Helping McLaren Health Care Significantly Reduce Energy Demand Through OR Optimization

Industry: Healthcare/hospitals


To help McLaren Health Care meet its energy demand reduction target, Resolute is using its analytics software to fine-tune the systems that operate McLaren's buildings across the network. To this end, operating room (OR) heating, ventilation, and air conditioning (HVAC) systems quickly emerged as the top energy demand reduction target for McLaren. HVAC is the single most energy intensive component in the McLaren portfolio, which includes more than 100 ORs running multiple procedures each day. Because of OR requirements that include air changes per hour, strict temperature and humidity parameters, pressure relationships and energy-intensive (and often heat-generating) surgical lighting systems, optimizing OR HVAC systems represented a significant energy reduction opportunity.

Occupied Settings

ORs require proper ventilation, specifically fresh outside air. State and federal codes govern the minimum total and outdoor air change rates for ORs to maintain temperature, ensure particulate removal and overcome equipment loads. ANSI/ASHRAE/ASHE Standard 170- 2013 states that ventilation of health care facilities requires a minimum of 20 total air changes per hour (ACH) and four (4) ACH of outdoor air when the room is in use. McLaren had no ACH design specification/standard across its portfolio, and various sites were exchanging air in excess of the minimum ACH. Using the Resolute analytical data and working with McLaren leadership at the corporate and site levels, McLaren Health Care has standardized around ASHRAE 170 and is in the process of adjusting all ORs to 20 ACH.

Unoccupied Settings

ASHRAE 170 and many state codes allow the number of air changes to be reduced “when the space is unoccupied providing that the required pressure relationship to adjoining spaces is maintained while the space is unoccupied and that the minimum number of air changes indicated is re-established anytime the space becomes occupied.” (7.1-Subsection a.3)

OR Cost Impact of Air Distribution

  • Studies show that 20 ACH provides significantly better particle control than 15 ACH; however, 25 ACH does not provide cleaner air than does 20 ACH. More air is not always better.

  • A conservative estimate indicates that it costs $1,500 per ACH per year provided to an OR (based on 24/7 operation).

  • Cost savings from reducing a single OR at 25 ACH to the standard of 20 ACH is roughly $7,500 per year.

  • If that same OR can be set-back to 8 ACH during unoccupied times, an additional savings of $8,800 per year can be achieved (based on unoccupied times of 11pm to 6am M-F and all day S-S).

McLaren OR Optimization Impact

OR Optimization Tactics and Potential Savings

  • Balance all ORs to a maximum of 20 ACH (those currently between 15-20 ACH remain as is) for potential annual portfolio savings of $485,000 to $490,000

  • Set-back all ORs to 8 ACH during unoccupied times (based on unoccupied times of 11pm to 6am M-F and all-day S-S) for potential annual portfolio savings of $720,000 to $725,000.

  • Total potential annual portfolio savings equals $1,205,000 to $1,215,000.




McLaren Health Care, headquartered in Grand Blanc, Michigan, is a fully integrated health network committed to quality evidence-based patient care and cost efficiency.

The McLaren system includes: 12 hospitals, ambulatory surgery centers, imaging centers, an employed primary care physician network, commercial and Medicaid HMOs covering more than 630,000 lives, home health and hospice providers, retail medical equipment showrooms, pharmacy services, and a wholly owned medical malpractice insurance company.