Artificial intelligence (AI) policy: ASHRAE prohibits the entry of content from any ASHRAE publication or related ASHRAE intellectual property (IP) into any AI tool, including but not limited to ChatGPT. Additionally, creating derivative works of ASHRAE IP using AI is also prohibited without express written permission from ASHRAE.

logoShaping Tomorrow's Built Environment Today

Standard 170 Evolves With Health Care Trends

Standard 170 Evolves With Health Care Trends

From ASHRAE Journal Newsletter, August 24, 2021

Like many industries, health care is constantly changing, said Michael Sheerin, P.E., Member ASHRAE, chair of Standing Standard Project Committee 170. Because of technology changes and innovations in the delivery of care, heath care spaces’ ventilation requirements oftentimes must adapt to address these changes.

Some of these changes have been added to ANSI/ASHRAE/ASHE Standard 170, Ventilation of Health Care Facilities. The recently released 2021 edition of the standard offers guidance, regulation and mandates to designers and operators of heath care facilities and incorporates 17 addenda from the 2017 standard.

One such trend affecting heath care ventilation is the evolution of imaging modalities—such as CAT-Scans and X-ray units—especially in assessing how the ventilation requirements should be aligned to support the clinical activities in these spaces, said Sheerin. “Users of the standard will see updated guidance related to these as the Class 1/2/3 imaging spaces,” he said.

The more frequent and wider use of anesthetics across the heath care environment is another trend the standard project committee had to evaluate with present ventilation requirements. “Previously, the use of these gases would require ventilation similar to an operating room. The latest standard has modified the ventilation requirements to be more reasonable, recognizing the function, use and safety measures in place for these gases,” said Sheerin.

The evolution of heath care moving toward outpatient environments has also led to assessing and establishing guidance for these types of spaces. “Users of the updated standard are better informed and know that they are applying the most up-to-date knowledge in designing heath care spaces,” he said.

The Effect of the COVID-19 Pandemic

Amid the COVID-19 pandemic, heath care ventilation has been in the spotlight. Sheerin said the SPC has
“been generally reassured that the basic principles and minimum standards that are prescribed by Standard 170 held up well through the challenges of this pandemic.”

“Obviously, emergency condition actions and modifications occurred as there were so many unknowns and the cautionary path was to protect staff,” he said. “While the committee retrospectively reviewed the present requirements extensively with a view to better pandemic readiness and can identify numerous elements that a designer and owner should consider, there were few elements that applied to revising the standard as these were all considered ‘beyond minimum’ items.”

He said addendum s, which allows airborne infectious isolation room exhaust discharge to the general exhaust system under certain criteria, specifically developed out of feedback from heath care systems seeking increased flexibility to overcome the challenges of creating these rooms—especially retrofitting them into various departments or in older or high-rise buildings. 

What’s New in the Standard?

The 2021 edition of Standard 170 includes new content that supports the framework introduced in the 2017 revision that expanded the standard into three sections: hospital spaces, outpatient spaces and residential heath care spaces. The framework aligns with Facility Guidelines Institute (FGI) publications, said Sheerin. SSPC 170 works closely with key industry partners—such as FGI— to “identify any conflict areas and incorporate industry specific changes in a manner that ensures that we harmonize the content of our documents,” he said.

Other updates to the 2021 revision include:

  • Revised scope with improved guidance on thermal comfort conditions;
  • Extensive modifications to address the outpatient section, including the addition of a new outpatient ventilation table to address non-acute-type spaces;
  • Extensive revisions to air filtration requirements, including new columns in the ventilation tables to prescribe filtration requirement and designate unoccupied turndown;
  • Expanded requirements to allow airborne infectious isolation room exhaust discharge to general exhaust under certain conditions;
  • Improved guidance on space ventilation requirements needed for anesthetic gas use;
  • Clarification of Class 1/Class 2/Class 3 imaging in coordination with FGI;
  • Revised definition of “invasive procedure”; and
  • Improved guidance related to behavioral and mental health.


Dive in deeper to ventilation or heath care facilities’ HVAC needs: