Volume 37, Issue 8, August 2002

Low-E Growth

Slow, But Definitely Not Low
by Nick Limb

It has been 20 years since low-E was introduced to the North American glazing market. The product has developed from a premium option limited to residential windows in cold, Northern markets, to now a standard window component across many glazing applications. With annual shipments exceeding 600 million square feet, low-E is a testament to both the patience required in developing building-product markets and the success of the glass industry in enhancing the value of its product offering. Current developments in energy policy are likely to ensure continued strong growth.

low e charts

Low-E Product Cycle
Ducker Research has been researching the low-E market since the late 1980s, and we continue to track shipments through ongoing studies of both flat glass and glazing applications. We have also recorded and tracked the evolution of dozens of building products over our 40-year history. This allows us to assess low-E market adoption against the typical pattern of a product life cycle within the construction industry. 

The first statement that can be made about product adoption in construction (the rate at which a new product gains share of a market) is that it is slower than essentially all other market segments. Product life cycles in software can be measured in months, and in years for consumer electronics and even automotive vehicles. But in construction products, it is measured in decades, particularly for commercial (nonresidential) construction products. It is not uncommon for a construction product to have reached only half its market potential a full ten years after introduction, and such is the case with low-E. Product extensions and demand side factors have extended the life cycle well-beyond 20 years.

A major theme of low-E evolution has been competing coating technologies, primarily between off-line or sputtered coatings and on-line or pyrolytic coatings. This competition has driven a series of product enhancements for the ultimate benefit of both customers and suppliers. 

Pyrolytic and Sputtered Coatings
The first low-E coatings introduced were sputtered, and were soon to find 
applications in the residential window market. However, they were constrained by their fragile nature and by the difficulty insulating glass fabricators had in processing. Pyrolytic coatings were introduced a few years later, providing a very durable coated surface, which facilitated handling and distribution, and also provided the first post-temperable low-E product that could be tempered after coating (rather than having to coat glass that had already been tempered). One result of this technology development was that the commercial glazing market started to develop, as pyrolytics provided a market entry point for independent, architectural glass fabricators who could rapidly deliver a custom glazing solution.

While pyrolytics grew in share in the early 1990s, the next generation of coatings saw sputtered low-E regain share. Traditional low-E products combined low U-values with high solar heat gain. These products are suited ideally for heating-dominated cold climates, where solar heat gain provides a free passive energy source in winter, along with excellent thermal insulation. However, the same product does meet the ideal solar control needs of cooling-dominated buildings and homes.

High-performance or double-stack sputtered coatings were introduced that offered both very low U-values and good solar heat control, combined in a product that still maintained the clear appearance preferred by most homeowners and many architects. This extended the opportunity for low-E across all climates. Pyrolytic coatings with solar-control properties have now been introduced, and post-temperable sputtered products are also available. The range of low-E products available offers a high-performance energy management solution for practically every window application—and one that is fabricator-friendly. 

low e charts2

Continued Growth
Developments in energy policy and regulations have also supported the growth of low-E. Specific codes and utility rebates requiring low-E performance have been somewhat sporadic, and the regulatory process is long and drawn out, but the long-term adoption of low-E has been supported by several key events. The work of the National Fenestration Rating Council was important in setting a credible measurement standard for the fenestration industry. The subsequent introduction of the ENERGY STAR® program, with three regional performance qualifications all requiring low-E, has brought renewed impetus to the use of low-E in residential applications. The ENERGY STAR® performance requirements are also serving as a benchmark for future energy codes at national, state and local levels.

So what position has low-E reached 20 years in? More than two out of every five residential windows shipped today incorporate low-E, and it will likely exceed one in two windows within the next couple of years. On the commercial window side, low-E accounts for more than 20 percent of glazed openings. 

Just as insulating glass units became the standard glazing product before low-E, glass coatings and low-E in particular are successfully transforming the market again, providing a better product to end users and adding value to the industry as a whole. 



Nick Limb is a partner with Ducker Research in Bloomfield Hills, Mich.


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