between the energy used to run your AC all day and the energy used to restart your AC and recalibrate your target temperature is miniscule. However, if you prefer to keep your home significantly colder than the outside temperature, turning the AC off during the day can actually cost you more money as the AC works harder to compensate for the time the rooms spent warming up.


How Does an Air Conditioning System Work?

Air conditioners come in a variety of shapes and sizes, but they all operate on the same basic premise. An air conditioner provides cold air inside your home or enclosed space by actually removing heat and humidity from the indoor air. It returns the cooled air to the indoor space and transfers the unwanted heat and humidity outside.

A standard air conditioner or cooling system uses a specialized chemical called refrigerant, and has three main mechanical components: a compressor, a condenser coil and an evaporator coil. These components work together to quickly convert the refrigerant from gas to liquid and back again. The compressor raises the pressure and temperature of the refrigerant gas and sends it to the condenser coil where it is converted to a liquid. Then the refrigerant travels back indoors and enters the evaporator coil.

Here the liquid refrigerant evaporates and cools the indoor coil. A fan blows indoor air across the cold evaporator coil where the heat inside the home is absorbed into the refrigerant. The cooled air is then circulated throughout the home while the heated evaporated gas is sent back outside to the compressor. The heat is then released into the outdoor air as the refrigerant returns to a liquid state. This cycle continues until your home has reached the desired temperature.


Will Turning My Air Conditioner On and Off Waste Energy?

Leaving your air conditioner on all day and increasing the temperature is more cost-effective than turning the system off when you are away. Here’s why:

Your AC never exceeds the thermostat setting. This means the system will not run unnecessary and costly cooling cycles to maintain a comfortable indoor temperature while you are not at home.

By leaving the system on and increasing the temperature while you are away, the thermostat will reach the desired temperature faster than if the system was turned off completely. This process requires less energy to cool your home, thus saving you money on your monthly electric bill.

When you turn off the system while you are away, it has to work harder to reach the desired temperature once you return home. The unit sometimes requires more energy to complete the cooling process, thus increasing your monthly electric bill.

Additionally, your AC system can only remove humidity from the air when it is turned on. If you turn off the system when you are away, humidity levels will increase and the system must work harder to remove it from the air. This also increases your monthly electric bill.


If You Are Leaving Home For the Day or Weekend

It is best not to turn off the unit entirely if you are simply going to work. It is more energy efficient to keep your air conditioning turned on when just leaving for the day. In these cases, however, you should turn it a few degrees higher than you might set it for comfort if you were at home. The same directions apply if the house is going to be unoccupied for only a day or two as it is more energy efficient to keep the unit on but turn the temperature setting up.

Also keep in mind that central air conditioning is not just about cooling your space. It also drastically reduces humidity levels. When the system is shut off for more than a few hours, the humidity levels will begin to rise, which can result in mold growth, damage to electronic items and the warping of wood. Any pets left in the house could also be at risk of overheating and discomfort.


If You Will Be Gone For a Longer Period

If the entire household (pets included) are vacating the premises for more than two days, it is a good idea to turn everything off. You will save the most energy and money by turning your unit off in this case.

That said, your house’s temperature might be very uncomfortable when you get back. Avoid coming home to a sweltering abode by installing a smart thermostat. Investing in a smart or programmable thermostat is a great way to monitor and control your home’s energy efficiency even when you are not there.


While You Are In the House

We recommend keeping your thermostat at 78 degrees Fahrenheit or higher in the day, 82 degrees F for sleeping and 85 degrees F when you are away from home. While these temperatures may seem too high for you, consider that cooling your home to 78 degrees rather than 72 could cut your electricity bill by 25 percent. As a rule, raising the temperature by just 2 degrees will help reduce cooling costs by 5 percent.


What About Vacations?

When you plan to leave your home for multiple days and up to a week or two, your home will likely create a higher bill if it is left with a running AC than it would if the unit was turned off. Just keep in mind that the interior temperature will be very high when you return if your trip is planned during the summer and understand that it might take a little extra time and energy to get things back to the way they were.


 Actual Ways to Save Energy


  • Set Your Thermostat to a Higher Temperature

Setting the thermostat at 78 degrees typically keeps enough cool air in the room for comfort. Unless you have a very keen temperature sensitivity, you won’t likely notice the difference between 73 degrees and 78 degrees.

On the other hand, you will notice a big difference in your electric bill because your AC will not run as frequently, nor will it have to run as long. And if you spend the day outside in the summer heat, a home temperature of 78 degrees will feel a lot better, by comparison.


  • Upgrade to a Programmable Thermostat

Whether you turn your central air off or turn the programmed temp up when you’re out of the house, a programmable thermostat can crank up the cool factor before you get home. That way your house will be comfortable when you walk in the door.

You will need to buy a thermostat that suits both your cooling and your heating systems. Some models don’t work with heat pumps, which can pose a problem in the winter, so check with whoever installed or services your system. If you use a window unit, an appliance timer can serve a similar purpose and newer models may include a timer as well as a thermostat.


  • Turn On Your Ceiling Fan

Your ceiling fan uses significantly less power than your AC unit, so keeping your ceiling fan running throughout the day will keep that air circulating and feeling refreshing. Turning your fan on high when you leave the house can help pick up the slack if you move the temperature up a few degrees. Remember, though, that fans cool people; they do not change the temperature. So, be sure to turn them off when you leave the room, otherwise, you will be paying to power that appliance unnecessarily.


  • Regular Maintenance

Regular maintenance plays a crucial role in ensuring the optimal functionality and efficiency of your air conditioning system. Even if you adjust the thermostat frequently, a dirty filter or neglecting seasonal maintenance can hinder efficiency and strain your system. One key element homeowners often overlook is the importance of clean filters.

In addition to changing the filter during every maintenance appointment, homeowners should also make it a habit to check and replace (or clean) their filters at least every three months. For those living in areas with high dust levels or households with pets, our Aire-Tech HVAC specialists recommend changing filters monthly, which allows air to flow freely without any obstructions, preventing the system from overworking.

By prioritizing regular maintenance, you not only enhance the efficiency of your air conditioning system but also extend its lifespan, ensuring comfort and savings in the long run.


Give Us a Call

At Aire-Tech, we can help keep your home at the optimal temperature! We give you countless resources to help you explore and learn about HVAC options, including incentive programs. We work closely with agencies to pass on savings programs and information to our valued customers.

If your system needs repair or inspection, call Aire-Tech on 951-926-1002. You can also visit our Contact page and complete the contact form.