Problem 4: Thermal conduction through snow (3 pnts)\ Snow acts as an excellent insulator. When snow piles up on a roof, it can add additional insulation to a building. Engineered insulation typically comes with "R values" that measure the thermal resistance to temperature differences across the insulation. The

R

value describes the temperature difference across the insulation per unit heat flux,

R=T

/ Q. When a building's

R

value is increased through adding insulation, the heat flux for a given temperature difference decreases.

R

values in the US are given in imperial units (

ft

{

(

:_(2)^(2)(F)h(r)/(B)TU)

}. Internationally,

R

values are in SI units

(m^(2)(K)/(W))

, and the conversion between these units is

R

-value

(SI)=R

-value (US) / 5.67. Typical buildings may have roofs with (US) R values of 40 .\

Problem 4: Thermal conduction through snow (3 pnts) Snow acts as an excellent insulator. When snow piles up on a roof, it can add additional insulation to a building. Engineered insulation typically comes with "R values" that measure the thermal resistance to temperature differences across the insulation. The R value describes the temperature difference across the insulation per unit heat flux, R=T / Q. When a building's R value is increased through adding insulation, the heat flux for a given temperature difference decreases. R values in the US are given in imperial units ( ft 2 ? Fhr/BTU). Internationally, R values are in SI units (m2K/W), and the conversion between these units is R-value (SI) = R-value (US) / 5.67. Typical buildings may have roofs with (US) R values of 40 . 40/567=10+18