EMPAC: RPI’s Fascinating New Landmark

On a steep slope in Troy, New York between the city center and Rensselaer University rests a large building: the university’s Curtis Priem Experimental Media and Performing Arts Center, or EMPAC. On a sunny day, the building appears at even a relatively short distance to be an austerely minimalist box, sheathed entirely with glass that reflects the site’s vista over Troy and the Hudson River. However, a closer look at the box uncloaks an astonishingly dramatic architectural  setpiece within: almost the entire space is filled by a curving, bulbous cedar-clad object. Venturing inside the building causes the structure to appear even more wondrous: the oblong wooden mass seems to float like an ochre zeppelin, tethered to the steel frame around it by struts and cables, accessible only by elegantly thin ramps sloping from balconies. Every beam and column of the frame is hinged, skylights give the impression that the roof is opening, cables crisscross the curtain walls; though static, the building seems to be on the verge of motion, of opening outwards to release the concert hall.

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The building’s north side

The background of the design and construction of EMPAC is just as fascinating as the outward appearance, for the structure is a product of cutting edge architecture and engineering that would not have been possible two decades ago. The architect is Briton Nicholas Grimshaw, who won an international competition to design the center, beating other high-profile figures like Bernard Tschumi and Thom Mayne. Just as important to the project were the engineers: Buro Happold for structure, Kirkegaard Associates for acoustics.

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The “grand staircase” between the hull and northern wall

This confluence of different fields of design and engineering was a key part of the vision Rensselaer’s administration had for the center. Spending hundreds of millions of dollars on a bog standard, arts-exclusive performance venue would have been unwarranted at Rensselaer, a college with a focus on engineering. Therefore, Rensselaer’s president gave the architects a brief to construct a theater with an acoustic quality unmatched in the region and by other universities so that “musicians will beat a path to it across the world”. The planning board wanted to create a landmark of engineering, reflecting the school’s background and providing a case study for students.

 

Grimshaw’s design won the competition not only because of its dramatic appearance but also because of its thoroughness: almost every detail of the design had the purpose of enhancing the theater’s acoustics. The basic concept is what is known as the “box-within-a-box” model, where the inner box, holding a theater, has a structure that is somewhat isolated from that of the outer box, which holds servant spaces and is directly connected to the foundations and neighbouring structures. This setup allows the theater to remain relatively unaffected by interfering vibrations and resonance from the ground and mechanical systems like elevators and air conditioning, leaving the acoustics within the theater isolated and unaltered.

 

This wish to isolate the theater is the logic behind EMPAC’s unique features, like the void separating the wooden “hull” from the outer shell, the hinged columns and struts, and the flexible plastic skylight joining the theater and steel roof. It is also the cause of unseen innovations; for instance, the cedar cladding is not curved only for aesthetic reasons: it covers up a precisely shaped and positioned concrete mass that acoustically “insulates” the theater. In addition, the theater is mounted on flexible “mini-piles” independent from the primary foundation.

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Inside the theater

Acoustics-oriented design can be found within the theater as well as outside. The hall seems small for such an important performing arts center; this was a purposeful move by Grimshaw, as studies have shown that, for optimal acoustics, a concert hall should be no larger than 1200 seats and no wider than sixty feet. All major surfaces in the theater are convex, so as to scatter rather than focus sound. The ceiling, a tessellation of canvas panels, is mounted on an adjustable frame; it can be reshaped or repositioned to meet the acoustic needs of a specific event. For full optimization of acoustics, cutting-edge modelling and simulation software was used for many purposes, including ideal positioning of wall tiles and developing a method of diffusive ventilation that minimized vibration. Having gone inside the theater, I can testify that all the effort has not gone to waste: a whispered conversation on the stage can be heard in the highest seats in the rear of the space.

 

Just as they were used to create the theater and its world-class acoustics, engineering innovations were employed by EMPAC’s designers to establish a defining theme behind the building’s architecture: contrast. The dissonance between the featureless grid of the curtain wall and the warmth of the curved and patterned cedar is one of the most memorable aspects of the structure. Both elements proved challenging to build. Columns and “wishbone” struts that support the curtain wall had to be shaped precisely in order to bear their load without cross-bracing. The glass itself is double-glazed and embedded with small tubes that can carry heated water in the winter, allowing the whole wall to act as a radiator. The wood cladding proved to be a particular challenge because the form of the hull “could not be described by a manageable set of mathematical equations”. Construction managers had to base their work on a complex digital 3D model of the structure, rather than conventional flat blueprints. CNC laser cutting was employed to cut the complex shapes of the wood planks and the steel structure beneath.

 

The problems discussed above are only a few items in a long list of challenges that Grimshaw’s design posed; others include unstable soil on the hill and stringent earthquake regulations. The fact that this ambitious structure has been completed pays huge testament to the skill of all involved. In the future, the theater is almost certain to become a landmark in Troy, and the performances staged there will bring a cultural spotlight to the university and region. If you are anywhere in the vicinity of the city- Albany or Saratoga Springs, for instance- EMPAC is undoubtedly worth a visit.

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All photos by author

 

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