Detailed Walk-In Heat Load Calculator

Calculate each heat load component for a walk-in cooler or freezer with detailed breakdowns.

Inside length of the walk-in box.
ft
Inside width of the walk-in box.
ft
Inside height of the walk-in box.
ft
Insulation R-value. Typical: R-25 cooler, R-32 freezer panels.
Temperature surrounding the walk-in (kitchen, dock, outdoor).
deg F
Desired interior temperature of the walk-in.
deg F
Number of times the door is opened daily. Heavy use: 50+, moderate: 20-50, light: under 20.
per day
Weight of product loaded daily that must be cooled from entry temp to box temp.
lbs/day
Temperature of product when placed in the walk-in.
deg F
Total wattage of lights inside the walk-in.
watts
Total wattage of evaporator fan motors. Each is typically 50-200W.
watts
Person-hours per day. Each person adds approximately 950 BTU/hr of heat.
person-hrs

Results

Wall/Ceiling Transmission:
Heat gain through insulated panels based on area, R-value, and temperature difference.
-BTU/hr
Floor Transmission:
Heat gain through the floor. Uses lower R-value for slab-on-grade.
-BTU/hr
Infiltration (Door):
Heat gain from warm air entering when doors open. Major load component.
-BTU/hr
Product Load:
Heat removed from product cooling. Based on weight, specific heat, and temperature pull-down.
-BTU/hr
Lights + Fans + People:
Internal heat gains from lighting, fan motors, and occupants.
-BTU/hr
Total Heat Load:
Sum of all heat load components with 10% safety factor.
-BTU/hr
Required Compressor:
Cooling capacity in tons of refrigeration (1 ton = 12,000 BTU/hr).
-tons
Reference: ASHRAE Refrigeration Handbook Ch. 24. Heatcraft, Bohn, Larkin walk-in engineering guides.