Associations, IAQ

ASHRAE Approves Groundbreaking Standard to Reduce the Risk of Disease Transmission in Indoor Spaces

July 06, 2023

A Major Step Forward in Reducing the Risk of Infectious Disease Spread in Buildings

ATLANTA, June 27, 2023 (GLOBE NEWSWIRE) — ASHRAE announced the approval for publication of its highly anticipated standard to reduce the risk of airborne infectious aerosol transmission in buildings, bringing numerous benefits to occupants and promoting healthier environments.

ASHRAE Standard 241, Control of Infectious Aerosols establishes minimum requirements to reduce the risk of disease transmission by exposure to infectious aerosols in new buildings, existing buildings, and major renovations. Infectious aerosols are tiny, exhaled particles that can carry pathogens that cause infections or disease. These particles are so small that they can remain in the air for long periods of time. Use of this standard could reduce exposure to the SARS-COVID-2 virus, which causes COVID-19, the flu virus and other pathogens. Standard 241 provides requirements for many aspects of air system design, installation, operation, and maintenance.

Important aspects of the standard include:

  • Infection Risk Management Mode – Requirements of Standard 241 apply during an infection risk management mode (IRMM) that enhances the normal mode of operation, via engineering controls, to reduce the infectious aerosol exposure of the occupants. IRMM is enabled when and authority having jurisdiction (such as government, local code enforcement officials or local health authorities) have determined that there is an increased risk of infection. Owners and operators of buildings (offices, schools, medical facilities, homes, etc.) can also decide to enact the enhanced protections of Standard 241, for example, during flu season. The requirements in Standard 241 introduce the concept of resilience (the ability to respond to extreme circumstances outside normal conditions, such as the global pandemic) into indoor air quality control design and operations.
  • Requirements for Equivalent Clean Airflow Rate – Standard 241 breaks new ground by setting requirements for equivalent clean airflow rate target per occupant of pathogen free air flow, reducing the risk of infection. Other indoor air quality standards, including ASHRAE Standards 62.1, 62.2, specify outdoor airflow rate and filtration requirements to control normal indoor air contaminants. Building owners and operators can achieve this target-equivalent clean air through a combination of outdoor air, filtered indoor air and air cleaning devices such as UV light or HEPA filters that meet their budgets and energy goals.
  • Requirements for Use of Filtration and Air Cleaning Technology – The use of additional outdoor air to ventilate a building can increase energy usage and be expensive. Standard 241 provides extensive requirements for use of filtration and air cleaning (such as HEPA filters, air ionizers, or UV lights) to effectively and safely achieve the equivalent clean airflow requirements and be cost effective. These include testing requirements to establish performance and to demonstrate that operation does not degrade indoor air quality in other ways, for example by elevating ozone levels.
  • Planning and Commissioning – Standard 241 provides assessment and planning requirements for being ready for the times when there is an event with increased disease causing pathogen transmissions. The standard has a building readiness plan, that documents procedures for assessing existing or new HVAC systems to determine if they are working properly and attributing to the equivalent clean air delivered to spaces. This was a concept carried over from the work of the ASHRAE Epidemic Task Force during the COVID-19 pandemic.

“Standard 241 represents a significant step forward in prioritizing indoor air quality,” said 2022-23 ASHRAE President Farooq Mehboob, Fellow ASHRAE. “By implementing the requirements outlined in this standard, we can improve the health, well-being and productivity of building occupants. This standard empowers building owners, operators and professionals to take proactive measures in safeguarding indoor environments. It’s an essential tool for creating healthier indoor environments and promoting sustainable practices.”

“Volunteers and staff dedicated their expertise and thousands of hours of their time to address this urgent industry and societal need,” ASHRAE Presidential Fellow and Standard Project Committee 241 chair William Bahnfleth, Ph.D., P.E. “The development of this standard shows not only ASHRAE’s ability to respond rapidly to a societal need, but also a steadfast commitment to the health and safety of people in buildings everywhere. This is a significant achievement and milestone in connecting building design and operation with public health.”

The Standard 241 committee will continue and work on improving sections of the standard adding additional requirements, clarifying requirements and developing tools to help the public use the standard. Industry and consumer-friendly resources such as courses, podcasts, factsheets and information events will be introduced in the future.

Standard 241 available now for presale in the ASHRAE Bookstore.

Founded in 1894, ASHRAE is a global professional society committed to serve humanity by advancing the arts and sciences of heating ventilation, air conditioning, refrigeration, and their allied fields.

As an industry leader in research, standards writing, publishing, certification and continuing education, ASHRAE and its members are dedicated to promoting a healthy and sustainable built environment for all, through strategic partnerships with organizations in the HVAC&R community and across related industries.

The Society is showcasing integrated building solutions and sustainability in action through the opening of the ASHRAE Global Headquarters building in metro-Atlanta, Georgia.

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