If you want to buy an air conditioning system, you should know the power required. This is often given in BTU/h. You can find out what this is all about and how you can easily calculate the cooling capacity of an air conditioning system in our guide.
BTU/h and Watts
BTU/h stands for“British Thermal Unit” and describes the power required to heat one pound of water (453.59 ml) by 1°F. This value is measured from 39°F (3.89°C), as water reaches its highest density at this temperature. To get a better overview of the cooling performance, the unit BTU/h can easily be converted into the more common unit of watts in this country. This works like this:
1,000 BTU/h=293, 17 W
This means that if you are interested in an air conditioner with a cooling capacity of 9,000 BTU/hr, it has 2,638, 53 W, which is often offered as a 2,600 or 2,650 W model. Of course, this works in the other direction as well. All you have to do is follow this formula:
- (Cooling capacity in W/293, 17) x 1,000=Cooling capacity in BTU/h
- (2,638, 53/293, 17 W) x 1,000=9,000 BTU/h
Calculate the cooling capacity of the air conditioning system
In order to determine the optimal cooling performance for your premises, you must calculate the existing cooling load. The following rule of thumb has proven useful:
Room size in square meters (m²) x solar radiation and insulation factor in W=cooling load in W
While the size of the room can be measured quickly, the solar radiation and insulation factor is not so easy to determine. That's why these guidelines are used in most buildings:
- 60 W: good insulation, low solar radiation
- 75 W: sufficient insulation, higher solar radiation
- 100 W: low insulation, very high solar radiation
Using these values, you can quickly determine what cooling load is present in your living space. The cooling load indicates how high the cooling capacity of the air conditioning system must be. We have prepared a sample calculation for you. This example is a 30 square meter room with a cooling load of 75 W, for which we want to determine the required cooling power:
Cooling load: 30 m² x 75 W=2,250 W
Now use this value using the conversion formula described above to calculate the cooling capacity of the air conditioning system in BTU/h:
(2,250W/293, 17W) x 1,000=9,407, 53 BTU/h
In order to keep the sample room at a pleasant temperature, a cooling capacity of 9,407.53 BTU/h is required. Corresponding models with 9,400 to 9,500 BTU/h are offered.
Tip:
If you need to cool more than one room or multiple rooms, we recommend using multiple devices. This allows a larger area to be cooled efficiently.
Factors influencing cooling performance
In addition to the size of the room to be cooled, there are other factors that can have a significant impact on the cooling performance of the air conditioning system. These are usually objects or people that also generate heat, which must be taken into account when determining the required cooling capacity. You simply have to add these elements to the actual result to get the necessary cooling performance. These include, for example:
- Person: 100 to 200 W
- Window: 150 W
- Ceiling heights from 240 cm: 6 W per 10 cm
Of course there are still elements that reduce the required cooling capacity. They are difficult to calculate, but they have a significant effect on the room temperature. These include:
- Sun protection films
- Fans for air circulation
- Remove carpets over summer (they store a lot of heat)
- light wall colors (retain less heat)
Note:
Heat-generating electrical devices such as laptops or lamps cannot be added as a flat rate. To do this, use the device performance and add it to the total value.
Frequently asked questions
How can you cool a room without air conditioning?
Rooms without air conditioning can be cooled effectively by using shutters and curtains and closing windows and doors during lunchtime and in the afternoon. This means that sun rays and heat do not reach the rooms unhindered. It can also help to dip towels, sheets and other pieces of fabric in cold water, wring them out and hang them up in the room. The humidity cools the room down.
What should you pay attention to when using the air conditioner?
Make sure to keep doors and windows closed during use to prevent further heat from entering the room. In order to enable the device to work optimally, it is also important that the exhaust and intake connections are clear. Furthermore, the air conditioning system should not be placed behind an obstacle to allow unhindered air flow.
Why do air conditioners need to be cleaned regularly?
Clogged or contaminated air conditioning systems perform significantly worse. This has a direct impact on the cooling performance, as the device has to work significantly harder to reach the target temperature. This in turn increases the electricity costs, which can be prevented by regular cleaning.
