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