Each year, millions of birds accidentally fly into glass windows, doors and facades, with many of these collisions being fatal. As glass continues to make up more and more of the external building envelope, it is likely that the number of birds affected by this problem will increase over the coming years. Building requirements are becoming more stringent across the world, which means architects are now looking for glass solutions that are safer and which help to reduce the risk of bird collisions, whilst still providing the aesthetic and performance attributes that their projects require.
The two most common causes of birds colliding with glass are its transparency and its reflectivity.
Birds cannot differentiate between reflections of tree sky, or habitat, and the real thing. Even low-reflecting glass can act like a mirror when it is bright outside and dark inside. When coupled with certain façade designs, the reflections can create areas that are visually confusing to birds.
When there is a direct line of sight from one window to another (e.g. walkways, corners, bus stops, or transparent wind/sound barriers), birds do not perceive the glass as a barrier, and attempt to fly through, causing the collision. Also, birds can see wooded atriums or indoor plants as an inviting habitat.
The design of the building and its location can have a significant impact on the collision risk as well as the maximum effectiveness of deterrents. Building shape, location, and landscaping (especially the anticipated height of the tree canopy once mature) all have considerable impact on the collision risk profile of the facility.
Birds use the night sky and ambient light levels to aid their migration navigation. This causes nighttime collisions as lighting inside buildings, especially those buildings with potential habitat, attracts birds. Artificial lights, particularly those that point upward, can lure and trap birds in their haze, where they potentially die of exhaustion.
Glass lends itself to sophisticated design, and is a timeless, integral component of architecture. While humans can use environmental cues to identify glass as a barrier, there is growing realization that birds cannot.
The expanding Bird1st™ product offering from Guardian Glass is a work of innovation, and the clear answer when seeking high performance glazing that does its part to help protect birds.
Paired with select Guardian SunGuard® low-E coatings, Bird1st glass delivers on creating smart, beautiful structures cognizant of various performance and energy standards. Bird1st products may meet LEED Pilot Credit 55 and Toronto Green Standard Bird Collision Deterrence values.
Bird1st products visually signal an impending barrier to birds, helping decrease collisions as confirmed by the acceptable Avoidance Index score from the American Bird Conservancy (ABC). To further defend birds, Bird1st adheres to the 2" x 4"* rule accounting for different bird sizes and species.
*2″ x 4″ rule: Two inches or less of horizontal space or four inches or less of vertical space between etch-markings.
There are three different preferred ways to treat glass that range in visibility to humans and have all been shown to be the most effective for bird-friendly applications. The decision on which one to use can be based on the project criteria for aesthetics, cost and keeping birds safer.
Note that these treated glass deterrent applications primarily address daytime collisions, although frit may help with nighttime collisions too.