WE Credit 1.2: Water Efficient Landscaping, No Potable Water Use or No Irrigation
LEED-NC Credit: YES | UNSURE|NO
Credit Intent
Completely eliminate reliance on potable water sources for irrigation by using only non-potable water for landscape watering.
Feasibility
This credit should certainly be pursued. In his presentation, Cole Roberts of ARUP noted that the water strategy for the GSB includes “no potable water for irrigation”. In fact, the only two uses for potable water at the new campus will be for faucets and processes. Roberts also notes that the non-potable water will come from three sources: rainwater, lake water, and graywater. Non-potable water not used for irrigation will be used for flushing toilets in GSB buildings.[1]
Analysis
Achieving this credit is fairly straightforward: Use no potable for landscaping and prove it. We know that initial plans call for the achievement of this credit, but there are several things the design team can do to ensure that adequate non-potable water is supplied for all landscaping needs.
Figure 4: Non potable water use in the GSB10
Stormwater should be retained, especially in the winter when it rains quite frequently at Stanford. The outline specifications note that a stormwater collection tank will be used at the GSB site for this purpose.[2]
Use water from the Searsville water system, as noted in Stanford’s landscaping guidelines.[3] This water, used for Stanford irrigation, comes from SearsvilleLake, which is roughly 4.5 miles from the new GSB campus (see Figure 5 below). This is positive because the link between SearsvilleLake and campus had already been established. However, other non-potable sources should be used before tapping into the Searsville system, so the new GSB does not strain existing campus landscaping needs.
WE Credit 1.2: Water Efficient Landscaping, No Potable Water Use or No Irrigation
LEED-NC Credit: YES | UNSURE|NO
SearsvilleLake and Stanford
Figure 5: Map showing distance between SearsvilleLake, a non-potable irrigation
water source, and the new Stanford GSB campus. From Google Maps.
As Cole Roberts showed in Figure 4 above, the majority of irrigation water will most likely come from graywater, which is defined as any wastewater that hasn’t been in contact with toilet waste or kitchen sinks. In this case, graywater will come from sinks in restrooms, water fountains, showers, and laundry facilities on the GSB campus. Another source of graywater, as mentioned in credit 1.1 above, will come from the Central Energy Facility (CEF) on campus. This graywater, supplemented with captured rainwater and water from Searsville lake, can be expected to meet the irrigation needs of the new GSB campus.
[1] Roberts, Cole. ARUP, Presentation: GSB Engineering, 4/30/07.
[2] Schematic Narrative and Outline Specifications, BCJ Architects, 4/30/07, pg. 1.7.
[3]StanfordUniversity, Landscaping Guidelines, http://facilities.stanford.edu/fdg/docs/Landscaping%20Guidelines.pdf.