This credit is complicated! I realize now that we did not even go for it, because it is an either/or possibility for the three previous sections — SS 2.2, 2.3, and 2.4 being prescriptive measures, and this one being performance-based. If we had gone for points in this section, we could have garnered up to 10 points by reducing irrigation water usage by over 60% (20% is the minimum, and you get two points for that). I really have no idea how hard that would have been or how much it would have cost to even calculate that percentage.
Briefly, this credit requires an irrigation specialist to calculate the baseline irrigation usage using assumptions about baseline evapotranspiration rates, which represents the rate of water loss for a particular climate. Other variables include Landscape Coefficient (the volume of water lost via evapotranspiration), the Species Factor (the water requirements of different plant species), the Microclimate Factor (environmental conditions specific to the landscape, including temperature, wind, and humidity), Irrigation Efficiency, and other things I don’t understand. When I showed this credit to our irrigation subcontractors, their brows furrowed. Luckily, we have easier areas under water efficiency to understand and rack up points.
Sustainable Sites points so far: 3
Cumulative points: 17
Additional points needed to get to Gold: 71