Enter Shop Data
Example Data Table
| Shop type | Area | People | Equipment | Typical concern |
|---|---|---|---|---|
| Auto repair bay | 2,400 sq ft | 6 | 9,000 W | Door cycling and motors |
| Woodworking shop | 1,800 sq ft | 4 | 7,500 W | Dust exhaust makeup air |
| Fabrication shop | 3,500 sq ft | 8 | 14,000 W | Process heat and ventilation |
Formula Used
Net wall area = 2 × (length + width) × height − windows − doors.
Envelope load = U × area × temperature difference for each surface.
Infiltration CFM = shop volume × air changes per hour ÷ 60.
Air sensible load = 1.08 × total CFM × temperature difference.
Air latent load = 0.68 × total CFM × humidity grain difference.
Electrical heat = watts × 3.412 × use factor. Motor heat = HP × 2545 × run factor.
Final load = (sensible load + latent load) × (1 + safety margin ÷ 100).
Required tons = final load ÷ 12,000. Supply CFM = sensible load ÷ (1.08 × supply air split).
How to Use This Calculator
- Choose cooling or heating mode.
- Enter shop length, width, height, and design temperatures.
- Add U-values for walls, roof, floor, windows, and doors.
- Enter infiltration, ventilation, humidity, people, lighting, and tools.
- Add solar, motor, process, and safety values.
- Press the calculate button and review the result above the form.
- Download CSV or PDF results for early project records.
Shop Thermal Load Planning
A shop gains heat from many paths. Walls, roof panels, doors, windows, people, lights, tools, motors, and fresh air all add load. A small missed item can change the cooling size. This calculator keeps each part visible. It helps builders compare upgrades before work starts.
Why Loads Change
Thermal load is not fixed. Outdoor temperature changes it. Solar exposure changes it. Door use changes it. Equipment schedules can change it fast. A welding bay may need more capacity than a clean storage zone. A woodworking area may also need more ventilation. That air must be cooled or heated after it enters the shop.
Construction Inputs Matter
Good measurements make better answers. Wall area should exclude windows and doors. Roof area should match the actual shop footprint. U values should reflect the final assembly. Insulation, sheathing, cladding, roof color, and air sealing all affect the number. The calculator accepts custom values so you can model rough walls, insulated walls, metal panels, and mixed openings.
Internal Gains
Lights and tools become heat inside the shop. Motors also add heat, especially when they run for long periods. People add sensible and latent load. Process heat can include ovens, curing rooms, compressors, welding stations, or finishing equipment. These gains can exceed the envelope load in busy shops. That is why the form separates each source.
Airflow and Moisture
Infiltration and ventilation are important. Air changes per hour estimate leakage and door cycling. Ventilation CFM covers required fresh air or exhaust makeup. Temperature difference drives sensible load. Humidity difference drives latent load. Latent load matters for comfort, coatings, storage, and corrosion control.
Using the Result
The final load is an estimate. It is not a permit design. Use it to compare options, budget systems, and speak with a licensed designer. Check local codes. Confirm ventilation rules. Review equipment manuals. Add safety margin carefully. Too little capacity hurts comfort. Too much capacity can short cycle. A balanced estimate supports better shop performance, lower energy waste, and more reliable construction decisions.
Result Checks
Review the largest line item first. It may show a weak roof, leaky doors, or heavy machine load. Test one change at a time. Save each result. This habit makes budget choices easier and helps teams explain upgrades more clearly.
FAQs
What is a shop thermal load?
It is the heating or cooling demand created by the building shell, air leakage, ventilation, people, lighting, machines, motors, and process heat inside a shop.
Can this size my final HVAC equipment?
Use it for planning and budget checks. Final equipment sizing should be reviewed by a qualified designer who knows local code, ventilation rules, and the exact shop use.
Why are equipment watts included?
Most electrical power used inside the shop becomes heat. High tool loads can dominate the final total, especially in fabrication, repair, and woodworking spaces.
What does ACH mean?
ACH means air changes per hour. It estimates how often shop air is replaced through leakage, door openings, cracks, and general infiltration.
Why does ventilation increase load?
Fresh air must be heated or cooled to indoor conditions. It may also add moisture, which creates latent cooling demand in warm climates.
How should I enter U-values?
Use values that match the finished wall, roof, floor, window, and door assemblies. Lower U-values usually mean better insulation and lower load.
What is roof solar allowance?
It is an extra temperature allowance for sun-heated roofing. Use a higher value for dark roofs, metal roofs, and exposed sunny buildings.
Why include humidity grains?
Humidity difference helps estimate latent cooling load. This is useful for shops with fresh air, open doors, coatings, storage needs, or moisture-sensitive work.
What safety margin should I use?
Many early estimates use 5% to 15%. Use caution. Oversizing can cause short cycling, poor humidity control, and higher equipment cost.
Can I use this for heating mode?
Yes. Select heating mode and set indoor and outdoor design temperatures. Solar and latent cooling items are reduced where they do not apply.
Why is supply airflow shown?
Supply airflow helps connect the thermal load to duct planning. It is based on sensible load and the selected supply air temperature split.