When calculating the capacity of an air conditioner, several important factors must be considered to select the appropriate device with the desired efficiency. These factors include:

 

 

Area (Surface)

Air conditioner capacity is usually expressed in BTU, which is expressed in the following types of capacities according to area:

 

9,000BTU for 10 to 15 square meters

12,000BTU for 15 to 25 square meters

18,000BTU for 25 to 40 square meters

24,000BTU for 40 to 50 square meters

30,000BTU for 50 to 70 square meters

36,000BTU for 70 to 100 square meters

 

Geographical location and climate

Tropical areas such as southern Iran require higher capacity.

In temperate areas, standard capacity is sufficient.

 

Number of windows and amount of sunlight

The number and type of windows (single or double-glazed) and direct sunlight on the interior space affect the heating and cooling load.

Sunlit spaces require higher capacity.

 

Number of people in the room

Each person adds about 600 to 800 BTU of heat to the space.

The constant presence of several people in a space increases the capacity of the air conditioner.

 

Presence of heat-generating devices (television, computer, stove, etc.)

Electronic equipment also generates heat.

In work spaces or kitchens, the capacity should be calculated more.

 

Ceiling Height

A typical height is considered to be up to 3 meters. If the ceiling is high, more air volume needs to be cooled and the capacity increases.

 

Building Insulation

If walls, ceilings, windows, and doors are not properly insulated, more heat will enter the environment.

Older buildings usually require more powerful air conditioners.

 

After the factors influencing the selection of an air conditioner, accurately calculating its capacity has a great impact on performance, durability, energy consumption, and thermal comfort. The approximate formula for calculating the capacity of an air conditioner (for residential and low-traffic office use) is as follows: for temperate regions, it is 400 to 800 BTU per square meter, and for tropical and humid regions, it is 600 to 800 BTU per square meter. If the capacity of the air conditioner is not selected correctly, it will have undesirable consequences. Choosing the right or wrong capacity can have positive or destructive consequences. Its positive effects include increasing efficiency and effectiveness, reducing electricity consumption, increasing the useful life of the device, and maintaining proper air humidity. Also, the destructive consequences can be examined from two aspects: less than required capacity and more than required capacity:

 

- Undersized

⦁ The environment is not cooled sufficiently.

⦁ The compressor is constantly running (increasing electricity consumption and wear and tear).

⦁ Humidity is not removed properly. The air remains stuffy and unpleasant.

 

- Oversized

⦁ The air conditioner cools the environment quickly but turns off quickly (short cycles).

⦁ Electricity consumption increases without necessarily creating a feeling of comfort.

⦁ The air becomes very dry.

⦁ Increased initial purchase cost.

 

Choosing the right air conditioner capacity will affect both your comfort and long-term maintenance and energy consumption costs. To understand the above, let's consider a real example as follows:

 

 

Environment specifications:

⦁ Type of space: Living room

⦁ Area: 30 square meters

⦁ Ceiling height: 2.8 meters (normal)

⦁ Geographical location: Ahvaz city (hot and humid climate)

⦁ Window direction: South (direct sunlight during the day)

⦁ Number of windows: 2 large windows (no thick curtains)

⦁ Average number of people living in the room: 4 people

⦁ Heat-generating devices: Large TV, small refrigerator, laptop constantly on

 

Analysis of the conditions:

Area × Thermal coefficient of tropical regions:

We multiply 30 square meters by 800 Btu, which results in = 24,000 Btu

 

Increase due to direct sunlight and large windows (10% increase):

24000Btu/h*1/1 = 26000Btu/h

 

Effect of 4 people approximately 600Btu each

We multiply the number four by 600, which comes to 2400Btu 

 

Electronic equipment: About 1000 to 1500Btu/h is added.

 

Approximate capacity required for this space:

26000 + 2400 + 1500 = 30000Btu/h

 

Therefore, a 30000Btu/h inverter air conditioner is the best option for this room in Ahvaz.