When shopping for a new home or updating your current house, one of the first questions many homeowners have regarding air conditioning is sizing. Unfortunately, many people will take the word of a contractor or even a handyman when it comes to getting the correct size AC unit rather than doing their research to understand how to size this integral piece of equipment properly. At Blue Ox Heating And Air, our staff of experts is here to answer your questions, provide guidance if you like, and help you select the ideal AC unit for your new build or existing home installation.
Calculating Square Footage
Most homeowners in the Minneapolis/St. Paul area knows the approximate square footage of their homes. It is a simple calculation of the width times the depth. Once you have that number, you can use the industry-standard formula to complete the estimation process. The formula is:
HOUSE SQUARE FOOTAGE TIMES 30 THEN DIVIDE BY 12,000 AND SUBTRACT 1.0
The number that you come up with will be the starting point for the required tonnage for your new central air conditioner. But remember that number is just the starting point. There are several other factors to take into consideration before making this significant purchase.
In the perfect world, the number from your calculation would be a perfect fit. But in the real world, there are other considerations. The first of which is your sun exposure. If the house is heavily shaded, the cooling will be much easier than if your home bakes in the full sun all day. Also, account for the type of roof and ceiling height to evaluate how the heat will rise away from your living spaces to increase comfort. And if you are in a single-family home, you will need more cooling power than an attached home with fewer exterior walls.
In addition, you should think about your lifestyle and expectations for your ideal temperature. If you like a crisp cold house, even in the peak of the summer heat, you might want to upgrade slightly. Likewise, if you are pretty comfortable with just a little cooling on the hottest days, you could lean towards the more conservative side when sizing your AC.
Being in the northern part of the country, Minnesota residents can typically expect to follow the standards listed below to estimate the starting point for their AC tonnage:
- 900 to 1,200 square feet = 1.5 tons
- 1,200 to 1,500 square feet = 2 tons
- 1,500 to 1,800 square feet = 2.5 tons
- 1,800 to 2,100 square feet = 3 tons
- 2,100 to 2,400 square feet = 3.5 tons
- 2,400 to 2,700 square feet = 4 tons