Air Quality Matters

This week, we dive into a study published in Building and Environment titled The Impact of Energy Retrofit on Indoor Air Quality in Classrooms and Offices, to explore a question that fundamentally challenges how we think about building performance and climate action: What if the single biggest barrier to decarbonising our building stock isn't our lack of technology or ambition—but our complete failure to recognise that when we tighten buildings to save energy, we risk sealing in pollutants, moisture and carbon dioxide, turning our classrooms and offices into actively harmful environments unless we treat mechanical ventilation as an absolute physical necessity, not an optional luxury?

Buildings in Europe are responsible for about 40 percent of our total energy consumption. If we are going to meet our climate and decarbonisation goals, we have to retrofit our existing building stock. There is no way around it. But there is a massive fear in our industry, and we have seen it happen time and time again, that when we tighten up these buildings to stop heat loss, we end up destroying indoor air quality. This Irish study is important because it did a rigorous pre and post retrofit evaluation of over 50 classrooms and offices, measuring CO2, fine particulate matter, nitrogen dioxide, temperature, humidity and a whole suite of volatile organic compounds.

Key Topics Discussed:

The One Week Snapshot Problem: The biggest methodological limitation is that the monitoring campaigns are only one week long per phase. A week is just a snapshot in time. It does not capture seasonal variations. If the pre retrofit monitoring happened during a mild windy week in autumn when the windows were open and the post retrofit monitoring happened during a freezing calm winter day with everything shut down tight, the weather and teacher behaviour would heavily skew the results. A classroom environment is highly dynamic. The number of students, the specific lessons being taught, and even the type of cleaning products being used can vary wildly from one week to the next. This is a critical limitation that must be acknowledged when interpreting the results.

The VOC Wildcard: The study noted that while ventilation improved overall, the response of volatile organic compounds was highly variable across different buildings. Why? Because energy retrofits introduce new synthetic materials into the built environment. New insulation, new sealants, new paints and sometimes new carpets and furniture. These materials off gas chemical compounds leading to short term spikes in total VOCs, even when the overall ventilation rate is technically higher. This is a critical warning to our industry. We cannot just focus on the ventilation rate. We must also practice strict source control by selecting low emitting natural materials during retrofits where we can or perhaps increase ventilation rates in the early stages of habitation of these spaces.

The Carbon Dioxide Victory: Carbon dioxide concentrations in the retrofitted classrooms actually reduced by an average of 28 percent. That is a massive improvement. And why did this happen? It happened because the retrofits did not just focus on insulation and air tightness. They actively integrated mechanical ventilation with heat recovery.

The Particulate Matter Win: PM2.5 levels decreased by 27 to 30 percent in both classrooms and offices. Before the retrofits, the buildings exceeded the WHO daily average guidelines for PM2.5 on 48 percent of the monitored days. After the retrofit, that number dropped to 26 percent. This is a huge public health victory, likely driven by the high efficiency filtration systems in the new mechanical ventilation units and tighter building envelopes keeping outdoor traffic pollution from leaking in.

The Impact of Energy Retrofit on Indoor Air Quality in Classrooms and Offices

10.1016/j.buildenv.2026.114963 (https://doi.org/10.1016/j.buildenv.2026.114963)

The Air Quality Matters Podcast in Partnership with

Mann + Hummel https://www.mann-hummel.com/en.html Particles Plus https://particlesplus.com/

Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) - S&P UK (https://www.solerpalau.com/en-uk/)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) - Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast) - Farmwood (https://farmwood.co.uk/) - iE Electronics (https://www.eielectronics.ie/) and iAir Group (https://iair-group.com/)

Zehnder https://www.zehndergroup.com/en

Charity Partner - https://www.saferairproject.org/

This week, we sit down with Dennis Naughton, former Member of Parliament and Minister for Communications, Energy and Natural Resources in Ireland, to explore a question that fundamentally challenges how we think about science, policy and political decision making: What if the biggest barrier to transforming our built environment isn't our lack of scientific knowledge or technology—but our complete failure to recognise that the people who make policy decisions operate in a completely different world from researchers, and unless we learn to speak their language, translate evidence into clear actionable asks, and understand the brutal political realities they face, even the most overwhelming evidence will never make it through the door?
Dennis brings a rare and fascinating perspective. He comes from science, having worked in food microbiology research, before spending over 28 years in Parliament. As a former Minister, he worked at the point where evidence, politics, public policy and implementation meet.
Key Topics Discussed:
The Three Audiences Problem: As a scientist, you are trained to communicate evidence to peers so they can repeat your study. As a politician, you have three completely different audiences. First, you have to convince your cabinet colleagues that this is a good idea, because if you don't have a majority, your proposal is dead. Second, you have to convince the finance ministry, because most policy changes have a financial cost. Third, you have to convince the public that this is worth doing. Researchers often present to policymakers as if they are speaking to technical experts. The evidence goes way over their heads. The facts don't change, but how you frame them must.
The Blank Page Reality: One of the hardest decisions any minister can make is a decision with a blank page in front of you, with no evidence and no base whatsoever. Even partial evidence, even evidence with caveats, is infinitely better than nothing. When politicians work off a blank page, they go back to ideology. If the research community can provide even incomplete evidence, it gives policymakers a framework to start. But here's the reality. Politicians don't make evidence-based decisions. They make evidence-informed decisions. There are economic, social, cultural and political factors that must be weighed. Evidence is critical, but it's not the only input.
The Six Question Framework: Every researcher needs to be able to answer six questions if they want policy impact. What is the problem you are trying to solve? Why is it a problem? How are you proposing to solve it? What is the policy ask? What is the difference if that policy ask is delivered? What is the barrier to implementing that policy? If you can answer those six questions and frame them in the context of the three C's, clarity, context and connection to people, you will have something powerful that resonates with both policymakers and decision makers.
Political Capital is Finite: Politics is a rough business. You only have a certain amount of political capital. If you use it up on the wrong proposals, you are not heard. Worse, if you push something through cabinet and it fails in Parliament, or if it passes Parliament but the public revolts, you have burned capital and damaged your reputation. Every proposal a minister brings forward, they are putting their name, their reputation and their career on the line. That is why timing, framing and understanding the political landscape is everything. Ministers only bring proposals to cabinet when they know they will get approval. The skill is in reading the room, building the coalitions and presenting the case in a way that lands with peers, with finance and with the public.
GUEST:
Dennis Naughten
https://www.linkedin.com/in/denis-naughten-77231112/
The Air Quality Matters Podcast in Partnership with
Mann + Hummel https://www.mann-hummel.com/en.html
Particles Plus https://particlesplus.com/
Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) - S&P UK (https://www.solerpalau.com/en-uk/)
The One Take Podcast in Partnership with
SafeTraces (https://www.safetraces.com/) - Inbiot (

This week, we dive into a landmark policy paper published in Building and Environment titled Integrating Health and Indoor Air Quality into European Building Policy: A Landmark Policy Shift, to explore a question that fundamentally challenges how we think about building performance and public health: What if the single biggest barrier to transforming our built environment isn't our lack of scientific knowledge or technology—but our complete failure to recognise that the very directive designed to decarbonise European buildings has, for decades, systematically ignored the health of the people breathing the air inside them, until now?

Key Topics Discussed:

The Directive Versus Regulation Problem: The biggest weakness of the EPBD recast is that it is a directive, not a regulation. The European Union cannot dictate exact binding indoor air quality numbers or ventilation rates. It is up to each of the 27 member states to write these requirements into their own national laws and building codes by May 2026. This is where the real danger lies. We are at risk of a heavily fragmented European market. Some progressive countries might adopt strict health-based limits, while others, concerned about short-term compliance costs for developers, might do the absolute bare minimum. A race to the bottom.

The Paper Compliance Risk: There is a major risk of paper compliance, where buildings are designed and certified to meet high indoor environmental quality standards on paper, but in reality, the ventilation systems are turned off, uncommissioned, or poorly maintained once the occupants move in. Many member states simply do not have the technical infrastructure, the trained inspectors, or the enforcement mechanisms to monitor indoor environmental quality on an ongoing basis. Without strict enforcement and penalties, these new laws risk becoming toothless tigers.

The RHEVA Model: To combat fragmentation, the authors make a strong call to action for member states to adopt a harmonised, health-based framework. They point to the REVA model, Indoor Environmental Quality Regulation, as the gold standard, ready-to-adopt framework. REVA recommends continuous monitoring of two key parameters: PM2.5 and CO2. PM2.5 is a direct measure of exposure to fine particulate matter, which has devastating long-term health consequences. CO2 serves as a real-time proxy for overall ventilation adequacy and airborne infection risk.

Countries Leading the Way: Belgium has a history of air quality legislation dating back to 1946. In 2022, they passed a comprehensive law that treats indoor air quality in public spaces as a right-to-know issue, requiring monitoring, certification and public labelling. France is also leading by requiring indoor air quality monitoring in schools and nurseries to protect sensitive populations. These examples prove that robust, enforceable indoor air quality legislation is not only possible, but already happening.

Integrating health and indoor air quality into European building policy: A landmark policy shift

Building and Environment

https://doi.org/10.1016/j.buildenv.2026.114508

The Air Quality Matters Podcast in Partnership with

Mann + Hummel https://www.mann-hummel.com/en.html Particles Plus https://particlesplus.com/

Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) - S&P UK (https://www.solerpalau.com/en-uk/)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) - Inbiot (

This week, we sit down with Plum Stone, founder and CEO of the Safer Air Project, to explore a question that fundamentally challenges how we think about indoor air quality and accessibility: What if the single biggest barrier to transforming indoor air quality isn't our lack of scientific knowledge or technology—but our complete failure to recognise that millions of people living with chronic health conditions face invisible barriers to accessing public spaces every single day, and that fixing air quality for the most vulnerable fixes it for everyone

Key Topics Discussed:

The Lived Experience of Poor Air Quality: For people living with chronic health conditions, poor air quality is not an abstract future risk. It is a daily, immediate barrier to participation in public life. For someone with a compromised immune system, an underventilated classroom or meeting room can mean a week of illness, hospitalisation, or worse. For their families, it means constant vigilance, isolation, and the burden of protecting themselves when policymakers and building operators fail to act. This is not just a health issue. It is an accessibility issue. And yet, unlike wheelchair ramps or hearing loops, air quality remains invisible, unregulated, and largely ignored.

Prevention as the Biggest Lever: Whilst the Safer Air Project started by advocating for people with existing chronic health conditions, Plum has come to see air quality as the single biggest lever we have to prevent chronic disease in the first place. Cardiovascular disease, stroke, dementia, asthma, and long term respiratory conditions are all driven by exposure to poor air quality. If we can push down on air pollution and airborne infection transmission, we give ourselves a real head start on prevention. This is not just about protecting the vulnerable. It is about reducing the growing burden of chronic disease on society and freeing up resources to invest in health, not just treat illness.

Making the Invisible Visible: The first step to solving any problem is measuring it. The Safer Air Project is running a global campaign called Making the Invisible Visible, asking organisations to monitor air quality in public spaces and display that information transparently. If you are not measuring it, you are not managing it. And if you are not making it visible, people cannot make informed decisions about their safety. The campaign is simple. Monitor your air quality. Display your air quality. Commit to transparency. This is not just about CO2 numbers. It is about giving people the information they need to assess risk in real time, whether that is a vulnerable person deciding whether to enter a space, or a facilities manager realising their ventilation system is not performing as it should.

The Role of Unions and Workplace Safety: Unions have been at the forefront of workplace safety for centuries, yet they have been almost entirely absent from the air quality conversation. That is starting to change. The Australian Council of Trade Unions has been a strong advocate, recognising that air quality is a workplace health and safety issue. Employers have a responsibility to provide safe working environments. That includes the air employees breathe. The new Model Code of Practice for the Control of Biological Hazards in the Workplace recognises biological hazards that transmit through the air. This is a huge step forward. But enforcement and implementation remain the challenge. Unions have the power to demand safe air for workers. And when you fix air quality for workers, you fix it for students, patients, and the public.

GUEST:

Plum Stone

Founder and CEO, Safer Air Project

https://www.saferairproject.org/

The Air Quality Matters Podcast in Partnership with

Mann + Hummel https://www.mann-hummel.com/en.html Particles Plus https://particlesplus.com/

Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) - S&P UK (https://www.solerpalau.com/en-uk/)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) - Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast) - Farmwood (https://farmwood.co.uk/) - iE Electronics (https://www.eielectronics.ie/) and iAir Group (https://iair-group.com/)

Zehnder https://www.zehndergroup.com/en

Charity Partner - https://www.saferairproject.org/

This week, we dive into a study published in Building and Environment titled A Scalable Framework for Impact Analysis of Faults on Indoor CO2 in Buildings, to explore a question that fundamentally challenges how we think about building maintenance and indoor air quality: What if the single biggest barrier to delivering healthy indoor environments isn't our lack of technology or standards—but our complete failure to recognise that the faults we routinely ignore in HVAC systems are actively degrading the air we breathe, and we've had no systematic way to prioritise which faults actually matter until now?

Key Topics Discussed:

The Correlation Versus Causation Problem: In a building, everything is connected. If you just look at raw data, you might see counterintuitive things. For example, when the outdoor air damper is wide open, CO2 levels might actually be higher. A simple correlation analysis might conclude that opening the damper causes CO2 to rise, which makes no physical sense. What's actually happening is demand controlled ventilation. The system opens the damper because CO2 is rising. High CO2 is causing the damper to open, not the other way around. It's a classic feedback loop. To get around this simultaneity bias, the researchers used a clever approach called double machine learning. They stripped away all the noise and confounding variables like building ID, time of day, weather and current CO2 baseline, so they could isolate the true causal impact of a specific fault on CO2 levels.

The Worst Faults for Air Quality: The absolute worst fault for indoor air quality is an AHU discharge fan failure. When the fan isn't generating the static pressure needed to move air, supply airflow drops off a cliff and return air CO2 spikes. The next worst is a poorly tuned system where the outside air damper is oscillating wildly, constantly cycling back to its closed position, severely reducing the overall volume of fresh air entering the building. Then there are valve leaks. A leaking cooling valve causes the supply air temperature to drop too low. The control system opens the heating valve and closes the outside air damper to keep warm air in. Because of a leaking cooling valve, your fresh air intake gets choked off and indoor CO2 shoots up. A leaking heating valve does the opposite. It opens the outside air damper to take advantage of free cooling, which actually dilutes indoor CO2 and improves air quality, but at a massive energy penalty.

Zone Level Faults: At the zone level, the worst fault is terminal unit airflow set point unreachable low. This is when the VAV box damper is stuck or there's a ductwork issue, and the actual airflow to the room is consistently lower than what the thermostat is asking for. You get localised underventilation and zone CO2 spikes dramatically because fresh air is simply not getting into the space.

The Prioritisation Framework: In facility management, we are constantly bombarded with fault alerts. In a large building, you might have hundreds of alerts a day, and maintenance teams are almost always stretched thin. Without a way to prioritise those faults, you end up ignoring them or focusing only on the ones that trigger immediate comfort complaints. This paper provides an evidence-based, data-driven ranking that lets facilities teams prioritise maintenance actions based on their actual impact on both energy and indoor air quality.

A scalable framework for impact analysis of faults on indoor CO2 in buildings

https://doi.org/10.1016/j.buildenv.2026.114443

The Air Quality Matters Podcast

Mann + Hummel https://www.mann-hummel.com/en.html Particles Plus https://particlesplus.com/

Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) - S&P UK (https://www.solerpalau.com/en-uk/)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) - Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast) - Farmwood (https://farmwood.co.uk/) - iE Electronics (https://www.eielectronics.ie/) and iAir Group (https://iair-group.com/)

Zehnder https://www.zehndergroup.com/en

Do check them out in the links and on the Air Quality Matters Website. (https://www.airqualitymatters.net/podcast)

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