How many Btu per square foot for air conditioning?

Answer 1

600 spf

A good general rule of thumb is 20 BTU per square foot. So, a 200 sf room would require a 4000 BTU ac unit.

If you use 20btu per square foot to determine the required tonnage, you will be under sizing your system. For example 20btux1500sf=30000btu. There are 12000 btu per ton so you are using a 2.5 ton system to cool 1500 sf. On a hot summer day your electric meter will be spinning like a tilt-a-whirl at the county fair. Your air conditioner is designed to run at it peak performance when the ambient temperature is 95 degrees or below. When the ambient heat or heat index exceeds 95 degrees you a/c is working harder and running longer. When sizing an a/c system you should take into consideration the summer climate where you live. In Texas we use 500 sf per ton as a rule with homes that have 8 foot ceilings, however walls with western exposure, windows facing the west (sun set) and vaulted or high ceilings should be considered in your determination. In commercial application you use 400 sf per ton, but you also factor the number of people occupying the space, equipment that generates heat and the amount of make up air that is required.

0sf-750 sf= 1.5 ton

751-1000sf= 2.0 ton

100sf1-1250sf=2.5 ton

1251sf-1500sf=3.0 ton

1501sf-1750sf=3.5 ton

1751sf-2000sf=4.0 ton

2001sf-2500sf=5.0 ton