I have never quite understood what happens when a building uses many different types of fixtures. We are working on a gated community where all the villas use same type of fixtures but the common facilities like the club house and the spa use different type of fixtures. If there are 1200 FTE then how is one supposed to know how many times the fixtures in the common facilities will be used and how many times the fixtures in the villas will be used?

If the fixtures in the common facilities are more efficient, the project team would automatically be tempted guesstimate a higher number of uses in the common areas, hence getting a higher net saving. What protocol should one follow in such a case?