# Homework Help: Thermal values for a double pane window

1. Feb 25, 2010

### jghlee

1. The problem statement, all variables and given/known data

So there's a double pane window, where between two identical sheets of glass is air. So on the outer surface side, there 3mm of glass, then 9mm of air, and then another 3mm of glass. Outside temp is 50 degrees C and inside temp is 25 degrees C.

Heat of conductivity for glass is 0.8W/(mxK) and for air is 0.024 W/(mxk).

a) What is the total R-value for the double pane window?
b) What is the conductive heat flow rate per square meter of window area through the double pane window?

2. Relevant equations
R = d/k

U = 1/R

3. The attempt at a solution

a) So for part a) I dug up an equation online stating the R-value = thickness/K-value.

Since the K-values and thickness are given.... I plugged it in the equation...

R = [(.006m)/(0.8W/mxK)][(.009)/(.024W/mxK)] = .00281 m^2K/w

b) But for part b i'm not sure what the "conductive heat flow rate per square meter" is...

Is it the U-value? In which cause U = 1/R so it's just the reciprocal of the answer in part a?

I'm completely lost. Any help would be great!