A WORD OF CAUTION CONCERNING HIGH PERFORMANCE GLASS
High performance glass is the talk of the building industry. Terms such as Low Emissivity, Heat Mirror, Pyrolytic, Sputtered, Argon Filled, Double Sealed, Glass Sealed and others are being used with increasing frequency. Trade magazines are featuring articles on high performance glazing in one issue after the other. And why not? Energy conservation is serious business.
Unfortunately, and as with any new, high-tech products, the relevant details are usually complex. Miscommunication, misunderstanding, mistakes and misuse come with the territory of high performance glazing as well. The following areas of concern have become apparent to those of us at Woodstone who's job it is to stay abreast of current developments in high performance glazing techniques. And, while we do not profess to be expert in physics or chemistry, we have had significant and increasing experience with the development and use of several of these new products and would like to take this opportunity to share the following thoughts with you.
1. There is currently no standard for performance, appearance, texture or compatibility of most high performance glazing techniques. The National Glass Association, U.S. Department of Energy, American Society of Heating, Refrigeration and Air Conditioning Equipment and others are scrambling to establish various benchmarks. However, there is no indication that standards will be established anytime soon and, furthermore, that those standards will be acceptable to the industry.
Note: This circumstance is especially relevant in the manufacture of custom windows and doors where glass sizes vary from order to order, various manufacturers may be used on the same project and expensive larger scale manufacturing methods are not applicable to one-of-a-kind orders.
2. Hard Coat Low E (pyrolytic) coatings vary in color from one manufacturer to another and often vary from time to time from the same manufacturer. It is very difficult (next to impossible) to match coloration when adding to or replacing glazing that was manufactured several years ago. While the consistency factor is improving with individual manufacturers, differences from one manufacturer to another persist for many reasons.
Note: Coloration of Soft Coat Low E (Sputtered) coating does not seem to vary as much as Hard Coat Low E, especially soft coatings on suspended films as with Heat Mirror glazing.
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GLASS CAUTION (Continued):
3. Argon gas is proving to be a very elusive material. Because the molecular structure of Argon is so tiny, the gas tends to leak from even the most exacting double sealed units over a period of time. Furthermore, Argon is odorless, colorless and virtually undetectable without using expensive and sophisticated instruments.
4. Because of the above mentioned circumstances, Woodstone cannot accept responsibility for variations in performance, appearance, texture or compatibility of any high performance glazing. Clients may specify glazing type and product manufacturer.
Included with this newsletter are two reports from Alpen, Inc., a widely respected manufacturer of Heat Mirror products and supplier for Woodstone. The reports are indicative of the complexity of High Performance Glazing considerations.
Conclusion: Woodstone's position on these circumstances is currently one of caution. Coloration differences may prove to be an aesthetic nuisance. Argon Gas may not be worth the investment until sealing techniques are improved. The pay back from using Hard Coat Low E coatings may be much longer than previously anticipated.
There are acceptable alternates to these products that provide only slightly diminished performance levels. Standard clear insulating glass is a significant improvement over single glazing and Heat Mirror applications offer clear high performance units as well as Low Emissivity, Wave Length Selective and Reflective coatings.
Woodstone is currently establishing a method for certifying each piece of insulating glass that is installed in any of our units. The documentation will include the name of the manufacturer, the date of manufacture and a code that indicated the specific high performance qualities for that unit. Single glazed pieces are, as yet, not identifiable because there is no suitable area on which to place a label.
This kind of certification is essential because Woodstone can now provide Wave Length Sensitive Coatings, Low Emissivity Coatings and Reflective Coatings to satisfy the optimum requirements for every unique circumstance created by climate and/or the facing direction of your building elevations. Provision of replacement parts will require accurate documentation.
There are more High Performance Glazing developments that Woodstone will be scrutinizing in the near future.
If you have any questions concerning High Performance Glazing, please contact our customer service department at your convenience.
Filename: Product\Glazing\Caution.sam Revised 07/19/95 HJE