How to Choose the Right Unit
How to Calculate the Correct BTU
EXAMPLE: Window AC in a Bedroom
You have a 10' by 20' bedroom with 4 large windows that face the sun in the morning and the evening. Your ceiling is vaulted and the room usually has 2 people and a large dog in it.
To estimate the BTU required to cool the space, the math would break down like this:
- Baseline square foot coverage:
10 x 20 = 200 sq. ft. = 6,000 BTU
- For rooms with a lot of windows, increase BTU by 10%:
6,000 BTU x .10 = 600 BTU + 6,000 BTU = 6,600 BTU
- For ceilings higher than the standard 8 ft. height, increase BTU by 20%:
6,600 BTU x .20 = 1,320 BTU + 6,600 BTU = 7,920 BTU
- For ceilings higher than the standard 8 ft. height, increase BTU by 20%:
12,100 BTU x .20 = 2,420 BTU + 12,100 BTU = 14,520 BTU
- Add in 1,800 BTU to account for both room occupants and the large dog:
7,920 BTU + 1,800 BTU = 9,720 BTU
With all factors accounted for, to effectively cool your bedroom, you would need a: 10,000 BTU window air conditioner