Measure Up or Get Out: Why Rigorous Ventilation Testing is Non-Negotiable for UK Buildings
Introduction: The Airtightness Paradox
Welcome back to the conversation around building performance and air quality. On a recent episode of the Air Quality Matters podcast, I sat down with Barry Cope , Group Managing Director of ATTMA UK & SITMA (part of the @BCTA group ) and the author of a vital new ventilation commissioning and testing course in the UK. Our discussion centred on a critical, yet often neglected, aspect of modern construction: ventilation.
We've become adept at making our buildings more airtight for energy efficiency – a laudable goal. But as Barry highlighted, this airtightness creates a paradox. Homes are becoming less leaky, reducing natural air exchange, yet ventilation practices haven't kept pace. The result? Airtightness often gets blamed for issues like mould and poor indoor air quality (IAQ), when the real culprit is inadequate or improperly functioning ventilation. As the old adage goes, "you can't manage what you don't measure," and in the ventilation sector, we're often failing to measure, let alone manage.
Why Airtightness Testers Stepped into the Ventilation Void
Barry explained that ATMA (the Air Tightness Testing and Measurement Association) initially had no intention of entering the ventilation space. However, they were repeatedly forced to defend airtight construction against criticism stemming from poor ventilation outcomes. He described a fractured industry where responsibility for ventilation installation is scattered – plumbers, electricians, even general labourers – often with no dedicated testing or commissioning at the end.
A stark anecdote from Barry illustrated the problem: witnessing zero airflow from newly installed fans in a building, only moments later to see the installer sign off a certificate claiming specific flow rates. This lack of rigor, coupled with the increasing airtightness of new builds tracked by ATMA's data, prompted them to act. Leveraging their expertise in measurement and calibration, they decided to develop a robust ventilation airflow commissioning course and certification scheme, aiming to upskill existing air tightness testers. The goal, inspired partly by the Future Homes Hub's simple breakdown (Design, Install, Commission, Maintain), was for ATMA members to become the crucial third step: Commissioning.
Learning from the Air Tightness Journey: A Blueprint for Ventilation?
The journey of air tightness testing provides valuable lessons. When regulations mandated air tightness testing around 2006, Barry recalled, there was initial shock and pushback. However, the industry adapted. Crucially, air tightness testing had a clear consequence: the certificate was required to produce the Energy Performance Certificate (EPC). This simple mechanism made testing non-negotiable. SAP assessors effectively became the "air tightness police."
Barry argues compellingly that ventilation needs a similar mechanism. The high failure rate of ventilation systems (studies suggest 60-80% non-compliance with minimum standards, even) has led some testers to abandon ventilation testing altogether to avoid difficult client conversations – a truly alarming situation. The solution? Link mandatory, competent ventilation commissioning certificates to the new Home Energy Model (HEM) needed for EPCs. This creates accountability and drives compliance, just as it did for air tightness.
Getting Measurement Right: Competence, Tools, and Data
Our conversation delved into how we measure. Barry strongly advocated for the "unconditional" testing method using powered flow hoods, which provide accurate airflow readings without being affected by back pressure – unlike "conditional" methods using vane anemometers, which require complex corrections often misunderstood or ignored in the field. While cheaper methods might seem appealing, accuracy is paramount. Why guess when precise tools exist? Misdiagnosis can lead to unnecessary replacement of perfectly functional fans or, conversely, signing off underperforming systems.
The new ATMA course emphasizes this rigor, taking two days to cover what was previously rushed in an hour. Competency is key, especially with the Building Safety Regulator now demanding it. Beyond individual competence, Barry stressed the power of data. ATMA’s lodgement system, already holding 1.6 million air tightness records with billions of data points, is being expanded for ventilation. This will allow tracking the real-world, as-installed performance of specific fan models, identifying potential quality control issues, comparing manufacturers (perhaps even creating performance league tables), and correlating ventilation performance with airtightness, acoustics, and energy use. Data, Barry asserts, is the "new gold," enabling evidence-based improvements and true performance feedback loops that construction has traditionally lacked.
The Future: Smart Systems, Regulation, and Responsibility
Looking ahead, we discussed the inevitable rise of demand-controlled ventilation driven by IAQ sensors (CO2, VOCs, PM2.5). Systems will automatically adjust airflow based on real-time conditions, potentially changing how we commission – focusing on proving minimum/maximum capacity rather than fixed rates. The industry could shift from selling ventilation units to selling guaranteed "air quality."
However, reaching this future requires overcoming present hurdles. The most significant barrier? Lack of clear, unambiguous regulation. Barry was unequivocal: the industry, particularly volume housebuilders, responds primarily to regulation. Until ventilation commissioning by competent persons is mandated and linked to a consequence (like the EPC), widespread change won't happen. We also touched upon the risks in retrofit (PAS 2035), where dangerous loopholes allowing bypasses of fundamental ventilation requirements are emerging, potentially creating warm, airtight, but unhealthy homes – a disaster waiting to happen.
Conclusion: Time to Demand Better
The message from our discussion was stark. The link between airtightness and effective ventilation is undeniable. The technology and knowledge for proper ventilation testing exist. The data shows widespread underperformance. The consequences for occupant health, though often slow-acting, are severe and increasingly understood.
The path forward requires:
Clear Regulation: Mandate ventilation commissioning by competent individuals, linked to property completion (e.g., EPC/HEM).
Accurate Measurement: Prioritize unconditional testing methods for reliable data.
Accountability: Leverage data to drive transparency and real-world performance improvements.
Industry Responsibility: Manufacturers, designers, and installers must prioritise installed performance over shortcuts. As Simon passionately stated, if you don't feel the weight of responsibility for occupant health, you're in the wrong industry.
The time for ambiguity and corner-cutting is over. It’s time for the UK ventilation sector to measure up, embrace accountability, and deliver the healthy indoor environments occupants deserve.
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