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Zinc winds around control tower

Edmonton, Alberta, Canada-based DIALOG's design for Edmonton International Airport Central Tower, Edmonton, was inspired by Alberta wind, which sculpts the tall prairie grasses and seasonal snowdrifts.

Building information technology and 3-D modeling fuel design departure

Edmonton, Alberta, Canada-based DIALOG's design for Edmonton International Airport Central Tower, Edmonton, was inspired by Alberta wind, which sculpts the tall prairie grasses and seasonal snowdrifts. Stephen Boyd, principal at DIALOG, says, "We felt this imagery expressed a sense of place and its people."

The façade of the tower features an undulating wrap of Woburn, Mass.-based RHEINZINK America Inc.'s Interlocking Flat Lock Shingles applied to a continuously curving surface system. Approximately 50,000 square feet of prePATINA blue-grey RHEINZINK was fabricated by Grant Metal Products Ltd., Rocky View, Alberta, to create ribbons that wrap around the 107,000-square-foot building, completed in November 2013. The exterior wrap begins 43 feet above the ground and twists upward 148 feet. Each metal ribbon contains either two or three facets that vary in height, width, thickness and angle as they trace around the building.

The profile of the exterior zinc cladding provides passive solar shading on the south and west façades while allowing maximum light penetration on the north side. Approximately 35,000 individual RHEINZINK panels, each 1- by 2 feet, were installed. Additionally, approximately 50,000 square feet of metal decking, 1,128 support trusses and 700 square feet of architectural louvers were utilized.

EllisDon Corp., Edmonton, was the general contractor. Thermal Systems KWC Ltd., Calgary, Alberta, the project's building envelope contractor, partnered with Los Angeles-base Gehry Technologies Inc., parametric modeling experts, and Minneapolis-based Radius Track Corp. and collaboration of the three companies helped produce the building's curves. The fabrication challenge was to find a way to make the metal curves smooth while accommodating the undulating design of the wrap. The team developed a curving hat channel system that provided a smooth attachment surface for the RHEINZINK shingles.

Tyler Weisgerber, Thermal System's commercial division manager, says the challenge centered on geometry and design team partners were essential assets in providing the necessary 3-D modeling and building information modeling (BIM) technology to create the system. "But you can only assume that a material is going to react a certain way until you actually apply it to a certain type of geometry," he says. "To be absolutely certain, we built a proof-ofconcept mockup to test and refine our system."

Weisgerber says a ribbon section was constructed and was wrapped around a 40-foot sea container in his company's yard. They discovered what worked and what needed to change after building all the components. The same craftsmen lead the teams that completed the installation. "Our leadership trades guys were really crucial in refining the system," he adds. "Going through that mockup process was key to the success of the project."

RHEINZINK was also installed in the interior concourses as a design accent element and to highlight retail storefronts. Weisgerber says he has always enjoyed working with zinc because of its characteristics. Zinc's life span and maintenance-free aspects make it very appealing to customers, he notes.

Targeting LEED Silver certification, NAV Canada's air traffic control tower is located on the top of the outer edge of the eight-story structure, which includes administrative offices, retail space, dining outlets and observation deck.

RHEINZINK America Inc., www.rheinzink.us