but because humans have a more limited range of color
perception, the UV pattern is relatively unobtrusive.
Product testing for UV glass and films is now focusing on
which patterns are best at deterring birds while requiring
the least amount of window coverage.
Netting and screens: Subtle netting placed a few inches
out from the glass can soften a bird’s impact. Some screens
can be attached with suction cups or eye hooks, according
to American Bird Conservancy’s Bird-Friendly Building
Guide, while larger installations may require a specialist.
Investigate Envelope Improvements
If your budget allows for a larger investment into the
envelope, you may be able to find a multi-faceted solution
that takes care of other problems in addition to cutting
down on bird collisions, notes Bates.
“Facilities managers are just as concerned about birds
roosting and defecating on the buildings. It’s unsightly
and unsanitary and it also causes excess weathering of
materials,” Bates says. “One of the things we’ve imple-
mented is a very thin suspended wire above the canopy to
deter roosting. They’re basically imperceptible and have
proven to be very effective on bird roosting.”
One recent project, the U.S. Embassy in London, required
a specialized solution. The building was designed as a glass
cube, leading to outcry from local citizens concerned about
unusual species that live in and migrate through the area.
Kieran Timberlake opted to add a tension ethylene tetraflu-
oroethylene (ETFE) membrane as an outer envelope, creat-
ing a structured surface that provides a unique appearance,
preserves the glass, and eliminated reflection issues.
“We also had a pattern implemented on the ETFE itself
like the one that’s also embedded in solar panels,” notes
Bates. “That way, we can moderate the solar radiation on
the inside and improve bird strike performance.”
Other areas of the building still have exposed glazing,
so the architect designed a specialized frit that acted as a
clever design element in addition to a safety feature.
“The fritting has to be such that the space between dots
is no bigger than the palm of your hand,” says Bates. “We
set up a grid of these dots in a star pattern, which enabled
us to create a visual scene with a little American iconography
while also integrating proven bird-safe architecture.” B
Janelle Penny firstname.lastname@example.org is senior
editor of BUILDINGS.
1) Small Frits
Examine potential frit patterns from a
distance. How well can you make out the
dots? If you have a hard time distinguishing between them, it will be even harder
for birds, who may perceive the dots as
small clouds on the horizon. Ideal frits are
prominent and arranged into patterns, such
as stripes or larger shapes, to drive home
the point that your window is not sky.
2) Indoor Patterns
Films or tapes attached to the inside of
your glass may not ameliorate the whole
problem because the outside of the
windows is still reflective. Depending on
the angle, birds may not see your film at
all thanks to the reflection on the outside.
The best films and tapes attach to the
outside to help break up the glare.
Giant patterns of hawks and owls (such
as the one at right) are popular choices
because many people believe smaller
songbirds will fear the predators, but
this is rarely the case, Sheppard notes:
“Birds don’t recognize silhouettes as
dangerous. They just recognize it as
something they can fly around.” If
you’re sold on window films, Bates recom-
mends working with an architect to design
a film that mimics frit patterns.
3 TACTICS THAT DON’T WORK
COMPARISION OF DIFFERENT RETROFIT OPTIONS
MATERIAL EFFECTIVENESS COST APPLICATION APPEARANCE LONGEVITY UPKEEP
solutions ★★★★★ ★ ★ na na
Netting ★★★★★ ★★ ★★★ ★★★★ ★★★
Window film ★★★★★ ★★★★ ★★★★★ ★★★ ★★★★
Screens ★★★★★ ★★★ ★★★★ ★★★★★ ★★★★
Shutters ★★★★★ ★★★★ ★★★★★ ★★★★★ ★★★★
Grilles ★★★★★ ★★★★ ★★★★★ ★★★★★ ★★★★
Replace glass ★★★★★ ★★★★★ ★★★★★ ★★★★★ ★★★★
5 stars/$ = Highly effective Expensive Easy Attractive Long-lasting Minimal