RE: [GBlist] Low E glass

["Ralph Bicknese" <ralph.bicknese@christnerinc.com>]

Alan:

>Can it be assumed that most places selling windows know about such things,
or is it wise to learn enough about them to specify to a contractor or
window supplier?<

Some know the differences, some do not. It is always good to be as educated
before hand as you can be.   You could go armed with a product printout
showing the data.  They are available from most window companies on line.  I
particularly like the one Southwall has because it shows data for many
options.  Ask around and see if you are comfortable with the answers you
get.  If no, get in contact with the product rep.  They can sometimes be
located through the window companies' website or home office.

>How permanent are the coatings used?  Can one assume that they're MOL
permanent?<

The coatings last a long, long time.  I do not know how long though.  They
have only been on the market about 15 years.  I think the biggest risk of
failure is similar to that of any insulated sealed windows.  If the seal
breaks, the coatings can be compromised.  And of course, if the windows are
gas filled (usually argon or krypton) and the seal breaks, the gas
disappears and so does some insulating value (usually about R-1 would be
lost).  Another problem is that some units can develop small speckles that
look a little like microbial growth.  I know from experience that Hurd
Windows with Heat Mirror film have had problems with this.  I cannot testify
whether or not the low e windows without Heat Mirror suffer this malady.

Cheers,
Ralph Bicknese

-----Original Message-----
From: Alan Courtright [mailto:acourtri@linknet.kitsap.lib.wa.us]
Sent: Wednesday, January 02, 2002 9:38 PM
To: Ralph Bicknese
Cc: Richard Averett; greenbuilding@crest.org
Subject: RE: [GBlist] Low E glass

Thanks for the good rundown and the URL; much appreciated.  A couple of
further questions:

On Wed, 2 Jan 2002, Ralph Bicknese wrote:

> Low e coatings are selective coatings.  That means one can choose coatings
> with different properties.  Having various low e properties to choose from
> gives a designer the option of specifying different glass for different
> climates or at different orientations.  The "northern" and "southern"
> designations are really just marketing buzzwords and I think confuse
rather
> than clarify the issue. The main difference between "northern" and
> "southern" coatings is that the southern coating provides more shading and
> less solar penetration through the glass.

Can it be assumed that most places selling windows know about such things,
or is it wise to learn enough about them to specify to a contractor or
window supplier?

> Southwall Technologies offers glass with selective low e coatings with
> various shading coefficients.  If a person wants a window with high solar
> heat gain potential and high light transmittance to increase daylighting,
> one would select a highly insulating glass with a low shading coefficient.
> This will give a high solar heat gain factor. This type of window is often
> used in passive solar heating applications.

How permanent are the coatings used?  Can one assume that they're MOL
permanent?
                         -|//*Alan Courtright*\\|=
                                Poulsbo, WA
                             acourtri@krl.org




______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
Solstice http://www.crest.org, and BuildingGreen, Inc., publisher of
Environmental Building News and GreenSpec http://www.BuildingGreen.com
______________________________________________________________________


______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
Solstice http://www.crest.org, and BuildingGreen, Inc., publisher of
Environmental Building News and GreenSpec http://www.BuildingGreen.com
______________________________________________________________________