Bird-Friendly Design — Part Three: Glazing Solutions
by Christine Sheppard
It is possible to design buildings that can reasonably be expected not to kill birds. Numerous examples of this kind exist. These are not necessarily designed with birds in mind, but to be functional and attractive. These buildings usually have windows, but may use screens, latticework, grilles, and other devices outside the glass or integrated into the glass.
Designing a new structure to be bird friendly does not need to restrict the imagination or add to the cost of construction. Architects around the globe have created fascinating and important structures that incorporate little or no exposed glass.
In some cases, inspiration has been born out of functional needs, such as shading in hot climates, in others, aesthetics. Being bird-friendly was usually incidental. Retrofitting existing buildings can often be done by targeting problem areas, rather than entire buildings.
Finding glass treatments that can eliminate or greatly reduce bird mortality while minimally obscuring the glass itself has been the goal of several researchers, including Martin Rössler, Dan Klem, and Christine Sheppard.
Their research has focused primarily on the spacing, width, and orientation of lines marked on glass, and has shown that patterns covering as little as 5% of the total glass surface can deter 90% of strikes under experimental conditions.
This research has consistently shown that most birds will not attempt to fly through horizontal spaces less than 2 inches (5 centimeters) high nor through vertical spaces 4 inches (10 centimeters) wide or smaller.
We refer to this as the "2 by 4 rule." There are many ways that this can be used to make buildings safe for birds.
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This external screen of tinted glass on the GSA Regional Field Office, in Houston, Texas, designed by Page Southerland Page, means highly reflective windows are not visible to birds from most angles.
Photo: Timothy Hursley
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Emilio Embasz used creative lighting strategies to illuminate his Casa de Retiro Espiritual (1975), located north of Seville, Spain. Only a small portion of the building is above ground, and most of the glazing surrounds a subterranean courtyard, limiting its danger for birds.
Photo: Courtesy Emilio Ambasz and Associates
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