Applewood Air Conditioning

Size it right! Three reasons you need to ensure your air conditioner is sized correctly for your home

Posted in Resource Tips, Featured, Air Conditioning

Size it right! Three reasons you need to ensure your air conditioner is sized correctly for your home Does size matter? When it comes to the air conditioning (AC) system in your home, the answer is a resounding ‘yes’.  

Even if you feel that a higher capacity air conditioner might be required in your home, it could be a mismatch for your home’s needs. A too-big AC will overcool the air in your home and shut off before the building structure itself has been cooled adequately. This allows heat and humidity to creep back in, causing your AC to turn on for brief periods again and again. Your energy bills will rise, and your comfort will suffer with a ‘clammy’ feeling to the air.

Let’s look at the reasons for getting an air conditioning unit that is the correct size for your space. Although the calculations should be done by an HVAC specialist, it is a good idea to be familiar with the factors involved.


1.    Properly sizing your air conditioner will help moderate the temperature of the entire home.

An air conditioner’s cooling capacity is measured in British Thermal Units (BTUs). Understanding the square footage of your home will allow you to determine the cooling capacity required.

Begin by finding out the area of each room in your home. You can do this by multiplying the length by the width for each space. Once you have reached a final square footage number for your home, multiply it by 25 BTUs.

This gives you a very rough estimate and starting point for understanding the cooling capacity required for the entire home.


2.    Sizing your air conditioner correctly considers factors both within the home and external to it.  

As we’ve discussed previously on the blog, a home is a complete system! This means that the building envelope is influenced by various factors both indoors and in the environment surrounding it.

In your kitchens, for example, a lot of heat tends to be produced. In these spaces, you will want to add about 4,000 BTU to your total. A heavily-used family room also tends to get quite warm and will add additional BTU to the cooling requirements.

If your home is heavily shaded by trees, this will help to moderate the temperature in the home overall or in the affected room(s). In these rooms, reduce the BTU capacity by 10%.

Sunlight is an important consideration for your overall cooling requirements. If your home is oriented towards the sun, and you have many large windows facing south during the heat of the day, you will have higher cooling capacity requirements.


3.    Sizing your air conditioner unit correctly entails consideration of future renovations, as well.  

You may be on the cusp of redoing the insulation in your home, or perhaps you plan to extend your home with a new addition. If your wall insulation and air duct insulation is updated, your cooling requirements will not be as great.

Adding a new room to the house, however, will increase the cooling capacity required for your interior spaces.


It’s important that you correctly size your air conditioning system so that the entire building envelope, internal and external factors, and future renovations are incorporated into your cooling capacity needs.

Although it is important to understand the various factors at play in sizing an AC system, there is no replacement for a seasoned HVAC technician! We would be happy to help guide you through the complexities of properly sizing your air conditioner. Give us a call today to start the conversation.

Contact us for advice you can trust and service you can depend on.

Call 1-800-487-7307

Applewood Air Conditioning

3525 Hawkestone Road, Mississauga, Ontario L5C 2V1
(905) 275-4500

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Phone: (905) 275-4500

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