FAQ: ASHRAE 62.1 Indoor Air Quality Procedure (IAQP) – What You Need to Know
Answered by Dr. Angela Southey · Airmid Healthgroup
The Indoor Air Quality Procedure (IAQP) is one of the most technically nuanced compliance routes in ASHRAE Standard 62.1, and it is increasingly relevant to manufacturers and developers of air cleaning technologies. Below, the Airmid Healthgroup expert team answers the most frequently asked questions about IAQP and what it means for your product’s evidence base.
What is ASHRAE 62.1 and the Indoor Air Quality Procedure?
ASHRAE Standard 62.1 is the recognised standard for ventilation system design and acceptable indoor air quality in commercial and institutional buildings. It specifies minimum ventilation rates and other measures to protect occupant health.
Standard 62.1 offers three compliance methods:
- The Ventilation Rate Procedure (VRP): a prescriptive approach based on outdoor air supply rates
- The Indoor Air Quality Procedure (IAQP): a performance-based alternative
- The Natural Ventilation Procedure
The Indoor Air Quality Procedure allows a design team to demonstrate that acceptable IAQ can be achieved through a combination of outdoor air supply, filtration, air cleaning, source control, and contaminant modelling, rather than simply following prescriptive outdoor air rates.
What is the core principle of the IAQP?
The fundamental idea behind IAQP is that ventilation is not the only control measure available to achieve acceptable indoor air quality.
Under IAQP, the design team:
- Identifies relevant contaminants, referred to as “design compounds”
- Assesses both indoor and outdoor sources of those contaminants
- Establishes acceptable concentration thresholds
- Demonstrates, through mass-balance calculations and contaminant modelling, that the proposed system will keep concentrations below those thresholds
This may include PM2.5, VOCs, particulates from indoor sources, or other design-specific compounds.
Can IAQP be used to reduce outdoor air rates?
In some circumstances, yes. If the engineering analysis demonstrates that acceptable IAQ can be maintained, IAQP can justify lower outdoor air rates than the prescriptive Ventilation Rate Procedure. This can reduce heating and cooling loads and contribute to energy efficiency in the building design.
However, IAQP is not a blanket permission to reduce ventilation. It requires project-specific engineering, thorough documentation, and, in most cases, acceptance by the authority having jurisdiction or the relevant design team. The 2025 edition of Standard 62.1 also includes updated requirements relating to filtration, controls, air cleaning systems, and operations and maintenance.
Why does IAQP matter for air cleaner manufacturers?
IAQP is a compliance route where the performance of air cleaning products becomes directly relevant to building-level IAQ calculations.
When an air cleaner is proposed as part of an IAQP contaminant-control strategy, the design engineer needs credible, defensible evidence to support that contribution. This includes:
- Appropriate performance test data for the specific contaminants of concern
- Realistic maintenance and performance assumptions
- Data from accredited, independent testing laboratories
- A clear understanding of how the product performs across relevant particle sizes or contaminant types
Without this evidence, a product’s inclusion in an IAQP calculation cannot be properly substantiated.
How is ASHRAE 62.1 IAQP different from ASHRAE Standard 241?
This is one of the most common points of confusion. The two standards address different questions.
| Aspect | ASHRAE 62.1 IAQP | ASHRAE 241 |
|---|---|---|
| Main purpose | Achieve acceptable general IAQ using a performance-based approach | Reduce risk of disease transmission from infectious aerosols |
| Scope | General IAQ: ventilation, particulates, contaminants, odours, source control, air cleaning | Infection risk control: respiratory aerosols that may carry pathogens |
| Normal operation? | Yes, part of routine building ventilation and IAQ design | Focuses particularly on Infection Risk Management Mode, when enhanced protection is needed |
| Key metric | Contaminant concentrations remain below acceptable thresholds | Equivalent clean airflow required to mitigate infection transmission risk |
| Relationship to ventilation | Can justify a different outdoor air approach than the prescriptive VRP | Requires sufficient equivalent clean air from ventilation, filtration, and/or air cleaning |
| Relationship between the two | IAQP is within 62.1 | Compliance with applicable 62.1/62.2/170 is a prerequisite for 241 |
In plain terms: IAQP asks whether a building can provide acceptable indoor air quality for normal occupancy, potentially using air cleaning and source control in place of additional outdoor air. ASHRAE 241 asks whether, when infectious aerosol risk is elevated, the building can deliver enough equivalent clean air to reduce airborne disease transmission.
For air cleaner developers, the distinction is important. Under IAQP, evidence supports claims around reducing selected contaminants as part of a general IAQ design. Under 241, the evidence must support the product’s contribution to equivalent clean airflow for infectious aerosol control, with specific requirements around mechanical filter performance, safety testing, and emissions including formaldehyde, ozone, and particulates.
What test data is typically needed to support an IAQP claim?
The data requirements depend on the contaminants designated as design compounds for the specific project. Relevant testing may include:
- ASHRAE 52.2 particle filtration efficiency (MERV rating) for PM-focused designs
- CADR testing to ANSI/AHAM AC-1 or AHAM AC-5 for portable air cleaners
- Bioaerosol capture or reduction data where microbial contaminants are a concern
- VOC removal data where chemical contaminants are designated as design compounds
- Real-world or chamber-based performance validation under simulated use conditions
All ASHRAE 62.1 IAQP testing data should come from an accredited, independent laboratory and be supported by clear documentation of test conditions, performance assumptions, and maintenance factors.
Can Airmid Healthgroup support ASHRAE 62.1 IAQP testing?
Yes. Airmid Healthgroup provides a full range of testing services relevant to air cleaner performance under IAQP design frameworks, including:
- ASHRAE 52.2-2017 and 2022 filter efficiency testing (MERV ratings across E1, E2, E3 size bins)
- ANSI/AHAM AC-1 and AHAM AC-5 CADR testing for portable air cleaners
- ASHRAE 241 testing for infectious aerosol reduction
- Bioaerosol performance testing using bacteria, viruses, fungi, and allergens
- VOC emissions analysis to ASTM D6670
- Modified ASHRAE 52.2 for in-duct and in-sequence air purification systems
Our ISO/IEC 17025-accredited laboratory and GLP-level quality systems mean the data we generate is suitable for use in regulatory submissions, certification programmes, and engineering calculations, including IAQP design documentation.
How long does ASHRAE 62.1 IAQP testing take?
Timelines vary depending on the test standard and scope. Single-metric studies such as ASHRAE 52.2 MERV testing can typically be completed within two to three weeks. More comprehensive programmes incorporating bioaerosol, CADR, and VOC testing may take four to eight weeks. Our technical team will advise on the most efficient testing sequence for your specific evidence requirements.
How do I get started on ASHRAE 62.1 IAQP testing?
Contact our team to discuss ASHRAE 62.1 IAQP testing for your project. We will help you:
- Identify the relevant test standards for your product and target application
- Design a testing programme that supports your IAQP evidence package
- Understand how your test data maps to contaminant modelling inputs
- Access accredited, independent validation that stands up to engineering and regulatory scrutiny
Related Tests and Services
- ASHRAE 52.2 Testing Services for HVAC Filters and Air Cleaners
- AHAM AC-1 Testing for Portable Air Cleaners
- AHAM AC-5 Testing for Portable Air Cleaners
- ASHRAE 241 Testing Services
- Claims Verification Services
Related External Links
Keywords
ASHRAE 62.1; IAQP; Indoor Air Quality Procedure; air cleaner testing; contaminant modelling; MERV rating; CADR testing; ISO 17025; IAQ compliance; ventilation rate procedure; ASHRAE 241; indoor air quality
