Cooling Load Calculator

Cooling Load Calculator

Wiratama

11/16/20252 min read

1. Definition

A Cooling Load Calculator estimates the amount of heat (in kW or TR) that must be removed from a space to maintain a desired indoor temperature. Cooling load accounts for heat gain from walls, windows, people, appliances, and ventilation.
This tool is widely used in HVAC design for sizing air conditioners, chillers, and ventilation systems.

2. Background Theory

Cooling load is the total heat entering a room due to:

1. Heat Conduction (Walls, Floor, Ceiling)

Heat transfer occurs whenever outdoor temperature is higher than indoor temperature.
A simplified form is:

Where:

  • AAA = area (m²)

  • UUU = overall heat transfer coefficient (W/m²·°C)

  • ΔT\Delta TΔT = temperature difference

For simplified calculators, an average “heat gain factor” is applied.

2. Heat Gain from People

Each person adds sensible + latent heat:

(120 W is typical for offices/houses)

3. Solar Heat Gain from Windows

Depends on area, glazing type, and ΔT:

4. Internal Loads (Equipment, Appliances)

Every electrical device ultimately releases heat:

5. Ventilation / Fresh Air Load

Heat from outside air introduced for ventilation:

Total Cooling Load

The calculator sums all contributions:

4. How the Calculator Works

The calculator performs the following steps:

  1. User inputs:

    • Room area

    • People count

    • Appliances wattage

    • Window area

    • Temperature difference

    • Ventilation rate

  2. The script computes:

    • Conduction load (walls, floor, ceiling)

    • People heat load

    • Window heat gain

    • Ventilation heat load

    • Appliances load

  3. Sums all loads into Watts

  4. Converts to kW

  5. Converts to Tons of Refrigeration (TR)

Finally, it displays:

  • Total cooling load

  • Load breakdown for each component

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