Choosing an air conditioner with the right capacity is essential to achieve a comfortable indoor temperature without unnecessarily increasing electricity consumption. A unit that is too small will have to work continuously to try to reach the desired temperature, while an oversized system may be unnecessary and increase both the purchase price and energy use.
Although the correct calculation should take several characteristics of the property into account, there is a simple formula that can be used to make an initial estimate based on the number of square metres.
Quick Calculator: How Many Frigories Do I Need?
As a general guideline, you can use the following reference:
Square metres × 100 frigories/hour
For example:
- 15 m² bedroom → approximately 1,500 frigories/hour
- 20 m² room → approximately 2,000 frigories/hour
- 25 m² living room → approximately 2,500 frigories/hour
- 30 m² living room → approximately 3,000 frigories/hour
- 40 m² space → approximately 4,000 frigories/hour
- 50 m² space → approximately 5,000 frigories/hour
This formula is a useful starting point for homes with relatively standard conditions, but it should not be considered a definitive calculation.
Approximate Capacity According to Room Size
| Approximate surface area | Recommended capacity |
|---|---|
| 10 m² | 1,000 frigories/hour |
| 15 m² | 1,500 frigories/hour |
| 20 m² | 2,000 frigories/hour |
| 25 m² | 2,500 frigories/hour |
| 30 m² | 3,000 frigories/hour |
| 35 m² | 3,500 frigories/hour |
| 40 m² | 4,000 frigories/hour |
| 50 m² | 5,000 frigories/hour |
Therefore, if you have a living room of around 30 m², you could start by considering a unit with a capacity close to 3,000 frigories/hour.
However, the number of square metres is not the only factor that matters.
Why Can Two Rooms of the Same Size Need Different Capacities?
Imagine two 25 m² living rooms.
The first faces north, has good-quality windows, limited direct sunlight and adequate insulation.
The second faces south, has large windows, receives direct sunlight for many hours and is located on the top floor.
Although both rooms have exactly the same surface area, their air conditioning requirements may be very different.
That is why, in addition to the number of square metres, several other factors should be considered.
Orientation of the Property
Rooms with high sun exposure, especially during the hottest hours of the day, often require greater cooling capacity.
In areas such as Torrevieja, Orihuela Costa and the south of Alicante, this factor is especially important because of the high level of solar radiation throughout much of the year.
Window Size
Large windows can significantly increase the amount of heat entering a property.
In addition to their size, the type of glass, the quality of the frames and the presence of blinds, awnings or other sun protection systems also make a difference.
Thermal Insulation
A modern property with good insulation will maintain its indoor temperature much more efficiently than an older property with inefficient windows or poor thermal protection.
The greater the heat loss or heat gain, the harder the air conditioning system will have to work.
Ceiling Height
The rule of calculating capacity according to square metres works best in rooms with standard ceiling heights.
If the ceilings are particularly high, there is a greater volume of air to cool, so additional capacity may be required.
Number of People
People also generate heat.
Cooling a bedroom normally used by one or two people is not the same as cooling a living room where five or six people regularly spend several hours.
Electrical Appliances
Televisions, computers, household appliances and other electrical devices also generate heat and can affect the cooling requirements of certain rooms.
Real Example: 15 m² Bedroom
Let us assume we have a bedroom measuring approximately 15 m².
Using the simple formula:
15 × 100 = 1,500 frigories/hour
Under normal conditions, this would be approximately the minimum cooling capacity we should consider.
However, if the bedroom faces south, receives a lot of afternoon sun and has a large window, it may be advisable to consider a slightly higher capacity.
Real Example: 30 m² Living Room
For a 30 m² living room:
30 × 100 = 3,000 frigories/hour
In this case, a unit with a capacity of around 3,000 frigories could be a good initial reference.
However, if the living room is open-plan with the kitchen, has large glass doors and receives a lot of direct sunlight, the calculation should be adjusted because the thermal load will be higher.
What If I Want to Cool Several Rooms?
When you want to air-condition several rooms in the same property, simply calculating the total number of square metres is not always the best approach.
Depending on the layout of the home, it may be more suitable to install:
- An individual split air conditioning unit.
- A multi-split system with several indoor units.
- A ducted air conditioning system.
The best option will depend on how many rooms you want to cool, the layout of the property, how each room is used and the characteristics of the home.
Is It Bad to Install an Air Conditioner That Is Too Powerful?
Choosing “the most powerful unit possible” does not necessarily mean achieving better results.
An oversized air conditioning system may reach the desired temperature very quickly and operate in shorter, less efficient cycles. You may also end up paying for cooling capacity that you do not actually need.
On the other hand, an undersized unit will have to work for longer periods and may struggle to maintain a comfortable temperature during the hottest days.
The goal is to find the right capacity for the actual needs of the property.
Frigories, kW and BTU: Why Are Different Units Used?
Depending on the manufacturer, air conditioning capacity may be expressed in frigories/hour, kilowatts (kW) or BTU/hour.
As an approximate reference:
1,000 frigories/hour are equivalent to around 1.16 kW of cooling capacity.
Therefore, an air conditioner with around 3,000 frigories/hour will provide approximately 3.5 kW of cooling capacity.
This cooling capacity should not be confused with the electrical consumption of the unit, as they are different concepts.
Square Metres Are Only the Starting Point
Calculating approximately 100 frigories per square metre is a quick way to get an initial idea of the air conditioning capacity you may need, but a professional installation should always take the specific characteristics of the property into account.
Orientation, insulation, windows, ceiling height, layout and sun exposure can significantly affect the final calculation.
At AC Torrevieja, we assess the characteristics of each room before recommending an air conditioning system, helping to avoid both insufficient cooling capacity and unnecessarily oversized equipment.
If you are thinking about installing or replacing air conditioning in your home in Torrevieja, Orihuela Costa or the surrounding areas, we can help you determine the most suitable capacity and system for your property.