Everything old is new again in the fenestration trade.

For most in the design and construction community, the choice of window materials usually revolves around the three mainstays of wood, vinyl and aluminum. Probe the topic of metal windows with an architect or construction specifier and they might mention code-required steel fire-rated windows in addition to aluminum. Despite their historic significance and renewed appeal, few designers are familiar with windows fabricated from special metals, such as hot rolled steel or bronze, But this was not always the case.

The first significant emergence of metal windows occurred early in the Industrial Revolution with cast metal window frames. Usually made from cast iron, window frames were sometimes made from other metals such as copper. Although wood windows remained the predominant choice, expensive but elegant metal windows were first introduced in large public buildings, as well as exclusive residences, and later in more common houses.

As the production of steel advanced in the mid-1800's, solid hot rolled steel window frames soon became available in Europe and North America. Hot rolled steel was the predominant metal window material from the 1890's into the post World War II era; during this period, metal windows became a serious competitor to wood windows.

Hot rolled steel offered many design benefits over wood. The strength of steel permitted the construction of very large windows with narrow frames and expansive glass areas, increasing the amount of light and ventilation entering the space. Fire resistance was an added benefit, as hot rolled steel windows were widely used in commercial, industrial, institutional and multifamily residential buildings. The thin profile window designs contributed greatly to the period's major architectural trends such as Art Deco, Art Moderne and International Modern.

In the wake of World War II, aluminum windows were introduced and by the 1960's had clearly captured the metal window market. Fire rated steel windows were used only where required by fire and building codes. Aluminum superseded steel was the design window material of choice.

But the tides of architectural choice are shifting once again and special metal fenestration products are seeing resurgence in interest. While aluminum remains, and will remain, the leading metal window material, special metals are being used increasingly in design driven niche applications.

Optimum Window Manufacturing has served as supplier to many restoration projects involving pre-War warehouse spaces and historic institutional and commercial properties.

We have also seen tremendous interest from upscale urban penthouse residences and ultra high-end private estate properties. So be it a landmark building restoration or a new construction project striving to differentiate itself with a unique style, special metal windows and doors are an important and growing part of those efforts.

Besides hot roiled steel, new special metals include cold rolled steel, stainless steel and bronze. Cold rolled steel offers a smooth surface finish and many style options, in addition to strength and durability. Stainless steel windows are renowned for their anti-corrosive, maintenance free properties, as well as "high tech" aesthetics.

Besides decorative applications, bronze products' immunity to salt air corrosion is useful for shore construction.

Today's modern bronze, hot rolled, cold rolled and stainless steel fenestration products offer numerous modern features and options. Many new special metal windows utilize insulated glass systems for enhanced thermal performance and sound attenuation. Glazing options include tinted, low-E, tempered and laminated glass. Modern conveniences include aesthetic and ergonomic hardware, multi-point locking systems, insect screens, special shapes and custom colors and finishes. Manually and electrically controlled mechanical operators are available for projected window styles.

To aid designers and installers alike, special metal windows are available with interior and exterior matching trim accessories, as well as modern installation and anchoring systems.

Clearly bronze, cold roiled steel, and hot roiled steel windows are not relegated to fenestration history. They are a vibrant, exciting and growing part of the sophisticated design and specification professional's portfolio.