We are working on a project that has a chilled water plant, cooling towers, DOAS units that supply cooled outdoor air to Chilled Water Sensible Cooling Terminal Units installed in each thermal zone. 

The Chilled Water Sensible Cooling Terminal Units condition each thermal zone with the primary air (100 % outdoor air), secondary air using a variable speed fan and chilled water through in its cooling coil. These units are only installed in the tenants' spaces.

We are measuring energy consumption of the chilled water plant (chillers and associated pumps), cooling towers and associated pumps, DOAS Units, and of each Chilled Water Sensible Cooling Terminal Units. We are also measuring total water flow leaving the chilled water plant and condensing water.

The question is: since we are measuring the total water flow leaving the chilled plant, the energy consumption of the chilled plant and of each Terminal Units (bearing in mind that the energy consumption of the terminal unit varies according to its cooling needs), can we use the following strategy to calculate the water consumption of each tenant?

Water consumption of one tenant = (tenant terminal units energy consumption / total energy consumption of all  terminal units in the building) * (total water consumption - water consumed by the base building).

Any help will be appreciate!