Unbroken bands of window walls sit beyond an exterior concrete structural frame.Completed earlier this year, a new market rate rental building on Manhattan’s Upper West Side by Handel Architects features a striking exposed cast-in-place concrete diagrid “exoskeleton” structure. The system is designed in response to required zoning code setbacks that restrict building area to a mere 35’ wide at times. The project, named after it’s address at 170 Amsterdam, is located two blocks north of Lincoln Center, situated between two greenspaces – Central Park and the Lincoln Tower superblock – via 68th Street. The lobby is a prominent glassy space containing a mix of community programs, formally and programmatically connecting the two sides of the building together, while abstracted tree-like columns punctuate the building envelope. Frank Fusaro, Partner at Handel Architects, says the use of exposed architectural concrete is a contextual response to its location between the muscular buildings of Lower Amsterdam, where Lincoln Center resides, and the heaviness of classic Upper West Side apartment buildings. “LaGuardia High Schools exposed concrete, MLK School’s corten metal and glass skin wrapped around an opaque core, and the heavily ornate Beaux-Arts exterior of the Dorilton with its quoining, ironwork, brackets, cartouches, oriels and other details all share something in common: these are tough, robust and bold buildings.” Aside from the contextual benefits to exposing a concrete system, the architects noted several benefits to a structural exoskeleton system, contributing to the client’s full support from nearly the beginning of the project. The most significant benefits to the building envelope design were seen when interior floor area was able to be maximized. The structural system of the building resembles a shell structure, achieving high stiffness from an exterior diagrid of columns tied together with repetitive structural floor slabs. This stiffness allows for no shear walls to be required in the core of the building and relatively few interior columns. By moving the columns to the outside of the building, the city’s zoning department allowed for the floor area of the building to be measured to the face of the window wall, rather than the face of the structure. This allowed the architects to add an entire extra floor of program to the building. Additionally, the depth of the facade assembly acts as a brise soleil, passively helping to manage a less-than-ideal solar orientation (unavoidable due to the city grid and buildable area on site). Beyond the columns, a continuous band of window units, spanning from floor to ceiling, establishes the building’s thermal envelope. The windows feature a high performance low e coating to allow for high levels of transparency without sacrificing solar performance. Fusaro says the unbroken line of windows in the apartment units was essential: “The studios are sized just over 400 square feet, so having an exterior wall of glass makes the units feel much larger.” An extremely dense mix of concrete allows for the smooth finish and eliminates voids. The use of less rebar permits a pump tube to be placed in the column and minimizes vibration. Slag was added to the mix to make the color of the concrete more like limestone. Installation of the building envelope after the concrete was poured occurred surprisingly quickly, at a rate of about one floor per week, adding value to the system. The design of the diagrid was optimized to reduce the quantity of fabricating costly “X” forms by shifting the grid on a diagonal axis. The success of 170 Amsterdam has led Handel Architects to further work with exposed architectural cast in place concrete. Most notably, in the Upper West Side, another market rate rental building is under construction currently. For Fusaro, the elegance of exposed concrete is activated with an underlying connection to nature: “I love the organic nature of concrete, you can add or subtract a little of this or that and make it into something entirely different.” Handel Architects: Partner in Charge/Design Principal; Frank Fusaro Project Manager; Honyi Wang Design Team; Alan Noah-Navarro, Elga Killinger, Shridhuli Solanki, Rinaldo Perez, Ren Zhong Huang, Jessica Kuo, Jordan Young, Shujian Jian, Hong Min Kim, Ade Herkarisma, Ana Untiveros-Ferrel
Posts tagged with "cast-in-place concrete":
If you walk down Fifth Avenue and 14th Street toward Union Square and notice a building under construction with crooked columns, don’t worry—it is not about to collapse. According to NBC New York, the SOM-designed New School University Center, previously detailed by AN, is raising eyebrows from the local community because some of its columns are slightly skewed. But it’s no mistake. “It's the most efficient way to carry all of the different structural loads of the building from the top of the foundation, " Joel Towers, Parsons The New School for Design dean told NBC. The New York City Department of Buildings has confirmed there are no safety issues with the project.
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A south-facing heat sink mass wall stores heat and diffuses light, creating an all-seasons solarium for an energy efficient home in Upstate New York.Dana Cupkova and Kevin Pratt, founders of Ithaca-based design and research practice Epiphyte Lab, met the client for which they built Hsu House in one of Cupkova’s classes at Cornell where she teaches design and fabrication strategies for ecologically adaptive construction systems. The client, a medical doctor, was in the class with the goal of designing his own energy efficient home in Danby, New York, but after an initial consultation, asked Cupkova and Pratt to design it instead. The 2,200-square-foot house is designed using passive solar principles. Interiors are organized around a three-story living space, which also functions as a ventilation stack. At its center, a south-facing, cast-in-place concrete mass wall creates a heat sink for the house, absorbing heat in warm weather and releasing it when the temperature drops. “It tempers the internal environment of the house,” said Cupkova. “It’s a giant radiator and cooling device. The house has no AC.” Designing the wall posed several challenges. The team had to create a shape with a large surface area to maximize thermal transfer from the sun to the wall to the home’s interior. But the wall also had to let daylight into the space and, as the sculptural focus of the house, have an interesting shape and texture. The team began by testing hundreds of parametric iterations of the wall using Grasshopper software, optimizing the design for four-foot-wide concrete formwork components to keep costs down. When Cornell’s CNC mill became unavailable, they turned to Syracuse fabrication company SCCM. Because CNC-milling the high-density polystyrene concrete form liners resulted in a bumpy texture, the team had to rethink its fabrication strategy. “Andy McDonald at SCCM was seminal in helping us figure out the project,” said Cupkova. Frank Parish, Cornell’s digital fabrication shop technician, helped oversee the work. Instead of working with the concrete form liners directly, the shop CNC milled more than 100 guides for the forms, which were then laminated and hand-cut using a hot wire-cutting knife. Once the forms were in place at the house, the entire structure was reinforced with rebar, allowing it to support part of the floor above. The wall is 23 feet long and 14 feet high with widths varying from 5 1/2 to 16 inches. As Its conical shapes created funnels in the formwork, the concrete mixture had to be adjusted to be more fluid. According to Cupkova, the job is an atypical one for the Ithaca area’s concrete trades, and she credits general contractor Paul Hansen Construction with making the project run smoothly (the fact that she was eight months pregnant also helped her gain some sympathy). As concrete was poured the wall was vibrated, allowing the material to fill the small spaces in the forms. The entire pour was completed in three hours. Now, the house has weathered two seasons without much use of heating or even electric lights thanks to the mass wall. “In the summer, after it was finished, the temperatures were in the 90s and it was 70 indoors,” said Cupkova. “It works.”