Andy Wade wrote:

Taking a 4mm (t = 0.004 m) pane of glass with k = 1 W/mK (given earlier
in the thread) t/k is 0.004 m^2K/W so contributes negligibly to the sum.
The U value is 1/0.184, i.e. about 5.4 W/m^2K

Replacing the glass with a sheet of 16 swg copper (t = 0.0016 m, k ~ 200
W/mK) only increases U to about 5.5 W/m^2K.


Thanks for the input Andy. While I understand your logic, something
still feels instinctively wrong - can't the same calculation be done to
show that the difference between copper walls and 100mm celotex walls is
negligible? What am I missing?


--
Grunff