There are a number of considerations when it comes to ventilating and air conditioning needs for hospitals. Different sections must not just meet building codes, but also government requirements. And at a time when COVID-19 has put a strain on staffing and infrastructure alike, it has become more crucial than ever to ensure that upgrades and new construction are able to meet Centers for Medicare & Medicaid Services (CMS) requirements for operating room HVAC systems.
Unlike heavily trafficked areas such as lobbies, waiting rooms, and cafeterias, the temperature and relative humidity in operating rooms must be carefully controlled.
The CMS, along with other HVAC standards providers, have noted that there is an acceptable range of humidity and temperature that limit microbial growth and reduce infections and maintain occupant comfort.
The key guidelines for operating room HVAC revolve around several key concerns:
As such, the key measurement is relative humidity. The CMS requirements for hospital operating room HVAC require relative humidity levels of at least 20 percent, with a recommendation of an upper relative humidity of 60 percent. More importantly, the CMS encourages hospitals to incorporate the recommendations of other standards organizations, including the Association of Operating Room Nurses (AORN) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
Due to the combination of AORN recommendations and ASHRAE Standard 170 (applicable to all new construction projects, retrofits, and upgrades), a more precise recommendation for operating room HVAC performance includes:
ASHRAE’s Standard 170 has emphasized the value of ceiling-mounted air delivery units. In the 2017 update, they recommend a large diffuser array that is at least one foot larger than the operating table. In addition, the general recommendation is to include at least two exhaust grilles on the walls near the floor. Finally, ASHRAE recommends the use of air diffusers that have an average discharge velocity of 30 feet per minute.
This clearly demonstrates the importance of ceiling-mounted laminar flow diffuser arrays for medical HVAC requirements in operating rooms. However, there has been recent research into the airflow pathways in the sterile and non-sterile zones of these rooms. There are some indications that the current best practices may lead to issues regarding the transfer of contaminants into the sterile zone.
A recent study indicates that a higher number of air changes per hour (ACH) by an operating room HVAC system decreases the likelihood of contaminants entering the sterile zone. ACHs should be higher within operating rooms dealing with complex procedures like treating burn patients, doing skin grafts, and performing transplants.
Unfortunately, hospitals are often working in constrained financial environments. As such, trying to design a system that can reduce the growth of bacteria and other contaminants while staying within budget remains an ongoing issue for design engineers and HVAC contractors. Still, being mindful of current research in computational fluid dynamics and related fields regarding airflow can help HVAC engineers stay ahead of future requirements and recommendations.
Ultimately, having access to a variety of systems to design the right hospital HVAC systems for installation is crucial to meeting CMS requirements, staying under budget, and remaining on schedule. Windy City Representatives is a leading distributor of air handlers and other units that can be used to meet these guidelines from trusted manufacturers like Reznor Heaters, AAON, and more.
To learn more about what systems make the most sense for your project, contact us today. We look forward to matching you with the right fit for your budget and operating room HVAC performance envelope.
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