Heating and Cooling Load Calculator for Produce Coolers and Warm Rooms

This calculator provides an estimate of the heating or cooling load for a produce storage room of given dimensions, insulation, and sealing characteristics at a given set of temperatures. More information about cooling load calculations can be found in the Heatcraft Engineering Manual.

Target Inside Temperature (°F):

More information on storage temperatures for different crops can be found in the Crop Storage Planner or Handbook 66.

Quick reference:

  • Roots, cabbage, onions, garlic: 32 °F
  • Potatoes, tubers: 40 °F
  • Winter squash, cukes, peppers, tomatoes, sweet potatoes: 55-60 °F
  • Outside Design Temperature (°F):

    More information on outside design temperatures can be found in the Energy Star Design Temperature Limit Reference Guide.

    Quick Reference: In Vermont:

  • Winter (heating) design temperatures are between -4 and -18 °F.
  • Summer (cooling) design temperatures are between 84 and 87 °F.
  • Ground Temperature (°F):

    Ground temperatures can be found on the map at Build It Solar.

    Quick Reference: In Vermont, the range is 42 to 47 °F.

    Room Dimensions
    Width (ft):
    Length (ft):
    Height (ft):

    Insulation (hr-ft2-F/BTU)
    Wall R-value:
    Ceiling R-value:
    Floor R-value:

    Insulation R-values are typically given on a "per inch" basis and can be found at the Colorado Energy site.

    Quick reference: R-values per inch of thickness:

  • Polyurethane spray foam: 6.25 per inch
  • Foil faced polyisocyanurate: 5.6 per inch
  • Rigid extruded polystyrene board: 5 per inch
  • Mineral wool: 4 per inch
  • Wood lumber and plywood: 1.25 per inch
  • Concrete: 0.08 per inch.
  • The R-value of layered materials adds together. For example, 2 inches of polystyrene board (2x5=10) under 4 inches of concrete (4x0.08=0.32) has an R-value of 10.32.

    Sealing and Tightness
    Air Changes Per Hour (ACH):

    ACH is a measure of 'tightness', how well sealed the space is and how frequently the door is opened.

    Quick Reference: For long-term storage which is well-sealed with few door openings use 1. For a less well-sealed cooler or a walk-in with lots of traffic in and out, use something closer to 3 ACH.


    You will need to this space with BTU/hr (or watts).

    Heat Loss (+) or Gain (-) in BTU/hr:




    Air Changes:

    Wall Area: ft2

    Ceiling Area: ft2

    Floor Area: ft2

    Wall Perimeter: ft

    Overall Heat Transfer Coefficient (UA): BTU/hr-°F-ft2



    Inside: °F

    Outside: °F

    Ground: °F


    Width: ft

    Length: ft

    Height: ft

    Insulation R-value:

    Walls: hr-ft2-F/BTU)

    Ceiling: hr-ft2-F/BTU)

    Floor: hr-ft2-F/BTU)

    Air Changes per Hour: