They say there are two sides to every story. That’s certainly true of The Hub at Prairie Shores, a dynamic new community space by Gensler in Chicago’s Bronzeville neighbourhood. Whether you’re looking at the building’s custom acid-etched glass façade, its effect on the local community, or its pioneering role for bird-friendly Chicago architecture, each aspect of this project tells multiple stories. Heck, even the Walker Textures® acid-etched glass panels were turned on their heads! We sat down with project architect Sean McGuire to discuss the building’s design concept, its connection to the local community, its contribution to bird-friendly Chicago architecture, and the challenges of bringing this architectural design to light.
Imagining The Hub at Prairie Shores
Many years ago, sandy dunes swept the area now known as Bronzeville, in Chicago. That geological history inspired the dune-like appearance of The Hub at Prairie Shores. The acid-etched façade evokes the motion of a wave crashing over a dune and produces a delicate shadow effect, while the brickwork sparkles subtly like sand.
Custom acid-etched glass was integral to the project’s design narrative. Like water, it’s a dynamic material that creates different reflections depending on the lighting and time of day. Before building, Gensler created a full-scale mock-up of the curtain wall to see how it would interact with the façade’s lighting. This mock-up revealed the multifaceted nature of acid etch glass, showing how it can look different at night, in the morning, and in the afternoon. The finished building lights up at night like a beacon, and its light is dispersed and amplified by the acid-etched glass. The effect is stunning.
The Hub at night. Acid-etched glass blurs and enhances light from within, giving the building the look of a giant beacon pointed toward the city.
Why use custom acid-etched glass?
Creating a façade like this came with some challenges. Gensler planned the curtainwall with first-surface acid etching and multiple custom designs. They needed the glazing to respond dynamically to the lighting conditions at any given moment and have an organic, “living” quality. After all, it was supposed to be reminiscent of the waves of Lake Michigan. First-surface acid etching provided this dynamic quality in a way that opaque treatments like frit or back painting simply cannot.
Then there are the five custom Walker Textures® patterns. These patterns complicated the production and assembly processes, in part because every new acid-etched pattern requires its own bespoke manufacturing setup. However, the patterns were a non-negotiable part of the façade. They create a modulated effect that grades up and down across the width of the façade, creating a hazy, organic wave shape and reinforcing the building’s lakeshore concept.
Initially, Gensler had thought of using a different acid-etched pattern for every pane of glass: a whopping seventy-two patterns in all. This was quickly reduced to eighteen in the early design stages, then streamlined to ten unique patterns. In the end, the team was able to achieve the look they wanted with just five acid-etch glass patterns. John Just, Walker’s Architectural Manager for the US North-Central region, provided the key. He suggested using symmetrical patterns and installing half the panels “upside down”. This way, each etching pattern could work as two different designs in situ and Gensler could achieve the look of ten patterns for the cost of five.
Getting from seventy-two designs to five changed the project from an impracticable dream to an attainable challenge. The Hub at Prairie Shores was still a complex and demanding project, but solving the riddle of the custom acid-etched glass brought it one big step closer to success.
Gensler had a clear vision for The Hub at Prairie Shores, one which required original acid-etched patterns created especially for this project.
If you’re working on an out-of-the-box concept that deserves truly unique glazing, we’re here to help. Check out our Patterned Acid-Etched Glass product page to see what’s available, or reach out to the Architectural Manager in your region for expert advice on designing with custom acid-etched glass.
“The design was complex and challenging. With all the custom patterns, nuanced patterns – it was a new process for everyone. It took time, but we knew that getting these patterns right was important to the effect and the narrative. That’s part of the design process with anything that’s new, inventive, and exciting.”
- Sean McGuire, project architect for The Hub at Prairie Shores
The Hub’s standout feature is its highly nuanced façade, which owes its enigmatic appearance to seventy-two bespoke acid-etched glass panes. These large panels feature five different custom patterns, meticulously graded to create the impression of a hazy, windblown wave over dunes. These patterns were developed through close collaboration between the teams at Gensler and Walker Glass.
Interior daylighting was a primary consideration in designing this project. The etched pattern on surface one diffused natural light throughout the building’s interior, while the low-iron Starphire Ultra-Clear® substrate from Vitro Architectural Glass delivers pure, clear light without the greenish tint of regular “clear” glass.
Although Gensler was not aiming for sustainable building certification for this project, sustainability was still a priority, and the façade glazing was an important part of their green building strategy. The etched designs on surface one deter bird strikes, while a Solarban® 72 low-e coating on surface three improves energy performance.
6mm Starphire Ultra-Clear® glass with custom acid-etched pattern on surface 1
Form follows function: custom acid-etched glass for a user-driven design
User-driven aspects like light transmittance and privacy played a huge part in The Hub’s design. The building includes co-working spaces, a café, exercise rooms and a games room, with each space needing different amounts of privacy and natural daylight. For example, people exercising in the gym areas would enjoy views of the outdoors, but they’d also appreciate some privacy while they worked out. On the other hand, people working in office spaces would benefit from plenty of daylight to boost their energy, but they wouldn’t want sunlight falling directly onto their laptops and making the screens unreadable.
Gensler leveraged the unique qualities of acid-etched glass to give occupants exactly what they needed, where they needed it. In the gym, for instance, the etched patterning extends from the floor to just above eye level. Gym-goers have a clear view of the sky and nearby trees, as well as a diluted sightline to the street. On the other hand, they’re hidden from passers-by because the etched glass blocks views from the exterior.
In the coworking offices, etch patterns cover almost the whole surface of the glass. This extensive coverage makes the glazing behave more like full-surface etched glass: increasing VLT (visible light transmittance) while eliminating glare. In most buildings, it’s common for people with laptops to stay away from bright windows because the strong sunlight interferes with their screens’ visibility. At The Hub, though, people set down their computers right next to the glass. Even next to the window, they get soft, diffused light that brightens up the space but doesn’t cause glare.
Much of The Hub’s internal lighting works with daylight sensors. If there’s plenty of daylight in the building the lights will stay off, and so far, they almost always do stay off during the daytime. The diffused light washing through the custom acid-etch glass is enough.
Gensler designed The Hub’s façade to serve occupants’ comfort, as well as aesthetics. In the second-floor fitness centre, the etched pattern on the glass is just high enough to provide privacy to gym-goers, while still offering clear views of the sky and surrounding trees.
A first for bird-friendly Chicago architecture
“Given the site’s proximity to the lakefront, special consideration was given to the migratory paths of native birds with the use of a bird-safe acid etched glass, the first of its kind in Chicago”.
Illinois doesn’t have bird-friendly building legislation, and neither does the city of Chicago, but it was important to Gensler and the Prairie Shores management team. Project architect Sean McGuire explains, “This building is on a migratory path for birds, right next to Lake Michigan. It would be remiss of us to have this beautiful nature metaphor and not consider the effect that glass has on birds.”
There’s a common misconception that the risk of bird strikes increases with elevation, but in fact, most collisions occur within the first few storeys from grade, so low-rise buildings like The Hub can be just as dangerous as skyscrapers. The Gensler team was acutely aware of this risk, especially considering that nearly half of The Hub’s building envelope is made of glass.
Fortunately, the first-surface acid-etching that gives the façade its ephemeral aesthetic is also the most effective option for bird deterrence. It’s a fantastic example of purpose-driven design, with an aesthetic concept aligned to the project’s environmental goals. The resulting structure is one of the first ground-up bird-friendly buildings in Chicago: something to be proud of!
The first-surface etched pattern on The Hub’s glazing deters bird strikes against the façade. This project is among the city’s first ground-up bird-safe projects, paving the way for more bird-friendly Chicago architecture.
In designing The Hub, the Gensler team had a very specific, multi-layered vision. They were creating a space that would bring the community together for a variety of activities, and it needed to serve each one of those functions. At the same time, they were building around a symbolic reference to the site’s history in a beautiful, dynamic way. Finally, there was the team’s commitment to sustainable development. Custom acid-etched glass helped achieve all these goals. Inside The Hub, the first-surface etched patterns optimize daylighting and give privacy where it’s needed. From the exterior, they contribute to the façade’s ephemeral, glowing appearance. The first-surface etch deters bird strikes, making this one of the first bird-friendly projects in Chicago. The glazing design for this building wasn’t cookie-cutter, and the effort that went into it paid off in a big way. We’re delighted to see Gensler’s innovative use of custom patterning on the first surface, and can’t wait to see what other architects will do with acid-etched glass!