Bird Vetted & Approved

The evolution of bird-safe technology and how to test and evaluate new products

In North America, as many as 1 billion birds are killed every year flying into glass.

Fortunately, this is a solvable environmental issue with the development of bird safe glass technologies. However, as a relatively new product category, the industry has yet to develop a set of standardized guidelines for testing, performance and quality.

Despite this, the due diligence and process of evaluating and testing new bird-safe solutions is critical, as with any new technology.

While Vitro is letting the wildlife experts handle bird deterrence, it has leveraged its expertise in glass product development and testing to develop its own rigid protocol of testing standards for its latest bird-safe product, BirdSmart^® Bird Safe Glass.

Why Birds Have a Hard Time Seeing Glass

Compared to humans who have strong binocular vision, which enhances depth perception, a bird’s anatomy provides more spatial vision, enabling them to constantly scan their surroundings in search of food and places to land. This lack of depth perception makes it hard for birds to perceive glass as a barrier.

Unlike people, many bird species see ultraviolet light. Because UV rays are absorbed by transparent and reflective glass, this makes the glass appear invisible to birds.

Another issue is the fact that glass reflects the sky and surrounding trees. Birds confuse these illusions with reality and attempt to reach these destinations.

Consequently, the combination of poor depth perception, UV rays and reflections create scenarios where birds see indoor habitats like plants and attempt to fly towards them with no awareness that a glass façade or window is standing in the way.

Bird-Safe Legislation and Building Codes

With growing awareness of the bird collision issue, at least 25 cities and states have enacted legislation requiring bird safe glass in buildings.

Toronto was the first, followed by New York City, which is currently the largest bird safe glass market. Some other cities with bird-friendly glass requirements include Madison, Wisconsin, Washington, D.C., Portland, Oregon and several cities in California.

On the state level, Minnesota, Michigan, Wisconsin, Virginia, Maryland and Maine have enacted legislation for government buildings. The Canadian provinces of Ontario, Alberta and British Columbia also have passed bird safe legislation for all buildings.

On the national level, the Federal Bird Safe Buildings Act could potentially mandate bird-friendly practices in federal buildings.

In addition, a number of sustainable building rating programs award credits for bird-friendly designs. For example, in the U.S. Green Building Council’s latest LEED^® v5, projects can earn a credit for the specification of bird friendly glass in the Sustainable Sites Biodiverse Habitat category.

Driven by code requirements, green building programs and voluntary bird-safe standards, the frequency of building owners asking architects to specify bird-safe glass for their projects is growing.

How Bird-Safe Glass Prevents Collisions

Bird-safe glass works by etching dots or patterns with a maximum spacing of 2” x 4” into the glass to break up the optical illusion of open space and the continuous transparency of glass thereby enabling the birds to detect its presence. That is two inches horizontally in rows or 4 inches vertically in columns. The pattern is best seen when applied to Surface #1, otherwise the color and reflection of the glass can weaken the bird deterrence.

The 2x4 rule was originally established to cover any gaps small enough for the birds to attempt to fly through. But to protect smaller birds, such as hummingbirds, 2” x 2” patterning has now been accepted as best practice.

Types of Bird Safe Glass

Laser-etched glass like BirdSmart^® glass by Vitro applies the markers on the first surface. The laser etching process is non-caustic and uses no harsh chemicals.

Unlike acid etching, which is performed in select plants, the laser-etching process can be done anywhere. Vitro laser etches glass in the same facility where it is produced and coated, making the laser etched bird-glass manufacturing process streamlined and efficient.

When laser etched glass is paired with low-e glass on the second surface, it does not have any impact on the glass’ solar heat gain or visible light transmittance (VLT). In addition, laser etching the exterior lite does not impact the strength, durability or cleanability of the glass as proven by rigorous testing.

Product: BirdSmart^® Glass + Solarban^® 65 Glass
Location: Pittsburgh, PA — USA
Photographer: Scott Witalis

Acid-etched glass like AviProtek^® E bird safe low-e glass by Walker Glass in partnership with Vitro has acid-etched visual markers on the first surface of an insulating glass unit (IGU) with a Solarban^® solar control low-e coating on the second surface. This configuration optimizes energy performance as opposed to ceramic frit bird-safe glass, which relegates the low-e coating to the third surface where solar performance levels are lower. Similar to laser etched glass, acid etched glass does not impact the glass’ solar heat gain or VLT.

The National Aviary — Wetlands
Products: Starphire Ultra-Clear^® Glass by Vitro, AviProtek^® Pattern 214 Glass by Walker Glass
Location: Pittsburgh, PA — USA
Architect: Montgomery Smith
Glass Fabricator: Isoclima Specialty Glass
Photographer: Jim Cunningham

UV-coated laminated glass tunes in to birds’ UV vision. While many birds can see UV rays, not all species do, making this option potentially less effective than etched glass, particularly at certain times of day.

Bird Glass Testing Best Practices

Applying its extensive knowledge of current and potential bird-safe glass-related ASTM standards, Vitro’s team of experts mapped out what it expects will eventually be the industry-required battery tests for bird safe performance. BirdSmart^® glass was then rigorously tested in the following five categories: Gloss, Taber Abrasion, Strength, Stain and Weathering.

Gloss

Measuring the dot’s level of gloss gives a good indication of how easily a bird can see them.

A standard pattern of 6mm laser etched dots on a 2” x 4” grid on clear glass was submitted to the American Bird Conservancy for testing. The glass received a threat factor score of 25, on a scale of 1 to 100, which makes it a bird-friendly material for codes where threat factors apply. Additionally, the appearance of the laser etch was noted to be very matte compared to acid etch. This can be attributed to the precision symmetrical etching process that removes the glass from the surface uniformly.

Vitro’s laser etch dots are created with a symmetric removal of material from the surface; see micrograph on the left. The resulting etch is very smooth to the touch and creates a matte finish on the glass.

Taber Abrasion

For this ASTM C501 scratch test, two pads of sandpaper were run over the BirdSmart^® glass laser-etched dots, and the level of scratching on the glass was observed. The laser-etched glass performed just as well as clear glass, proving that the laser-etched glass can withstand typical exposure and handling on a project site.

Strength

The widely accepted ASTM C158 test was performed to establish the strength of the laser-etched glass. The results showed that the integrity of the glass was not compromised by the etching.

Contradicting the misnomer that the etching might compromise performance, the tests proved otherwise. The laser-etched glass was found to be just as strong as clear glass, essentially proving the etching doesn’t compromise the structural integrity and protection against breakage.

Strength Testing – Ring on ring ASTM C1499

Stain

Per ASTM C1378, this test measures how easily six common stains from environmental contact — grout, black carbon lamp, black waterproof ink, washable ink, potassium permanganate solution and methylene blue solution — can be removed from the dots on the bird-safe glass.

In most instances, the stain on the BirdSmart^® glass was easily removed with hot water and wiped clean resulting in an average of a Grade A rating for all the tests and indicating the etched glass is as resistant to stains as clear glass.

Weathering

There is not an established ASTM test for weathering that applies to a first surface etching. However, Vitro has been performing accelerated weather testing on glass for decades. The Vitro tests include both the Cleveland Condensation Chamber test and natural weathering of samples left outside.

Both tests were performed for annealed, non-tempered glass, along with acid-etched glass. In all instances, the etched glass was proven to be as resistant to weather conditions as clear glass.

Moving Forward

As bird preservation and bird-friendly architecture continues to gain traction, architects and building owners will be seeking high-quality products and solutions to prevent bird collisions while maintaining the strength and glazing performance characteristics of glass.

The vetting and testing process of BirdSmart^® glass serves as a valuable resource to the industry for evaluating bird safe glass performance.

For more details on bird-safe testing, see the white paper, The BirdSmart® Bird Safe Glass Story: Best Practices for Testing and Evaluating Bird Safe Glass Technology.

For more information on Vitro bird-safe solutions, visit vitroglazings.com/BirdSmart.