Load planning guide
HVAC Load per Square Foot Guide
BTU/h per ft² is a useful comparison ratio only after the total load and its assumptions are known.
Formula
Load per ft² = total heating or cooling load (BTU/h) ÷ conditioned area (ft²)
Read the ratio with its conditions
| Same floor area, different result | Why the ratio changes |
|---|---|
| Large west-facing glass | Solar cooling gain can raise the peak. |
| Tight, insulated envelope | Conduction and infiltration can be lower. |
| High-occupancy space | People, lighting, equipment, and outdoor air can dominate. |
| High ceiling or exposed area | Geometry and envelope area differ from a compact plan. |
Example
A documented 24,000 BTU/h cooling load over 1,200 ft² equals 20 BTU/h per ft². The same building also needs its design condition, window data, ventilation, internal gains, and humidity assumptions recorded; without those, the ratio cannot be transferred to another project.
Use it correctly
- Calculate or obtain a documented total load.
- Divide by the same conditioned area used in the calculation.
- Compare only with projects of similar climate, envelope, occupancy, and use.
- Return to a project-specific load calculation before selecting equipment.