Cooling Load Calculator

Calculate building cooling load in BTU/hr to properly size your air conditioning system.

Room Dimensions

Windows

Internal Loads

Total Cooling Load
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BTU/hr
Tons of Cooling
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kW Equivalent
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Envelope Load
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BTU/hr
Internal Load
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BTU/hr
Recommended AC Unit Size
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How Cooling Load Is Calculated

A cooling load calculation estimates the total heat gain in a space that the air conditioning system must remove. Key components include:

  • Envelope load: Heat gain through walls, roof, and windows based on area, insulation, and outdoor temperature
  • Solar gain: Heat from sunlight entering through windows, varying by orientation
  • Internal gains: Heat from people (~400 BTU/hr sensible per person), equipment, and lighting
  • Infiltration: Warm outside air entering through gaps and cracks

1 Ton of cooling = 12,000 BTU/hr. Residential systems typically range from 1.5 to 5 tons.

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