In addition to the mainstream, there are also some other benchmarking approaches. Customized benchmarks, as discussed by Cohen et al. (2006), can take account of individual areas or energy end-uses, i.e. the breakdown of energy use into its components, hence it will allow the most meaningful and fairest assessments of a building’s energy use. It is not hard to imagine the considerable time and effort needed to establish such a benchmark. And that is why it is very rare at present. Model-based benchmarking, as the name indicates, establishes energy consumption benchmarks by using mathematical models. The principle is to construct a benchmark that represents the minimum amount of energy required to meet a set of basic functional requirements of the building. The ratio of the bench-mark to the actual consumption is an effectiveness metric, which enables energy performance of buildings to be compared, even if they are with dissimilar features and functional requirements (Federspiel et al., 2002).