Volume 41, Issue 1 January 2006
the Farnady Files
Hero or Goat?
They Can Have the View and the Comfort, Too
by Dez Farnady
On Sunday mornings we occasionally take a walk along the oceanfront road that runs along the palisades above the beach. The walkway and bike path are on the ocean-side of the street and houses with the view are on the other. The houses have been there for ages and still these people canít find an escape from the heat of the summer. All the houses face the southern sun and its heat glare blasting off the water. All of the windows are clear glass; sometimes they are draped, covered or even shuttered to keep out the heat of the afternoon sun and the view.
And here we are in the glass business with dozens of great and attractive performance products available off-the-shelf to provide the view and the required energy performance. But who is going to tell them?
Searching for Energy Performance
If the homeowner goes to the average glass shop he will be given the canned answer supplied by the windowmakers hyping their own products with the offer to replace all the windows. In the re-glaze business, there is often no answer at all. Or, when the answer is forthcoming, it is the latest panacea off the shelf and seldom the real solution to the specific problem.
The whole concept of tuning a house for maximum energy performance by varying the glass products is not only a lost art but also an art that was never really found. I am certainly not going to volunteer to tell anyone anymore. I have tried for decades to preach the glass gospel but it mostly falls on deaf ears. So let them stew in their own ovens and I will help the few who ask and who are willing to listen. The answers are out there Ö
As a matter of fact, I think I may have just solved a problem for someone who asked and was willing to listen. The project is about to start and I promise to show pictures in a future column when the project is completed. You are not going to believe it. Although at this point I only have the numbers to prove it, soon I will have the real facts. It will be either a happy client or a contract out on my head.
The project is on a Bay Area coastal property, just like the ones I mentioned earlier, facing due south with a 180-degree ocean view. It is wide enough to be looking directly into the sun off the ocean from sunrise to sunset all year round. It is about 40 lineal feet of vertical glass from waist level up 4 feet covered with 8 feet of roof glass running along the same 40 feet. If my math is correct, that is 480 square feet of vertical and sloped glass facing the sun. Clear glass would enable these people to fry eggs on the breakfast table.
Exploring the options for a residential application and staying away from any reflective products, the first option was going to be a second generation low-E. We tried Cardinal and Solarban 60 on the vertical first with low-E Sun on the overhead, but I did not think that would provide enough protection.
Because there is a great deal of green on a lower level glass wall, we decided on the combination of green and low-E because it came up with great numbers. Evergreen, Solargreen, Atlantica or whatever they call it now, over Solarban 60 or Cardinal 170 comes up with 53 percent light transmission. This is a hair lighter than quarter bronze so itís not too dark for a residential application. But, while bronze with 53 percent light has a shading coefficient of .72, our combination has shading coefficient of .35. Those numbers are pretty tough to get with glass that you can still see through. Both lites are tempered so we donít have any thermal stress breakage concerns.
Because the overhead area is so large we decided to give up on the green and try tempered Optigray 23 over Solarban 60 heat-strengthened lami. The 18 percent light transmission is a little darker than a bronze or gray reflective that has a .52 shading coefficient, but itís not darker than Graylite #14 with only .53. Even low-E Sun canít get below .36. Since the glazing is overhead we can live with the 18 percent light particularly with the remarkable .21 shading coefficient.
Well, I asked for it. I told someone who was willing to listen. Stay tuned to find out if I end up being a hero or a goat. If you hear nothing, there is probably a contract out on me. On the other hand, if it works, you know that I am going to let all of you know about it.
© Copyright 2006 Key Communications Inc. All rights reserved. No reproduction of any type without expressed written permission.