A Decade Later:
Why AIVC's Technical Note 68 is More Relevant Than Ever
Ten years can be a lifetime in the world of technology and research. Standards evolve, new evidence emerges, and our understanding of complex issues deepens. So, what happens when we look back at a foundational document from nearly a decade ago? Do we find outdated ideas, or do we discover insights that are only now coming into their own?
This was the central question in a recent special episode of the Air Quality Matters podcast, produced in partnership with the Air Infiltration and Ventilation Centre (AIVC)). We convened a panel of leading experts Pawel Wargocki of DTU, Valerie Leprince of Cerema, and Benjamin Jones of the University of Nottingham—to revisit a landmark 2016 publication: AIVC’s Technical Note 68: Residential Ventilation and Health.
For more insight and material, check out https://tn68-aivc.com/
The conversation that unfolded was a fascinating exploration of how far we’ve come, the persistent challenges we still face, and why the core ideas of this report are shaping the future of building regulations today.
Key Discussion: Shifting from Simple Limits to a Harm-Based Approach
Perhaps the most significant contribution of TN68 was its advocacy for a paradigm shift in how we think about ventilation. For decades, standards have been built around prescriptive flow rates—numbers designed to control odours and provide a baseline of "acceptable" air quality. TN68, however, championed a more profound, health-centric perspective: a harm-based approach.
As the guests discussed, this involves moving beyond simply setting exposure limits for pollutants. Instead, it quantifies the actual health impact using metrics like Disability-Adjusted Life Years (DALYs). This allows us to compare the harm caused by poor indoor air quality to other public health risks. As Ben Jones noted, the analysis suggests the harm from indoor contaminants is significant, falling somewhere "between tobacco smoking and transport traffic accidents." This shift from a simple limit-value paradigm to a harm-based one is now directly influencing the development of crucial standards, including ASHRAE 62.2 in North America and Europe's Energy Performance of Buildings Directive (EPBD).
Identifying the Real Culprits in Our Homes
If we’re going to focus on harm, we need to know which pollutants are causing the most damage. The panel dove into the "contaminants of concern," both those identified in the original report and those confirmed by more recent research.
The consensus was clear: Particulate Matter (PM2.5) remains the single most critical pollutant to address in residential settings, proving to be an order of magnitude more harmful than the next contaminant. Beyond PM2.5, the conversation highlighted the continued importance of tackling formaldehyde, radon, nitrogen dioxide (NO2), and ozone. The discussion revealed a complex picture where source control has successfully reduced some pollutants like benzene, while energy efficiency measures—specifically increased airtightness—have inadvertently led to rising indoor radon levels in some regions. Understanding this delicate balance is more critical than ever, and the full conversation provides essential context on where our focus should lie.
The Persistent Challenge of Real-World Ventilation Performance
While the science has advanced, a recurring theme was the frustrating gap between design intent and on-the-ground reality. Valerie provided a stark reminder that ventilation systems frequently fail to perform as intended due to improper design, installation, and maintenance. This raises a critical question that spurred a lively debate among the panel: as the industry moves toward more complex, performance-based standards, are we putting the cart before the horse?
Should we be mastering the fundamentals of delivering basic, prescriptive ventilation rates before embracing sophisticated, sensor-driven systems? Or do these new "smart" systems, with their potential for self-diagnostics and user feedback, offer the very solution to the problems that have plagued traditional approaches? Hearing the experts weigh the pros and cons of this transition offers a nuanced view of the challenges and opportunities facing the entire built environment sector.
Looking Ahead: Air Cleaning, Smart Sensors, and the Future of Healthy Homes
The conversation also explored the evolving landscape of indoor air quality management. We touched upon the role of air cleaning as a supplementary strategy, the data deluge from low-cost sensors, and the critical need for standards to keep pace with technology.
Finally, each guest shared their hope for the next ten years, envisioning a future where ventilation is no longer an afterthought but a valued and visible component of a healthy home. From making the "invisible visible" for homeowners to establishing ventilation as a respected trade, their aspirations map out a clear direction for the industry.
The full discussion is a rich tapestry of scientific insight, practical experience, and forward-thinking vision.
Also on the Podcast: A Critical Look at Mandating IAQ Standards
In our companion One Take episode, I explore a recent perspective piece from the journal Indoor Environments that wades into one of the most pressing debates in our field: Should we mandate indoor air quality standards for all public buildings?
This paper is a direct response to a high-profile article in Science, which proposed a simplified, four-parameter mandate (PM2.5, CO2, CO, and a minimum ventilation rate) as a global solution post-COVID-19. While the goal is laudable, the authors of this critique urge caution, arguing that such a one-size-fits-all approach could be a step backwards.
Their central argument is that we must learn from the vast body of regulations that already exist across more than 40 countries. They highlight several critical issues with the simplified mandate:
It ignores other key pollutants like formaldehyde and radon, which are already regulated in many places.
The proposed ventilation rate is nearly double what many standards require, carrying enormous energy and economic implications, particularly for developing nations.
The suggested limits may be unrealistic in urban areas with poor outdoor air quality, placing an unfair burden on building owners.
Instead of a new global mandate, the paper advocates for a more pragmatic "adopt and adapt" model. This approach encourages countries to use international guidelines (like those from the WHO) as a starting point and tailor them to their unique climate, building stock, and economic realities. It’s a call for a more thoughtful, equitable, and sustainable path toward healthier public spaces.
Towards equitable and sustainable indoor air quality guidelines − A perspective on mandating indoor air quality for public buildings
The One Take Podcast in Partnership with
SafeTraces and Inbiot
Do check them out in the links and on the Air Quality Matters Website.
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