In the Know

Expert Advice: Specification Considerations for Bird-Friendly Glass

Whether you call it bird-friendly or bird-safe, this type of glass is desired by a wide audience, including environmentally conscious building owners and developers. Bird-friendly glass is making its way into building codes and standards in both Canada and the U.S. New York City recently enacted a bill requiring that the exterior wall envelope and associated openings of new construction and renovations that include the replacement of all exterior glazing be constructed with bird- friendly materials up to 75 feet above grade. And more cities are expected to follow suit.

Danik Dancause, marketing operations manager for Walker Glass Company Ltd. of Montreal, tells Architects’ Guide to Glass & Metal that anywhere glass and birds mix can be fatal. This is evidenced by the fact that, according to the American Bird Conservancy, up to 1 billion birds die in collisions with glass each year in the U.S.

When Should Bird-Friendly Glass Be Considered?

“Architects should pay attention to the location of a building site. There are flying paths for migration and, at certain times of year, the volume of birds can increase 40% in a given area … Number two is the position of a building. If a building is facing a forest, bushes or water, then yes, absolutely all windows facing that area will attract birds,” explains Dancause.

In those cases, the entire building wouldn’t require bird-friendly glass, only the façade facing the highly vegetated area within the birds’ flying range. However, Dancause suggests checking on local legislation. Commonly, the glass portion of a building should be treated up to about 40 feet. This usually applies to more than just new construction.

In retrofit situations where the glass creates a condition dangerous for birds, Dancause recommends having visual markers for the first 40 feet. This can be a preferable alternative to cutting down old trees being reflected in the glass.

Dancause also says it’s important to use bird-friendly glass at train stations, bus stops, walkways and railings.

“Any structure that is glass and see-through should have bird-safe glass,” he says. “Bus stops made of glass in rural areas or parks are a trap for birds and deadly. Any glass structure attached or not attached to a building with-in the first 40 feet of the ground should be thought about.”

Bird-Friendly Glass Options Explained

Bird-friendly glass comes in several different forms. One thing they all have in common is that they adhere to the 2 x 4 rule created by ornithologist Dr. Daniel Klem. Glass that has visual markers 2 inches by 4 inches apart will significantly reduce the risk of collision with glass, according to Dancause. These markers are visual cues that make the glass more apparent to birds.

Dancause says Canada is moving toward a 2 x 2 rule. Canada adopted the CSA 460 Voluntary Standard last year. The Standard also recommends the visual markers be placed on the first surface of the glass so it’s easier for birds to identify that the reflection is distorted. Some markers can also be more visible to the human eye, such as a frit or digitally printed patterns.

Walker Glass has partnered with Vitro Architectural Glass on AviProtek E, a glass that features acid etching on surface one with a low-E coating on the second surface. In its partnership with Pilkington North America, Walker Glass offers AviProtek T, which incorporates acid etching on pyrolytic coated glass for a solution that reflects UV light. This makes the pattern visible to birds but less perceptible to humans. In an insulating glass unit, AviProtek T can be combined with a low-E coating on surface three. Several pat-terns are available, including lines, dots and an organic pattern.

Other solutions include Guardian Bird1st glass, which features a patent-pending UV stripe coating on the first surface. It can also be paired with a low-E coating on surface two. There’s also a product called Feather Friendly, a retrofit solution that can be applied to existing windows.

“This is perfect for a residential house or in a building where the glazing is not being changed. It’s also helpful if there are only a couple of problem windows,” says Dancause.

He recommends that architects consider whether their ultimate goal is wildlife protection or energy performance when choosing which product would work best for their new construction or renovation project.

The Bird-Friendly Movement

Legislation is bringing more awareness to the issue of bird collisions with glass and Dancause believes the movement will continue to grow. He says people want to contribute to environmental protection and do something positive for the world. There also have been several cases of environmental groups suing building owners due to high rates of bird fatalities, which is another factor he says owners should consider.

“There are solutions out there. The glass world will find a way to continue innovating and finding ways to protect wildlife,” he says.

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