Learn how engineers can improve IAQ performance by moving beyond prescriptive ventilation rates and defining clearer control and commissioning expectations.
IAQ insights
- In this Q&A, Jason Jones of Fellowes says one of the biggest HVAC coordination challenges is aligning ventilation codes and energy codes, as prescriptive outdoor air requirements can work against decarbonization goals and lead to oversized systems that increase energy use, carbon emissions and inconsistent IAQ outcomes.
- Clearer control sequences, measurable performance criteria and broader use of ASHRAE 62.1โs IAQP can better support long-term IAQ by relying on verified contaminant control, filtration and air cleaning rather than fixed ventilation rates alone.
In this conversation with Jason Jones, Director of Air Quality Management, Fellowes, Itasca, Illinois, a wide range of heating, ventilation and air conditioning (HVAC) topics are covered, with a focus on air quality.
Jason Jones Director of Air Quality Management at Fellowes Brands. In his role, Jones is responsible for the market success of Fellowes’ air quality management products, overseeing the sales teams and leading a team of regional sales directors across the U.S.
Question: Which code and standards developments are creating the most coordination challenges within the mechanical engineering discipline right now?
One of the largest coordination challenges is that key standards are advancing on parallel tracks without full system-level alignment. ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality continues to be applied largely through prescriptive outdoor airflow rates, while standards like ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings and the International Energy Conservation Code (IECC) push decarbonization, electrification and reduced energy intensity.
This often results in systems sized for peak ventilation that conflict with energy goals. The outcome can be over-ventilated, over-sized systems that increase both operational energy use and embodied carbon impacts, forcing engineers to reconcile competing priorities within a single design framework.
Question: What is the most overlooked specification issue that affects commissioning and post-occupancy performance across multiple building systems?
The most overlooked issue is the lack of clearly defined ventilation and indoor air quality (IAQ) control intent. Specifications often focus on airflow rates and equipment performance but do not fully define the sequence of operations or how systems should respond to changing occupancy, outdoor conditions or energy operating modes.
ASHRAE guidance emphasizes that acceptable IAQ depends on control, verification and ongoing performance. Without measurable criteria, such as contaminant thresholds, control tolerances and response strategies, commissioning is often limited to startup validation. This often leads to systems that meet design intent on paper but fail to maintain consistent performance over time.
The greatest gap exists between design assumptions documented in the basis of design and how systems are ultimately operated. Ventilation and IAQ strategies are often diluted through submittals and value engineering unless explicitly reinforced during commissioning and turnover.
ASHRAE has long identified this disconnect as a common cause of underperforming buildings. Without clear alignment on sequences of operation, control strategies and performance expectations, the original design intent can be lost. The result is systems that technically meet requirements but operate differently in practice, particularly as owners adjust for energy use, defer maintenance or respond to occupant needs.
Question: How should consulting engineers think about the relationship between decarbonization goals and ventilation strategy when applying the compliance pathways in ASHRAE Standard 62.1?
Because the ventilation rate procedure (VRP) has historically served as the default basis of design, the industry has largely accepted prescribed outdoor air quantities and relied on equipment efficiency, envelope performance and heat recovery to mitigate the carbon impact of conditioning that air.
ASHRAE Standard 62.1 recognizes the indoor air quality procedure (IAQP) as an alternative compliance pathway that allows outdoor air rates to be determined based on demonstrated contaminant control, rather than fixed assumptions. By permitting reduced ventilation rates when acceptable IAQ can be maintained through air cleaning, filtration, source control and mass-balance analysis, IAQP enables engineers to address one of the largest inherent inefficiencies in HVAC systems: conditioning more outdoor air than is necessary to meet the buildingโs actual IAQ needs.
Question: In practice, where do you see the ventilation rate procedure (VRP) working against decarbonization goals?
In practice, the VRP can work against decarbonization when it drives outdoor air volumes beyond what is required for effective contaminant control. Because those volumes must be heated, cooled and dehumidified, ventilation often represents one of the largest contributors to HVAC energy use, especially in more extreme climates.
Because VRP is based on peak occupancy and floor area assumptions, systems are sized for conditions that occur infrequently but must still be supported. This increases equipment sizing, peak demand and overall system energy use. While controls can help reduce airflow in operation, baseline ventilation requirements still drive design decisions, making alignment with carbon and energy reduction goals difficult.
Question: How can VRP-based designs unintentionally increase carbon emissions?
VRP-based designs can increase carbon emissions by driving both larger system sizing and higher ongoing energy use. Because ventilation rates are tied to peak occupancy and floor area, systems are designed for conditions that occur infrequently, resulting in larger air handlers, coils and distribution systems that increase embodied carbon.
Operationally, continuously conditioning higher volumes of outdoor air increases heating, cooling and humidity loads, even when spaces are not fully occupied. In areas with poor outdoor air quality, additional filtration or treatment may be required, further increasing energy use. This also drives increased demand on central plant systems such as chillers, boilers or heat pumps, along with higher peak demand in electrified systems, leading to increased energy consumption and associated carbon emissions over time.
Question: What are common misconceptions about the tradeoff between prescribed outdoor airflow rates and actual indoor air quality outcomes?
A common misconception is that increasing outdoor airflow will always improve IAQ. ASHRAE has made it clear that ventilation alone does not ensure acceptable IAQ.
Outdoor air is not necessarily clean air, particularly in areas with variable ambient conditions. If contaminants are not identified and controlled, higher outdoor air volumes may have limited impact and can introduce additional pollutants. Effective IAQ depends on a combination of source control, filtration and air cleaning.
Prescribed airflow rates provide a baseline for design, but they do not guarantee performance outcomes without a broader strategy to manage indoor contaminant levels.
Question: How does the IAQP better align with a decarbonization mindset?
IAQP better aligns with a decarbonization mindset by focusing on measurable IAQ outcomes rather than fixed ventilation rates. ASHRAE 62.1 allows IAQP to meet defined contaminant limits through a combination of ventilation, filtration, air cleaning and source control.
The IAQP approach decouples IAQ performance from outdoor airflow assumptions. By targeting specific contaminants and verifying performance, it can reduce reliance on conditioning large volumes of outdoor air, thereby reducing energy use and associated carbon emissions while maintaining or improving IAQ. IAQP also introduces a level of accountability, as performance must be demonstrated and maintained over time, aligning IAQ strategies with both energy and carbon objectives.
Question: Why does IAQP remain underused despite being permitted by ASHRAE?
IAQP remains underused largely due to familiarity, perceived risk and documentation requirements. Many engineers default to the VRP because it is prescriptive, widely accepted and straightforward to apply.
IAQP introduces additional steps, including contaminant identification, performance modeling and verification, which can create uncertainty around implementation, review and long-term operation. There is also concern about acceptance by authorities having jurisdiction and how performance will be maintained over time.
However, ASHRAE has clarified IAQP as a valid compliance pathway and as tools and monitoring capabilities improve, these barriers are becoming more manageable.
Question: Looking ahead, what factors could increase IAQP adoption?
Several factors are likely to increase IAQP adoption. Growing pressure around decarbonization, electrification and peak energy demand, particularly in the context of rising energy costs, is prompting engineers to re-evaluate ventilation strategies that drive significant system loads. At the same time, updates within ASHRAE standards, including expanded filtration expectations, are reinforcing the role of nonventilation strategies in achieving IAQ.
Owners are also placing greater emphasis on measurable performance and operational outcomes. Simultaneously, emerging policy discussions related to IAQ and building resilience are contributing to increased interest in performance-based approaches among building owners and design professionals.
As monitoring, controls and verification tools continue to improve, engineers will have greater confidence in demonstrating IAQ performance, making IAQP a more practical and accessible option.
