Five factors to understand for the indoor air quality procedure

As building owners and design professionals seek new ways to improve efficiency, lower cost and reduce carbon emissions in their buildings, many are considering ventilation optimization through the ASHRAE Standard 62.1: Indoor air quality procedure.

By Rob Landes January 13, 2025
Courtesy: Daikin Applied

As building owners and design professionals seek new ways to improve efficiency, lower costs and reduce carbon emissions, many are turning to ventilation optimization through the indoor air quality procedure (IAQP) outlined in ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality.

Traditional ventilation rate procedure (VRP) uses occupancy and area to determine an outdoor air ventilation rate. The IAQP, on the other hand, allows design professionals to leverage additional methods, such as air-cleaning devices, to reduce the need for high rates of outdoor ventilation while still providing clean and comfortable air to the building occupants.

This approach reduces the load and energy use associated with conditioning outdoor air by cleaning the air before addressing any remaining contaminants. It also improves the likelihood of meeting both energy and carbon emissions reduction goals and provides lower first cost by reducing the heating, ventilation and air conditioning (HVAC) system’s required capacity. As the ASHRAE Standard 62.1 user’s manual states, “the IAQP may allow for a more cost-effective solution to providing good air quality, as all design strategies may be considered.”

When considering air-cleaning technologies as part of an IAQP-enabled optimized outdoor air strategy, there are five key actions design professionals should take.

Keep up to date on the latest ASHRAE 62.1 changes

As carbon emissions, energy efficiency and building resiliency have driven HVAC system improvements over the past few years, ASHRAE has made corresponding changes to the 62.1 standard. In the past, the IAQP method was less well defined, leaving key considerations up to the design professional. In the 2019 and 2022 standards or addenda, the society made clarifications and additions to help guide the design professional in leveraging the IAQP. While many states have not yet formally adopted the latest version, design professionals should consider whether to apply the latest standard (as long as not excluded or prohibited by local codes or standards) so that the design can take full advantage of these improvements.

This article refers to the 2022 version of the standard unless otherwise noted.

Figure 1: Examples of changes to the ASHRAE 62.1 standard that those applying the indoor air quality protocol should be aware of. Courtesy Daikin Applied

Figure 1: Examples of changes to the ASHRAE 62.1 standard that those applying the indoor air quality protocol should be aware of. Courtesy Daikin Applied

Address all contaminants of concern

A key clarification first introduced in the 2019 version of ASHRAE Standard 62.1 is the designation of 14 specific design compounds or ‘contaminants of concern’ that must be evaluated and addressed to ensure suitable air quality. Past versions left this undefined and up to the design professional to determine what contaminant(s) to address. Addendum aa, Sections 6.3.1 and 6.3.2 state, “The system design shall be based on the design compounds (DCs) and pm2.5 specified in table 6-5 … the concentration limits, referred to as design limits, shall be as specified in table 6-5 and … design ventilation shall be such that the calculated concentration of each dc, mixture of dcs and pm2.5 does not exceed its limit.”

With a better understanding of what contaminants to evaluate, it is important to leverage the IAQP to ensure they are addressed. If using air-cleaning versus traditional strategies, it is critical to ensure that the specific technologies used can address the contaminants. It is also important to consider that some elective building rating systems, such as LEED, may require more stringent targets than ASHRAE Standard 62.1. So be sure to check whether those standards apply to the project in question. For example, the LEED pilot credit (EQpc165) for an IAQP compliance path has an option to earn an additional LEED point by using a limit of 20 g/m3 for formaldehyde instead of the limit of 33 g/m3 in ASHRAE Standard 62.1-2022.

Ensure proof of effectiveness

For an air-cleaning technology to comply with the updated IAQP, it must have third-party cleaning efficiencies for the applicable design compounds and PM2.5. This means they must not only advertise effectiveness on addressing all contaminants of concern, but also demonstrate efficacy and ensure that no harmful byproducts are produced through independent lab testing.

Third-party testing must be performed according to defined test methods (e.g., ASHRAE Standard 145.2: Laboratory Test Method for Assessing the Performance of Gas-Phase Air-Cleaning System or ASHRAE Standard 52.2: Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size) and other “national consensus standards” approved by the authority having jurisdiction. “Custom efficiency tests” that comply with ASHRAE defined requirements and are approved by the authority having jurisdiction are an option as well. Efficiency testing must be performed for all 14 DCs and PM2.5.

For devices that use adsorbent media, it is important to design around the removal efficiency of the filter at the end of life (i.e., the point when the sorbent filter is considered depleted and must be replaced), rather than when new.

Review maintenance considerations

The maintenance requirements of an air-cleaning device can be a critical factor in the overall outcome. For example, if a device requires maintenance more frequently than the facility’s established maintenance schedules, then it runs the risk of overlooking required maintenance. For some air-cleaning technologies, one to two years of operation before substantial maintenance, excluding simple particulate filter swaps that most facilities plan for, may be feasible and in line with typical annual maintenance schedules. But other air-cleaning technologies may begin to lose effectiveness more quickly, especially when dealing with compounds like formaldehyde, which is often the DC that drives the highest ventilation requirement.

Figure 2: A sorbent filtration rendering demonstrating airflow. Courtesy Daikin Applied

Figure 2: A sorbent filtration rendering demonstrating airflow. Courtesy Daikin Applied

Validate IAQP designs

ASHRAE Standard 62.1 requires IAQP designs to be validated for efficacy as part of the commissioning process. The requirement ensures that designs on paper translate into real-world performance, delivering clean air and comfort to occupants. Both an objective evaluation, which measures if design compounds are within allowable limits and a subjective evaluation “to demonstrate the occupants’ level of acceptability of 80% or more within each zone served by the system” are required. However, “substantially similar zones” don’t each need their own survey. Refer to Section 7.3.2 Informative Note for further details.

These validation requirements make it even more important for the design professional to have confidence in the air-cleaning solution. Choosing devices that are tested to an accepted industry standard, effective against all listed DCs and have good longevity all become increasingly important to give the designer, owner and occupants confidence in the design’s performance. This also minimizes the risk of unplanned redesign or modification during commissioning and throughout the life of the HVAC system.

IAQP moving forward

Addressing all the details to successfully apply the IAQP is beyond the scope of any single article, but these five steps are critical when evaluating different air-cleaning technologies. It is also important to note that ASHRAE Standard 62.1, along with local and national codes, are living documents that change over time. Design professionals should always review all the current, applicable codes and standards.

As organizations push to shrink their carbon footprint and improve air quality — all while reducing operating costs — ASHRAE Standard 62.1 and the IAQP are more important than ever. Leveraging air cleaning can allow designers to meet both decarbonization and energy savings goals while delivering clean air to occupants. So, it’s beneficial for design professionals to become familiar with the requirements of 62.1, as well as the particulars of air-cleaning device testing, effectiveness and maintenance. This will provide a critical set of tools to improve the understanding and evaluation of air cleaning for buildings.


Author Bio: Rob Landes is the director of HVAC system applications at Daikin Applied. He has been with the company for 15 years, working in both product management and engineering roles.