[Greenbuilding] Glass roofing (was Re: Toxic Materials in Roof Runoff)

[RT]

On Tue, 12 Aug 2014 22:00:51 -0400, candtcampbell at juno.com  
<candtcampbell at juno.com> wrote:

> Does glass roofing actually exist? If so, who makes/sells it?


"Famous" glass roofs that come to mind:

1. Galleria Vittorio Emanuele II, Milan, Italy:  It's been around since  
the mid 1800's and its imitations can be seen over shopping malls in  
almost every city in North America.

2. Grand Palais, Paris, France: It was built for the 1900 World's Fair,  
replacing London's Crystal Palace as the world's largest  
ironwork/glass-roofed structure. In the late 1930's it found an adaptive  
reuse as the Palais de la Découverte, a science museum.

etc. You get the idea. Glass roofs have been around for a long time. Any  
glass supplier in any town can provide the glass and will likely carry the  
sloped glazing components of at least one or more manufacturers for those  
who opt to go the "store bought" route.

Green builders will know that the best option is to re-use tempered glass  
which has been diverted from the waste stream and will often design their  
own glazing components from readily-available stock materials.

The biggest challenge for novices will likely be configuring the joints so  
that the assembly does not leak. Even many "experienced" architects seem  
to struggle with this.
Back in the 1990's, Fred Unger, a frequent contributor to this List at  
that time, wrote an excellent article for Fine Homebuilding magazine on  
the subject of flat glass residential sloped glazing and how to do it so  
that the assembly doesn't leak. It's probably on the web now for all I  
know.

One of the bonuses of glass as a roofing material is that it can  
multi-task.
For parts of the roof that are facing the equator, it would make sense to  
take advantage of glass's excellent solar transmission properties to  
provide clean energy to the building beneath it -- PV arrays, DWHW  
heating, direct gain over-roofs & wintergardens ... to name a few examples.

For those who want to go the store-bought route and like the look of  
traditional roofing tiles, SolTech system may be of interest:

http://soltechenergy.com/soltech-system/

I'm pretty sure that I saw a comment in this morning's GB List email (from  
Reuben ?) about not throwing stones to which I say "Pwah!". Tempered glass  
is pretty much invulnerable to stones or in my case, large boulders. I've  
had not-yet-installed tempered glass panels picked up by the wind and  
tossed well over ten feet to land on some large landscaping boulders  
without breaking.

But in the same breath I should mention that I've also seen large tempered  
glass windows spontaneously implode/explode due to some schmoe who  
installed the glass with improper edge clearances and thermal expansion  
resulted in the Achilles heel of tempered glass (the edges where stresses  
 from the tempering process are concentrated) bearing on the shank of a  
fastener.


-- 
=== * ===
Rob Tom  .  .  . T60BOM
Kanata, Ontario, Canada

A r c h i L o g i c  at  Y a h o o  dot C A
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