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.
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.
Product Respiration
Respiration Rate (mg/kg-hr):
Product respiration is the heat produced naturally from stored, living produce.
Respiration rate is given in units of mg of CO2 produced per kg of product per hour. The calculator converts this to BTU/hr based on product amount provided above.
The rate of respiration decreases with temperature.
Respiration rates are available in USDA Handbook 66 .
Quick reference: Some selected rates for common produce crops are provided below:
Apples (Fall, storage): 5 mg/kg-hr (between 32 and 41 °F)
Alliums (Garlic, Onions): 5 mg/kg-hr (at 32 °F)
Storage Root Crops (Beets, Carrots): 5-15 mg/kg-hr (at 32 °F)
Cabbage: 8 mg/kg-hr (between 32 and 41 °F)
Potatoes (cured): 12 mg/kg-hr (at 41 °F)
Tomatoes & Peppers: 19 mg/kg-hr (between 50 and 60 °F)
Sweet Potatoes: 20 mg/kg-hr (at 59 °F)
Leafy Greens, Lettuce: 21 mg/kg-hr (between 32 and 41 °F)
Cucumbers: 27 mg/kg-hr (between 50 and 60 °F)
Winter Squash: 99 mg/kg-hr (at 50 °F)
Results
You will need to this space with BTU/hr (or watts). This figure includes no margin.
Most referigeration systems are designed to run for 16 of every 24 hours (67% run time) to allow for defrost cycling. This results in a higher cooling load sizing point. In this case, that design point would be BTU/hr
The use of window air conditioning units as a CoolBot(TM) system will require additional adjustment of this load due to the derate of the AC units. In other words, this number is not the size of the AC unit (or units) you will need. Consult the StoreItCold website for additional guidance.
Details
Heat Loss (+) or Gain (-) in BTU/hr:
Total:
Walls:
Floor:
Ceiling:
Air Changes:
Pull Down:
Respiration:
Wall Area: ft2
Ceiling Area: ft2
Floor Area: ft2
Wall Perimeter: ft
Inputs
Temperatures:
Inside: °F
Outside: °F
Ground: °F
Dimensions:
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:
Product Pull Down:
Amount of product: lbs
Specific Heat: BTU/lb-°F
Entering Temperature: °F
Storage Temperature: °F
Pull Down Time: hr
Product Respiration:
Respiration rate: mg/kg-hr
Respiration rate: BTU/ton-day
Respiration rate: BTU/lb-hr