[Greenbuilding] Windows - double hung

[Keith Winston]

Hi And welcome John (and hi Laren):

That's a good article you linked to, John. Does a nice clear job of 
spelling out shortcomings of double-hung (I'd never thought about the 
double-sided exposure of the bottom edge of the upper sash issue, for 
example).

And thanks for the addendum Laren, like so many things its one of those 
things (window screens) that I knew all the information but hadn't put 
it together and considered implications in a consistent way. Thanks for 
helping me do so.

Warmly, Keith


LarenCorie wrote:
> 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
>
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-- 
Keith Winston
Earth Sun Energy Systems
Hyattsville, MD 20781
301-980-6325
send me mail at 
keith at the company below
www.EarthSunEnergy.com