We are investigating the potential to demonstrate that the cooling solution in our project is more water efficient than a baseline according to LEEDv4.1 Optimize Process Water Use, Option 2.  However, the reference guide isn't particularly clear on how to calculate the baseline water consumption.  The text states that we should calculate relative to "a water-cooled chiller system with axial variable-speed fan cooling towers having a maximum drift of 0.002% of recirculated water volume and three cooling tower cycles."

We can calculate the consumption for the proposed system, but does anyone have any tools or methods for simply calculating an accurate baseline consumption?