Calculator Inputs
Enter envelope, occupancy, equipment, and airflow data. The calculator estimates sensible cooling load for preliminary engineering sizing.
Example Data Table
| Parameter | Example Value | Unit |
|---|---|---|
| Floor area | 120 | m² |
| Ceiling height | 3 | m |
| Outdoor temperature | 38 | °C |
| Indoor temperature | 24 | °C |
| Wall / roof / window area | 140 / 120 / 28 | m² |
| Wall / roof / window U-value | 0.65 / 0.45 / 2.70 | W/m²·K |
| Occupants | 10 | persons |
| Equipment load | 3200 | W |
Formula Used
This calculator estimates sensible cooling demand. For detailed HVAC design, latent load, humidity control, duct losses, and local standards should also be reviewed.
How to Use This Calculator
- Enter the conditioned floor area and average ceiling height.
- Set the outdoor design temperature and desired indoor temperature.
- Add exposed wall, roof, and window areas with their U-values.
- Input a realistic window solar gain factor for sun exposure.
- Enter occupants, sensible heat per person, lighting density, and equipment load.
- Provide air changes per hour, air density, and air specific heat.
- Adjust diversity and safety factors to reflect design practice.
- Click the calculate button to display the result above the form, then export the summary to CSV or PDF.
Frequently Asked Questions
1. What does thermal load mean?
Thermal load is the amount of heat a cooling system must remove to maintain the selected indoor condition. It combines heat entering through the building envelope, air movement, people, lighting, and equipment.
2. Is this calculator for cooling or heating?
This setup is mainly for sensible cooling load estimation because it assumes outdoor temperature is higher than indoor temperature. A heating tool would reverse the condition and often use different assumptions.
3. Why are U-values important?
U-values measure how easily heat moves through walls, roofs, and windows. Lower U-values mean better insulation, smaller conduction loads, and potentially reduced equipment size and operating cost.
4. What is a solar gain factor?
A solar gain factor estimates the heat entering through glazing from sunlight. It depends on orientation, shading, glass type, season, and local climate. Higher solar gain increases cooling demand.
5. Does the calculator include latent load?
No. This version focuses on sensible load. Moisture removal from outdoor air, occupants, and processes should be evaluated separately when selecting complete HVAC capacity and dehumidification strategy.
6. What does the diversity factor do?
The diversity factor adjusts subtotal load to reflect that some internal gains may not peak at exactly the same time. It helps make preliminary sizing more realistic for many projects.
7. Why add a safety factor?
A safety factor covers uncertainty in assumptions, occupancy variation, solar exposure, and operating changes. It should be used carefully because excessive margin can lead to oversized systems.
8. Can I use this for equipment selection?
Yes, for early comparison and preliminary sizing. Final equipment selection should still consider latent load, ventilation standards, manufacturer data, zoning, duct losses, and applicable engineering codes.