Migratory bird populations colliding into the glass facades of tall buildings is a growing concern in the building industry. Architectural glass fabricator Viracon has published a new technical document titled Bird-Friendly Glass. Designed to divert birds away from collision with glass and contribute to sustainable building practice, Viracon says silk-screen patterns help birds distinguish glass windows from the open sky.

The risk of bird collision with glass poses design and environmental challenges for both the architect and the conservationist, according to the announcement. In 2009, it was estimated that more than 1 billion birds die annually due to collision with glass. In order to understand bird-glass collisions, Viracon has been involved with the American Bird Conservancy, Washington D.C.’s testing involving silk-screen patterns and how birds in flight responded to those various patterns. According to the company, the researchers learned that horizontal and vertical lines are most effective in decreasing the number of collisions. The results concluded that the effectiveness of all-over patterns increases as the coverage increases and that because silk-screen patterns are found inside insulating units, lower efficacy is expected in situations where the angle of view obscures the pattern. Viracon adds that on-going testing is being conducted to determine the effect of alternate silk-screen patterns, colors and low-E coatings.

The announcement also points out that in most cases, the lower stories of a building run the highest risk of collision because birds become confused by reflections of surrounding landscapes. Equally concerning are buildings with clear glass curtainwalls that suggest seemingly unobstructed passageways.