[Greenbuilding] apples, oranges, and u values

[Alan Abrams]

once again, agonizing over how to get the best $ value and best thermal
value out of a set of windows.  for a relatively small premium (15-20%) I
can go from your basic U-0.30 low-e argon clad casement wood window, to a
similar triple glazed unit at U-0.25 or 0.24.

or...for something commensurate with the latter cost, go with a Euro UPVC
3x tilt-turn at maybe U-0.18 or lower.  going to insulated frames and
sashes takes the U's down even lower, but the cost increase steepens for
that performance.

...or so they say...

at the same time, I've heard it said that european windows are rated
differently, and that US or Canadian windows perform as well.

moreover, it is difficult to imagine that a few uninsulated air chambers in
a set of vinyl sashes and frames can knock off 25% of total heat
transmission.

looking to wiser heads to sort this out...

-a


*Alan Abrams**
Abrams Design Build LLC*
*A sustainable approach to beautiful space*

6411 Orchard Avenue Suite 102
Takoma Park, MD 20912
office  301-270-NET- ZERO (301-270-6380)
fax      301-270-1466
cell     202-437-8583
alan at abramsdesignbuild.com
www.abramsdesignbuild.com
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