While some companies prefer to estimate heat load based on the volume (ie. cubic feet) of the ice box, we have found it more accurate to make the calculation based on the interior surface area. This method better estimates the additional heat load which occurs when an odd box size gives reduced volume but a large surface area.
Use the numbers below to estimate the total 24 hour heat load experienced by a couple living aboard in a tropical climate. First, measure your box to determine it's interior surface area (including partition dividers) in square feet. Then multiply it by the numbers below.
HEAT INFLUX PER 24 HRS., PER SQ. FT. OF INTERIOR BOX SURFACE AREA
Insulation “R” Value |
Insulation Thickness |
Refrigerator Box (BTUs) |
Freezer Box (BTUs) |
10 |
2” |
150 |
280 |
15 |
3” |
120 |
225 |
20 |
4” |
100 |
185 |
25 |
5” |
90 |
170 |
30 |
6” |
80 |
160 |
BARRIER Ultra-R |
1” |
70 |
150 |
The performance given is based on the typical “R” value for good
quality polyurethane foam board. Two-part "pour-in" foam and wet foam
of any kind will have a lower insulation value. Do not base estimates on manufacturer's
claimed “R” value unless you are certain that the testing method used has
eliminated the influence of radiant type heat.
Copyright Protection:
This information reflects data
gained through tests conducted by Glacier Bay, Inc. and is distributed
free of charge as an educational service to the cruising community. No
aspect of this data may reproduced, published, distributed or referenced
by any organization whether profit or non-profit without crediting Glacier
Bay, Inc. as its source. Additionally, no profit making organization may
do so without the written permission of Glacier Bay, Inc. To obtain such
permission contact Glacier Bay, Inc.
