What Size AC System Do I Need for My Home?

There are many factors that determine the size of an air conditioning system you need in your home, including the number of people who live there, the square footage of the rooms, and how much energy efficiency your home has. It’s crucial to know what size air conditioner you need before you get quotes from HVAC contractors so you don’t end up paying more than you have to.

Here are some steps you can take to figure out what size AC system you need for your home based on your current heating and cooling needs, as well as what square footage your house has and how it’s constructed.

How Much Cooling Power Do I Need?

It is the foremost step to determine how much cooling power you need before choosing a specific AC system. The cooling capacity (measured in BTU/hr) will determine the size of your air conditioner, which means the cooling requirement is directly proportional to no. of BTUs.

The number of people living in your home also plays a role, small homes with only one or two people will not use as much air conditioning as larger homes with four or five people. So be sure to take into account these factors when determining how big an AC system you need.

Location and Orientation and of the building

Another important thing you need to take into account when sizing an air conditioner is the orientation and location of your building or house. If your home is located in a hotter climate, you’ll need a larger unit to cool it down. On the other hand, if your home is located in a colder climate, you will want to size your system with a smaller tonnage so that it doesn’t cycle on and off as often.

You also have to keep in mind the orientation of your building. A south-facing window offers much more light than a north-facing one so more BTUs are required to cool down that room.

Take into account the Outside Temperature & Room Insulation

If your home is not well insulated, you cannot get the most out of a smaller air conditioner. Make sure to take measures such as caulking or weather-stripping doors and windows, insulating pipes and ducts in crawl spaces or attics, or adding insulation to exterior walls before installing an air conditioner in order to maximize efficiency.

The other factor that affects size needs is the outside temperature. The hotter it gets outside, the more powerful (more BTUs) your system will need to be in order to keep up with the demand for cooling inside.

Calculation of Square Foot for AC sizing

In order to calculate the size of the air conditioner that you need for your home, you must take into account the square footage of your home. This is paramount step because it will help to determine how much space the air conditioner will need to cool.

To get a more accurate estimate, you should measure the dimensions of each room in your house and write them down on a sheet of paper so that you can enter them into an online calculator.

Selecting the BTU Rating for 800 sq. ft. Room:

According to the US Department of Energy (DOE), an air conditioner generally requires 20 BTU for each square foot of living room/space. If you have an 800-square-foot room with 8-foot ceilings, then you need about 16,000 BTU. In other words, a 1.5 Ton AC system would be enough to provide cooling for this space.

Keep in mind that more BTUs can be required if your roof isn’t properly insulated or facing more sun exposure or you’re located in hot areas like Sunny Texas, Arizona, and Hawaii.

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