Infection Risk Management Mode: Resilience in A Changing World

A group of people standing in a room with windows, ASRAE 241 proposes minimum requirements to reduce risk of disease transmission to help keep all occupants of your business safe.

Recently, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) released Standard 241-2023 -- Control of Infectious Aerosols, proposing minimum requirements to reduce the risk of disease transmission indoors. One core concept of Standard 241 is a building’s Infection Risk Management Mode (IRMM.) ActivePure would like to share the following executive summary of IRMM and how it can help your organization build resilience against infectious threats to your bottom line.

What Is Infection Risk Management Mode?

IRMM — along with “Normal Mode” and “Temporary Shutdown” — is one of three potential settings for your building’s indoor air quality interventions. Standard 241 defines Infection Risk Management Mode as “the mode of operation in which measures to reduce infectious aerosol exposure documented in a building readiness plan are active.” In other words, IRMM is a policy for moving your building’s ventilation, filtration, and air cleaning, (along with other protections) into red alert.

According to ASHRAE, IRMM “applies during periods when higher levels of infection risk mitigation are desired or are required by authorities based on public health data.” Examples of such periods may include:

  • Large events or conferences in your building
  • Flu season in your hemisphere
  • Rising COVID cases in your region

Though it is designed for infectious aerosols (i.e., bacteria, mold spores, and viruses,) ASHRAE believes that IRMM may even be adapted for protection against wildfire smoke.

What Does IRMM Require?

If the above definition still seems rather nonspecific, that is by design. Standard 241 strives to accommodate all building types, business needs, and budget levels. This ASHRAE infection standard establishes very few specific requirements of IRMM, leaving the details up to the Authority Having Jurisdiction, (which is defined in the next section).

However, Standard 241 does specify some requirements for all IRMMs including:

  • Clear documentation in the Building Readiness Plan
  • Compliance with other applicable ASHRAE standards
  • A ban on intermittent ventilation during occupied hours (Per ASHRAE, an example of intermittent ventilation would be “fans that supply primary air cycling ON/OFF with heating/cooling.”)

Standard 241 also requires that all systems operators:

  • are trained in IRMM ventilation procedures;
  • and have access to the BRP.

The new ASHRAE standard also requires that the authority having jurisdiction maintain and inspect all ventilation systems at a minimum frequency as defined by ASHRAE Standard 180 and Table 9-1 of Standard 241. The authority having jurisdiction must also maintain and inspect all air cleaning equipment at a minimum frequency as defined by the manufacturer and Table 9-2 of the Standard 241.

Occupants also need to have access to all IRMM information. This involves:

  • posting IRMM information publicly in the building;
  • and displaying “required settings” near all adjustable system controls.

Who Is the Authority Having Jurisdiction?

ASHRAE defines the Authority Having Jurisdiction (AHJ) as the “agency or agent responsible for determining compliance with this standard [241].” This could mean a building operator, business owner, facilities manager, tenant occupant, or humble homeowner. Of course, if there are local or state regulations, these supersede the AHJ’s ability to define IRMM entirely. However, in many cases, the authority determining the details of IRMM is you.

What Does Establishing an IRMM Policy Involve?

The details of Infection Risk Management Mode are established as part of the creation of a Building Readiness Plan (BRP). This means that if you follow the steps (of assessment, planning, and implementation as outlined in Standard 241) to create a BRP, you will create an IRMM policy in the process.

IRMM aims for greater air quality goals than Normal Mode, resulting in the need for distinct engineering and non-engineering controls. This might involve:

  • increased HVAC fan speeds and/or ventilation rates;
  • the creation of negative pressure “separation” and “isolation” areas for potentially infected individuals;
  • the reduction of the maximum allowed occupancy;
  • and/or the use of additional portable air cleaners.

These interventions must be tested both when the building is occupied and when it is unoccupied. This verifies if the target Equivalent Clean Airflow Rate (ECAi) is being reached.

If the building is new, IRMM is included in the planning process by the owner. Owners must provide potential IRMM controls to designers and builders via the project requirements. This does not exempt new buildings from the need to test these controls for efficiency.

Why Not Use IRMM All the Time?

IRMM is designed to create building resilience, i.e., the “ability to respond to extreme circumstances outside normal conditions.” In a world where pandemics can pop up at a moment’s notice and wildfire smoke chokes major cities hundreds of miles away, building resilience via IRMM is a valid investment.

This may lead one to wonder: If IRMM is so helpful, why shouldn’t buildings use Infection Risk Management Mode all the time? After all, sick employees and customers impact the bottom line.

The unfortunate answer is that many buildings will not take advantage of Standard 241’s ability to accommodate multiple layered technologies. Instead, they will choose to create an IRMM policy that increases ventilation and filtration to unsustainable levels. To reduce both energy costs and the system strain, such buildings will use IRMM intermittently as an acute intervention.

Of course, organizations that know about ActivePure® Technology have a better plan. With ActivePure devices, your business can neutralize up to 99.9% of many viruses, mold spores, and bacteria in the air and on surfaces — all while keeping ventilation and filtration at affordable levels.

To learn more about how ActivePure can help your organization build resilience, visit our FAQ page that has answers and resources that are guaranteed to help your business ensure peace of mind and curb the transmission of infections.

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