Birds can't see glass. It's estimated that thousands of birds collide into Chicago buildings annually and die because they cannot see glass. During the day, trees are reflected in glass and birds head towards the reflection. Separately, birds sometimes see interior landscaping and head towards that, too. It doesn't end well. The Cornell Lab of Ornithology estimated that Chicago is the most dangerous city for migrating birds because of its location on a major migration route.
Bird Friendly Chicago is a coalition of groups that is supporting an ordinance to change the situation here. Alder. Brian Hopkins, 2nd Ward, has proposed an ordinance that would require building façades to be “bird friendly”, reducing the propensity of bird strikes. This would be in addition to the building code modernization that was introduced in March, the City Council may consider another building code change.
The proposed ordinance, O2019-320, would require that all new construction buildings, and renovations that require permits, shall use façade materials that have a low "threat factor". In addition, other structures, including railings, windscreens, bus shelters, and pedestrian bridges must be constructed entirely of materials with a low threat factor.
The threat factor, according to the proposed ordinance, "refers to the degree of risk that a material poses to birds, as defined by the most current American Bird Conservancy's Bird Collision Deterrence: Summary of Material Threat Factors".
For example, clear glass has a threat factor of 100. Modified glass can achieve a threat factor as low as six. Download ABC's façade materials ratings or see table.
Building designs would have to accommodate bird-friendly façades. The ordinance states, "At least 95% of the exposed facade material from ground level to 36 feet and the first story above any podium, including but not limited to a green roof or landscaped area, is not glass or has [modified] glass…".
Modified glass, according to the proposed ordinance, includes glass that is opaque, etched, stained, frosted, or translucent; the glass can have elements mounted outside it that eliminates reflectivity (including netting, screens, and shutters, among others).
The Spertus Institute for Jewish Studies building, for example, has an all-glass façade with a 40 percent ceramic frit pattern made up of 0.125" white dots, which, according to the façade materials ratings has a threat factor of 24.
The proposed ordinance also has a standard for the exposed façade above 36 feet and in the first story above any podium, as well. Sixty percent of it must have patterns applied to or integral to glass (see the proposed ordinance for the full rules).
The other way to comply with the requirements of the proposed ordinance would be to design to the standards in the LEED Pilot Credit 55 (Bird Collision Deterrence. The requirements of the proposed ordinance and LEED Pilot Credit 55 appear to have a lot of overlap, and LEED's Pilot Credit instructions show architects how to analyze their design in the context of making it bird-friendly.
In addition to its materials ratings, the American Bird Conservancy has a bird-friendly design guide.
The proposed ordinance has parts that are not specific and seem difficult to enforce or comply with. It may be easier, upon passage, to follow the design instructions in the LEED Pilot Credit and achieve compliance through that program. The U.S. Green Building Council, which administers the LEED rating program, has a bird collision threat rating calculator in addition to instructions on how to divide the building into the different threat zones.
Visible interior landscaping would always have to be enclosed with "the highest level" bird-friendly glazing because "interior landscaping creates an extremely hazardous avian environment", according to the ordinance.
The proposed rules also stipulate interior and exterior lighting requirements. Inside, all lighting must be connected to occupancy sensors or timers, to turn lighting off when not necessary. Outside, certain light types would be prohibited and certain lights would have to be turned off between 11 PM and sunrise.
Additionally, the proposed ordinance has rules for site selection (although no clear standard), buildings adjacent to natural areas, and at-grade building ventilation grates.
The bird-friendly rules would not apply to single-family houses and apartment buildings with six or fewer units. The rules also wouldn't apply to any new building or existing building that is already built with all materials having a threat factor of 15 or less. However, in both of those exceptions, if the building has glazing on any of its façades that exceeds 30 percent of that façade, it would have to comply with the ordinance.
If approved, the rules would apply to buildings undergoing permit review beginning January 1, 2020.
The American Bird Conservancy, which co-created the LEED Pilot Credit, has a gallery of bird-friendly building designs from around the world. Two of the buildings are in Chicago: Aqua Tower, and the Kam L. Liu Center, both designed by Studio Gang. However, MAP Strategies is researching examples of more common-to-Chicago bird-friendly building designs or adaptations to guide our clients.
The ordinance was referred to the Committee on Health and Environmental Protection, which hasn’t yet scheduled a meeting to hear the bird-friendly ordinance. Additionally, since the ordinance would amend the Chicago Building Code, it might be heard in the Committee on Zoning, Landmarks, and Building Standards.