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August 28, 2008

Green goals guide UW’s Architecture Hall renovation

  • Engineers turn to a blend of modern technology and time-tested know-how in makeover of historic building
  • By CHRIS JOHNSON
    CDi Engineers

    mug
    Johnson

    Architecture Hall at the University of Washington reigns as the sole surviving structure of the 1909 Alaska Yukon Pacific Exposition.

    Listed on the State Historic Register, the building’s three floors and attic were designed in the beaux-arts classical revival style. But the years had taken their toll. It was time for a complete renovation and seismic retrofit — a challenge, given the historical nature of the building.

    As one might expect, given the users of the building, “green” design was a top priority. Architect Thomas Hacker Associates worked closely with engineers to brainstorm workable solutions. Some, considered cutting edge today, actually continued time-honored principles built into the building more than 100 years ago.

    Open-and-shut decision

    Photo by Nick Gunderson Photography/CDi Engineers
    New concrete seismic reinforcements inside Architecture Hall made some walls 3 feet thick. The added thermal mass helps control temperature inside the building.

    Like similar structures of its era, Architecture Hall featured exterior windows that could be opened and shut. Natural ventilation with windows went out of style with the advent of central heating and air conditioning, but is now becoming increasingly popular for its environmental benefits. Because it affects the entire building and not just mechanical systems, natural ventilation is best optimized when the entire design team is involved from the beginning of the project.

    In this case, keeping natural ventilation was almost a given, allowing existing windows to be saved, and maintaining natural daylighting. But thermal comfort and energy consumption improvements were needed.

    Designers put in new thermal glazing to keep rooms warmer in winter and cooler in summer. Window shades were also added to help prevent solar heat gain. But designers would need creativity to blend the best of older architectural elements with new mechanical solutions.

    Thermal modeling

    Many of the building’s spaces had open ceilings. Others had lay-in ceilings. Almost none had room for standard modern mechanical systems. So engineers installed mechanical systems only where necessitated by the university’s programming requirements. Classrooms and the auditorium were designed with mechanical cooling and heating systems, while perimeter studios and offices utilized natural ventilation with baseboard hydronic heating.

    Engineers used three-dimensional modeling to simulate the dynamic thermal performance of the building. The data they obtained was then used for estimating space temperatures and airflow under various conditions. Data temperature recorders were also used to monitor existing space temperatures to confirm data from the model.

    Two-dimensional computational fluid dynamics modeling allowed engineers to quickly create cross-section microclimate variations in spaces. Color-coded images on a cross-section of each room showed airflow patterns and temperature gradients. This data, combined with information from monitoring, helped engineers determine where to locate shafts, grilles, louvers and transoms.

    During modeling, engineers noticed pockets of warm air in the upper-floor studios. These rooms had high, angled ceilings that trapped warm air. A logical solution was to use ceiling fans to provide a good mix of air throughout the year. Although the design team wanted similar fans in all studios, rooms on other floors lacked sufficient ceiling height.

    A green seismic fix

    Seismic retrofitting included the installation of concrete shear walls on the interior face of the perimeter walls and the addition of interior concrete shear walls. The original building’s walls were built with unreinforced masonry, making them susceptible to earthquake damage. With the additional concrete, some walls are now up to 3 feet thick in places.

    Super-thick concrete walls increased the thermal mass of the structure, helping to control both heat loss and gain — yet another way in which an age-old building convention contributed to modern “green” building practices.

    Rediscovered shafts

    A unique characteristic of the original building was a series of shafts down the center of the building connecting each floor to the attic, which had an open cupola on the roof. These shafts had been used originally as exhaust shafts when the building served the chemistry department, but had been boarded up since the 1940s.

    Again, space for new mechanical systems was an issue. So engineers found ways to reuse the shafts to take advantage of a stack effect. Air’s natural buoyancy carries warmer air up the shafts and out the cupola. Careful modeling helped determine optimal positions for grilles and louvers.

    Interior spaces, like the 300-seat auditorium and two larger classrooms, required mechanical systems for heating and cooling. To reduce the amount of energy used, designers installed carbon dioxide sensors. As carbon dioxide levels rise due to increased occupant loads, outside air dampers open to provide additional fresh air, ensuring that occupants are comfortable.

    Eager input

    Architecture faculty members and students alike were eager to provide input for the renovation. Professors offered several suggestions for eco-friendly design, while students participated in user groups, commenting on features they would like to see in the renovated structure.

    The result is a unique blend of old and new — a university hall that complies with modern codes and expectations, yet maintains all the dignity of its glory days more than a century ago.


    Chris Johnson is a project manager at CDi Engineers, a mechanical engineering consulting firm in Lynnwood.



     


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