Example Data Table
| Example Input |
Value |
Reason |
| Room size |
30 ft × 20 ft × 10 ft |
Small commercial room |
| Indoor and outdoor temperature |
75 F and 95 F |
Common design difference |
| Window area |
120 sq ft |
Solar and conduction load |
| Occupants |
8 people |
Sensible and latent load |
| Ventilation |
160 CFM |
Outdoor air load |
| Safety margin |
10% |
Planning allowance |
Formula Used
Wall load: Wall U value × net wall area × temperature difference.
Roof load: Roof U value × roof area × temperature difference.
Window conduction: Window U value × window area × temperature difference.
Solar glass load: Window area × SHGF × shading coefficient × cooling load factor × orientation factor.
People load: Occupants × sensible heat per person, plus occupants × latent heat per person.
Lighting load: Lighting watts × 3.412 × lighting use factor.
Equipment load: Equipment watts × 3.412 × equipment use factor.
Ventilation sensible load: 1.08 × ventilation CFM × temperature difference.
Ventilation latent load: 0.68 × ventilation CFM × humidity grain difference.
Infiltration CFM: Room volume × air changes per hour ÷ 60.
Cooling tons: Final cooling load ÷ 12,000.
How To Use This Calculator
Enter the room dimensions first. Add indoor and outdoor design temperatures. Enter U values for the wall, roof, and glass. Add window area, door area, and roof area. Then enter solar, occupancy, lighting, equipment, ventilation, and infiltration data.
Press the calculate button. The result appears above the form. Review the breakdown before using the final size. Download the CSV file for spreadsheet review. Download the PDF file for a simple project record.
What This Cooling Load Example Shows
A cooling load estimate explains how much heat a room gains. The result helps choose a practical air conditioning capacity. This calculator separates heat sources. It shows envelope gain, solar gain, people load, equipment load, ventilation load, and infiltration load. That makes the example easier to audit.
Why Construction Details Matter
Cooling load is not only a floor area number. Wall area, roof area, glass area, and insulation all change the answer. A small room with poor glass can need more cooling than a larger shaded room. Construction assemblies control conduction. Window exposure controls solar heat. Air leakage can add a hidden load when doors, cracks, or joints are not sealed.
Sensible And Latent Heat
Sensible heat raises dry bulb temperature. Walls, roofs, windows, lights, and equipment usually add sensible heat. Latent heat comes from moisture. People, ventilation air, and infiltration air can add latent heat. A good sizing example includes both parts. This helps avoid a system that cools air but leaves the space humid.
Using The Result
The total load is shown in Btu per hour, tons, and kilowatts. One refrigeration ton equals 12,000 Btu per hour. The tool also estimates supply airflow. It uses the indoor temperature and supply air temperature difference. The rounded capacity helps compare common equipment sizes. The energy estimate uses EER, hours, and power cost.
Good Practice
Use realistic temperatures. Measure windows carefully. Use tested U values when available. Enter higher air changes for loose construction. Use lower values for tight buildings. Add a safety margin only after the base load is complete. Too much margin can cause short cycling. Too little margin can cause poor comfort. Review each line item before selecting equipment. This calculator gives a planning example. Final projects may require local code checks, full room by room design, and professional judgment.
Example Review
Start with the room shape. Then add the wall, roof, and glass data. Next add people, lights, equipment, and air loads. The subtotal shows the basic demand. Duct gain and safety margin are then added. Use the final value for early equipment comparison. Keep notes for every assumption used. This makes later design review easier and clearer for teams.
FAQs
What is a cooling load?
Cooling load is the heat that must be removed from a space. It includes heat from building surfaces, sunlight, people, lighting, equipment, ventilation, and air leakage.
Why is cooling load measured in Btu per hour?
Btu per hour shows the rate of heat gain. Cooling equipment capacity is often compared with this rate, then converted to tons for equipment selection.
What does one cooling ton mean?
One cooling ton equals 12,000 Btu per hour. The calculator divides the final cooling load by 12,000 to estimate the required tonnage.
What is sensible heat?
Sensible heat changes air temperature. Walls, roofs, windows, lighting, and equipment usually add sensible load to the room.
What is latent heat?
Latent heat comes from moisture. People, outdoor air, and infiltration can add moisture load that the cooling system must remove.
Why include infiltration?
Infiltration is unwanted outdoor air entering the room. It can add sensible and latent load, especially in loose or frequently opened spaces.
Should I always add a safety margin?
A small margin helps planning. A large margin may oversize equipment. Oversized systems can short cycle and may not control humidity well.
Can this replace a full HVAC design?
No. It is a planning calculator and example tool. Final construction projects may need room by room design, local standards, and professional review.