목차
- Published in June 2023 as Standard 241-2023, Control of Infectious Aerosols, ASHRAE 241 is the first comprehensive consensus standard for managing airborne disease transmission in buildings. It is a voluntary standard given legal force only when adopted by a code authority, written into a project specification or lease, or applied voluntarily by an owner. Addendum a was published in October 2024, and the standard is maintained continuously, so it should always be read with its current addenda rather than the 2023 text alone.
- The standard is built on equivalent clean airflow (ECA): the flow rate of pathogen-free air that, if delivered uniformly to the breathing zone, would match the infection-risk reduction of the actual mix of outdoor air, filtered recirculation, and air cleaning. Each technology is credited on a common basis, outdoor air at full value, recirculated air at its filter single-pass removal efficiency, and in-room cleaners at their tested clean-air delivery rate. Required rates come from Table 5-1 as ECAi per person. These are not outdoor-air rates: Space type cfm/person L/s/person Office 30 15 Classroom 40 20 Retail 40 20 Food and beverage 60 30 Gym / exercise 80 40 Healthcare waiting 90 45 Auditorium / worship 50 25 The target is set to achieve roughly a 0.1% hourly infection probability 96% of the time (Wells-Riley model).
- Compliance requires prerequisite outdoor air per ASHRAE 62.1 and a minimum filtration of MERV-A 11 (effective January 2025). Buildings operate in Infection Risk Management Mode (IRMM) during periods of elevated transmission. Crucially for efficiency, ASHRAE TC 5.5 practical guidance for epidemic operation of energy recovery ventilation systems shows that properly configured energy recovery ventilators can keep running in IRMM, so infection-risk resilience need not abandon the carbon savings of heat recovery.
- Because 241 credits filtered air, owners can meet targets without crushing ventilation heating and cooling loads, supporting both IAQ and energy management goals at the same time.
피ublished in June 2023 as Standard 241-2023, Control of Infectious Aerosols, ASHRAE 241 is the first comprehensive consensus standard for managing airborne disease transmission in buildings. It is a voluntary standard given legal force only when adopted by a code authority, written into a project specification or lease, or applied voluntarily by an owner. Addendum a was published in October 2024, and the standard is maintained continuously, so it should always be read with its current addenda rather than the 2023 text alone.
The standard is built on equivalent clean airflow (ECA): the flow rate of pathogen-free air that, if delivered uniformly to the breathing zone, would match the infection-risk reduction of the actual mix of outdoor air, filtered recirculation, and air cleaning. Each technology is credited on a common basis, outdoor air at full value, recirculated air at its filter single-pass removal efficiency, and in-room cleaners at their tested clean-air delivery rate.
Required rates come from Table 5-1 as ECAi per person. These are not outdoor-air rates:
| Space type | cfm/person | L/s/person |
|---|---|---|
| Office | 30 | 15 |
| Classroom | 40 | 20 |
| Retail | 40 | 20 |
| Food and beverage | 60 | 30 |
| Gym / exercise | 80 | 40 |
| Healthcare waiting | 90 | 45 |
| Auditorium / worship | 50 | 25 |
The target is set to achieve roughly a 0.1% hourly infection probability 96% of the time (Wells-Riley model).
Compliance requires prerequisite outdoor air per ASHRAE 62.1 and a minimum filtration of MERV-A 11 (effective January 2025). Buildings operate in Infection Risk Management Mode (IRMM) during periods of elevated transmission. Crucially for efficiency, ASHRAE TC 5.5 practical guidance for epidemic operation of energy recovery ventilation systems shows that properly configured energy recovery ventilators can keep running in IRMM, so infection-risk resilience need not abandon the carbon savings of heat recovery.
Because 241 credits filtered air, owners can meet targets without crushing ventilation heating and cooling loads, supporting both IAQ and energy management goals at the same time.