ASHRAE, the global leader in building technology and environmental sustainability, has announced the approval for publication of its highly anticipated standard for airborne infection risk mitigation in buildings. The new ASHRAE Standard 241, Control of Infectious Aerosols, establishes crucial requirements to reduce the risk of disease transmission and enhance indoor air quality in new buildings, existing buildings, and major renovations.
Infectious aerosols, microscopic particles exhaled by individuals carrying disease-causing pathogens, pose a significant threat as they can remain suspended in the air for extended periods. By adhering to ASHRAE Standard 241, building owners and operators can effectively minimise exposure to various pathogens, including the SARS-COV-2 virus responsible for COVID-19, as well as influenza viruses and other harmful pathogens causing substantial personal and economic damage annually. The standard encompasses various aspects of air system design, installation, operation, and maintenance, ensuring comprehensive and effective control of infectious aerosols.
Key features of ASHRAE Standard 241:
- Infection Risk Management Mode – Requirements of Standard 241 apply during an infection risk management mode (IRMM) that applies during identified periods of elevated risk of disease transmission. AHJs (Authorities Having Jurisdiction) can determine when the enhanced protections of Standard 241 will be required, but its use can also be at the discretion of the owner/operator at other times, for example, during influenza season. This aspect of Standard 241 introduces the concept of resilience – ability to respond to extreme circumstances outside normal conditions – into the realm of indoor air quality control design and operation.
- Requirements for Equivalent Clean Airflow Rate – 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. Standard 241 breaks new ground by setting requirements for equivalent clean airflow rate, the flow rate of pathogen free air flow into occupied areas of a building that would have the same effect as the total of outdoor air, filtration of indoor air, and air disinfection by technologies such as germicidal ultraviolet light. This approach allows the user of the standard flexibility to select combinations of technologies to comply with the standard that best satisfy their economic constraints and energy use goals.
- Requirements for Use of Filtration and Air cleaning Technology – Dilution of indoor air contaminants by ventilation with outdoor air can be an energy intensive and expensive way to control indoor air quality. Standard 241 provides extensive requirements for use of filtration and air cleaning to effectively and safely achieve meet equivalent clean airflow requirements efficiently and cost effectively. 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 culminating in the development of a building readiness plan, a concept carried over from the work of the ASHRAE Epidemic Task Force. It also describes procedures for commissioning systems to determine their installed performance.
“Standard 241 represents a significant step forward in prioritizing indoor air quality,” said 2022-23 ASHRAE President Farooq Mehboob. “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.”
The consensus process involved in the development of Standard 241, from project approval to final publication, including a comprehensive public review, was completed in just six months. “Volunteers and staff dedicated their expertise and thousands of hours of their time to address this urgent industry and societal need,” highlighted ASHRAE Presidential Fellow and Standard Project Committee 241 William Bahnfleth, PhD, PE.
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