Volume 34, Number 10,  October 1999

Frames, Panes and Technology

A Look at Trends in Window Design

by John Stephenson

Technology continues to change the window industry. Advancements in frame manufacturing and the development of new glazing materials have increased the variety of window products available in today’s marketplace. Technology, such as the Internet, has provided increased knowledge for consumers who now have instant access to a wealth of window information before they make a purchase. However, all these options can make window selection seem like a complicated task.
Consumers need a reliable source to turn to — a glass manufacturer, window fabricator, distributor or retailer — someone who can sort out the information, clearly explain product differences and match the best product to their individual needs and desires. As you know, a window “perfect” for one application may not be suitable for another. Several factors must be considered before choosing a frame and glazing option. These include: climate, weather conditions, amount of sun exposure, aesthetic preferences and lighting, heating and cooling requirements. To make a fully-informed decision, your customers must understand the benefits different window and glazing components provide and under which conditions they perform most effectively. Because consumers have easier access to information than they did years ago, you will likely find yourself facing more in-depth questions about products. Following is an update on some of the most recent industry developments.

wpe2.jpg (11227 bytes)For many years wood (such as this woodclad bay window from Milgard) was the most popular window frame material.

Vinyl Volume
For many years, wood was the most popular window frame material. In 1991, wood held 48 percent of the market share, whereas vinyl represented just 25 percent, according to the Window and Door Manufacturers Association (WDMA). Last year, for the first time in history, vinyl surpassed wood as the market leader. From 1991 to 1998, vinyl’s market share increased 18 percent, with vinyl commanding 43 percent of the market by year’s end. This rising trend is forecasted to continue, according to the WDMA. The association estimates 23.4 million vinyl windows will be produced in 1999 (representing 44 percent market share), compared with 21.3 million wood windows (40 percent market share).
New processing techniques and the use of different vinyl compounds have improved the performance and appearance of vinyl window products and enhanced their popularity. Vinyl’s durability, low maintenance and energy-efficient nature make it a popular choice today.

wpe3.jpg (73057 bytes)Vinyl windows from Milgard.

New Wood Looks
Although no longer the market leader, wood windows remain in high demand. Wood has long been cherished for its inherent beauty and insulating qualities. Traditional wood frames have low U-values and withstand extreme temperatures. But, unlike vinyl, wood windows require regular painting and maintenance. If wood frames are not protected properly from moisture, they can warp and crack.
To address these concerns, some manufacturers now offer special composite frame materials that minimize the need for maintenance. Generally these composite products have high insulating values and exceptional durability. For example, our company manufactures a Wood-Clad™ line constructed of fiberglass on the outside
and vertical grain Douglas fir on the inside. Fiberglass provides the look of painted wood, without the maintenance. It withstands ex-treme temperatures and resists moisture and corrosion. It is also an excellent insulator, with very low U-values. Fiberglass frames do not warp, shrink, swell or rot. On the inside, vertical grain Douglas fir provides energy efficiency, while offering the fine detail and genuine beauty of wood. This type of wood is prized for its ability to resist dents and scratches. It also accepts stains with consistency and ease. Composites such as WoodClad keep the wood on the inside where there is less exposure to harsh elements, reducing the need for maintenance and protecting and preserving the wood’s natural beauty.

Bigger Views
Aluminum windows are making a comeback. They are structurally rigid, allowing for less frame and more glazing area than vinyl. Aluminum windows with large glazing areas are particularly popular in homes where view is paramount. They commonly are used with a clear anodized finish in high-end, contemporary custom homes where less focus is placed on the window itself. Low maintenance is one of the benefits of aluminum windows. Aluminum doesn’t rot, peel or require painting. Special glazing options can be added to aluminum windows to enhance energy efficiency and increase comfort.

Glass Options
Once a frame type has been selected, glass is the next consideration. Does your customer have concerns about energy efficiency or comfort? Perhaps you should recommend an insulating glass unit with a low-emissivity (low-E) coating. Low-E coatings reduce the amount of heat a window radiates, thus improving a window’s energy efficiency.
Another attraction of low-E is its ability to usher in visible sunlight, while blocking most infrared and ultraviolet (UV) rays that can cause fading of interior carpets and furniture fabrics.
At one time, low-E glass was recommended primarily for cold climates. But now manufacturers have introduced a new generation of products called low-E2 which also work effectively in warm climates. As a comparison, standard low-E glass reduces ultraviolet rays up to 54 percent, whereas low-E2 can decrease ultraviolet rays up to 85 percent. Tinted glass is also effective in warm climates. It minimizes the amount of solar heat that enters a home and reduces uv light damage. It also adds an element of privacy by decreasing visibility to the interior of a home.

Warm-Edge Technology
Condensation is a common complaint among homeowners. In a typical window, the thermal resistance around the edge is lower than that in the center. Heat can escape, making the window susceptible to condensation. To combat this problem, manufacturers have made advancements in warm-edge technology.
In an insulating glass (IG) unit, the layers of glazing are held apart by spacers. Air currents between the panes of glass carry heat to the top of the unit, while cold air settles at the bottom. Filling the space with a slow-moving, low-conductive gas such as argon, is one way to reduce the amount of heat transfer that occurs between the inside and outside of the unit. Argon is heavier than air, which slows the rate of heat transfer.
The spacer it-self also can affect a window’s ener-gy performance. Traditionally, spacers were constructed of four sides of aluminum. Aluminum was not highly effective, however, because it conducts heat. In other words, heat was able to escape through the edges of the window, causing energy loss and condensation. A more recent approach utilizes a U-shaped steel spacer. Steel transfers less heat than aluminum, thereby increasing energy efficiency. The U-shape means only a small percentage of the steel touches the air space. The remaining space is filled with butyl, an elasticized adhesive. The U-spacer also absorbs much of the glass movement that can occur when temperatures fluctuate, reducing the chance of seal failure and glass breakage.

Window Savvy
Whether it’s warm-edge technology, glazing or framing options, manufacturers continue to develop new and improved products. Keeping up-to-date on these advancements will increase your credibility with consumers. They will know they can count on you as a reliable source for window information, which may lead to referrals and future business for you. To provide the best advice and service to your customers, find out about the surrounding conditions where the windows will be installed. Will they be in direct sunlight with no overhang protection, or in the shade? What is the climate like? What factors is your customer most concerned with—appearance, maintenance, energy efficiency, cost?
Every application is unique, and your recommendation should be based on each customer’s individual needs and desires. Emphasize the benefits and features that different products offer. For example, many people choose wood for its flexibility in staining or painting, energy efficiency or for aesthetic
reasons. Vinyl is a good choice if your customer wants low maintenance. If budget is a concern, aluminum is a cost-effective alternative. Special glazing options such as low-E coatings, can enhance thermal efficiency and protect interiors from damage caused by UV rays. Perhaps you can recommend mixing two types of windows, depending on the exposure the home faces. Composites, such as WoodClad, may be a good solution for someone who wants the natural beauty of wood, without the worries of maintenance. Whatever the case, taking a few extra moments to provide personalized service will pay off in the long-run.    


John Stephenson is marketing manager for Milgard Windows, based in Tacoma, WA.


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Copyright 1999 Key Communications, Inc. All rights reserved. No reproduction of any type without expressed written permission.