How does FCU runtime effect chill water supply temp.

[Cassia]

With in room energy management controls we can reduce Fan Coil Unit run times by creating room set backs based on occupancy. Typically around 30-35% reduction in HVAC FCU run time and therefore we are able to reduce the load on the chiller. So my question that I am trying to figure out is how can I calculate the actural energy savings in $$ by having different set back temperatures that reduce my HVAC FCU runtimes. The most obvious is the electrical consumption of the Fan motors, but what about the real energy savings in the reduced chiller load? Can we not increase chill water temperature for additional energy savings and how would I be able to calculate how much I can raise chill water supply temp. to the reduction in chill water to the room when not demanded. The rooms are hotel rooms typically a 4 pipe system vertical and around 350-450sqft.

 

[willard3]

As delta T changes in the CW loop, btu/hr changes given similar operating times. Pretty basic thermodynamics.