Abstract: Methods, apparatus, and systems are provided for measuring the supply of a consumable product/energy source, such as electrical power, to a facility over time and analyzing the measurements to determine the consumption or supply of the product by one or more loads and/or sources in the facility, and to determine induced and residual heat flow through the facility's envelope. Various aspects compare the measured supply of the consumable product to a database of consumption signatures, which characterize access to the consumable product by particular users. In doing so, costs for the product may be more accurately divided between different tenants of the facility without having to install individual services or measurement equipment for each individual tenant. Operating conditions and facility characteristics, such as temperatures, load factors, insulation factors, etc., may be further considered in determining a particular user's access of the consumable product.