one only gains benefit from the inside film factor on an exterior wall.

so, you cut the loss in half, for how many $$$? play what if -- calculate the total heat loss & gain using the various combination of windows & look how much the grand total changes!

hi preformance houses are keeping glass <11% of floor space --

that is why you have the load calc program --

you are going to install a window having only 55% light transfer? It would be cheaper to buy a window having only 50% of the area!!! And, one hell of a lot cheaper every day due to much less energy loss!!! Compare the heat transfer thru a window then thru the adjacent wall!

Not only that, drive thru any neighborhood, and see just how many houses have the blinds | drapes | curtains pulled back --