Indoor Air Quality: The Hidden Retrofit Challenge
9th October 2025
Jenny Danson
Why Indoor Air Deserves Equal Priority
Indoor air quality (IAQ) is no longer a fringe concern, it is a fundamental component of healthy housing. “We are not capturing the value of indoor air for health and well-being in the built environment,” says Dr Douglas Booker, Lecturer in Indoor Air at the University of Leeds, Co-founder of NAQTS, and Regional Clean Air Champion for the UK’s £42.5m Strategic Priorities Fund Clean Air Programme.
He argues that while energy efficiency programmes are critical for net zero, they can have unintended consequences. “If this is not done with sufficient purpose for ventilation, it can make various aspects of indoor environmental quality worse,” he warns.
The upcoming implementation of Awaab’s Law has made poor air quality and its link to damp and mould, impossible for landlords to ignore.
Lessons from Schools
NAQTS recently monitored IAQ across 20 schools in England and Wales, measuring pollutants such as PM2.5, nitrogen dioxide and volatile organic compounds (VOCs).
The results were striking: ventilation rates during occupied periods were often “wholly insufficient”, with CO₂ levels regularly exceeding 3,000 ppm well above BB101 guidelines.
What Social Housing Can Learn
“Cooker hoods are a huge opportunity,” Booker explains. “Getting them in place, making sure they’re extracting to the outside, not just recirculating, will dramatically reduce PM2.5 levels.” Bathrooms, he adds, require similar attention: adequately sized extractor fans or openable windows are essential to reduce moisture and prevent mould growth.
Data: From Black Boxes to Golden Threads
One of the key barriers to progress is the “black box” nature of much of the UK’s housing stock. “We lack this golden thread of data about our buildings,” Booker notes, referencing a finding from the Hackitt Review.
Emerging projects like the proposed UK Indoor Air Quality Observatory inspired by a 20-year French initiative aim to standardise long-term data collection across homes and public buildings. “It would be a step change in what we can say and do about improving indoor air,” Booker says.
However, data collection brings its own challenges. Social landlords need to navigate privacy, transparency, and ethical use of occupancy-related data. “Data is powerful, but we must think about who owns it, who has access, and ultimately what it’s used for,” Booker cautions.
Hestia: A National Retrofit Network
Booker’s latest project, Hestia, aims to bridge these gaps. Named after the Greek goddess of the hearth and home, Hestia brings together eight universities including Leeds, Birmingham, and UCL with housing associations, local authorities, and partners like Healthy Homes Hub.
It will explore how retrofit can align carbon reduction with health equity. “We want to make sure that by improving planetary health, we’re also providing homes that reduce health inequalities,” Booker explains.
Hestia will fund pilot projects through “sandpits”, intensive workshops pairing academics with housing providers, tech developers, and residents. “My dream is a sociologist working with an engineer, a housing association, and people with lived experience, all pulling in the same direction,” Booker says.
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