What is the BTU measurement?

If you’ve ever looked at the specifications on an air conditioning system, you will have noticed the term BTU. You might have wondered what it meant and what it measured. The BTU measurement is actually a key consideration when it comes to choosing an air conditioning system.

Here we take a quick look at BTU, what it is, how you calculate it and how it impacts on your choice of air conditioning system.


What is BTU?


BTU stands for British Thermal Units and it’s used to measure thermal energy. It was developed in the late 1800s and, over the decades, it has become the most widely used unit of measurement in both heating and cooling appliances.

As it was developed before decimalisation, it used imperial measurements. For instance, 150 British Thermal Units is equal to the amount of energy used to raise the temperature of a room by 1 degree Fahrenheit. You will often see BTU used in conjunction with radiators. The higher the BTU of the radiator, the more heat that radiator can output into the room.


What about air conditioning?

If BTU is used to measure thermal energy and is generally seen in relation to heating products such as radiators, how does it apply to air conditioning units? It’s actually quite simple and the calculation merely works in reverse. With an air conditioning system that’s required to remove heat from the room, the measurement is expressed in terms of how many BTUs per hour the product can remove from the room.


Why the BTU is important


A common mistake people make is to presume that a higher BTU is always better when it comes to air conditioning systems. Using an air conditioning unit with a BTU level that’s higher than you actually need can cause the unit to cool too quickly. It will then cycle off and then to maintain the desired temperature it will have to cycle on again soon after. This pattern of cycling on and off again repeatedly will cause the air conditioning unit’s air compressor to overwork itself. If this frequently happens it will shorten the lifespan of your unit.

By contrast, a unit with too low a BTU will struggle to reach your comfortable temperature level. The heat load could end up overloading the unit, causing it to run continuously without reaching the required temperature. It’s also likely to reduce the lifespan of your air conditioning unit.


How do you measure the BTU of a room?


Measuring the BTU of a room can seem like quite a complex process, but in actual fact it’s relatively straightforward. All you need to do is take a few measurements.

Firstly, you will need to measure your room to find out its square footage. To do this you will need to measure the width of the room by its length, and then multiply these together. So, if for instance the width of your room was 10ft and its length was 12ft, the square footage of the room would be 120ft.

This is relatively simple if your room is a regular shape such as a square or a rectangle. But what if your room is irregular? If that’s the case, you will need to divide your irregular room into as few regular shapes as you can find. If you have an older property, it might be that quirky room shapes and dimensions make this more difficult. It doesn’t have to be an exact science, getting as close to the accurate BTU as possible should be your aim.


Calculating the BTU

To find the BTU of a room take that square foot calculation and multiply it by 25. For example:

  • Room size 150sq ft x 25 = 3750 BTU

Therefore, a room of 150sq ft will require an air conditioning unit with a minimum cooling capacity of 3750 BTUs.

So, is that it?


Other factors that will determine the BTU of a room

While you can get a rough estimate of the BTU of a room by working out its square footage, for more accurate results you’ll need to take account of the following:

  • Room dimensions, including the ceiling height
  • The size and number of windows in a room
  • The type of glazing at your windows/patio doors. Is it single or double-glazed?
  • The outside wall material
  • What’s above and below the room

Once you have a BTU figure based on the square footage of the room you should then consider some of the above factors and adjust the figure accordingly.

If, for instance, a room has lots of windows that let in sunlight, then you may need a greater cooling capacity during the summer months.


Domestic Air Conditioning that’s ideal for your home

There’s a huge range of domestic air conditioning options available so it shouldn’t be difficult to find one that’s ideal for your home. If you’re in any doubt about the BTU rating of the rooms in your home, it might be advisable to talk to experienced air conditioning supply and maintenance professionals.

Here at Enviro Chill, we have a wide range of domestic and commercial air conditioning clients often with very different requirements. Our team of experienced and qualified engineers can install the perfect air conditioning system for your home in no time at all. As well as installing the perfect air conditioning system for your premises, we can take care of its ongoing maintenance.

Why not contact us to find out more?