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What Size Air Conditioner Do I Need For A Home In North York?

Large AC for "What size air conditioner do I need for my home in North York?"

If you’ve lived in the North York area for some time, you know how hot it can get in the summer. With average temperatures like these, a nice cool breeze is all you’re thinking about. Many homeowners who have had an air conditioner for more than 15 years might see a decline in the time it takes to cool their home. If your home isn’t even getting cool enough, it might be time to avoid a/c repair and invest in a new air conditioner. You might be wondering “How do I know what size air conditioner I need? A few simple calculations can quickly tell you what size air conditioner you need for a home in North York. 

How to determine the size of air conditioner you need

The following variables influence the size of the air conditioner you need:

  1. The size of your home
  2. The number of rooms in your home
  3. The climate you live in
  4. Your family’s cooling needs
  5. Your home’s insulation

Once you’ve gathered this information, you can use one of two methods to determine the size of the air conditioner you need for your home in North York.

The BTU Method

The first method uses British-Thermal-Units (BTUs) that measure the amount of heat a unit can remove from the air in an hour. When determining the size of air conditioner you need, you’ll want to look for a unit with a greater BTU rating.

The rule of thumb is: You may roughly estimate one ton per 1000 square feet. So, if your home is 3,000 square feet, you’ll need an air conditioner with a 3.0-3.5 ton unit.

The Tonnage Method

The second method uses the unit of measurement known as a “ton.” A ton is equivalent to 12,000 BTUs per hour. To calculate the number of tons you need, divide the total BTU rating by 12,000. Using our previous example, we would need an air conditioner with a cooling capacity of 3-3.5 tons for a 3,000-square-foot home.

It is worth noting that most central air conditioners come in half-ton increments (1.5, 2, 2.5, 3, etc.), so you may need to round up when using this method.

So, how do the above variables affect the size of the air conditioner you need for your home? Let’s take a closer look.

Variables that affect the size of the A/C unit you need

There are a lot of factors to consider when you’re trying to decide on the appropriate size of air conditioner for your home. 

Energy efficiency

The type and efficiency of the air conditioner are important factors, and this will depend on whether or not you live in an area with high humidity or if it’s mostly dry. Canada is an environmentally conscious society so it would be best to your part by aiming for an air conditioner that has a high EER (energy efficiency rating) or even better, an ENERGY STAR® rating. 

energy star means a higher efficiency ac unit
Image source: Energy Star

To qualify for an ENERGY STAR® rating an A/C unit must pass the Canadian minimum of energy efficiency by 10%. Today ENERGY STAR® units use 30-40% less energy than units sold 15 years ago!

Size. Yes, it matters

When it comes to sizing, a perfectly sized air conditioner will keep your house cool and dry at the lowest cost possible. You don’t want it too big because your unit will start and stop too frequently for short bursts. You don’t want an undersized unit because you may never achieve an ideal temperature-even if it’s running all the time. 

Age of your house and how well it’s insulated

Another thing to think about is how much insulation your house has because less insulation requires a more powerful unit. Older homes tend to have more “air leaks” from poor insulation and deterioration. 

Structural layout and configuration

The layout of your house is also key in this decision. If you have a lot of windows, they will let in more heat and sunlight, which means you’ll need a bigger unit to counteract that. Windows facing east and west will get a lot more sun unless you have trees or window shades to block out the rays. 

Number of people in your household

The number of people who live in your house and their daily activities also play a role. If you have a big family or if everyone is home during the day, you’re going to need a more powerful unit. If people are constantly going in and out it will affect how much “air leakage” your home experiences. 


You must also take into account the climate of the city you live in. North York, Ontario can experience high humidity. Experts will assess your home using what’s called the “peak load cooling” method. This accounts for things like moisture in the air and how it affects your home’s ability to cool down.

After taking all of these factors into consideration, you should have a good idea of the size of the air conditioner you need for your home. From there, you can start shopping around for the perfect unit to keep you cool all summer long.

Significance of a proper size air conditioner

different size a/c units
Image source:

Why is it important to get the proper size air conditioner?

An undersized air conditioner will have to work harder and run longer to cool your home and remove humidity. This causes the air conditioner to wear out faster and will cost more to operate because it is consuming more energy. An air conditioner that is too small will also not remove humidity effectively, leaving you feeling damp and clammy.

Too big, no good

An oversized air conditioner is also not ideal. It will cool your home too quickly and then shut off before it has a chance to remove the humidity. This can leave your home feeling cold and damp. Additionally, an oversized air conditioner will cost more to operate because it will cycle on and off more frequently.

The best size is custom fit to your home

The bottom line is that you want an air conditioner that is properly sized for your home to get the most efficient cooling and humidity removal. A good way to determine the proper size air conditioner is to have a load calculation done by a qualified HVAC contractor.

Measuring the square footage of your home

One of the most common mistakes people make when sizing an air conditioner is measuring the square footage of their home. It is important to understand that cooling capacity is not directly related to square footage. The number of windows, the amount of insulation, the layout of the home, and other factors all play a role in how much cooling capacity is required.

The ideal method to go about it is to rely on a contractor to do a load calculation. This will take all of the above factors into account to determine the proper size air conditioner for your home.

Do-it-yourself load calculations

If you want to do a load calculation yourself, there are a few different methods you can use. One is the rule-of-thumb method, which relies on some basic assumptions about your home. This method can be inaccurate, so it is best to use it as a starting point and then adjust as needed.

Another option is to use one of the many online load calculation tools. These tools will ask you for specific information about your home and your cooling needs to give you a more accurate estimate.

You can also find load calculation worksheets online. These can be helpful if you want to sit down and work through the calculation process step-by-step.


Many factors will determine the size of the air conditioner you need for your home, Some people go to a store and buy the first AC that fits their window. Others rely on gut feeling and online reviews from neighbors, but the ideal method is to get load calculations done by an experienced HVAC installer. They’ll know how much power you need, what the ideal range of temperatures is for your area, and whether or not the A/C will be compatible with your home.

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