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Does corrugated glazing transmit less light than flat glazing?

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Posted by Gary on August 28, 2006, 11:41 pm
 
Hi,

The question came up in the Yahoo Home Energy group as to whether corrugated
glazing (like SunTuf) transmits less light than the equivalent flat glazing?

When you let the sun shine through a piece of the SunTuf glazing onto a surface,
it does produce a series of dark and light bands at each corrugation wall -- so
this seems like a valid question.

I had a go at testing a piece of SunTuf, and came to the conclusion that there
is little or no penalty compared to flat glazing.  Test here:
http://www.builditsolar.com/Experimental/CorgGlaz/CorgGlazing.htm

Anyone have any thoughts/opinions on this?

When you let sun shine through a piece of the TwinWall Polycarb glazing it also
produces an even more dramatic pattern of darks and light bands -- wonder if you
pay a transmittance penalty for this?

Gary



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Gary

www.BuildItSolar.com
gary@BuildItSolar.com
"Build It Yourself" Solar Projects









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Posted by SJC on August 29, 2006, 1:59 am
 


surface,

you

  The Fireball collector people use twin wall and have certifications on
performance.
I think what ever reduced transmission occurs is offset by the increased
insulation it
provides.

 http://www.solarroofs.com/home.html


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Posted by Jeff on August 29, 2006, 12:16 pm
 Gary wrote:

   It looks to me like you've already researched this pretty thoroughly.

Some observations from what I've read:

It may be a toss up. There's an angle of incidence loss for light
transmission. The shoulder for this loss seems to be at about 50 degrees
(half transmission at about 75 degrees). You may gain some early and
late transmission coming through the corrugations. (those figures were
for generic glazing, caveat emptor)

Of course, the overall surface area of corrugated is somewhat higher, so
the losses should be a bit more too.


I think that the absorber fins will distribute the temperature (and the
radiation losses) so that the overall effect is marginal. Since the
corrugations are spaced differently than the fin risers, there probably
is no worst or best case (where all the light fell furthest from the riser).


   That's good to know. It's impossible to find anything UV treated in
the states at an affordable price other than SunTuf, that is easily
available.

I've seen the light transmission figures for twinwall and triple wall
(but I don't have them now). It amazed me that triple was very close to
double.

   Jeff


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