How To Properly Size a Commercial HVAC System

Whether upgrading your existing commercial HVAC unit or getting a new one, it’s important to consider the size and suitability. The size of an HVAC system affects its cost, performance, and maintenance needs. To get the correct size of a unit, you have to do some calculations and understand the basic principles of how an HVAC unit works. How do you size a commercial HVAC system? Let’s take a look.

How To Size a Commercial HVAC

You must consider several factors when deciding the right size of an HVAC unit for your commercial building. They include:

  • The average size of the room and total number of occupants
  • The activities taking place in the room, such as cooking or hot baths
  • The specific amount and type of lighting used in the room. This can be halogen or LED.
  • The position of the building in relation to the sun. Is the property in a shaded area?
  • The difference between your desired temperature and the outside temperature
  • The building’s design and if it has been insulated on the walls and ceiling

HVACs are measured in tons, with most commercial units weighing between 2 and 30 tons. One ton can eliminate approximately 12,000 British Thermal Units (BTU) of heat per hour. With that information in mind, you now need to calculate the cooling load of your building to know the appropriate capacity of the AC to get. But as a general rule, HVAC technicians agree that 25 BTU is enough to cool one sq ft.

HVAC System Sizing Is Important for Energy Efficiency, Performance, and Low Installation Costs

Getting a big HVAC unit does not automatically mean it will serve you well. For instance, if you have a small office, a large HVAC unit can have poor humidity control, leading to discomfort. It will also lead to energy wastage, increasing your bills. On the other hand, an undersized HVAC unit has to overwork to cool or heat a space efficiently, leading to premature wear and tear.

Another thing you have to consider is commercial HVAC load calculation. That means you calculate the exact estimate of the heat gain and heat loss in the building. Heating load calculations allow you to estimate the amount of heat the building is losing during cold seasons. Cooling load calculations estimate the amount of heat the building is gaining during the hot season.

Heat Flow Rate Calculations

You can also get an estimate of the size of the HVAC by calculating space heat gain and the space cooling load. That is the amount of air entering your building versus the amount of air to be removed. To get accurate calculations, you have to consider things like solar radiation going through the window, heat generated by building occupants, equipment, lighting, conduction via the walls and roof, appliances, etc. 

If you’re about to get a new commercial HVAC unit for your building and are unsure of the correct size, Air Climate Control, Inc. is here to help. Our team of experts will come and do the calculations and help you select the right size unit. Contact us about your commercial air conditioning needs.

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