This project utilizes a parallel water distribution system (Viega\'s Manabloc) for domestic water on all lavatories, mop sinks, and water coolers (water closets are served by grey water). The design uses two strategically placed manifolds located close to the hot water recirculation loop. Individual supply lines from the manifolds are routed the shortest possible distance to each fixtures (hot and cold) in a home-run style minimizing lengths to
The project team is inquiring as to whether a reduction in building water use for achieved by means other than the measures recognized in WE credit 3 is eligible for an ID credit. A major difference between the proposed measure and the fixture efficiency used in WEc3 is that the savings from this proposed piping design depend on the relative use of hot water and only apply to that fraction of the overall water use. As a result, in order to justify an ID credit for this system, the project would need to demonstrate that the projected water savings attributable to the piping design are equal to or greater than 10% of the total regulated water use in WEc3. The description provided references a 40% improvement overall conventional piping design (the report was not accessible via the CIR system). You will need to clarify whether this 40% savings is relative to total building water use or just hot water use, etc. It is assumed that the project is already achieving WE credit 3.1 and 3.2. If those credits are not already being achieved, you would simply apply this same approach as an alternate compliance path for WEc3, as opposed to an ID credit.