A new office-building project has implemented several water-saving strategies, achieving a 25% reduction in potable-water...

The combined strategies produce a 35% reduction in potable-water consumption: 25% from efficiency measures plus another 10% from harvested rainwater. Under the WEc2 Whole-Project Water Use approach, that level of reduction reaches the four-point performance tier represented by Option C. The whole-project method evaluates applicable water end uses collectively rather than treating plumbing fixtures, irrigation, process water, and alternative supplies as unrelated measures. Rainwater used for suitable nonpotable applications reduces demand on municipally supplied potable water and therefore contributes to the calculated reduction when properly included in the project water balance. The project must document baseline demand, proposed demand, end-use assumptions, alternative-water availability, storage, treatment, and intended uses to demonstrate the claimed reduction and earn the corresponding points.