Mercer Slough Environmental Education Center is a campus of buildings overlooking the Mercer Slough wetland in Bellevue, Washington. The primary goal for the project was to create a facility that engages users - from school-age students to adults - with nature at the wetland's edge and at the doorstep to the city of Bellevue. Situated on a steep slope among mature trees clustered around an existing classroom building, the facility reaches out to the city as it embraces the forest. Treading lightly on the land, it simultaneously provides a teaching tool for its educators and a memorable experience for visitors.
MSEEC provides a venue for environmental education and public gathering that is immersed in the very landscape it teaches about: the wetland edge, forest floor, understory, and mature tree canopy. To support this connection to the landscape, the mature Douglas Fir and Bigleaf Maple trees had to be preserved, and the buildings had to be scaled to fit between them. By finding the middle ground between the top of the slope and the forest floor, the design team threaded the buildings and elevated walkways between the mature trees, providing a shaded, elevated learning place among the native Pacific Northwest understory. A thin and light methodology lifts the modern shed forms off the hillside as an extension of the landscape into the view beyond, creating vibrant interior and exterior spaces at a human scale. Elevated buildings and walkways utilize a pin pile foundation system, allowing the natural systems of the forest floor to function below the buildings unimpeded.
Seeking LEED Gold certification, the project expands upon standard sustainable building practices by reducing the scale of the facility to the minimum footprint required by the program while preserving the majority of the existing forest. Passive ventilation and the mature tree canopy shade eliminate the need for air conditioning and reduce energy consumption by more than 30%. Preservation of the mature tree canopy continues predevelopment level carbon sequestration. Pre-loading of the peaty soils instead of removal minimized the carbon release that would have resulted in removal. Beyond the use of FSC-certified wood, recycled materials, daylighting, and energy, the structure is an important integrated feature of the facility that bridges aesthetic, structural, and civil capabilities. To build so close to the trees, a point load system and further footprint reduction rather than a linear footing was used. With helical pilings (reused from a natural gas extraction site) placed below grade, concrete pile caps, a cantilevered footprint, and reused foundations, the buildings float from six to thirty feet above the forest floor, framing wide views across the Slough or sheltering small understory moments up close to the trees.