Bird-Friendly Glass Makes Headlines in 2019

New buildings in New York City will soon include bird-friendly glass, which could save tens of thousands of birds’ lives each year during the migratory season. The New York City Council passed Int. No. 1482-2019-B in December, making it the largest U.S. city to adopt bird-friendly legislation.

The bill requires that the exterior wall envelope and associated openings be constructed with bird-friendly materials up to 75 feet above grade. Materials other than bird-friendly materials are not allowed to exceed a total of 10 square feet within any 10- by 10-foot square area of exterior wall below 75 feet above grade. The law also specifies that in instances where a building renovation includes the replacement of all exterior glazing, the alteration must comply with the updated building code.

The amendment to section 1403.8 of the New York City building code defines bird-friendly materials as “a material or assembly that has, or has been treated to have, a maximum threat factor of 25 in accordance with the American Bird Conservancy (ABC) Bird Collision Deterrence Material Threat Factor Reference Standard, or with the ABC Bird-Friendly Materials Evaluation Program at Carnegie Museum’s Avian Research Center test protocol, or with a relevant ASTM standard.”

In addition, the exterior wall envelope and any associated opening installed adjacent to a green roof system on the same building must be constructed with bird-friendly materials up to 12 feet above the walking surface.

The law also requires that bird hazard installations regardless of height above grade and fly-through conditions located 75 feet or less above grade be constructed with bird-friendly materials.

The bird-friendly glass bill passed by a vote of 43-3, and was enacted on January 10, 2020. It will go into effect one year after the enactment date.

Dr. Christine Sheppard, Glass Collisions Program director for the ABC, responded to the bill’s passage, saying that bird-friendly building design shouldn’t be perceived as an add-on or an extra.

Marc Deschamps, director of products and business development for Walker Glass Company Ltd., which creates bird-friendly patterns on glass, said he wondered how much of the consulting process was done with product manufacturers.

“It’s a valuable effort to reduce collisions but the specifics are not positive,” he said, adding that the threat factor of 25 seems to be chosen arbitrarily.

Deschamps also explained there isn’t an ASTM Standard addressing the testing of bird-friendly glass, which leaves product manufacturers with no option but to use the ABC’s test method. He said the ABC has a limited capacity to test because they have a limited capacity to catch birds for the test.

“The test is quite flawed,” he added. “It produces inconsistent results, variables are not controlled and there are test issues in terms of credibility and reliability … This makes compliance of the legislation difficult in my opinion. There are no ASTM test standards to measure the product against. In our experience, we believe that trying to obtain an arbitrary number is not the right approach. Other cities created legislation around best practices, such as geometry and visual markers, established by scientists and studies.”

A Case Study for the Birds

While New York City is focusing on bird-friendly building design, the owners of U.S. Bank Stadium in Minneapolis are considering responses to a study showing the bird fatality rates caused by the stadium’s glassy façade. According to the study, titled “Factors Influencing Bird-Building Collisions in the Downtown Area of a Major North American City,” U.S. Bank Stadium and three high-rise office buildings in the city accounted for 68% of estimated fatalities in the periods monitored in 2017 and 2018 (March 15-31, June 1-30 and August 15 – October 31 of both years). Estimated fatality rates for these buildings ranged from 79 to 216 fatalities per year, with the stadium accounting for 111 per year.

The estimated fatality rates for the top buildings exceed the rates at the majority of U.S. high-rise buildings, according to collision data from 11 cities. However, several large and/or glassy buildings have been shown to exceed these rates, such as the McCormick Place Convention Center in Chicago with an average of 1,028 fatalities per year from 1978 to 2012. Chicago’s lawmakers put forward a bird-friendly design ordinance in January 2019 that has not yet been passed by the city.

When analyzing the causes of collisions at the 21 buildings studied, glass area and vegetation within 50 meters were included as some of the top causes.

Glass area can lead to bird collisions due to several factors, according to the study, including greater confusion of birds due to larger amounts of reflective and/or see-through surfaces. This is especially true when the glass is featured in large, unbroken expanses. An increase in light emission increasing numbers of nocturnal migrants attracted to buildings is another factor.

The study also indicates that a major reduction in bird collisions can be achieved by focusing mitigation efforts on a small number of especially problematic buildings as well as particularly problematic spans of glass.

Minnesota Vikings Football LLC and the Minnesota Sports Facility Authority (MSFA), the stadium’s managing body, helped fund the study.

While the fatality rate was lower than representatives for the MSFA expected, KARE11 reports that the authority is acting on the report’s recommendations that it turn off stadium lights at night and reduce surrounding vegetation. An MSFA representative told the news station that the organization will consider whether to apply a retrofit, bird-friendly film to the stadium’s glass and make a decision this year.

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