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ASHRAE Standard 241’s origins: how it came to fruition

What are the origins of ASHRAE Standard 241?

In December 2022, ASHRAE's pandemic task force met with the White House to discuss ways to limit the future spread of indoor pathogens, which contributed heavily to the proliferation of COVID-19. For context, ASHRAE had existing recommendations to maximize indoor safety and limit the spread of infectious airborne pathogens in certain industries; however, most public spaces, residential buildings, and businesses did not have standard measures for ongoing indoor air quality.

The majority of the prior recommendations were for the healthcare industry and centered around a space's ACH or eACH (Air Changes per Hour/Effective Air Changes per Hour), which measure how often indoor air is replaced with fresh or clean air from a variety of methods, including ventilation, filtration, outdoor air circulation, and disinfection (such as UVC).

These preexisting standards (62.1, 62.2, which specify outdoor airflow rate and filtration requirements to control normal indoor air contaminants) offered healthcare and other industry-focused air exchange guidance dictated by the space's size, usage, and other criteria. For example, ASHRAE suggests that medical or clinical settings have a minimum ACH/eACH of 6 or higher.

However, outside of focused industries like healthcare, global recommendations lacked guidance on risk and health. That recommendation varies from other commercial spaces, which are typically in the region of 4-5 ACH/eACH. This guidance intends to keep indoor air safe and healthy—as does Standard 241, but with some first-of-its-kind differences. It’s also important to remember that this initiative is driven by scientists, industry leaders, and other experts ins the science of indoor health.

We spend 90% of our lifetime indoors, yet indoor air can be up to five times more polluted than outdoor air. Poor air quality can lead to a range of health problems, including respiratory issues, allergies, and asthma, and also has a dramatic effect on loss of business productivity, more sick days, and increased healthcare costs.

How is a new recommendation created?

ASHRAE has thousands of members, including industry experts, scientists, engineers, and technicians. Each standard, including Standard 241, is the result of the organizations meeting a consensus regarding best practices, recommendations, and technology suggestions for the betterment of indoor health.

As part of this new building code, ASHRAE will release appendixes that offer practical guides to put this directive into practice. Some appendixes are for industries like education, while others are focused on how to execute this order. Appendix C is focused on what measurement systems, techniques, and standards can be used to be compliant with the code.

Why is ASHRAE Standard 241 a groundbreaking directive?

This first-of-its-kind directive aims to establish minimum requirements for controlling infectious aerosols, fine solid particles, or liquid droplets in air or another gas, like RSV or SARS-CoV-2, expelled from the lungs in human breath for ALL indoor spaces.

This includes everything from factory floors and retail shops to offices and apartments. Moreover, this standard applies to occupied spaces in new and existing buildings, including additions to already-built spaces. Obviously, this implicates millions of spaces around the world, in the 123 countries included in ASHRAE, hence its unprecedented magnitude.

About Poppy.

Poppy uses patented sensor technology to collect and interpret spacial airflow data in minutes, from measuring eACH and ECA to identifying over-ventilation and under-ventilation. Poppy partners with building owners, facility managers, and companies to quickly uncover ways to optimize, save energy costs, and align to new standards.

Partner with us to uncover ways to improve air health, optimize ventilation, sustainability, and reduce energy consumption and costs.


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