Hi
I think I understand how U-Values are calculated e.g.
(Layer thickness) X Lambda = R in m2 K/W
Add up all the R-values for each of the layers and
1/(Total R-Value) = U-Value in W/m2 K
However if you look at the calculations from my "As-designed" SAP 2009 report below, the calculated Total R-Value = 5.844 m2 K/W and if you take the inverse of that the U-Value is 1/5.844 = 0.171 W/m2 K and not the 0.14 shown on the report below.
Can anyone please explain how the 0.14 was achieved...what am I missing???
Thanks