1. The problem statement, all variables and given/known data The wall of a house consists of three layers: A wooden outer wall with an R factor of 1.0, a 3 inch layer of fiberglass with an R factor of 11, and a gypsium-board inner wall with an R factor of 0.33. (All R factors are in h*ft^2*F/BTU). When the temperature is 68 degrees Fahrenheit inside, and -4.0 outside, what is the rate of heat loss through an 8ft by 15ft section of this wall. 2. Relevant equations 3. The attempt at a solution I was a little confused as to what they means by "R factor", and basically tried to add of the R factors as the regular resistance, and calculate the heat loss through: rate of heat flow= (delta)T/R_eq However (not suprisingly), I was wrong. I know I am missing something with this problem, but I cannot figure it out.