Highland Park Hospital provides medical and surgical services, with special strengths in cardiac, cancer, and stroke care.
- The retro-commissioning effort focused on the mechanical operation and temperature controls sequence of operations for 14 air-handling systems.
- Ten retro-commissioning measures (RCMs) were identified through functional performance testing, plus reviews of the Siemens building automation system and the temperature control system trend logs. The owner opted to implement all 10 measures.
- RCMs included equipment scheduling and nighttime setbacks or shutdowns, supply air temperature reset to reduce reheat energy, improved economizer operation, and optimized discharge air static pressure set-point control and setbacks.
- One measure involved reprogramming the variable air volume terminal boxes from five different air-handling units (AHUs) in non-critical areas during unoccupied times to a reduced air volume setpoint. The hospital staff and engineering team collaborated in identifying 119 areas where airflows could safely be reduced at night. The measure will result in more than 200,000 kWh of electrical energy savings, which will yield $28,868 in annual savings and a 2.4 month payback.
- Retro-commissioning also revealed that five AHUs’ economizer modes were deactivated when the outside air temperature exceeded 50°F. This sequence negated a major benefit of the economizer mode, and cheated the hospital of significant potential energy savings. Modifying the sequence to allow the economizer to operate any time the outside air temperature is less than the return air temperature (typically around 74°F) is projected to save $6,000 in electric and gas costs per year, for a simple payback of 7.5 months.