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How to Size a Commercial Air Conditioner

Category: Rental

What to Consider When Sizing Your HVAC System

Your sizing evaluation should encompass multiple factors.

Square Footage

The building’s footprint plays a crucial role when sizing your commercial HVAC unit. Generally, a more spacious structure requires a larger and more powerful HVAC system. A 1- or 2-ton model can often meet the needs of a smaller facility, while a sprawling warehouse, manufacturing plant or office building may require up to a 30-ton system.


What’s the weather like in your area? If you enjoy moderate temperatures throughout the year, you could likely get by with a smaller system than a similar-sized building in a more severe climate zone. The Nebraska and western Iowa region is one that may require a larger HVAC system due to its hot, humid summers.

Number of Building Occupants

Is the building sparsely populated, or does it have many regular occupants, customers and visitors? Are people close together or spread out across the facility? Depending on the layout and spacing, you may not have the same cooling requirements in every area.

Amount of Insulation

A well-insulated building helps prevent the loss of cooled air and is more energy-efficient. You can often get by with a smaller, less powerful HVAC unit if you install updated insulation, especially in buildings with basements and attics.

Building Materials for Walls and Floors

Some building and flooring materials retain heated and cooled air better than others. You’ll need to assess these in all parts of your facility and note the differences in areas such as office spaces and warehouses.

Window Number, Type and Condition

If your windows are older or drafty, you’ll need a larger HVAC system to compensate for the energy loss. Another option is to upgrade to more modern and energy-efficient products. Also, the number of windows is important for determining the amount of natural light a space receives, which impacts HVAC system performance.

Presence of Heat-Generating Appliances

Does your building contain equipment or machinery that produces high volumes of heat? You’ll probably need a larger HVAC system to meet the building’s additional cooling requirements, especially during the summer months. Lighting and computer equipment can also contribute to a warmer indoor environment.


How to Pick the Right Size AC for a Business

Once you’ve assessed these factors, you’re ready to perform a more precise size calculation. HVAC units are sized in half-ton increments. Their output is measured in British Thermal Units (Btu), which represent the amount of heat necessary to warm a pound of water by one degree Fahrenheit. A 1-ton air conditioning unit can remove approximately 12,000 Btu per hour.

Commercial AC Calculator:

A commercial air conditioner size calculator can approximate your building’s Btu requirements through a step-by-step process:

  1. Determine the square footage of the facility or specific areas you intend to cool. This calculator applies a standard of an 8-foot-high ceiling. Buildings with higher ceilings will likely require a larger unit.
  2. Divide the square footage by 500.
  3. Multiply the figure you attained in the previous step by 12,000 to determine the approximate base Btu number you’ll need to meet your cooling requirements.
  4. Add 380 Btu for each person who occupies the building or space. If you can’t arrive at an exact figure, use a daily average or a ballpark estimate.
  5. Add 1,000 Btu for each window in the area. Include an additional 1,200 Btu for each kitchen present.

Example of a Cooling System Size Calculation

Here’s one example of using a commercial air conditioner size calculator for a 10,000-square-foot space:

  • Divide 10,000 by 500 to get 20.
  • Multiply 20 by 12,000 for a total of 240,000 Btu.
  • Assuming six workers occupy the space, add another 2,280 Btu (multiply 380 by 6) for a total of 242,280 Btu.
  • Add another 2,000 Btu if the area has two windows (multiply 1,000 by 2) for a total of 244,280 Btu.
  • Since there aren’t many multiplying factors present, dividing the result of 244,280 by 12,000 indicates that a 20-ton cooling system will likely be sufficient depending on insulation and other elements.

Get Expert Cooling System Sizing Assistance

Do you need help sizing your commercial HVAC unit in Nebraska or Pottawattamie County in Iowa? The professional team at NMC The Cat® Rental Store can point you in the right direction. Contact us today.