[Greenbuilding] Windows - double hung

[LarenCorie]

From: "John E. Beeson" <jbeeson at quinnevans.com>

> does anyone recommend a manufacturer that makes a good
> double-hung?
>
> And yes, I read this already, but I'm trying to match the historic
> windows:
> http://www.thermotechfiberglass.com/Column3.htm

Hello John;

  There is another factor, that virtually all of the window
manufacturers, and the article above, miss, which makes
all sliding and hung windows even less energy inefficient,
compared to hinged windows.   It has to do with Solar
gain, and has been left out of every claim of Solar trans-
mittance, I have seen from a manufacturer. First, sliding
windows are set deeper in their jambs, so they receive
less sunlight at higher angles of incident. This might not
be very important, except for the second, far more
important factor.   All of the sliding windows put their
screening on the exterior, where it blocks 15-20% of
the sunlight, from ever getting to the glass. The screens
also reduce the opening size, leaving much of the sun-
-light to just shine on the sill, or jambs, outside of the
actual  window.     You will not see this mentioned in
any of the manufacturer's literature, and if you mention
it to any of the window sales people (this can be fun,
and even profitable, if you turn it into a question and
a bet ;O), they will hear something they never thought
about before.  However, in any heating climates, like
here in Michigan it is a very important factor.  In the
Ann Arbor area, south facing windows should gain
more heat than they lose, every month, except may-
-be December. They should reduce the heating bills.
However,  when you stop 30% of your Solar gain,
by placing a screen a few inches out in front of the
glass, you are definitely not being green.    Hinged
windows place their screens inside, where they do
not shade the glass.   This is a critical factor on all
exposures, except north. In southern states, where
cooling is a greater factor than heating, you will
do better with double hungs, because of their
shading screens, and operable top sashes.

-Laren Corie-
Natural Solar Building Designs, Since 1975
www.LarenCorie.com

-LittleHouses- http://groups.yahoo.com/group/LittleHouses
-Energy Self-Sufficiency Newsletter- Free at  www.rebelwolf.com
-WoodGas- Power from Wood. http://groups.yahoo.com/group/WoodGas
-Refrigerator Alternatives-
http://groups.yahoo.com/group/RefrigeratorAlternatives