Load planning
HVAC Load Calculator
Aggregate documented preliminary load components; do not use this as a Manual J or final equipment-selection result.
Preliminary load inputs
How this calculation works
The tool sums user-supplied envelope, solar, people, lighting, equipment, and outdoor-air sensible components. Lighting and equipment watts are converted at 3.412141633 BTU/h per W; outdoor-air sensible load is calculated as 1.08 × CFM × ΔT.
Variables and limits
Enter envelope and solar loads from a documented method. Window area, orientation, insulation, exterior exposure, climate, infiltration, humidity, and occupancy affect those inputs. Latent loads, hourly heat-storage effects, equipment performance, duct losses, and codes are not resolved here.
Example
Enter the component loads from a preliminary worksheet, then use the output to compare BTU/h, tons, kW, and sensible supply airflow.
Important
Manual J evaluates residential heating/cooling loads; Manual S selects equipment from that load. Commercial work needs an appropriate detailed method such as ASHRAE heat-balance or RTS. Confirm final design with a qualified professional.
FAQ
Can I enter zero for a component?
Yes, only when that component is genuinely absent or accounted for elsewhere.
Does the CFM result set ventilation?
No. It is a sensible cooling airflow estimate using your supply-air temperature difference; ventilation must follow the applicable project and code requirements.