Great Glazing: Seattle-Tacoma airport clock tower

Photo by Laura Haddad, Haddad|Drugan (top).
Photo by Anthony Pereira altPOWER (bottom).

"The clock tower is an excellent example of how renewable energy can contribute to a larger vision; how technology and design can enhance each other."—Mary Gallagher, altPOWER senior project manager.

The basics: The new clock tower at Seattle-Tacoma International Airport is a landmark entry art piece highlighted by a vertical row of custom green building integrated photovoltaic modules. The installation, called "Emerald City," was designed by Seattle-based artists Laura Haddad and Tom Drugan. The modules power the tower's internal colored LED lights that create a visual thermometer by sensing the outside temperature and representing it with correlating colors. The custom-fabricated photovoltaics presented technical challenges due to the variation in module orientation, according to an altPOWER release. The company worked with the artists to perform shading studies to determine the appropriate spacing and tilt of the modules.

The players: BIPV fabricator, altPOWER; BIPV installation, Port of Seattle electrical subcontractor; glass artist, Haddad | Drugan, in collaboration with Peters Studios.

The glass and systems: Glass-glass modules comprised of 4-millimeter heat strengthened front glass, a 1.5-mm polyvinyl butyral interlayer containing custom green colored polycrystalline silicon cells, and 6-mm heat strengthened back glass. The back glass contains a dark grey screen print that was added to satisfy the artist's overall aesthetic requirement. The modules are about 7.5 feet by 3.3 feet each, and installed in a stainless steel mullion system that is attached to the clock tower stainless steel framing system by custom stainless tube steel angles. The angled pieces provide a fixed tilt for each module to minimize shading effects from module to module.