TABLE OF CONTENTS - The Professional Green Building Council

Theme B: Creating a livable, healthy and environmentally viable cities2.6.Rating Scheme DerivationThe original motivation for the study was to develop a performance basedbenchmark for water consumption in Australian office buildings. This followsfrom the success of the Australian Building Greenhouse Rating Scheme (ABGR)in Australia, which has motivated large market changes with respect to operationalenergy consumption in the office sector [6]. This scheme has been incorporatedinto the National Australian Built Environment Rating Systems (NABERS) tocover broader environmental issues, of which the current study forms the watercomponent [7]. ABGR and NABERS are administered nationally by the NewSouth Wales Government Department of Environment and Climate Change.The benchmarking philosophy follows that of ABGR, i.e.‧The benchmark is a five star scale with 1 star = poor, 5 star = excellent and 2.5star = market median‧The benchmark should aim to cover around 80-90% of the market, with theexcluded buildings generally being extremely inefficient;‧The star bands are linear, i.e. the gap between 1 star and 2 stars is the same as 4star and 5 stars;‧The rating should reflect efficiency rather than absolute consumption and thusrequires normalisation for unavoidable issues such as climate impacts.The application of this philosophy is complicated by the nature of the buildingpopulation with respect to water consumption; the presence of two stronglydifferentiated groups, being water cooled and air-cooled, raises the questionwhether a single scale can fairly capture the entire population. This is furthercomplicated by the fact that an air-cooled building will use fairly much the sameamount of water irrespective of climate, while water cooled buildings vary172