The LEED Letter Template and calculation equations for this credit allows for the reduction of potable water use by subtracting annual graywater or rainwater harvest. Our building project will include the design of a testing lab that requires the maintenance of a constant fully saturated environment (100% humidity) achieved through a water misting system. The system will be continuously supplied from the potable water supply and excess water will discharge to the sanitary waste drain. In order to reduce the waste of this potable water supply the misting system will include a provision where the excess potable water will be collected and re-circulated rather than made up with potable water. This reclaimed potable water will represent a significant potable water savings versus the baseline approach of draining it to sanitary waste.We, therefore, request an interpretation as to whether the reclaim of the excess potable water to be used for this process may be counted as graywater harvest for successfully meeting the intent of Water Efficiency Credit 3.2.
The water used by the water misting system would be classified as process water. WEc3 is specifically focused on the water usage of plumbing fixtures covered by the Energy Policy Act of 1992 (EPAct). These include toilets, urinals, lavatory faucets, kitchen faucets and metering faucets. Per CIR ruling dated 3/9/2004, process water includes, but is not limited to, water use from cooling towers, dishwashers and clothes washers. Optimization of process water use is eligible for LEED credit under the Innovation in Design category. Please see IDc1.1 CIR ruling dated 8/31/2004 for guidance on attempting this as an innovation credit. Applicable Internationally.