Partial Retrofit

Great question, Tim - this comes up a lot. In principle, you've setup your fixture groups perfectly; typically, you want the groups setup by building usage patterns. However, in this case, you need to differentiate between peformance levels for different versions of the same fixtures. The best way to approach this is to create two fixture usage groups. One will be for original fixtures and the other will be for retrofitted fixtures. Once this are setup, you'll need to determine the number of building occupants and visitors that have access to each fixture usage group and setup the occupancy accordingly; maybe the retrofits have occured only on specific floors and you can easily divide up the occupancy accordingly? This way, you're still addressing water consumption from the perspective of building usage patterns, but you're accounting for different flow/flush rates for certain fixture types. Make sure that your final occupancy figures are equal to the total occupancy reported in the general Project Information submittals. One other note, if these fixture retrofits occured for the purposes of this LEED project and just involved minor retrofits (aerators, flushing valves, etc.), you can actually use the 160% baseline for the whole building. See page. 85 of the LEED-EBOM v2009 Reference Guide for details.