Formula and input notes
Screening cooling load (BTU/h) = conditioned area × load factor × adjustment factor; nominal tons = BTU/h ÷ 12,000
| Input | Practical note |
|---|---|
| Conditioned area | Use the floor area served by the proposed system, excluding unconditioned zones; area alone does not describe the building load. |
| Load factor | This user-supplied BTU/h-per-square-foot factor controls the screening load directly. It is not derived from the envelope or weather by this tool. |
| Ceiling/climate factor | Use this multiplier only for an adjustment you can justify; it combines effects that a full load calculation would model separately. |
Worked air conditioner btu example
Air Conditioner BTU Calculator example: 721 ft² × 25 BTU/h·ft² × 1.1 = 19,828 BTU/h. Dividing by 12,000 gives 1.65 nominal cooling tons.
Use BTU/h as a preliminary load estimate
Read BTU/h as a screening load and nominal tons as a unit conversion, not as a recommendation to choose the next larger nameplate.
Envelope and weather inputs this model omits
Solar exposure, glazing, climate design temperatures, envelope leakage, insulation, humidity, ventilation, ducts, people, and equipment drive cooling load.
Questions specific to this calculation
What does the displayed BTU/h result represent?
It is conditioned area multiplied by the user-entered BTU-per-square-foot factor and adjustment multiplier. It is a screening estimate, not a room-by-room or whole-building load calculation.
Can the BTU estimate select an air conditioner?
No. Final equipment selection must follow a proper cooling-load calculation and equipment performance data at the relevant design conditions. Oversizing and undersizing both create performance problems.
For a final residential cooling load, use a calculation performed under ANSI/ACCA Manual J; the displayed BTU/h screen does not implement that procedure.