Industrial Cooling Load Calculation
Industrial Cooling Load Calculator
Calculate the cooling load (BTU/hr and tons) required for an industrial enclosure, control room, equipment shelter, or MCC building. ASHRAE-standard methodology with every calculation shown. Print or share the result with one click.
How this works
The cooling load for an enclosed space is the sum of every source of heat entering or being generated inside it. For an industrial enclosure, those sources are:
- Heat conducted through walls, roof, and floor from the warmer outside air
- Solar gain on sun-exposed surfaces (handled via the sol-air temperature method)
- Equipment heat — VFDs, MCCs, PLCs, servers, and other electrical equipment inside
- Lighting heat
- Occupant heat (people add ~450 BTU/hr each)
- Ventilation — outside air brought in for pressurization or fresh-air requirements
The total of all these, plus a safety margin, is the cooling load the air conditioning unit has to remove. Enter your enclosure details on the left and the result panel on the right updates immediately. The detailed calculations below show every step so you can verify the math or hand it off to your engineer.
Inputs Summary
Transparent calculation
Every value below is shown with its formula and inputs. If your engineer wants to verify or adjust any assumption, this is what they need.
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Reference data and methodology
Wall, roof, and floor U-values (sources)
U-values shown in the dropdowns above come from ASHRAE Handbook — Fundamentals (2017), Chapter 26 (Heat, Air, and Moisture Control in Building Assemblies) and Chapter 27 (Climate Design Information). They reflect the overall heat transfer coefficient of the assembly, including standard surface films and material conductivities.
| Assembly | U-value (BTU/hr·ft²·°F) | Notes |
|---|
Climate design temperatures (sources)
Outdoor design temperatures used in this calculator are the ASHRAE 2.5% summer dry-bulb design conditions from the ASHRAE Climate Design Conditions (2017). This means the actual temperature exceeds the design value only 2.5% of summer hours — a standard engineering assumption for cooling load sizing.
| City | Design °F (2.5%) |
|---|
Solar exposure (sol-air temperature method)
Solar gain is accounted for using a simplified sol-air temperature adjustment. The effective outdoor temperature for sun-exposed surfaces is increased to account for the absorbed solar radiation:
T_solair = T_air + (α × I / ho)
Where α = surface absorptivity (~0.7 for typical industrial finishes), I = incident solar radiation (BTU/hr·ft²), and ho = outside surface heat transfer coefficient (~4 BTU/hr·ft²·°F in summer).
The calculator applies these effective ΔT adders:
| Sun exposure | Walls (avg) | Roof |
|---|---|---|
| Mostly shaded | +0°F | +0°F |
| Partial sun | +10°F | +25°F |
| Full sun | +18°F | +45°F |
Equipment heat conversion
Electrical equipment in steady state converts essentially all input power to heat. The conversion factor is:
Q (BTU/hr) = Watts × 3.412
For typical industrial equipment:
- VFDs: dissipate ~3% of rated motor power as heat (100 HP VFD = ~2.2 kW = ~7,500 BTU/hr)
- MCCs: ~150-300 W per section (typical 12-section MCC: ~2,000-3,500 W)
- PLC / instrument panels: 50-500 W each
- Servers / rack equipment: use nameplate watts (typically 200-1500 W per server)
- UPS units: idle losses of ~5-10% of capacity
Occupant heat gain
Per ASHRAE, a seated person engaged in light office or control room work releases approximately:
- Sensible heat: 245 BTU/hr (raises air temperature)
- Latent heat: 205 BTU/hr (water vapor — increases humidity)
- Total: 450 BTU/hr per person
The calculator uses the total figure since most industrial cooling units handle both sensible and latent load.
Ventilation load
Outside air brought in for pressurization or ventilation must be cooled to the indoor temperature. The sensible load is:
Qsensible (BTU/hr) = 1.08 × CFM × ΔT (°F)
Where 1.08 is the product of standard air density (0.075 lb/ft³), specific heat of air (0.24 BTU/lb·°F), and 60 min/hr. This calculator handles sensible ventilation load; for humid climates the latent component should be added by the design engineer (typically 30-50% of sensible).
Safety margin
Industrial cooling loads are sized with a safety margin to account for:
- Equipment additions over the facility's life
- Door openings and minor air leakage not in the base calculation
- Equipment diversity factors and simultaneity
- Aging of insulation and seals
- Variation in actual climate conditions
ASHRAE-typical practice is 15-25%. We default to 20%, which is the industrial standard for new construction with reasonable load uncertainty.
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