LEED has created Letter templates to calculate the water reduction, and has guidelines for the proper sizing of the rain water cistern. If you assume the cistern is sized properly no water is used and no model would be required. Most plumbing codes already define the proper fixture unit to gpm requirement for sizing peak flow just as you would already design the plumbing w/o rainwater. The energy consumption of the circ pump should probably be assumed to run 24/7.
Good luck |