Brought to you with support fromA 23-acre public botanical garden in Denver—which contains North America's largest collection of plants from cold temperate climates around the world—has received a new science center inspired by biomimicry, technology, and the landscape. The project was a highly collaborative output from Burkett Design and StudioNYL. The appropriately titled “Science Pyramid” began formally as an inversion of an adjacent depressed triangulated amphitheater. The triangulated structure was initially planned as a self-supporting structural shell of honeycomb-shaped glass units, inspired by beehive structures. With a desire to control lighting for multimedia displays, the design evolved to an opaque shell with fiber cement panels, building integrated photovoltaics (BIPV), and electrochromic glass panels. Ben Niamthet, Associate Principal at Burkett Design, says the building was formally split into two halves, shearing down the middle of the pyramid to provide an opportunity for guests to locate themselves within the landscape of the gardens, and affording views to an adjacent historic fountain. The gap was clad with custom-made electrochromic panels that operate in coordination with rooftop light monitoring system to control daylight in the exhibition space below. Niamthet attributes this feature as one of the most successful aspects of the project. "It created a challenge, he said. "Not just an aesthetic challenge, but a structural engineering challenge." Niamthet said this challenge was met by a highly collaborative design process with StudioNYL's Skins Group—a team of facade designing structural engineers. The facade construction doubles as both a wall and a roof, and is technically understood as an open joint roof-mounted rainscreen system. The unique assembly is one of the first of it's kind in the world. A primary steel structure of 18" diameter HSS tubes provide the basis for a layer of plywood sheathing that forms the building's iconic tent-like structure. A secondary layer of structural thermal isolator standoffs set at 2-feet-on-center support for two layers of rigid insulation totaling 5-inches. This outboard insulation layer is protected by a gypsum cover board and a UV-resistant moisture barrier. A tertiary layer of cladding subframing systems provides standoffs for the final layer of hexagonal-shaped fiber cement panels. Will Babbington, principal at StudioNYL, calls the project one of the most iconic projects the facade engineering firm has completed: "The nice thing with all of these layers affords the tolerance that is required for what ended up being a very fast tracked project." To manage increased UV exposure from a slanted rooftop orientation, Cosella-Dörken's DELTA®-FASSADE S product was specified because of its properties as a highly stabilized material against damage from UV exposure. The product is designed for use in cladding systems that have open joints of up to 2-inches wide which expose up to 40-percent of the entire facade surface. Marrying the hexagonal grid with the buildings pyramidal form produced inherent alignment challenges for the design team. Babbington recounts, "we rotated that pattern well into the double digits... maybe even triple digits... [at] times trying to find a way to minimize tiny slivers of fiber cement board which were too small for standard fastening methods." StudioNYL says the greatest challenge associated from detailing a rainscreen on a sloped surface is the reduction of a natural "stack effect" ventilation—a performance requirement of typical open joint rainscreens. Babbington said the problem required research into fluid dynamics which accounted for specific environmental factors of the system. A digital model was able to conclude that the gap between the fiber cement panels and the exterior wall construction heats up enough to provide an efficient upward airflow. This—despite the slope of the pyramid's walls—promoted a passive method for circulating air in the manner rainscreens are designed to perform. The fluid dynamics model specifically accounted for solar orientation of the facade surfaces, local climate data, and the dark coloration of the Swisspearl panels. The project team is awaiting data from this high-performance building to evaluate the efficiency of the Science Pyramid's construction assemblies and systems, which have now been in operation for almost two years.
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Plate tectonics, honeycombs inspire new Denver Botanic Gardens research center.For their new Science Pyramid, the Denver Botanic Gardens sought a design that delivered more than just aesthetic impact. "They wanted an icon, but they also wanted to show an icon can be high performance," said Chris O'Hara, founding principal of Studio NYL. Studio NYL and its SKINS Group worked with architect Burkett Design and longtime Botanic Gardens general contractor GH Phipps to craft a structure to house the institution's conservation and research efforts. "People think of the Botanic Gardens as a beautiful place to go, but what most of them don't realize is what happens behind the scenes," said O'Hara. "The whole concept was to showcase that, and to educate the public not just about what the Botanic Gardens are doing, but a little more about their environment." Clad in a Swisspearl rain screen that serves as both roof and wall, the Science Pyramid's biomimetic design reconsiders the relationship between the built and natural worlds. Tasked with building a pyramidal structure with dynamic glass elements, the Burkett Design team turned to two natural metaphors. The first was the tectonic shifts that created Colorado's mountains, the second, the defensive structures built by honeybees. The geological metaphor influenced the building's form, a twisting, reaching variation on a pyramid designed to take full advantage of its site. The biological metaphor informed the building's skin, dominated by cement composite panels cut into honeycomb-like hexagons. Though they originally imagined a heavily glazed facade, Studio NYL soon realized that transparency would be impractical, given the projection elements involved in the Science Pyramid's exhibits. They opted instead for a rain screen system comprising custom-cut Swisspearl panels. The rain screen reduces thermal gain by venting hot air before it reaches the building. It encases the roof as well as the facade's vertical elements, the second such use of Swisspearl panels worldwide, and the first in the United States. "Here you don't hear about rain screen roofs often," said O'Hara. "Using the technology as a roof system was a little different." Because they still wanted some glass, Studio NYL incorporated electrochromic glazing from View. "They can tune the building—the user has a flip switch to black it out," explained O'Hara. "At the same time, you can have a visual connection to the gardens." To further boost performance, Studio NYL worked with Cosella-Dörkin to layer a UV resistant weather barrier system under the open joint rain screen. "Whereas the form was about this iconic, biomimetic structure, on a technical level, everything was about performance," said O'Hara. Fabrication and installation were complicated by two factors: a compressed timeline, and a need to work around the Botanic Gardens' ongoing operations. To help with the former, the Burkett Design team leaned heavily on digital fabrication, including having the structural steel digitally cut. As for the latter, the construction crew was forced to develop creative solutions to spatial restrictions. "There were a lot of logistical problems given that we were in the center of an active botanic garden," said O'Hara, noting that only machinery below a certain size could be brought to the site. "The primary axis we had could only go up twelve feet, to the extent that we were pushing tree branches out of the way with a broom." The design-build team came through in the end. "It's really quite spectacular," said O'Hara. But while the Science Pyramid achieves the landmark status the Botanic Gardens had hoped for, it nonetheless defers to its context—the gardens themselves. "The building is very oriented to the paths you take," said O'Hara. "Everything has a different moment. If you enter one way, you see the glass spine; if you come another, you see the canopy. It's playing constantly against the juxtaposed landscape."