American Architectural Manufacturers Association

12/03/2018 | News release | Distributed by Public on 12/03/2018 21:16

Case Study: Seattle Space Needle's Renovated Observation Decks Achieve High Thermal Performance with Technoform Spacers

Built in 1962 for the World's Fair, the Space Needle stands 605 feet above Seattle and welcomes more than 1.3 million guests from around the world each year. In June 2018, the historic landmark revealed its newly renovated observation decks and celebrated a milestone in its 'Century Project,' a multi-year, privately funded, $100 million effort to preserve and enhance the visitor experience for the next 50 years.

In reimagining the building, Olson Kundig respected the Space Needle's conceptual innovation and enduring legacy as originally envisioned by Edward E. Carlson, and as designed by John Graham with Victor Steinbruek, to reflect aspirations of the Space Age. Working with Olson Kundig from the renovation's earliest stages, glazing consultant and designer Front Inc. specified Technoform's spacers to help achieve the Space Needle's design goals.

'The Space Needle looked at all the options and decided which had the most value to attract people and keep relevant in the future,' said principal Richard Green, P.E. The renovations not only would enhance value and experience, dramatically expanding the views, but also needed to respect the historic building's overall appearance.

To accomplish the multiple objectives, more than 176 tons and 10 types of glass replaced entire walls, barriers and floors. Floor-to-ceiling glass on the interior and exterior now offer visitors 360-degree panoramas of the Puget Sound.

Targeting LEEDĀ® Gold certification through the U.S. Green Building Council, the Space Needle's renovation also focused on improving energy performance and controlling condensation risk. As part of the building envelope's high-performance insulated glazing units (IGUs), the TGIĀ®-Spacer M with wire were selected. Meeting the performance requirements were not only important to the building owners, but necessary to meet the Seattle energy code - one of the strictest in the country.

'The project utilized a 196 percent increase in glazed area and also needed to consider the relatively poor thermal performance of the opaque areas, where the existing structure passed from exterior to interior at many points without thermal separation,' explained the company's own Helen Sanders, Ph.D. 'Because thermal improvements in those opaque areas were limited, the onus was on the glazing to provide excellent energy performance.'

Preserving the project's historical aesthetic, the building needed to retain its deep, exterior-facing steel mullions at the top 520-foot Atmos level (formerly called the observation deck). This unique aspect of the building envelope glazing posed one of the project's most significant challenges in terms of thermal performance.

Describing it as a 'reverse curtain wall,' Sanders noted: 'It created a smooth surface on the inside to allow viewers to have less physical obstructions to getting close up to the glass. As a result, the deep mullions that would have been on the inside are on the outside and act as a heat sink with very little in the way of a thermal break between it and the glass edge.'

Green added, 'The only thermal separation we have is in the small thermal spacer [between the mullion and the glass] and in the IGU seals, making the company's spacer super-important in both thermal performance and condensation resistance.' With people sitting right next to the glass in all seasons, the radiant temperature on the interior also would affect the visitors' comfort.

According to Sanders, the spacers chosen were the only option to provide both the thermal performance and the necessary edge seal rigidity. 'The engineers needed the rigidity of a typical box spacer to manage the localized stresses in the seal area resulting from the special support conditions at the top and bottom of the units, which were required to reduce the displacement of the frameless glass.'

The high-performance IGUs on the Space Needle also have low-iron glass and multiple anti-reflective coatings for minimal glare and high transparency, achieving a museum-grade color rendering index. 'Whether you're in a museum or on an observation deck, you want to see the view as it was intended. You don't want to have the glass skew the color. It shouldn't be too yellow or too blue. You want a high quality of natural light,' explained Green.

Between autumn of 2017 and summer of 2018, up to 170 people were actively working on the Space Needle's renovation - 20 hours per day, six days a week. More than 500 workers representing 18 different trades contributed to the project.

The Space Needle was built to help define the skyline of Seattle, but has become so much more,' said Karen Olson, chief marketing officer at the Space Needle. 'With glass walls, glass barriers, glass benches and even glass floors, visitors can feel like they're floating over the city.'

Photo courtesy of Chad Copeland