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Air conditioning is very expensive and quantifying it here is almost impossible, but we give you an idea and a simple calculator.

how much does it cost to use an air conditioner

How much does it cost to run an air conditioner?

This is an almost impossible general question to answer as it depends on so many different factors, also you may be just wondering how to cool your house down a bit, .

Here are a few

  • The powers consumption of the air conditioning (AC) unit.
  • How hot it is and the temperature you want it to be, the temperature the thermostat is set for.
  • The volume of space you are trying to cool.
  • Whether a door or window has been left open to the area you are trying to cool.
  • How readily the space you are cooling heats up with windows, and roof building materials.
  • How well serviced the unit it.

I live in Northern England where the use of air conditioning is almost non existant, the temperature of my home town often sends me abroad to warmer climates, especially Spain and Greece. So my knowledge of cooling comes mostly from holidays, and I know how expensive it can be. I did also have to fit out a loft office in a factory with AC, many years ago. Some bright spark decided that a roof was a great place for the research scientists. Prior to the AC we all snoozed in the afternoon in the summer because of heat exhaustion and the management wondered why our productivity had reduced; apologies for the sentiment, but they were morons. I remember at the time doing a cost justification for AC based on the research group sleeping in the afternoon, that was fun!

So I'm going to keep this very simple. Consider an AC unit that has a power consumption of 3kW and is on for just 1 hour this will cost with the current UK electricity rate:-

£0.813 and by using it you will have emitted:-

0.7kg CO2e into the atmosphere.

This example is of a small unit, such a unit might be suitable to cool a single room on a hot day. Costs might reduce using it for longer if the thermostat temperature has been reached.

I have also tried several on line calculators to work out the AC requirement, to my mind they were all completely nonsensical. Some of them do not understand what power is or energy, they quote results in kW/h, this is the same as saying kj per second per second. Should they be using power consumption kW or do they mean energy required kWh, an example is on this web site Unfortunately I cannot recommend any of them, the calculation output makes no sense.

So Try this calculator it is crude, it only considers the equipment being on at 1 power rating, but it might give you an idea of costs.

Electricity Cost Calculator

Simply enter your own values below
Hours Used Per Day:
Power Use (Watts):
Price Per kWh:

Cost Per Hour:
Cost Per Day:
Cost Per Month:
Cost Per Year:
kWh Per Day:

Comments and Questions

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Understanding heat - Candoit  2018-08-13 20:52:04
Having looked at the BTU calculator, it would seem that you're confusing heating calculations with electricity ratings.

We used to measure heat in BTU's, but we've pretty much switched over to using Kilowatts now, and there are 3,142.12 BTU's in a Kw, but that's heat output or cooling capacity in the case of an air con system.

The Cleanair btu calculator asks for all the things in the room that will generate heat, and then gives you the capacity in both BTUs and Kw, to allow you to work out the size of the unit you need to install; but you can't equate a Kw heating/cooling requirement, with a KW of electricity costs - it's a bit like here, and hear; they sound the same, but have different meanings.

An aircon system will work at full capacity till the rooms been cooled, but if it's an inverter system (which is fairly efficient) then it'll costs less to run after that.
reply - rdh  2018-08-14 10:21:57

We need to get the language straight first off.

A BTU is a unit of energy, the SI unit Kw does not exist, the unit is kW, kW is a kilo Watt 1kW = 1 J/s (1 Joule/second).

A BTU can only be equated with a kWh not kW

Take a look here

3412.14 BTU's/hour = 1kW

look at it this way X energy units / time period = Y J/s (Power)

The statement "there are 3,142.12 BTU's in a Kw" is meaningless
It should read there are 3,142.12 BTU's in a kWh

Yes electricity ratings use power kW and energy kWh. You can express any other system using the same units. for an unusual example, food is usually measured in kilo-calories (often abbreviated to calories), this can be converted to joules, BTUs or kWh what ever you like. It requires 0.06 kWh of input food energy to walk 1km and if you walk at 6km/hour your power consumption is 0.000017 kW (dividing by 3600 seconds in an hour).

"you can't equate a Kw heating/cooling requirement, with a KW of electricity costs"

No it is exactly related. If you require a cooling output power of 2kW for example and the unit efficiency is 50% (for simple maths) you will require 4kW of input power to the device, if you run the device for one hour this will cost 4 X your electricity unit cost and consume 4kWh of energy .

The problem here is that air conditioners are thermostatic so their power consumption varies depending on all the things in the room as you correctly state including people, the external temperature, the time of day and the temperature you set the unit for.

You also absolutely correct the power demand and hence energy cost will reduce once a room is cooler. The article just has a unit on for 1 hour at one power rating as stated in the article, this is the same for heating, they are thermostatic.


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