ASHE membership weighs in on ventilation standards with public input to NFPA 99’s 2024 edition


Over the last few decades there has been an increasing uncertainty regarding the proper code or standard to apply to the operations of health care ventilation systems. While ASHRAE/ASHE Standard 170-2021, Ventilation of Health Care Facilities, is noted as the industry standard for the design of health care ventilation over the years, it also has unwittingly become a “de facto” operational standard when it is declared by facility personnel as the standard by which they maintain and operate their HVAC systems. While this can be an acceptable practice it unfortunately creates three major issues:

The standard is developed strictly as a design standard, and the ranges established in the standard are intended for design purposes and are not intended as operational ranges.

While the best designed HVAC system is intended to be able to meet the ranges within Standard 170 there are always excursions that occur.

Determining how to apply the code/standard in effect at the time of design/construction can be difficult especially when specifically trying to apply it to a portion of or a single system that is associated with multiple systems.

Due to these issues the American Society for Health Care Engineering (ASHE) of the American Hospital Association has encouraged health care organizations to develop facility specific HVAC management plans to detail the facility’s operational policy and procedures. While these have been successfully implemented in many organizations there have still been occurrences where authorities having jurisdiction have been hesitant to accept these management plans. 

To further address this issue and in collaboration with the Pacific Northwest-based Providence health care system, the ASHE Regulatory Affairs Committee developed recommendations for existing health care facility ventilation systems and submitted these to the NFPA 99 Mechanical Systems committee as Public Input Number 389-NFPA 99-2021. The proposed public input can be reviewed on the Public Input Report on the Next Edition of the NFPA 99 webpage.

Providence has 52 hospitals and over 1,000 clinics in seven western states with local and regional operational responsibility. These facilities combined “shared services” across all regions make up its Real Estate Strategy and Operations (RESO) division.

In late 2019 a cross-regional group made up of internal experts on accreditation, operations, design and construction started work on updating what’s now called the Critical Air Environments Technical Standard for RESO, which is intended to better align Providence’s operations in critical spaces for air change rates, pressurization, temperature, filtration and relative humidity.   

The nearly year-long effort underscored the challenges of knowing and understanding the “code in force at time of construction” and whether those or ASHRAE/ASHE 170 are the appropriate requirements. With the long lifespan of health care facilities, turnover within maintenance departments, and repeated renovation/expansion projects, the end result was an extremely challenging amalgamation of requirements.

The culmination of Providence’s effort was captured in the aforementioned public input which attempts to create code minimum criteria for operations within existing health care facilities. It also includes minimum criteria for maintaining mechanical equipment. It is anticipated that over time this format will allow for continuous improvement, but also consistency of requirements resulting in a greatly simplified set of requirements for operations.

While the proposal does face some challenges, the NFPA Mechanical Systems Committee has established a task force to evaluate and work on the proposal. If you are interested in getting involved with this effort, please reach out to ASHE staff member, Jonathan Flannery, MHSA, FASHE, FACHE, senior associate director, advocacy, at