On Tue, 15 Dec 2009 23:37:59 -0500, Tony wrote:
With the curtains closed there will a reverse convection current between
the curtains and the window with cold air coming out of the bottom. Not
a good place for feet! Two smaller registers sound like a good idea for
the large window.

OK, two votes for smaller... I need to do some reading to figure
out exact sizes (and for ductwork too) I suppose :-)

Not that you mentioned it, but many people still think that "heavy" or
"insulated" draperies hold in heat and save money. That is a long lived
old wives tale. They may make a tiny difference, maybe .5%.

A lot of it comes from Victorian days and open fireplaces, I think -
those would suck combustion air in through whatever gap they could find,
so having big curtains acting as screens would divert the cold air
away from the room's occupants.

Part psychological too, no doubt - a heavy curtain 'feels' like it should
be warmer than one you can see daylight through...

The only
way for insulated drapes to really save in heating demand is if they are
sealed to the wall all the way around all sides (and middle).

Yeah, that makes sense. For the ones on our big windows I made sure there
was a nice overlap (the tracks overlap by a few inches at the top), and I
put tie-backs at the sides which are handy as when the curtains are closed
I can tuck the sides 'behind' the tie-backs so they're flush with the
wall. There are still little gaps at the sides toward the top, of course,
and behind the rail, but it's better than a gap down the middle and a 3"
wide gap all the way down either side.

cheers

Jules