Balancing sustainability and safety: Reducing HVAC air exchange rates in operating rooms without increasing infection risk

Compared to other industries, the healthcare sector disproportionately contributes to negative environmental burdens. Operating rooms (ORs) are the most energy-intensive and waste-producing areas within a hospital. Heating, ventilation, and air conditioning (HVAC) systems in ORs are energy intensive and designed to maintain a high rate of air exchanges. The purpose of this study was to reduce HVAC air exchange rates while balancing surgical site infections (SSI) incidence rates as a key patient safety metric.

A quality/process improvement intervention was conducted at a large, urban, free-standing single-center children's hospital with multidisciplinary team collaboration including surgery, infection prevention, and engineering. The intervention involved implementing reduction of HVAC cycling rates to acceptable industry standard ranges in April 2024. SSI rates monitored by Infection Prevention and Control in accordance with the National Healthcare Safety Network (NHSN) definitions, and longitudinal run-charts are monitored for trends. Using negative binomial regression analysis, we compared the level and trend of SSIs between the pre-intervention and intervention periods. This approach was selected due to evidence of overdispersion in the data. Energy usage as well as cost savings were calculated to assess annual environmental and economic impact.

Across all 22 ORs, the HVAC cycling rates were decreased from a baseline of 22.9-33.5 air changes per hour (ACH) to 20.1 to 21.2 ACH (median 32.8 to 20.7 ACH, p < 0.01). There was a decrease in energy consumption, with a projected annual savings of approximately 500,158 kWh. This is equivalent to charging over 27 million smartphones and translates to projected $40,013 in energy costs annually. There was no significant difference in the level (p = 0.85) or trend (p = 0.97) of SSIs incidence rate between the pre-intervention and intervention periods.

Reducing HVAC cycling rates in ORs can significantly decrease energy consumption and generate cost savings without compromising patient safety, as demonstrated by stable SSI rates.