Given a choice between translucent or white stripes, white stripes perform better because light is more visible against the background reflections. The stripes should be at least 3 mm (0.125 in.) wide. While humans see patterns, birds focus on the spaces within patterns. Dot patterns have been found to work well using the traditional 2 x 4 rule if the dot diameter is at least 6 mm (0.25 in.) in size. Generally, products meeting this criteria do not need to be tested.
Coated glasses can be utilized with many of these materials; however, the key parameter is ensuring the visible light reflection (VLR) is low enough not to further confuse the bird in flight. The ABC typically sets an upper limit on VLR at 15 per cent, although, based on recent test results, some products may use coatings with a VLR of up to 19 per cent. The visual marker should be located as close to the external surface as possible, in some cases, for effectiveness, the technology may need to be put on surface 1, however, the markers are typically placed in front of the coating.
There are other technologies which utilize ultraviolet (UV) inks or coatings, three dimensional sequins, first surface etch or appliques. All the technologies are subject to the same guidelines on spacing with the goal to ensure a bird “sees” the visual noise and changes its path to fly away from the glazing.
Consideration of the technology may impact the decision of where to place the coating, for example, surface 2 with a frit on surface 1, or surface 4 or 5 of a laminated insulating glass may be the proper configuration for a project. Each project needs to be assessed based on the needs of safety, structural, security, energy, and bird-friendliness.
Canadian prescriptive guidelines
Canada uses a standard or set of guidelines different from the U.S., which allows both prescriptive and actual tests results to be considered for inclusion on a project. Key elements of these tests are:
- Visual markers should be used in a glazing unit
(first surface) to address both see-through and reflective conditions. - Spacing of visual markers should meet the “2 x 4” rule.
- Visual markers should meet a minimum size of 3 to 4 mm (0.119 to 0.159 in.), depending on the geometry.
- Visual markers should be in high contrast to the glazing material.
- Visual markers should be used in high-risk collision zones—the first 12 to 15 m (40 to 50 ft) from grade, corners, and floors adjacent to green roofs.
- Visual markers should be considered for glazing on building elevations, balcony railings, ramps, and free-standing glass structures.
The standard, CSA A460:19 was written in 2019, and has not been updated since. For manufacturers with emerging technologies, including products which are not placed on the first surface, certain locations in Canada may be a limited market opportunity and may require special review and approval of test results before permitting the use of a bird-friendly glazing. Although CSA A460:19 is a guideline and written in prescriptive language, emerging technologies with appropriate tests reports are being considered and utilized throughout North America.
Legislation and LEED
The United States Green Building Council (USGBC), which issues the Leadership in Energy and Environmental Design (LEED) certification, points, and credits when buildings achieve specific standards in several sustainable building categories, has also been influential in creating bird-friendly glass and glazing solutions. In 2011, USGBC added Pilot Credit 55 titled “bird collision deterrence” to its library. A revised version of the credit in 2015 expanded its availability to all LEED rating systems except neighbourhoods. The credit contributes to LEED points with Pilot Credit SSpc55 in Core and Shell. The Green Building Initiative, Green Globes’s New Construction 2021 Technical Reference Manual, also includes the opportunity for points in its rating system related to measures addressing bird strikes.
In the U.S., H.R. 1986—the Federal Bird Safe Buildings Act of 2021—has been introduced in Congress. If passed, the act will ensure that all U.S. government buildings, regardless of location, are built bird-friendly. In the meantime, many large North American cities, including Toronto, New York, San Francisco, and Chicago have passed strict local guidelines as well.
