Cooling Load Calculator

Cooling Load Basics

Proper cooling load calculation ensures optimal HVAC system sizing. It considers all sources of heat that must be removed to maintain comfortable indoor conditions.

Components of Cooling Load

The total cooling load consists of multiple heat sources:

• Envelope Load: Heat transfer through walls, roof, and windows
• Solar Heat Gain: Sunlight entering through windows
• Internal Gains: Heat from people, lights, and equipment
• Ventilation Load: Fresh air that must be cooled
• Infiltration: Hot air leaking into the building

Simplified Calculation Method

For residential applications, a simplified approach provides accurate estimates:

• Base load: Square footage × 25 BTU/sq ft
• Occupant load: Number of people × 400-600 BTU each
• Equipment: Wattage × 3.41 BTU per watt
• Windows: Window area × 20-100 BTU/sq ft (varies by orientation)
• Adjustments: Add percentages for climate, insulation, ceiling height

Climate Zone Factors

Adjust base calculations for your climate:

• Hot/Humid (tropical): Add 20-30%
• Hot/Dry (desert): Add 15-25%
• Moderate: Use base calculation
• Mixed/Cool: Reduce 10-15%

Why Accurate Load Calculation Matters

Proper sizing is critical for comfort, efficiency, and equipment longevity:

• Undersizing: AC runs continuously, can't maintain setpoint
• Oversizing: Short cycling, poor humidity control, wasted energy
• Right-sizing: Efficient operation, proper dehumidification, comfort