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By Nancy B. Solomon, AIA

Thermal comfort

When the Washington State Department of Veterans Affairs first approached Seattle-based NBBJ regarding a replacement skilled nursing facility on its existing campus in Retsil, Washington, the agency wasn’t focused on sustainable design. The department simply wanted a high-quality structure that would provide the best care. To this end, the client and architecture firm undertook strategic planning sessions with current residents to elicit what they really needed. The overarching themes that emerged were dignity, privacy, and a greater sense of control over their lives. “They wanted to be able to make individual choices, such as operating windows,” explains NBBJ project manager Elizabeth Jacks. They didn’t want air-conditioning, as it made them feel cold.

 

Images: Courtesy NBBJ

So, when the design team began to assess site conditions, the concept of natural cooling logically arose. After all, the campus is located in a mild climate atop a bluff next to Sinclair Inlet. Breezes coming across the water assure a constant flow of cool air all year round. What better way to give the residents more control over their environment and a connection to the outside world then by allowing them to tap into this natural resource as they saw fit?

There was, however, one glitch: All health-care facilities in the state of Washington must meet the Washington Administrative Code (WAC 388-97), which references ASHRAE 55. This standard requires mechanical cooling—regardless of microclimate—and stipulates that all patient areas must not exceed 75 degrees for 97.5 percent of the year. Although ASHRAE is now working on a standard for natural ventilation, and LEED has a much different understanding of the acceptable range of thermal comfort, the designers had to work with the code as it now stands.

NBBJ accepted the dual challenge of first meeting the temperature requirements—which far exceed LEED standards—with passive-solar strategies and then demonstrating that such a solution satisfied the intent of the health-care code. Both the design and the final proof relied heavily on computer modeling of thermal conditions.