The R value of fiberglass batting, 3.5 inches thick, is 11 ft²⋅°F⋅h/BTU. What is the thermal conductivity (in BTU/ft⋅°F⋅s)?

Question

Quizplus · Accepted Answer

The thermal conductivity (k) can be calculated from the R-value using the formula $k = \frac{d}{R}$, where $d$ is the thickness of the material. Given $R = 11 \, \text{ft}^2 \cdot ^\circ\text{F} \cdot \text{h} / \text{BTU}$ and $d = 3.5 \, \text{in} = 3.5/12 \, \text{ft}$, converting R-value to consistent units for thermal conductivity calculation (in BTU/ft·°F·s) involves converting hours to seconds, giving $k = \frac{3.5/12}{11 \times 3600} = 7.4 \times 10^{-5} \, \text{BTU/ft} \cdot ^\circ\text{F} \cdot \text{s}$.

The R Value of Fiberglass Batting, 3