how much electricity does a window ac use

How Much Electricity Does a Window AC Use?

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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One of the most common electrical appliances in apartments and homes is an air conditioner. Window air conditioners are a necessity in the majority of homes. They circulate cold air throughout the house during the summer to maintain a comfortable temperature. Of course, understanding how much electricity a window air conditioner unit uses is crucial to knowing your energy consumption. So how much electricity does a window AC use? Let’s find out below.

What Are Window AC Units and How Do They Work?

As the name suggests, a window air conditioning unit is a small type of AC unit that is placed on the frame of a window. It is considered one of the simplest air conditioning systems and only needs an electrical outlet. Furthermore, window ACs are not large enough to cool a whole house. However, they can circulate cool air within a room, making them energy efficient.

Of course, window air conditioners are portable, making them easy to install so that you can move them from one room to the next. Additionally, when the temperature in a room rises, it triggers the thermostat in the air conditioner. Like most air conditioners, the blower is activated, and the air in the room is pulled into the unit. The refrigerant coils cool the air and release cool air back into the room.

How Much Electricity Does a Window AC Use?

The wattage consumed by an air conditioner usually depends on 2 things:

  • The cooling capacity of the air conditioner unit (measured in (BTU) British Thermal Unit/hour )
  • The combined Energy Efficiency Ratio (EER)

For a better understanding of the above terms, let’s look at each individually:

The cooling capacity of the air conditioner is measured in BTU/hour. BTU is the unit used to measure the heat content of energy sources, for example, in furnaces, heat pumps, and air conditioners. It is the heat that is needed to increase the temperature of one point of water by 1°F. Typically, a small window air conditioner has a capacity of less than 12,000 BTU/hour. On the other hand, central air conditioners have a capacity of at least 60,000 BTU/hour.

How much electricity does a window AC need?

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An Energy Efficiency Ratio is the calculated ratio between the BTU/hour provided and the watts consumed. For instance, a small window air conditioner with a capacity of 12,000 BTU/hour using 1200 watts will have an EER of 10. While the EER unit is usable, it’s not always efficient. Furthermore, it only works within specific conditions (80°F for indoor and 95°F for outdoor temperatures).

So how many watts does a window use? While you can calculate the wattage using the formulations above, looking at the print information label on your window air conditioner for your specific model might be easier. However, large window air conditioners use at least 1440 watts, 900 watts for medium models, and 500 watts for smaller models. Of course, depending on the season, the state of your air ducts, and how many hours you keep your window air conditioner running, the watt hours could vary.

Electricity costs depend on electricity usage. Overall, a home window air conditioner can use 3,000 watts per hour. Of course, on the off-chance you leave your AC unit on an entire day, it will consume 72,000 watts of electricity. This could make your electricity costs soar. However, running the AC in fan mode will consume 750 watts in an hour, much less energy consumption.

How Much Does a Window Air Conditioner Cost to Run?

The average cost to run a window air conditioner that runs for 32 hours every month costs roughly $0.06-$0.88 per hour. If we assume that you run the air conditioner at least eight hours a day, the most affordable option is $14.40 per month. On the higher end, it could go upwards of $212 per month. Furthermore, it is easier to calculate the annual cost with these figures.

How Much Does a Window Air Conditioner Cost to Run?

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Of course, different-sized window units determine how much power consumption you will experience and how cost-effective they are. For a rough idea, here are different-sized window air conditioners and how much power consumption per kilowatt hour you should expect for each.

  • For a small bedroom, a 5,000 BTU window unit should only use 450 watts
  • A midsize window air conditioner 8,000 BTU AC should use fewer than 715 watts
  • A big 14,000 BTU air conditioner should only use 1,250 watts

Factors That Impact Your Air Conditioner Energy User Per Hour and Day

Several factors determine the air conditioner energy use. Some of them are:

1) Duration of Usage

How long you use your AC daily also determines how much energy it consumes. The more hours you have your window air conditioner on, the more energy usage you will experience. Additionally, To use your air conditioner more efficiently, you should ensure it’s running only when needed. Keep in mind that not all air conditioners need to rest, however, smaller AC window units do.

Duration of Usage

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If you leave the AC running all the time, its life will be drastically reduced. Furthermore, the more you use your AC, the more electricity is used, and the less energy efficient it is. Reducing your consumption can help to offset the daily cost, keep your window air conditioner running at the same capacity, and maintain air quality.

2) The Outdoor Temperature

A window AC unit consumes more energy when the outdoor temperature is high. The same principle applies to a central air conditioner. Additionally, your portable window air conditioner depends on the outside temperature to remove heat. Remember, when the outside temperature is high, the air conditioner’s cooling capacity is low. Of course, when the temperature is low, the cooling capacity is higher.

The Outdoor Temperature

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Sometimes, you will notice that the window air conditioner takes longer to cool a room during the day compared to at night. During the day, the AC unit is in direct sunlight, making it harder to cool a room.

3) The Efficiency of the AC

An AC’s efficiency depends on its EER, temperature settings, and the condition of the air ducts. A higher EER rating on a window AC unit means it functions better. Additionally, the more efficient a window AC unit is, the better its cooling capacity. A Window Ac unit that’s highly efficient will run considerably quieter compared to other units, and its cooling output will be remarkable for a long time.

The Efficiency of The AC

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In addition, with a quiet and more energy-efficient window ac unit, your electricity usage won’t be high, and it could save money in the long run. Like with any portable air conditioner, as long as your window AC unit has well-made parts and is well-maintained, you will get better use compared to central air conditioning.

Frequently Asked Questions About How Much Electricity a Window AC Unit Uses

i) Does a window AC unit use much electricity?

No. A window AC unit is relatively inexpensive, especially if you compare it to a central air conditioner. A window AC unit generally requires 500 to 1,440 watts to run. On the other hand, a central air conditioner requires at least 3500 watts to work. Of course, if you want to cool a small space, a window AC is the best option.

ii) How much electricity does a window air conditioner use per month?

Your midsize AC will consume approximately 130 to 150 kilowatt-hours of electricity per month and draw approximately 900 watts per hour. Of course, these figures are the estimation when you run your window unit for at least 8 hours a day.

iii) Do ceiling fans consume less electricity than window units?

Yes, they do. Window ACs use between 600 to 1500 watts depending on the size. A ceiling fan consumes between 30 to 50 watts of electricity.

iv) How much power does window AC use per hour?

Power usage of a window AC largely depends on it’s size. From a general standpoint, a window AC uses between 900 and 1440 watts per hour.

v) How much power does window AC use in 1 day?

A medium sized AC uses about 900 watts of electricity. Supposing the AC is on for 8 hours a day, it will consume about 15kW of electricity. (One kilowatt (kW) is 1,000 Watts (W).

The Bottom Line

On the off chance that you live in a space without cooling or just have to cool a little part of your home, a window AC unit could be the ideal choice for you. It will keep your residence cool in the most unbearable long stretches of summer without costing you dearly.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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