Bird safety testing
Photo courtesy Nick Merrick
ABC’s bird safety glass testing takes place at the Powdermill Nature Reserve in Pennsylvania. Avian researchers at the facility use fine, flexible nets to gather hundreds of birds during their spring and fall migrations. The researchers examine and band each bird. Then, they release them into a special test tunnel—one of only a few in the world. Each bird is tested once only, and no birds are harmed during testing.
Inside the tunnel, the bird is presented two glass options to fly toward: a plain, clear glass control sample and the test glass sample. The goal is to see whether the bird would avoid the test glass. A delicate flexible net at the end of the tunnel gently captures the bird, and prevents it from striking the glass. It is then safely released. Each flight path is digitally recorded and examined by the researchers. The results can determine whether the test glass is an effective bird-friendly material, worthy of ABC’s Bird-smart certificate.
Bird-friendly glass types
The following are some of the most effective bird-friendly glass solutions.
Textured glass
Photo courtesy Bendheim
One of the most effective bird-friendly solutions is glass featuring a surface texture that breaks up continuous reflections. Most of this glass is produced by the ‘rolled pattern’ process, where a ribbon of semi-molten glass is pulled through a set of steel rollers. Designs engraved on one or more of the rollers transfer onto the glass surface. The ‘imprinted’ glass ribbon is then slowly cooled, cut into sheets, and tempered and/or laminated for exterior applications.
This type of bird-friendly glass tends to perform well throughout the day and night. It is available in a large variety of regular and low-iron (ultra-colorless) glass designs. It is also one of the most cost-effective ways to add a decorative element to a building. As an added benefit, textured glass is an outstanding diffuser of light, often eliminating the need for secondary daylight control devices and creating an attractive soft glow at night.
Among its limitations are the relatively small sheet sizes (ranging anywhere from around 1270 x 2032 mm [50 x 80 in.] to 1270 x 3302 mm [130 in.]), the difficulty and expense of custom patterns, and a greater degree of view obscuration. Several of these concerns can be addressed by choosing a more specialized type of textured glass, such as channel glass.
Channel glass
Channel glass is a 3D, self-supporting glass that can reach heights up to 7 m (23 ft). Hundreds of channels can be lined up to create expansive glass walls free of interim metal framing. It is typically specified in one of several light-diffusing surface textures, and is also available in a relatively ‘clear’ form used as vision lites. The collision avoidance performance of ‘clear’ channel glass was a concern, and the glass was tested at the Powdermill Nature Reserve flight tunnel. In testing, it proved to be an effective deterrent and earned the ABC Bird-smart certification. The rhythmic vertical seams of the abutting glass channels likely contributed to this see-though material performing as a bird-friendly glass product.
Recent channel glass projects in major cities along migratory bird routes include New York City’s South Street Seaport, Pier 17, and Capital One Bank’s Chicago flagship. At Pier 17, approximately 4088 m2 (44,000 sf) of ‘rough cast’ textured channel glass create a 12-m (40-ft) tall, light-diffusing rainscreen façade, designed by SHoP Architects & R.A. Heintges and Associates. At Capital One Bank by IA Interior Architects, alternating clear and textured glass channels offer selective privacy, while maintaining visibility to the street.
