Power Draw and Energy Costs for Window Air Conditioners | What You Should Know

Are you planning to buy a window air conditioner to cool your room next summer?

Window air conditioners are a good solution to cool or heat a limited space that may not be connected to a central air conditioner.

They are compact, easy to install, and can be effective. Even with the above advantages, the window air conditioner may not work optimally if it is installed on an underrated circuit resulting in frequent tripping. Or, you may also be frustrated by the unusually high electricity bills.

So, in this post, I provide a guide:

  • to how much energy and electric bills it costs to operate a window air conditioner,
  • the amps they draw,

and lastly, and when to connect to a wall outlet or otherwise all to help you get the most out of your air conditioner without any frustration.

Note: This is only a guide, always consult the technical specifications section for your air conditioner.

Do Window Air Conditioners Use a lot of Electricity?

This mainly depends on the design and cooling/heating capacity of the air conditioner, user options selected and insulation of the space to be cooled.

Typical window air conditioners have a cooling capacity ranging from about 5,000 BTU/hr to as high as 28,000 BTU/hr.

The estimated annual energy consumption of the larger units is slightly over 2,000 kWh, which works out to be about over 166 kWh per month depending on usage while for the smaller units, it is about 346 kWh.

This is an estimate based on energy use data for selected major air conditioner brands. Assumes seasonal use of air conditioner 8 hours/day over 3 months.

Whether a window air conditioner uses a lot of electricity depends on the energy budget and source of power for the air conditioner.

This kWh might not be high if the window air conditioner is powered from the grid but can increase the cost of an off-grid power solution if this is the source of power used.

Note: Check that the minimum opening space – height, width that is available for your window is large enough to install the air conditioner.

Each air conditioner has a recommended minimum window opening space. Larger air conditioners require more space.

How Many Watts a Window Air Conditioner Uses?

There is no one number for the watts consumed by a window air conditioner.

The rated power consumption of the windows air conditioner depends on its cooling or heating capacity.

Larger air conditioners generally have a higher power consumption compared to air conditioners with a lower cooling capacity (BTU/hr).

The Table below shows power consumption (watts) for selected window air conditioner capacities.

This is only a guide and your window air conditioner’s power consumption may be different.

Always consult the Technical Specifications guide for your air conditioner model.

No.Air conditioner cooling capacity (BTU/hr)*Estimated Cooling space (sq. ft)Watts
15,000150455
26,000250535
48,000350695
510,000450875
612,0005501,050
714,0007001,230
818,0001,0001,600
924,0001,6001,925
1028,0001,9003,100

Source: Power consumption data for leading air conditioner brands – LG, GE, Frigidaire

How Many Amps a Window Air Conditioner Uses

As the cooling capacity of the windows air conditioners increases, so does the rated number of watts it draws.

The current draw also depends on the air conditioner voltage.

If an air conditioner has both 115V and 230V versions, the current drawn (amps) is higher in the 115V version.

The table below shows the current draw (amps) for selected window air conditioner capacities.

This is only a guide and your window air conditioner’s current draw may be different.

Always consult the Technical Specifications guide for your air conditioner model.

No.Air conditioner cooling capacity (BTU/hr)VoltageCurrent (A)
15,0001154.1
26,0001154.9
48,0001156.1
510,0001157.8
612,0001159.4
714,00011511
818,000208 – 2307.3 -7.7
924,000208 – 23011.3 – 12.3
1028,000208 – 23014.6

How Much It Costs to Run a Window Air Conditioner?

The estimated cost of running an AC depends on several factors: Its cooling capacity and energy drawn, how long and how often it is used, the specific user settings, and its energy efficiency rating.

As you can imagine, this estimate can vary so I have compiled a rough guide of estimated running costs (USD) for selected window air conditioner capacities.

No.Air conditioner cooling capacity (BTU/hr)Estimated Annual Energy (kWh)Annual running costs (USD)
16,00040753
28,00053069
310,00066086
412,000800104
514,000930121
618,0001,207157
724,0001,925250

Note: Always consult the Energy guide for your air conditioner model.

Energy costs assume seasonal use of the AC for 8 hours a day for a period of 3 months. Combined Energy Efficiency Ratio (CEER) is about 11.4 except for the 24,000 and 28,000 BTU/hr capacities with a CEER of 9.4.

Does a Window Air Conditioner Need a Dedicated Circuit?

Manufacturers generally recommend that smaller air conditioners with capacities 5,000 -6,000 BTU should be plugged directly into their own wall outlet, usually with a 15 amp circuit breaker.

The much larger air conditioners, however, should be connected to a dedicated circuit, rated 220 – 240V with a 30 amp breaker.

Consult the air conditioners’ user manual or a qualified electrician if not sure.

Why Does a Window Air Conditioner Keep Tripping

There are several possible reasons why your air conditioner may keep tripping including installing it on an undersized electrical circuit, loose wire connections, lack of servicing faulty AC, bad circuit breaker.

You may want to check out this post on: Why your air conditioner keeps tripping that includes fixes.

Final Word

There is no one number for power consumption, electricity consumption and energy costs as this varies mainly depending on an AC’s cooling capacity, energy drawn, how long and how often it is used, the specific user settings, and its energy efficiency rating.

For instance, the power consumption of a 5,000 BTU/hr air conditioner is about 450 watts while that of a 28,000 BTU/hr is estimated to be 3,100 watts.

It is best to consult the support team or the technical specification guide for your air conditioner model for power consumption, energy costs and amp draw information.

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