Sleeping Bags for Every Season A study of sleeping bag thermal resistance John Myers & Devin Anderson
Mar 30, 2015
Sleeping Bags for Every SeasonA study of sleeping bag thermal resistance
John Myers & Devin Anderson
Problem and Objective:
Sleeping bags are rated only by lowest temperature they are usable in
How can you combine sleeping bags and make sure you're warm enough for the climate?
Determine and plot relationship between temperature rating and thermal resistance
Use plot to determine effective temperature rating of combinations of sleeping bags
Method:
Place a heating pad with a 180 Watt power output in sleeping bags with various temperature ratings
Wait a sufficient time to reach steady-state conditions
Use thermometers inside and outside bag to determine temperature drop
Use relationship Q=(Tinside
– Toutside
)/Rtotal
to find thermal resistance of each bag
Results:
-70 -50 -30 -10 10 30 50-5.55111512312578E-17
0.05
0.1
0.15
0.2
0.25
0.3
0.35
f(x) = − 0.0010616951182989 x + 0.171527403414196R² = 0.927250355843698
Temperature Rating vs Thermal Resistance
Temerature Rating (Degrees F)
Th
erm
al R
esi
sta
nce
(K
/W)
Conclusions:
Data points are based on available bags and would be more accurate with a larger sample size of temperature ratings, and multiple bags for each rating
There may be variation in power output from the heating pad. A more consistent power source would improve the data
The trend line from the data plotted should allow you to combine sleeping bags and predict the effective temperature rating