[Greenbuilding] R20 window insulation?

[nick pine]

 "Bob Waldrop" <bwaldrop at cox.net> writes:

> I like the idea of turning the insulating panels into air heaters.   How 
> big
> should the slot be for the heater air to enter the room in a 4' x 8' 
> panel?

If the windows collect 200 Btu/h-ft^2 in full sun, a 3"-4"x48" slot could
limit the air temp increase to about 10 F and limit the daytime heat loss
to the outdoors.

> And where?  Close to the top but still open to the glass?

Sounds good to me. A single slot may be the crudest and least efficient way
to make a window into a solar air heater with minimal heat loss at night.
More efficient ways try to separate the moving air into up and downgoing
paths and keep the cooler incoming room airstream near the glazing.

Nick