Mar 09, 2022
Many consumers believe that buying a larger air conditioner would provide better cooling. Little did they know that a big air conditioner is inefficient, wastes energy, and cools your room too rapidly without eliminating humidity, making you uncomfortable and damp. Moreover, if you choose a unit that is too small, your room will not be properly cooled. That’s why choosing the proper air conditioning capacity for the size of your room will have a significant impact on both your comfort and your power cost.
When we talk about the size of an air conditioner, we’re not referring to its actual measurements. We’re talking about its cooling capacity instead. In this article, AllHome will show you a straightforward way for determining the right air conditioning capacity for your space.
The cooling capacity of an air conditioner is measured in kilojoules per hour (kJ/hr) or British Thermal Units (BTUs) (BTU). This is used to calculate how much heat your air conditioner can remove from the air per hour of operation. In the Philippines, kJ/hr is often used, so use this for your calculations.
Another way of evaluating an air conditioner’s capability is to measure its horsepower (HP). However, HP only measures the motor’s power, not its cooling ability. It is substantially more accurate to determine the capacity of your air conditioner in kJ/hr rather than HP when comparing units with the same horsepower rating. HP may not be as accurate as kJ/hr, but it is useful for filtering the models you’ll be examining. Keep in mind that one HP is equal to 9,495 kJ/hr.
The optimum floor size for an air conditioner is specified in square meters (sqm or m2). This will be simple if you have your house’s floor layout. Otherwise, use a tape measure and measure the length and width of the room, then multiply both values to obtain the square meter size.
Using the calculations below, calculate the cooling area (in square meters).
Even if you can’t take a precise measurement, you can get an idea of how much horsepower you’ll need by calculating a rough estimate. Multiply the size of your room by 500 to obtain a rough estimate. In the case of a 10 square meter room, a cooling capacity of 5,000kJ/hr is required, which most 0.5HP window air conditioners have. Here is a cheat sheet listing the base capacity per room size. However, there are a few other factors to consider in order to arrive at a more precise calculation, which we will discuss in the next section.
| Room Size | Capacity (kJ/hr) | Estimated HP Rating |
| ≤ 10 sqm. | 5,000 | 0.5 HP |
| 10 – 15 sqm. | 5,000 – 7,500 | 0.75 HP |
| 15 – 19 sqm. | 7,500 – 9,500 | 1.0 HP |
| 19 – 25 sqm. | 9,500 – 12,500 | 1.5 HP |
| 25 – 35 sqm. | 12,500 – 17,500 | 2.0 HP |
| 35 – 43 sqm. | 17,500 – 21,500 | 2.5 HP |
Knowing the size of your space can help you determine the size of your air conditioner. However, you should consider the heat load of your space to get a more exact estimate. The sum of the heat (expressed in kJ/hr) released by heat sources inside a room is referred to as the heat load (or heat gain).
One factor is the size of the room. Other considerations include the number of people in the room, the amount of windows, and the quantity of appliances. Take the cooling capacity as a starting point based on its size, then change your estimates based on the following factors:
One of the most important components in determining the heat load is the sun. If your room is exposed to direct sunshine, increase the cooling capacity by 10%; if it is shaded, reduce the cooling capacity by 10%. Meanwhile, the eastern orientation of windows allows heat to enter from the rising sun (hot in the mornings) while the western orientation lets heat into the room from the setting sun (cold in the evenings and warm in the mid-afternoon).
Insulation has a significant effect. The more insulated a space is, the less air conditioning it will require. As a general rule of thumb:
It is important to account for a person’s heat production. If two individuals are using the room, don’t make any adjustments, but more than two individuals are using it, add 633 kJ/hr per person.
It’s not always true that bigger is better. If the air conditioner is too big, it will use more energy, remove less humidity, and wear out faster than units that are the right size. Likewise, smaller isn’t always better. A tiny air conditioner will struggle to cool larger rooms, wasting energy and putting pressure on the engine. You may correctly determine where your sweet spot is using this method in our blog.
If you’re still unsure about finding the right aircon for you, don’t be afraid to talk to our staff as you shop at an AllHome store near you. You can also go to AllHome online for a hassle-free shopping. The AllHome online site offers fast delivery, cash on delivery, and easy payment terms. Be updated with the latest trend by following us on our official Facebook page, Instagram account and YouTube channel.
