How to Use the IAQP: A Streamlined Approach Based on the New ASHRAE 62.1 User’s Manual

Published 07/28/2021
By Doug Engel
ASHRAE 62.1-2019 User's Manual

This is the second in our series of blog posts on ASHRAE’s performance-based ventilation design standard, the Indoor Air Quality Procedure (IAQP). In our first blog post in this series, we summarized what the new 62.1-2019 User’s Manual says about when to apply the IAQP. In this post, we summarize how to apply the IAQP, citing guidance from the updated User’s Manual. 

The new version of the User’s Manual, which was published in June 2021, is an invaluable resource for engineers applying Standard 62.1. In particular, it provides helpful guidance on when to use the IAQP. It also includes tables and references to simplify the application of the IAQP to deliver good indoor air quality more cost effectively than with the Ventilation Rate Procedure.  

You can learn more about the most important updates to the User’s Manual by watching our recent webinar with Dr. Marwa Zaatari, a voting member of the ASHRAE committee that oversees Standard 62.1, and Anurag Goel, enVerid’s Director of Sales & Application Engineering.

How to Apply the Indoor Air Quality Procedure (IAQP) 

Applying the IAQP can be summarized in the following 4 steps:  

4 Steps to apply the IAQP

Steps 1-3 involve collecting inputs for the mass balance calculation performed in Step 4, which determines the minimum ventilation rate for each applicable zone using the IAQP.  

enVerid has developed tools to make completing these 4 steps as simple as calculating ventilation rates using the Ventilation Rate Procedure. enVerid’s tools also generate compliance reports for engineers and code officials with all the documentation required to comply with the IAQP.   

Step 1: Contaminants of Concern & Concentration Limits

The first step in using the IAQP is identifying the appropriate Contaminants of Concern (COCs) for the project and Concentration Limits from cognizant authorities such as the US EPA, California EPA, and the Committee for Health-Related Evaluation of Building Products (AgBB).  

The updated User’s Manual simplifies this step by listing the COCs and Concentration Limits for typical office spaces. Using peer-reviewed literature, enVerid has replicated this list for other common applications of air scrubbing technology. Thus, the only requirement for Step 1 is to confirm there are no unusual site-specific sources of pollution to add to the standard list. If there are unusual sources, then according to Standard 62.1 the IAQP should always be used rather than the VRP. 

 Here is the list of COCs and Concentration Limits provided in the User’s Manual (pg. 106): 

Contaminants of Concern and Their Concentration Limits - ASHRAE 62.1-2019 User's Manual

When an enhanced IAQ design is desired (such as for a LEED® or WELL project), more stringent Concentration Limits may be specified to calculate the minimum ventilation rate using the IAQP. These more stringent requirements can be used in enVerid’s IAQP Calculator.  

Step 2: Indoor Emission Rate & Outdoor Concentrations

The second step is to determine indoor emission rates and outdoor concentrations for the relevant COCs. 

The updated User’s Manual also simplifies this step by providing a list of emission rates and outdoor concentrations for a typical office space. enVerid has replicated this list for other common applications of air scrubbing technology using peer-reviewed papers provided in Appendix N of Standard 62.1-2019. Thus, the only requirement for Step 2 is to confirm or update outdoor concentrations based on the location of the project. This can be done using AirNow if site-specific information is not available from the local air quality board, fire department, or emergency management agency.  

Here is the list of emission rates and outdoor concentrations provided in the User’s Manual (pg. 106): 

Generation Rates and Outdoor Air Concentrations ASHRAE 62.1-2019 User's Manual
It should be noted that while the list of COCs may include 10-15 contaminants, formaldehyde usually drives the ventilation rate for an IAQP design. While NOT required by the IAQP, CO
2 limits for enhanced IAQ designs (including LEED® projects) may also drive the ventilation rate. Thus, controlling for formaldehyde and/or CO2 is key to an efficient IAQP design. enVerid’s HLR air scrubbers are very efficient at removing both formaldehyde and CO2 (see the next table), which make HLR modules a preferred air cleaning technology for use with the IAQP.  

Step 3: Air Cleaning Efficiency

Step three is assessing the efficiency of the air cleaning solution at capturing the relevant COCs (especially formaldehyde and CO2). This information can be provided by the manufacturer and should be based on third-party verified efficiencies using nationally recognized standard test methods such as ASHRAE 145.2 for gas-phase air-cleaning systems and ASHRAE 52.2 for particle removal systems. ASHRAE 145.2 testing is required for any device used to earn points under LEED® pilot credit EQpc124. 

For example, this table lists the third-party validated air cleaning efficiencies for enVerid’s HLR air scrubbers, tested using ASHRAE test methods.  

enVerid HLR 3rd Party Test Results 

A Note on Ozone-Generating Air Cleaners: ASHRAE Standard 62.1-2019 requires that ozone-generating air cleaners be listed and labeled in accordance with UL 2998, a zero ozone emissions environmental claim validation procedure. Qualifying zero ozone emission products must emit less than the maximum ozone concentration limit of 0.005 ppm (5 ppb).   

Ozone has been shown to be harmful to health, so ensuring that your proposed air scrubbing method is not emitting ozone or other harmful byproducts is key to protecting building occupants. For example, as a capture technology, enVerid’s HLR air scrubbers do not produce any byproducts. In fact, as the table above shows, enVerid’s HLR air scrubbers are very effective at removing ozone from indoor air.  

Step 4 – Mass Balance Analysis

The final step in the IAQP is to apply the data collected in the previous steps to the mass balance analysis for the zones served by the HVAC system. The mass balance analysis is used to calculate the minimum outdoor air volume such that the Concentration Limits for all COCs are not exceeded.  

Given the number of calculations required for each COC and each zone, enVerid recommends that engineers use an IAQP Calculator to simplify this step. Using enVerid’s IAQP Calculator, engineers simply enter basic design parameters for the whole system and any zones. The IAQP Calculator applies the appropriate emission rates for the appropriate COCs and Concentration Limits and calculates the minimum outside air according to the IAQP. This easy-to-use calculator shares most of the same inputs as Ventilation Rate Procedure calculators and shows the outside air reduction enabled by using the IAQP compared to the Ventilation Rate Procedure. 

Subjective evaluation

The final requirement of the IAQP is to conduct a subjective evaluation to ensure occupant satisfaction with the indoor air quality. As explained in the new User’s Manual, 62.1-2019 made it easier to comply by providing flexibility on when to test and how many occupants or independent observers to survey. 62.1-2019 also allows the use of previous surveys from “substantially similar zones” to comply with this requirement. According to the User’s Manual, “A minimum design level of 80% acceptability is consistent with the standard’s definition of acceptable IAQ.”  

Importantly, the User’s Manual clarifies that, “For the purposes of the IAQP, acceptable perceived IAQ excludes dissatisfaction related to thermal comfort, noise and vibration, lighting, and psychological stressors” as these factors are “beyond the scope of the standard.” (pg 103-104) 


As we come out of COVID-19, building owners, operators, and tenants are increasingly focused on sustainable approaches to achieving good indoor air quality. In this context, the IAQP provides a compelling pathway to use air cleaning technology in ventilation system designs to achieve good indoor air quality cost-effectively and energy efficiently. Thanks to the updated User’s Manual and tools to simplify calculations such as enVerid’s, applying the IAQP is now easier than it has ever been.  

Watch the webinar for an overview of project design with the IAQP:

Watch the enVerid Webinar The IAQP Easy Button 

Doug Engel

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