LoadCairn / Cooling load guide
Data center cooling load calculator guide
For data-center and critical-facility planning, review a first-pass cooling-load estimate built from IT power, lighting, people, and an envelope heat-gain value you supply. The calculator shows its arithmetic and assumptions alongside the result.
Estimate method
Arithmetic sum / planning only
Total BTU/hr = ((IT kW × 1,000) + lighting W) ÷ 0.2930711 + (people × 450) + envelope BTU/hr
Refrigeration tons = total BTU/hr ÷ 12,000
Thermal cooling kW = total BTU/hr × 0.0002930711
Thermal kW is a cooling-load quantity, not electrical demand. These conversions do not add equipment efficiency or fan power.
01 / Inputs and formula
What the estimate uses
IT kW is converted to watts and added to lighting watts, then divided by 0.2930711 to express the electrical input as BTU/hr. The calculator adds the people and envelope contributions, then converts the total to refrigeration tons and thermal kW.
Total BTU/hr = ((IT kW × 1,000) + lighting W) ÷ 0.2930711 + (people × 450) + envelope BTU/hr
The current editable example uses 8 kW IT load, 1,200 W lighting, 6 people, and 5,000 BTU/hr envelope heat gain. These are illustrative defaults, not recommended design values.
Supported inputs
- IT electrical load
- Enter the IT electrical load in kilowatts (kW).
- Lighting electrical load
- Enter the lighting electrical load in watts (W).
- People count
- Enter a whole-number count of people in the conditioned space.
- Envelope heat gain estimate
- Enter your own estimate in BTU/hr; the calculator does not derive envelope gain from building details.
Refrigeration tons = total BTU/hr ÷ 12,000
Thermal cooling kW = total BTU/hr × 0.0002930711
02 / Assumptions and limits
A planning estimate, with boundaries
This arithmetic total is a first-pass estimate. Its result depends on the values you enter and on the simplified heat assumptions below.
Assumes
- All IT electrical input is treated as heat in the conditioned space.
- All entered lighting electrical input is treated as heat in the conditioned space.
- Each person adds 450 BTU/hr: 250 sensible plus 200 latent, using the calculator’s illustrative moderately active office-work assumption at 75°F.
- Envelope heat gain is supplied by the user and is not derived from building details.
Does not model
- Design weather, solar gain, envelope construction, and thermal storage or time delay.
- Ventilation, infiltration, airflow, and cooling distribution.
- Schedules, load diversity, simultaneous peaks, and fan or system effects.
- Cooling redundancy and heat rejected outside the room by liquid-cooled equipment.
- Changes in occupant activity or room conditions that alter people heat gain.
This is a first-pass arithmetic estimate, not a peak design-load calculation, compliant design, or equipment recommendation. Equipment sizing needs model-specific manufacturer data at stated rating conditions.
03 / Run an estimate
Review your cooling-load inputs
Enter the values for your planning scenario, then inspect the worked calculation and assumptions alongside the result.