Laura Erickson's For the Birds

Monday, April 22, 2019

Essentia's Proposed Glass Building in Duluth

Black-and-white Warbler

Essentia, a large medical provider in Duluth, is planning to build a huge new building in downtown Duluth. I’ve attended a meeting at the Duluth Planning Commission regarding it, and then two weeks ago an information meeting about it. It sounds very much like the people working on the structure, which will be mostly glass, are taking seriously the needs of birds—they listed minimizing bird collisions at the very top of the list of issues they were trying to address in their building design. 

Duluth is at the epicenter of songbird migration in the Upper Midwest, and a tall, glassed-in building could lure a lot of nocturnal migrants to their deaths. To prevent this will involve employee discipline. It’s critical for every one of the shades in the building to be drawn at night during spring and fall as the default; individual patients can open them to look out, but unless someone is actively enjoying the view, the shades should always be closed at night, especially in the higher stories. 

Windows also kill birds during daytime when drawn shades don’t make much difference. And again, Duluth’s position on the western tip of Lake Superior ensures that plenty of migrants are present all day just about every day during spring and fall, in addition to all the local birds that live year-round in the area. The building planners seem to have learned a lesson from the US Bank Vikings Stadium disaster, and intend to use fritted glass—that is, glass that has been etched in a pattern to make it more visible. Unfortunately, the samples of fritted glass I saw had the fritting on the inside between double panes, rather than on the outside surface—what architects call Surface #1. I asked one of the architects about it, and he said that fritting on the outer surface weathers too quickly. 

As far as I could see, the sample fritted glass seemed just as reflective as non-fritted glass. I was troubled, so I wrote to Dr. Daniel Klem, the world authority on bird-window collisions, asking about this. He responded: 
Jury is still out as to how frit on the outside surface (what architects call Surface #1) will hold up to the weather. I am, however, aware of installations that have installed fritted glass on the outside Surface #1. Someone recently informed me that a Calgary glass manufacturer, Goldray, is the only company who will guarantee fritted sheet glass where the frit is on the outside Surface #1. 
You have reason to be concerned about claims that the frit will deter bird strikes if placed on any surface. This certainly is not true in all circumstances. For example, it is true if the fritted panes are used in a corridor (what our Canadian neighbors call linkways), atria, railings where looking at the windows from either side we humans and the birds will see the frit and if the frit is applied in the 2 x 4 Rule (pattern elements separated by 2 inches = 5 cm if oriented in horizontal rows or 4 inches = 10 cm in vertical columns) it will effectively deter, even completely eliminate strikes. But these are relatively rare installations for windows compared to most other placements; most windows cover a dark interior space, and as such even a perfectly clear pane with or without frit will reflect the facing habitat and sky off of Surface #1. In these majority of installations with Surface #1 reflecting like a mirror the frit or any other markings applied to interior window surfaces will be hidden from humans and birds. Without knowing, I suspect your new building will have sheet glass covering a dark interior compared to the outside, and any frit pattern applied on an inner surface will not deter bird-window collisions. In these majority of installations the frit definitely must be applied to the outside Surface #1 to be effective.  
I’m forwarding Dr. Klem’s comments to people involved in the project. With luck, they’ll at least try to get glass fritted on that outside surface, especially on the lower floor windows, except where Dr. Klem noted the more standard fritting would work fine. This building will serve Duluthians for decades to come. The better it can be constructed to protect our natural environment and precious wildlife, the better for all of us. I’m healthy and alive today thanks to Essentia’s cardiology, surgery, and oncology departments. It would be ironic indeed if I had another heart attack thanks to bird-killing glass at my own medical provider.

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