How to Determine the Number of BTUs You Need

When it comes to heating or cooling your home there is more simply hitting the button on your thermostat and enjoying the benefits of the comfortable temperature. Determining the number of BTUs needed for your space is a key element in ensuring that your heating or colling system is going to provide the proper amount of airflow to heat or cool your home, garage, shop, workplace, etc. While many HVAC professionals will do these calculations for you, for many, knowing how to do the calculations themselves provides a level of understanding when it comes to getting a new heating and cooling system.

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There are multiple factors that play a role in determining your BTUs, from your climate and weather, square footage, building material, quality, etc. The two most common ways to determine your needs are to use your climate and weather or your square footage and cubic footage, here’s a closer look at each calculation.

Climate and Weather

The U.S is broken into multiple different climate zones that help determine the average BTUs needed, for example, in climates that are either colder or warmer than the average “median” temperature, those areas will require more BTU’s for heating and cooling needs than areas with a more central climate. Oregon for example, is classified as zone 6, which requires an average of 60 BTUs per square foot, so if you have a 1500 square foot home, you could determine your needs with this calculation:

Square footage

As a general rule of thumb, the larger the space, the more BTUs needed. First and foremost, you’ll need to find out what the cubic space is of the area you wish to heat or cool. Once you’ve determined your cubic feet (see example below) the next step is to calculate your desired temperature change. For this scenario, we will say the temperature outdoors is 50 degrees, and you wish to heat your home to 70, the desired temperature change would be 20 degrees and if your home is 1500 square feet with 8-foot ceilings, you would use this calculation:

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Understanding all the elements that play a role in your heating or cooling needs can seem daunting which is why consulting a heating and cooling professional is often a great way to ensure that you understand the exact needs that are required to meet your heating or cooling needs. If you have any questions regarding heating or cooling, need HVAC maintenance or service, or would like to speak to one of our HVAC professionals, please feel free to contact our office at any time.


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