Volume 37, Issue 11, November 2002



The I.G. Alternative
    There’s a Time and a Place for Insulating Glass
        by Dez Farnady

The cold North and the steppes of Siberia require the best insulating glass that money can buy just to plug up those porthole size windows in those walls with the R-56 worth of insulation. The concepts that R-2 or maybe R-3 rated windows, at best, allow for large picture windows in that kind of a climate is a myth. There is no question that an insulating window is twice as good as one that is single-glazed, but if you really want to cut down heat loss in your polar residence you had better cut down on the size of the windows. But in the Sun Belt, insulating everything may just be more than you need.

At Home And At Work
I have been dealing with insulating glass for so long that it is about time to take a new tactic. For the record, I have some single-glazed, old wood sash windows in my house. I also have insulating in my house that replaced failed glass. (I also still have a few first-generation failed units that have not been replaced.) So, not only have I dealt with this stuff in other people’s houses, but have also been living with these issues personally since before 1977.

“Why ’77?” you may ask. Because that is the oldest date I can find stamped on the spacer of some of my failed units. The windows downstairs in the pre-remodel part of the house are still single-glazed and are going to stay that way. I am not going to replace them with insulating glass. What the heck? I live in California, not Minnesota. 

I may well become a heretic to the insulating business if I continue with the point I want to make, but here it goes anyway. Where is it written that all glass must be insulating? Oh, yes. The government, the Building Department and the energy watch dogs all have it in their books, but they don’t much care about the real world. Think of all the years they did not consider that the air conditioning costs in warm-climate areas often exceed the heating-cost requirements. No one ever told the homeowner that they needed to tint their windows to reduce energy costs. Today we just happen to be the fortunate beneficiaries of the second-generation low-E products that deal with heat gain. This was not always the case. Initially low-E was developed for cold climates, for passive solar heat gain. 

Clear insulating glass provides little protection from heat gain resulting from direct sunlight. This might make some people wonder why you would even need to bother insulating if you had no heat-loss problems. At this point, you are probably wondering where I am going with this. Well, I am preaching heresy and promoting single glazing again. No, I am not nuts, and I still sell insulating glass, but not always—and not for every application. 

The Right Applications 
I have seen too many situations where insulating unit failure persisted with unreasonable and escalating replacement costs. Have you ever seen windows that look like aquariums without the fish? They are half-full of water because the units are sitting in rotten wood glazing pockets that hold water like a sponge. In many cases, the replacement costs far outweigh the energy costs. I will say that this is mainly applicable to the Sun Belt, but here the answer is simple: single glaze. 

In the cold climate portions of the country you need to buy better windows and if your units fail continually, you need to find the reason why. However, in any application where heat loss is not an issue and continuing unit failures occur, it is foolish not to single glaze. Heat gain can be handled in a variety of ways with monolithic glass and it is often a cheaper, better and permanent solution. I am not really talking heresy. I am just trying to talk sense in a world where sometimes there is only a thin line between heresy and a little common sense. 


DEZMAN Dez Farnady serves as general manager of Royalite Manufacturing, a skylight manufacturer in San Carlos, Calif. His column appears monthly.


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