UncategorizedDecember 6, 2022by Alex

Calculation of power and selection of air conditioner according to the area of the room

In order for the air conditioner to work confidently and create coolness on hot days, it is important to consider its optimal cooling capacity, taking into account the area of your office or apartment.

In this article, we will consider what you need to know about calculating the capacity of the air conditioner, and what additional factors are important in its selection.

Why is it important to know the cooling capacity of the air conditioner

The cooling capacity of the air conditioner – is the most important technical parameter, which depends on the efficiency of the device in a particular room. If the power is not enough, the air conditioner will not be able to create comfortable coolness, and at the same time, it will work with wear and tear, which will lead to the fast breakdowns of the equipment.

Conditioner with a cooling capacity more than is necessary for a concrete premise will create a lot of noise and will not be able to be used to their full potential. Indeed, it will not entail the premature breakage of the equipment, but it can appear to be an unreasonable purchase with overpayment for a high-powered device and its installation.

And in order not to overpay and to buy a good air conditioner, which will create a comfortable temperature in a concrete room, it is necessary to calculate the optimum power of cooling the device correctly.

Methods of air conditioner capacity calculation

Each air conditioner has a marking from the manufacturer, where the cooling capacity parameter is indicated. Before you go for the purchase of split-system you should make a small calculation of optimum power according to a special formula, using the parameter of a room’s area or its volume.

Variants of air conditioners marking:

– 0.7 – MO 2 kW;
– 0.9 – MO 2.5-2.6 kW;;
– 10 – MO 2.9 kW;
– 12 – MO up to 3.5 kW.

Calculation of air conditioner by the area of the room
Calculation of the air conditioner according to the area of the room is made according to a simple formula: 1 kW = 10 m2. To calculate the cooling capacity you should divide the total area of the room by 10 and round the result. For example, the area of 1 room apartment is 24,5 m2. Divide this figure by 10 and get the optimum power of the device – 2.45 kW. In this case, it is optimal to buy an air-conditioner with a capacity of 2.5 kilowatts.

The minimal power parameter of split systems is 2 kilowatts, optimal for installation in premises with an area of up to 20 square meters.

Calculation of air conditioner capacity according to the volume of the room
It is possible to calculate the optimal value of the cooling capacity of the air conditioner more accurately by the volume of the room. In this case, the specific cold parameter per 1 square meter is used for the calculation.

Value of specific power (q):

– room on the sunny side – 40 W/m3;
– average illumination of the room – 30 W/m3;
– a darkened room – 20 W/m3.

The formula for calculating the MO: Q1 = q x V

Q1 – the power of the device;

q – specific parameter;

V – the volume of the room.

Since there are also household appliances and people in the room emitting heat, the amount of heat emitted by people and household appliances is added to the obtained result. Calculation formula: Q1 + Q2 + Q3 = Q

The norm of heat from people is 0.1 kW, from computers – 0.3 kW, and from home appliances and office equipment – 30% of power consumption.

How to conduct calculation

Calculation of the cooling capacity of the air conditioner without a calculator is made by simple formulas, published above.

For example, a buyer wants to calculate the device’s exact capacity according to the room’s volume. First, he needs to determine the value of V, the volume of the room, by multiplying the parameter of the height, length, and width of the room.

Then the specific power parameter is multiplied by the area and to the obtained result is added the parameter of the amount of heat from appliances and man. The received value is rounded off.

Examples of air conditioner calculation and selection
Here is a simple example of calculating the cooling capacity of an air conditioner.

Initial data:

– The area of the premise is 30 sq. m;
– One person lives in the room;
– Several home appliances with a power consumption of 165 W are installed in the room (computer, TV set, and refrigerator).
– The room is of medium light intensity.


– Q1 = S * h * q / 1000 = 30 square meters * 2.70 m * 30 / 1000 = 2.45 kW.
– Let’s calculate the heat flux of the household appliances. As the computer and TV set work at different times, we take for calculation one of the appliances that emit the most heat. For example, the computer is 0.3 kW. Calculation: 0.165 kW x 0.3 = 0.05 kW.
– The heat input from a person is Q2 = 0.1 kW.
– Now let’s calculate the total parameter of heat fluxes from household appliances. To the maximum power consumption of the refrigerator let’s add the heat input of the PC. Calculation: 0.05 kW + 0.3 kW = 0.35 kW. So, Q3 = 0.35 kW.
– Now let’s calculate the optimum power of the equipment using the formula: Q = Q1 + Q2 + Q3 = 2.45 kW + 0.1 kW + 0.35 kW = 2.9 kW.

In this case, the optimum capacity of the air conditioner is 2.9 kW. In a standard range of split equipment with different parameters of cooling capacity, we choose the closest variant possible.

Don’t wait for your air conditioner to fail. If not repaired promptly, there is a very high likelihood that a lengthy comprehensive repair will be required. Even a few days without air conditioning in the summer heat in San Diego County, California, will greatly discomfort the whole family. But by calling the handypersons at SDAC Heating & Air Conditioning, you can avoid this problem.

Contact us

(858) 788-1-777

[email protected]