Before investing in a new commercial air conditioner, it is important to do your research. How do you know what kind you need or what size it should be? Will it cool the entire workspace or just one room? We’re here to help you determine the right air conditioner for your business or condo building.
How To Calculate The Correct Size Of AC For Your Business
Warning: There Is Math Involved
There is actually a lot of math that goes into determining the right size of air conditioner for a structure. One rule of thumb to get a rough idea on system sizing can be used:
- Calculate the square footage of the space requiring cooling. (assuming 8’ ceiling)
- Divide the square footage by 500.
- Multiply the number from Step 2 by 12,000. This is the required Btu’s needed to be removed from the space in order to cool it.
- Add 380 Btu for each occupant working in the space all day.
- Add 1,000 Btu for each window in the space
Example: If you have a 5000 square foot space with 10 people working there and there are 6 windows.
- 5000 square feet
- 5000 ÷ 500 = 10
- 10 x 12,000 = 120,000 BTU
- 380 x 10 = 3,800 BTU
- 6 x 1000 = 6,000 BTU
- Total BTUs required is 129,800 BTUs
There are 12,000 BTU in one ton so the required cooling capacity would be 129,800 ÷ 12,000 =10.81 tons.
The result is a rough idea of the minimum BTU requirement to cool the space.
There are many factors that need to be taken into consideration to properly size an air conditioning unit. To properly size the unit required a heat load calculation should be performed to achieve the correct cooling capacity needed for each building.
Heat Load Calculation
Heat load calculation refers to the process of determining heat load for a certain space or quantity of matter. Heat load is the amount of heat energy that needs to be added to maintain a desired temperature setpoint. From there, it breaks down in to sensible heat loads and latent heat loads.
Sensible Heat Loads
This is heat that a substance absorbs. Sensible heat load of a building is the total of the following.
- Air introduced to the building by ventilation
- Solar heat transmitted through glass windows
- Heat generated by equipment and/or computers
- Heat transmitted through the building envelope thru floors, roof, and walls
- Body heat from building occupants
- Heat from lighting fixtures
Latent Heat Loads
Latent heat comes from moisture that is added to the space from external or internal sources, this requires dehumidification to remove the moisture. Sources of latent heat include.
- Outdoor air with high humidity levels from infiltration or ventilation
- Occupant respiration and physical activity.
- Moisture generated from equipment
Other factors to take into consideration include
- Outdoor climate
- Direction windows face
- Window construction
- Type of building envelope construction
- Fresh air requirements for occupants
- Ceiling height
Why Does Commercial Air Conditioner System Size Matter?
If you have a system that is oversized the unit will run for short periods of time and satisfy the setpoint at the thermostat but also create temperature swings with cold and hot spots. It will not properly dehumidify the space leaving a cool but humid space. If the unit is undersized the humidity will be ok, but the unit will run constantly and not be able to reach the temperature setpoint resulting in poor energy efficiency.
It’s important for a healthy indoor environment to include a cool , comfortable working temperature. Don’t wait for another heat wave to look into a commercial air conditioner for your business or building!
With over 40 years of professional HVAC experience, the experts at TRI-AIR can help improve your indoor air temperature and prepare your business for the new normal.
Contact us today to schedule an inspection and calculation to make sure your A/C is working according to specifications for building use and occupancy.
Call Now! (905) 470-2424