Commercial AHU cooling coil saving cost

I am interested in gaining some additional information on how I can calculate the savings possible from modulating a valve back for a commercial AHU cooling coil. I am trying to show for a project how an estimated saving can be achieved, by calibrating the Discharge Air sensor on multiple Air Handlers that are reading too low; will result in the cooling coil to back off. Which will save the facility money. I was thinking about using this equation from the AHU data (BTU/H= GPM X (detaT) X 500); Then convert that into TONS
(TON= (BTU/H)/12000). After I find the tons, I was thinking about calculating how much those tons would be saved from the chiller for that instant.


Please let me know if I need to use a different equation, or approach to find the saving cost for AHU cooling coil.

Thanks for any and all assistance!