Capture true loads from site equipment and systems. Plan HVAC capacity with transparent calculations today. Export reports, compare scenarios, and reduce costly oversizing risks.
Add multiple equipment lines and calculate a combined heat load.
These sample values help validate your entries and expected ranges.
| Equipment | Qty | Rated | Load % | Diversity | Heat % | Sensible % | Result Heat (kW) |
|---|---|---|---|---|---|---|---|
| Concrete mixer motor | 2 | 3.0 kW | 75 | 0.8 | 100 | 100 | ~4.00 |
| Lighting banks | 1 | 2.5 kW | 100 | 1.0 | 100 | 100 | ~2.78 |
| Welding set | 1 | 5.0 kW | 60 | 0.6 | 90 | 95 | ~1.90 |
1) Convert rated power to kW
2) Estimate electrical input
Electrical input is approximated using efficiency.
3) Base heat to the space
4) Apply operating factors
5) Unit conversions
Temporary offices, shelters, plant rooms, and enclosed work zones often fail comfort checks because equipment heat is underestimated. Motors, welders, compressors, pumps, and task lighting convert most input energy into room heat. When airflow is limited, the heat accumulates quickly, raising dry‑bulb temperature and forcing higher cooling capacity. A structured estimate prevents costly oversizing, yet avoids nuisance trips from undersized units.
Nameplate power is a starting point, not the delivered load. This tool converts rated power to kW, accounts for efficiency to estimate electrical input, and then applies operating intensity. A 5 kW machine at 60% load does not create 5 kW of heat continuously. Diversity further reduces the coincident peak when multiple items cycle or are used by different crews.
Most electrical equipment is mainly sensible heat. However, processes that introduce moisture—wet cutting, steam cleaning, or humidified curing—can add latent load. By entering a sensible fraction, you can split totals into sensible and latent kW, supporting coil selection and dehumidification checks. Reporting in BTU/h and refrigeration tons helps align with common HVAC schedules.
Some motors drive loads outside the conditioned space. When shaft power leaves the room, only motor losses become heat inside. Similarly, if heat is captured or exhausted, the heat‑to‑space fraction should be reduced. These two controls allow more realistic modelling for fans, conveyors, pumps, and outdoor-driven machinery.
Use the calculated peak heat as an internal gain input for your cooling load summary, then add envelope, people, ventilation, and solar loads as applicable. Keep assumptions visible: hours/day, diversity, and heat fractions should match method statements. Export the CSV or PDF to attach to submittals, RFIs, or commissioning records for temporary and permanent systems.
For shared handheld tools, 0.4–0.7 is common because crews rarely operate every tool simultaneously. Use higher values when tasks are continuous or tools are dedicated to each worker.
Yes in most indoor cases. Nearly all lighting energy becomes heat within the space. Reduce the value only if fixtures are outside the conditioned area or significant heat is vented away.
Use 85–92% for many small and medium motors. Older or heavily loaded equipment may be lower. When unsure, use a conservative lower efficiency to avoid underestimating electrical input.
Select “Yes” when a motor is inside but drives an external load through a shaft or belt, such as outdoor pumps or fans. The tool then counts mainly the motor losses as room heat.
Hours/day supports an energy estimate in kWh/day for planning generators and temporary power. Peak heat is still calculated from coincident factors like load and diversity.
This calculator is best for electrically rated power. For fuel-fired equipment, convert fuel input to kW and apply a realistic heat-to-space fraction. Add ventilation impacts separately for safety and exhaust control.
It is a strong internal-gain component, but not the whole load. Add envelope, people, ventilation, and solar gains, then apply appropriate safety margins and equipment derating for site conditions.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.