New ASHRAE Standard 241, Control of infectious aerosols – Guidelines for ventilation systems

New ASHRAE Standard 241 marks a revolutionary step in improving indoor air quality (IAQ). Indoor air quality is a key factor for human health and overall well-being. People spend 80–90% of their time indoors, meaning indoor air accounts for most of their lifetime exposure. However, IAQ quickly deteriorates when infectious aerosols are present.

The COVID-19 pandemic clearly demonstrated the extent of airborne transmission’s impact on human health. Moreover, many other communicable diseases spread in the same way. Influenza, tuberculosis, and measles are some of them. This is why the New ASHRAE Standard 241 is becoming an essential tool for public health protection.

A New Milestone: ASHRAE Approves Standard 241

On June 24, 2023, ASHRAE (the American Society of Heating, Refrigerating, and Air-Conditioning Engineers) approved the publication of the new and revolutionary ASHRAE Standard 241 — Control of Infectious Aerosols.

In this step, ASHRAE introduces minimum requirements for the design, installation, operation, and maintenance of HVAC systems to reduce human exposure to infectious aerosols.

Therefore, Standard 241 defines requirements related to:

• Equivalent outside air, i.e., the combined effect of ventilation, filtration, and air purification during the mode of mitigating the risk of infection,
• Air distribution in the room,
• Characterization of the efficiency and safety of filters and air purifiers,
• Commissioning,
• Operation of the system in the mode of mitigating the risk of infection during high-risk periods,
• Maintenance tasks and their minimum frequency.

Where the Standard Applies

The standard applies to:

• new buildings,

• existing buildings, and

• facilities undergoing major renovation.

Because of this broad scope, New Standard 241 becomes a powerful tool for improving health, well-being, and productivity in all types of buildings.

Benefits for Owners, Operators, and Users

By following New Standard 241, building owners, operators, engineers, and occupants gain:

• Improved ventilation and filtration,
• Optimized air distribution,
• Improved performance and safety of filters and air purification,
• Increased awareness and preparedness for periods of high risk,
• Reduced impact on the environment by minimizing energy consumption and emissions of harmful and dangerous substances.

A Foundation — Not the Final Step

Although ASHRAE Standard 241 represents a significant step forward in prioritizing indoor air quality and creating healthier indoor environments, it is necessary to continue improving the standard.

Finally, let’s note that ASHRAE Standard 241 provides flexibility to choose a combination of air purification technologies that best meet the user’s needs, economic constraints, and the goal of rational energy use, in which Marquis Intelligence will be happy to help.

This text by Marquis Intelligence is part of the series “Air Quality and Ventilation Standards.”
Document number: MI-NewLegislation-002.24 – New ASHRAE Standard 241, Control of infectious aerosols – Guidelines for ventilation systems.