Consider 3 layers of a wall. The first layer is plaster 1.0 cm thick(R=0.033 SI units), the second layer is fiberglass insulation 8.9 cm thick (r=2.97), and the outside layer is woodd 3.0 cm thick(0.33). What is the heat loss through one square meter of wall if the inside temperature is 20 degress celcius and the outside is -10 degrees celcius

Answer 1

Thermal resistance is series can be added. The SI units are, presumably,
Watts/*m^2^*degC)

Total thermal resistance = 0.033 + 2.97 + 0.33 = 3.33 W/m^2*C

Multiply that by tha area (1 m^2) and 30 C for the heat loss rate in Watts.

It looks like 100 Watts.

For a large house, that will lead to a big heating bill in winter.