How much does central air cost to run?

Written by David Lewis
5 Min read
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Table of contents

For the uninitiated, central air is what whole-home air conditioning is more commonly known as. It is a system that replaces warm air with air that has been cooled at a central location before being delivered to individual rooms within a house via air ducts or fans. It’s a very similar system to home refrigerators.

Did you know that three-quarters of homes in America have air conditioning, with around 6% of all energy used across the United States used by air conditioning units at an annual cost of around $29 billion?

During sweltering hot days (and nights) the luxury of being able to sit in a cool living room or sleep at a comfortable temperature should not be underestimated. But, as with everything, this comes at a price, and with the household bills rising at a worrying rate understanding how much central air will cost to run per month and being able to budget accordingly is vitally important.

What is central air and how does it work?

There are two different types of central air conditioners – split systems and packaged systems.

Split systems

A split system comprises both an indoor and outdoor unit that is housed in cabinets and connects via copper pipes. The indoor cabinet contains the evaporator coil, and the outdoor unit contains the condenser and compressor. Split systems can be ducted or ductless; ducted will circulate warm air from the furnace and cool air from the air conditioning unit whereas ductless use small air handlers around the house to warm or cool the air in that location.

Packaged systems

In a packaged system the evaporator, condenser, and compressor are located in a single cabinet that is situated on a roof or within the foundations of the house. Some packaged systems will also include a natural gas furnace or electric heating coils.

How does a central air conditioning unit work?

  • The system uses a thermostat which turns the unit on when the temperature inside rises above a specific level
  • A fan then pulls warm air from inside through ducts, where it passes through filters which remove dust and pollutants
  • The warm air passes over the cold evaporator coil and a chemical refrigerant absorbs the unwanted heat before pumping the cooled air back into living spaces
  • The warm gas refrigerant travels through copper pipes to the compressor
  • The compressor pressurizes the gas and sends it to the condenser coil which releases the heat outdoors and turns the refrigerant back to gas
  • The refrigerant travels back to the evaporator coil to continue the process

How much electricity does an air conditioning unit use?

If you’re wondering whether it’s okay to leave your air conditioning on all day, we’ve got the answer for you!

Of course, the amount of electricity your unit might use is dependent on the climate, the type of air conditioning unit you have, and the temperature you like to keep your home at.

A guide to wattage

As a very rough guide, you can expect your air conditioning unit to use between 3,000 to 5,000 watts per usage hour, with the average using somewhere in the region of 3,500 Wh when running on a ‘cool’ setting.

As a rule, appliances with moving parts or which produce heat use many more watts than those that produce light or sound. By way of comparison, a kettle will also use an average of 3,000 watts per usage hour, but of course, you’re only likely to use this occasionally throughout the day.

What’s the best air conditioning temperature to save money?

According to the Department of Energy, the best temperature to leave your air conditioning on is 78 degrees Fahrenheit. This temperature provides the perfect balance between a comfortable temperature and energy savings.

Tips for lowering your air conditioning costs

  • Install and set a programmable thermostat – this could help you save 10% on heating and cooling costs each year
  • Avoid adding unnecessary heat to your home, switch to using an outdoor grill on hot days instead of an oven
  • Maximize your air conditioning by using ceiling fans, these will allow you to increase the thermostat temperature by about 4 degrees without you even noticing a difference
  • Prevent solar heat gain by adding energy-efficient window coverings that will still let natural light into your home
  • Ensure the attic and walls of your home are well-insulated and seal any openings to stop additional warm air from entering
  • Invest in an Energy Star AC unit, which is proven to be around 15% more energy efficient than standard units
  • Around 30% of an air conditioning unit’s energy consumption is from air loss via ducts – make sure you have insulated and sealed all ducts
  • Make sure your unit is regularly maintained – annual maintenance helps improve the efficiency of your air conditioning as well as prolong the life of your unit

Is it better to turn the air conditioning off at night?

If the thought of your electricity meter continuing to tick over even when you are asleep drives you a little crazy, you may be considering turning off the AC at night when the temperature drops naturally anyway, but is it cheaper to do this or let it run on auto all day and night?

Well, the answer to this isn’t a simple one, it depends on a couple of different factors:

  • The night-time temperature outdoors – if the temperature outside is lower than you normally set your temperature to then switching off the air conditioning may be a cost-effective decision
  • The humidity outdoors – If the air outside is very humid when you switch off your air conditioning, it will have to work extra hard when it’s switched on again and will most likely cost more than if had you left it on overnight

Tips for lowering your air conditioning costs at night

If after considering all these options you decide to keep your air conditioning on overnight, consider using some of these top tips:

  • Use the ‘fan only’ function of the air conditioning overnight
  • Raise the thermostat to 83 degrees overnight
  • Use ceiling fans in bedrooms

Conclusion

It goes without saying that running an air conditioning unit is going to add a sizeable chunk to your household bills, but the benefit of having this luxury should not be overlooked. Whilst it is one of the most energy-hungry appliances in your home, there are lots of ways to maximize the efficiency of the system and reduce costs at the same time.

FAQs

How much does it cost to run central air for one hour?

Whilst It’s difficult to provide exact figures because of the number of variables involved, the average-sized air conditioning unit uses around 3,500 watts per usage hour, at a cost of around 14 cents per hour.

How can I reduce my air conditioning bill?

There are several ways you can reduce your air conditioning bill, including:
·       Setting your thermostat to 78 degrees during the day and 83 degrees at night
·       Use ceiling fans to maximize the efficiency of your air conditioning
·       Make sure you have insulated and sealed all the ducts in your house

Is it cheaper to run a window air conditioner or central air?

Window air conditioners can only serve one room at a time, whereas central air conditioning cools the whole house.
Window conditioners are much cheaper to install but if you’re purchasing more than one the costs can become much more expensive. If you want to cool an entire home a central air conditioning unit will work out cheaper in the long run.

Appliances made simple. 

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