Graywater Reuse to Irrigate a Living Wall at Bertschi School

Living Building Challenge Full Certification v2.0 (All 20 Imperatives)

AIA National 2012 CAE Educational Facility Design Award

USGBC Best of Green Schools 2012

AIA Seattle What Makes It Green 2012

ED+C 2012 Excellence in Design

Sustainable Buildings Industry Council Beyond Green High Performance Building 2011

Design and Build with FSC Award 2011

Washington Association of Landscape Architecture 2011

American General Contractors Alliant Build America Award 2011

NAIOP Private Education Development of the Year 2012

Square Footage: 1425ft²

To help meet the LBC’s “Net Zero Water” imperative the project incorporates a greywater system to irrigate a living wall within the classroom.  Potable water flows from the rainwater cistern or City connection to the classroom sinks, used primarily for handwashing.  Greywater drains from the sinks and into a tank in the cabinets below the sinks, an Aqua2 Use greywater system.  When the tank is full, or at least once every 24 hours the water is pumped to the living wall through a subsurface drip irrigation network.  The plants and soil of the living wall take up the greywater, releasing water vapor into the air through evapotranspiration.  Moist vapor from the plants is vented through the building’s ventilation system and any water not absorbed by the plants is cycled back through the system and onto the wall again until all of the water has been used.

According to Seattle Municipal Code, adopted from Uniform Plumbing Code Chapters 301.3, a system within the range of a municipal sewer that is serving a commercial or public building must have a conventional overflow to the city sewer system. The Bertschi School does not plan to expel any waste or greywater into the Seattle Sewer system; rather, it will be treated and reused on site, but in order to meet regulation the conventional overflow has been installed.

In keeping with The Bertschi School’s active learning environment, the Science Wing provides a living classroom and laboratory for students to learn first-hand about scarce resources such as clean water and air, and to see real solutions for protecting and conserving those resources.  In this case, graywater irrigates a living wall so that zero “waste” water flows to the City sewer.  Instead, students are taught to limit their water consumption to only the amount of water which the living wall can be expected to absorb and evapotranspire.

The Living Science Wing of the Bertschi school was the first “Living Building” in Washington state, a new addition to the school campus that also contains the first LEED Gold certified building on an independent school campus in the Pacific NW (completed 2007).  It was designed through an intense collaboration between Bertschi students and staff, and KMD Architects’ Restorative Design Collective.  The team interviewed the students to find out what they wanted in their classroom, and heard: “an indoor river, a bamboo fountain to relieve stress, and green house where something’s always growing”. Architects, landscape architects, engineers, and other consultants paired these requests with the rigorous standards of the Living Building Challenge v 2.0 (LBC) to design a 1,425 sq ft science classroom building on a 3380 sq ft site with an ethnobotanical garden.

• Seattle Municipal Code 21.16.040 side sewer connection
• WAC 51-56-1600 Ch. 16
• Chapter 246-274 WAC Greywater reuse