cubic ft
BTU

How to Calculate HVAC Load

The load calculation considers three primary factors:

  1. Room Volume: Calculate the cubic feet of the room by multiplying the length, width, and height.
  2. Insulation Level: Accounts for heat retention; rated as poor, average, or good.
    • Poor: 1.5 BTU/sq ft
    • Average: 1 BTU/sq ft
    • Good: 0.5 BTU/sq ft
  3. Climate Factor: Represents the heat or cooling demand based on your geographical zone.
    • Hot Climate: 10 BTU/sq ft
    • Temperate Climate: 8 BTU/sq ft
    • Cool Climate: 6 BTU/sq ft

Formula:

\text{Required HVAC Load (BTU)} = \text{Room Area (sq ft)} \times \text{Insulation Level} \times \text{Climate Factor}

Example calculation:

You have a 20 ft x 15 ft room with an 8 ft ceiling in a temperate climate, and the insulation level is average.

  1. Room Volume:
    20 \times 15 \times 8 = 2,400 \, \text{cubic ft}
  2. Room Area:
    20 \times 15 = 300 \, \text{sq ft}
  3. HVAC Load:
    300 \, \text{sq ft} \times 1 \, \text{BTU/sq ft} \times 8 \, \text{(climate factor)} = 2,400 \, \text{BTU}

You need an HVAC system with at least 2,400 BTU capacity for efficient heating or cooling.

Example diagram of a hvac system:

Air Conditionar Refrigeration line Indoor coil Register Supply Air Duct Furnace Thermostat