Praire State College

Energy Audit and Retro-Commissioning

Energy Audit and Retro-Commissioning - Chicago Heights, IL


Prairie State College is a 137-acre campus with 365,000 square feet of buildings in Chicago Heights, IL. GBA provided energy audit services through the Cook County Energy Efficiency Program and provided retro-commissioning services through the Illinois Smart Energy Assistance Center (SEDAC).

The college elected to implement five of seven identified energy savings measures. The implemented measures will result in an annual energy savings of 481,537 kWh and 81,475 therms, for an annual total cost savings of $98,705.


One retro-commissioning (RCx) measure involved programming all of the fan-powered boxes (FPBs) in the Health and Technology Center to a minimum airflow mode when the individual spaces are unoccupied.

  • This was achieved by scheduling each terminal unit according to the building class schedule at the beginning of the semester, and must be repeated before each semster.
  • Savings were estimated based on reduced airflow for 13 FPBs and a spring classroom schedule. Summer savings should be greater.
  • The estimated annual electrical savings is expected to be 134,241 kWh.
  • This measure was simple and inexpensive for the owner to implement.

Another energy savings measure  implemented during the RCx involved the air handling unit for the auditorium in the Business and Community Education Center (BCEC). This AHU was scheduled to operate seven days per week, 18 hours per day.

  • Variable frequency drives were installed on the 10,000-cfm constant volume units so that the VFDs can reduce airflow quantities when the space is unoccupied.
  • The resulting annual electric energy savings is 80,399 kWh.
  • This measure involved programming of the existing BAS by a controls contractor.
  • The implementation costs of this measure were under $13,000.

Other measures selected by the college for implementation as funds become available include:

  • Balancing AHUs in the main building, BCEC, and Health Tech Center to bring in the appropriate and consistent amount of outside air.
  • Installation of occupancy sensors in four (4) 600 square foot conference rooms for control of the operation of their associated AHU.
  • Reducing the hours of the ten main building AHUs by two hours; coordinating with the building's actual occupancy schedule.