Enter ASHRAE style inputs for cooling load estimates. Review sensible, latent, ventilation, and tonnage outputs. Plan HVAC capacity with clearer assumptions for site decisions.
| Input group | Example value | Reason for use |
|---|---|---|
| Outdoor and indoor dry bulb | 40°C and 24°C | Sets the main sensible temperature difference. |
| Glass solar gain | 18 m², SHGC 0.45 | Captures sun driven gain through windows. |
| People load | 18 occupants at 90% | Adds sensible and latent occupant heat. |
| Ventilation | 7.5 L/s per person | Estimates outdoor air sensible and latent load. |
| Allowances | 3% fan and 4% duct gain | Adds common system planning margins. |
The calculator uses simplified ASHRAE-style heat balance inputs for preliminary cooling load planning. It separates sensible and latent loads.
Humidity ratio is estimated from dry bulb temperature, relative humidity, and barometric pressure.
A cooling load estimate starts with clear inputs. Room size, wall area, roof area, glass area, and occupancy define the base load. Outdoor design temperature sets the driving difference. Indoor temperature sets comfort. Humidity adds hidden latent load. A small error in any value can change equipment size. That is why each field uses direct engineering units. The calculator separates envelope, solar, internal, infiltration, and ventilation loads. This keeps the estimate easy to audit.
Walls, roofs, windows, doors, and skylights move heat indoors. The U value measures heat flow through each assembly. A lower U value means better insulation. Glass also gains heat from sun. Solar heat gain depends on glass area, SHGC, shade, and cooling load factor. West glass often needs attention. Roofs can dominate low buildings. Use project drawings when available. Use conservative values when drawings are missing.
People create sensible and latent heat. Lights add sensible heat. Equipment can run hotter than nameplate expectations. Diversity factors reduce loads when everything is not active together. Infiltration covers uncontrolled leakage. Ventilation covers outdoor air required for health. Both streams add sensible heat when outdoor air is warmer. They add latent heat when outdoor humidity is higher. These air loads often decide coil capacity.
The result shows sensible load, latent load, total load, tons, and airflow. Sensible load guides supply air quantity. Latent load guides coil moisture removal. Total load guides capacity. Safety factor adds a planning margin. Use the component table to find large contributors. Improve shade, insulation, air sealing, or lighting where practical. The tool supports early design and budget checks. Final equipment selections still need local codes, full schedules, duct losses, and professional judgment.
Compare watts per square meter with similar rooms. Very high values may show poor glass data, unrealistic equipment loads, or too much outdoor air. Very low values may show missing people, lighting, or roof gains. Check the airflow result against diffuser limits. Check humidity ratio values when climates are humid. Keep notes beside every assumption. Good notes make later revisions faster. They also help owners understand why the selected system size changed before final purchase orders are released onsite.
A cooling load is the heat that must be removed to hold the indoor design condition. It includes heat from walls, roof, glass, people, lights, equipment, infiltration, and ventilation.
No. It is a preliminary estimator. Final selections should use approved design weather, room schedules, local code requirements, duct design, manufacturer data, and qualified engineering review.
Sensible load changes air temperature. Latent load removes moisture. A system must handle both. Humid climates can need more coil capacity even when the sensible temperature difference looks moderate.
The CLTD factor adjusts envelope conduction for solar exposure, time delay, and assembly response. This calculator uses it as a simplified multiplier for early design checks.
SHGC means solar heat gain coefficient. It measures how much solar heat passes through glass. Lower values reduce solar load and can lower cooling capacity needs.
Use values that match the activity level. Seated office work is lower. Kitchens, gyms, and active spaces are higher. Keep both sensible and latent portions documented.
Outdoor air can carry more moisture than indoor air. The coil must remove that moisture. The calculator estimates this with humidity ratio difference and airflow.
Common planning margins range from five to fifteen percent. Use lower values when inputs are reliable. Use higher values when drawings, schedules, or equipment data are uncertain.
Load density shows design watts per square meter. It helps compare rooms of different sizes. Very high or low values should be checked against assumptions.
This version uses metric inputs. You can convert imperial dimensions before entry. The output includes BTU per hour and tons for common cooling equipment references.
Airflow is estimated from sensible load and supply air temperature difference. It gives an early duct and diffuser planning value, not a final air balance.
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.