Aluminum can be found practically anywhere one looks in today’s society. It is the most abundant metal and the third most abundant element in the earths crust, yet it is a comparatively new industrial metal that has been produced in commercial quantities for just over 100 years. Measured either in quantity or value, aluminum's use exceeds that of any other metal except iron, and it is important in virtually all segments of the world economy. Street signs, tools, furniture and even aircraft components can all be made out of aluminum and the benefits of its use over other materials are infinite. Aluminum’s relative strength, durability, repair ability, and flexibility of design make it ideal for building windows and doors.

Champion Window and Door utilizes aluminum to produce all of its windows and doors for a variety of reasons. One of this extraordinary metals many benefits is its resistance to atmospheric corrosion. Aluminum’s natural tendency upon exposure to the atmosphere is to form a protective, oxide coating and it doesn’t need any further treatment in ordinary environments to protect it from tarnish and rust. Aluminum also possesses the best strength to weight ratio of any metal making it very reliable and even stronger then mild steel. Moreover, its relatively light weight is also a benefit (it weighs only about one third of steel) and it enables lower costs by facilitating movement in and out of the factory. And when an aluminum product’s life is over, it can be recycled into other products without losing any of its structural properties. Also, aluminum accepts paint readily and can be painted in virtually any color, including historic window colors, providing long-lasting aesthetic appeal.

Over the past fifteen years, vinyl windows have become very popular especially for residential use. Here at Champion, we don’t produce vinyl extrusions for a variety of reasons. The most pertinent is that when vinyl is exposed to fire and/or extreme temperatures, it emits a band full of toxins causing the use of vinyl windows to have been recently banned in several states. Also, when struck hard, vinyl can chip or crack and it has the propensity to fade over time. On top of that, many people simply don’t like the plastic and forged appearance that vinyl possesses.

All of these facts confirm that the most efficient and finest way to produce windows is through the utilization of aluminum.

Aluminum – The Most Successfully Recycled Material

Aluminum is a wonderful recyclable building material, with 45 percent to 50 percent reconverted into other usable products. No other material comes close, whether metal or nonmetal. It takes only 5,000 btus of energy to convert scrap aluminum to usable material. Vinyl, wood, and steel take up to three times as much energy to reprocess.

Aluminum Meets Architectural Glass Deflection Standards

In the commercial window and door industry, one of the most frequently specified criteria by architects is the glass deflection limit -- expressed as L/175 -- for all glass holding members. This is important because large commercial windows, such as those used in schools, must be able to withstand significant wind-loads without appreciable deflection and potential damage. Aluminum fenestration products easily make these requirements, whereas other nonmetal framing materials have difficulty achieving this safety design requirement.

The superior structural strength of aluminum windows and its resistance to deflection afford the industry’s best resistance to water and air infiltration caused by glass deflection, which can compromise the integrity of the seal against outside elements. The larger the window, the more pronounced aluminum’s structural strength advantage versus nonmetal framing materials.

A U-Value Comparison With Wood and Vinyl

While both wood and vinyl frames share a slightly better energy resistance factor than aluminum, this edge was long ago minimized with the addition of the thermally broken insulated glazing system common in all windows today.

Indeed, the aluminum window industry first addressed its perceived energy deficiency nearly a half century ago with the invention of thermally broken aluminum windows. If everyone had used thermally broken windows with insulated glass since the early 1950s, perhaps we would not be facing an energy crisis today!

It is also important to note that, since the ’50s, the evolution of high-performance glazing systems -- often combining low-e coatings, gas filling and warm-edge spacers -- has narrowed any thermal advantage that one window framing material has over the others. The relative importance of frame thermal performance (vs. total unit performance) is further diminished in the larger window sizes, most commonly used in educational buildings, where aluminum may be preferred for its superior structural strength.

Even Wood Windows Feature Aluminum-Clad Exteriors

Aluminum is the preferred exterior surface for most school windows, including those made from wood. That’s because aluminum won’t rust, warp or absorb moisture, and it has low expansion/contraction characteristics. These attributes allow aluminum cladding to enhance wood windows’ weathering and minimize maintenance.

The metal’s maintenance-free performance is reinforced by its long-lasting finishes (including Kynar 500). It’s a surface that resists chipping, cracking and denting. When scratched, it can be easily refinished to its original appearance. In the interior, solid aluminum windows are far more resistant to normal wear and tear. They won’t scuff like vinyl or dent like wood, both of which can sustain surface damage beyond repair.

The Detriments of Vinyl Windows

Recently the entire PVC industry has come under fire for environmental reasons. The loudest of these recent attacks are aimed not only at PVC but at the broader issue of chlorine use in industrial society. As reported in recent issues of EBN, Greenpeace is calling for the phase-out of all chlorine-based industries, including PVC, for a range of health and environmental reasons. In the wake of all this publicity, many builders and architects are questioning the wisdom of specifying materials made from PVC and looking into alternatives. At the end of their useful life, products made of PVC pose additional problems. Recycling post-consumer PVC products is difficult because of the wide range of additives and formulations that go into them.

PVC is not only difficult to recycle, it also greatly complicates the recycling of other plastics, particularly polyethylene terephthalate (PET). Clear PVC containers are very difficult to distinguish from those made of PET. During processing the PVC melts at much lower temperatures than the PET and actually starts to burn when the PET is melting. The burnt PVC creates black flecks in the otherwise clear PET material, making it unusable for many applications. Even worse, it can seriously damage the equipment. Since even a tiny amount of PVC can do expensive damage, optical scanners and other high-tech devices have to be installed at many PET recycling facilities to separate out unwanted PVC containers.

Solid vinyl windows have been promoted for their durability, but studies done for the Canada Centre for Mineral and Energy Technology call into question some of those claims. The study Long Term Performance of Operating Windows Subjected to Motion Cycling found that air leakage through the vinyl casement windows increased 136% (significantly more than the aluminum and fiberglass windows tested, and somewhat more than the wood windows tested).

One cannot ignore the million-plus pounds of vinyl chloride gas or the million-plus pounds of the plasticizer DOP emitted into the atmosphere each year. Or the 15% of cadmium emissions from municipal solid waste incineration that comes from PVC products. Or the evidence linking PVC production and disposal to dioxin, PCB, and furan emissions.

The architectural industry cannot ignore that the upstream and downstream impacts of PVC, and the low costs associated with PVC products do not include the societal costs of environmental remediation. To be responsible stewards of our environment, we need to consider the entire lifecycle of building products. For these reasons; in applications where better, safer, and more environmentally responsible alternatives to PVC exist or can be developed at a lower total cost (including environmental and health costs borne by society) than that of PVC, we at Champion Window and Door encourage the use of those products; used or developed.

References: