Healthcare facilities consist of a myriad of room types, all of which require varying degrees of HVAC design precision and sophistication. Class III imaging rooms rank among the most design-intensive spaces found in healthcare facilities, due to their strict airflow, temperature, and pressure control requirements, coupled with precise coordination to accommodate operational and spatial demands of imaging equipment. A Class III imaging room, as defined by the 2022 Facility Guidelines Institute (FGI), is “an imaging room designated for the performance of patient care activities, including invasive procedures and any other Class II procedure during which the patient will require physiological monitoring and is anticipated to require active life support.” When designing a Class III imaging room, there are 3 main questions that should be considered: What space temperature and humidity should be maintained in the procedure room? What efficiency of final air filtration is required? What space constraints and coordination challenges does the imaging equipment present?
Per the 2022 FGI Guidelines, Class III imaging rooms require conditions to be maintained between 68-75 degrees Fahrenheit and a relative humidity between 20-60%. Since Class III imaging rooms function similarly to operating rooms, clinicians often prefer cooler conditions, requesting 65–66 degrees Fahrenheit. Lower space temperatures, coupled with maintaining relative humidity below 60%, often require an HVAC system capable of producing supply air temperatures lower than 50 degrees Fahrenheit. This can be difficult to achieve with traditional building chilled water systems. Imaging equipment often requires minimum relative humidity levels of 30%, which mandates an active humidification system under certain conditions. These demands can present significant challenges, particularly when retrofitting existing spaces to accommodate a Class III imaging room.
Class III imaging rooms require a minimum of MERV 16 final filtration to deliver sterile supply air and reduce infection risk through the HVAC system. In instances where the space is used for orthopedic procedures, transplants, neurosurgery, or dedicated burn procedures, HEPA filtration is required to be provided at the air terminal devices of the ceiling installed laminar flow diffuser array. While these procedures may not represent the primary function of a Class III imaging room, the Owner’s operational intent must be considered, as Class III imaging rooms are often used as a backup operating room where these types of procedures could occur.
One of the greatest challenges in designing a Class III imaging room lies in managing space constraints and coordinating the structural supports required for imaging equipment. Each piece of imaging equipment has spatial clearances, which must be carefully coordinated with the HVAC system’s low return chase locations and the laminar flow supply diffuser array. These systems often incorporate boom arms or ceiling-mounted rails to allow precise equipment positioning during procedures. Supporting these components demands robust structural frameworks, typically involving diagonal bracing and framework assemblies to ensure stability and maneuverability. These supports frequently conflict with the laminar flow diffuser array positioned directly above the patient bed. In addition, supply and return ductwork pathing through the space must be coordinated with the additional structural elements within the room’s plenum. This often creates a design puzzle that calls for creative duct routing and smart ceiling integration to keep airflow uncompromised.
If you have questions regarding of Class III imaging rooms on current or potential projects, please do not hesitate to contact Ryan Davie, PE at 919-341-4247 or rcd@ba-inc.com.