Atypical approach when designing HVAC systems for operating rooms (ORs) is to go to ASHRAE Standard 1701 and identify what types of ORs are being designed (e.g., Class B, Class C). One would then determine the appropriate temperature and relative humidity design setpoints for all ORs in the suite. The next step would be to calculate the OR sensible and latent loads, followed by the selection and sizing of the related HVAC system. Since the OR HVAC system has been designed and sized per the requirements of ASHRAE 1701, one would expect that such system will meet all user expectations and operate as intended. Unfortunately, this “one size fits all” approach does not give the users the flexibility to perform complex procedures while having a reliable and energy efficient mode of operation.
With a continuous pressure to decrease turnover time while also providing the medical staff with utmost flexibility, the design of the HVAC systems for today’s operating rooms requires not just special attention but also complex analyses. As such, it is crucial for the OR HVAC systems to support a wide range of temperature and associated relative humidity setpoints. For instance, an orthopedic surgery room could require a design OR setpoint of 63°F and 40% rh; such procedure might then be followed by a long and demanding pediatric surgery that requires higher temperature and relative humidity setpoint (75°F and 50% rh).