A Bird Friendly Design Ordinance has been introduced in Chicago by Alderman Brian Hopkins to mitigate bird collisions with glass over time by establishing bird safe standards for new building construction and substantial renovations or rehabilitated buildings that require permits. If passed, the ordinance will go into effect for all permits applied for beginning on January 1, 2020.

The ordinance would not apply to detached homes, townhouses, two-flats or residential buildings of six units or less; however, the exemptions are inapplicable if glazing on at least one façade exceeds 30 percent of the façade. The ordinance also requires that site selection must be made in consideration of nearby existing bird habitats, landscaped plantings and known bird migratory paths. In circumstances where a building is adjacent to a natural area, or separated by a roadway from a natural area, the glazing treatment must be the greater of the height of the mature tree canopy or 50 feet above grade.

According to the ordinance, buildings would have to be designed so the building and site structures are visible as physical barriers to birds. Interior landscaping is deemed to be the “greatest threat potential,” therefore, visible interior landscaping should always be behind the highest level bird-friendly exterior glazing.

Structures such as railings, windscreens, skywalks and bus shelters must be constructed entirely of materials with a threat score of 15 or less. A threat factor 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. Clear glass, single pane or insulating, has a threat factor of 100.

Buildings must be designed and built in accordance with either of the following requirements:

  • At least 95 percent of the exposed façade 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 glass that:
    • Has elements mounted outside glass that eliminate reflectivity, like secondary facades, netting, screens, shutters or exterior shades;
    • Is opaque, etched, stained, frosted or translucent glass;
    • Includes patterns applied to or integral to glass on at least 60 percent of the exposed façade above 36 feet and in the first story above any podium which is:
      • Visible from the outside, from an inspection distance of 18 inches, regardless of location of pattern (side one or side two) and reflectance of surface;
      • Created by regular or irregular lines spaced no more than 2 inches apart at any point, with a minimum line width of 1/8-inch; or
      • Composed of dots or other shapes with a minimum dimension of 2/8-inch.


The ordinance also specifies requirements for external and interior lighting. Chicago already has a program called Lights Out Chicago which encourages owners and managers of tall buildings to turn off or dim their decorative lights during the migratory season.

The bill is supported by Bird Friendly Chicago, the city’s Audubon society, and architecture firms such as Studio Gang.

“If we keep environmental impact in mind from the start of the design process, we can create buildings that are functional and aesthetically pleasing, and also bird friendly. This ordinance is a great step forward by a city with a history of groundbreaking architectural advancement,” said Jeanne Gang, founding principal of Studio Gang in a release from Bird Friendly Chicago.

According to the Chicago Tribune, the ordinance could face opposition from real estate developers in the city.

“I think we’re all interested in doing what we can to protect the birds during their migration season,” said Michael Cornicelli, executive vice president of the Building Owners and Managers Association of Chicago, which represents most downtown commercial buildings to the Chicago Tribune. “I think it’s a matter of determining what are the most cost-effective measures to do that.”