Benchmarking the energy performance of a property—that is, measuring it and comparing it to similar properties—requires utility data on energy consumption and load over at least 24 contiguous months . Owners and operators of multifamily properties must have access to this utility data for the whole building in order to benchmark it accurately. However, whole-building energy data is often difficult for them to obtain.

http://umadvisory.org/another-roadblock-to-energy-management-in-multifamily-the-availability-of-whole-building-utility-data/