An Arizona hospital had recently completed an HVAC system upgrade serving their 10 operating room areas. One (1) air-cooled booster chiller and two (2) air handler units were designed, installed, and to maintain temperature and pressure requirements for these critical spaces.


                 Jon Zbuka                           Project Manager

Through monitoring-based commissioning (MBCx), ETC Group engineers observed the air-cooled chiller frequently cycling off/on due to low load and the air handlers operating at constant temperature and supply air flow set points.


Our engineering department and project management group put together a turnkey scope of work to optimize of the air-cooled chiller and air handlers serving the ORs. The project took approximately 2 months to draft and review new sequences, gathering implementation bids, execute the scope of work, and re-commission the changes.

Successful implementation of this project required extensive communication and coordination between the facilities support team, controls/balancing contractors, operating room staff, environmental services staff, and many others to perform smoothly in a critical space environment. The teams worked after-hour graveyard shifts to make system changes without disturbing the operating rooms’ scheduled cases. Upon project closeout, there were no interruptions, downtime, or disturbances to any procedures throughout the implementation and commissioning of the optimized sequences.


Optimizing the sequence of operation for these systems demonstrated a measured reduction in system energy and cooling/heating demand.

Overall, the project resulted in:

  • Zero interruptions or disturbances to procedures
  • ORs that continue to maintain temperature and humidity requirements, matching pre-project expectations and conditions
  • Reduction in booster chiller energy
    • 89% reduction in total booster chiller run time
  • Reduction in AHU fan power
    • 10% reduction in total AHU fan power
  • Reduction in terminal unit reheat
    • 51% reduction in terminal unit heating energy
  • Annual energy savings of over $28,000/year
Booster Chiller Running Only When Needed


Booster Chiller Running Only When Needed

AHU Fan Power and Cooling Load Reduction


AHU Fan Power and Cooling Load Reduction (One Fan Shown)

Booster Chiller Plant Energy Reduction


Booster Chiller Plant Energy Reduction