What Really Happens Inside a Aome After Retrofit

She was introduced by Stuart Smith of Zehnder, who set the scene perfectly. After nearly three decades in ventilation and indoor air quality, his message was that what we design on paper does not always survive the journey into a real home. The outcome depends on the property, on how measures are installed, commissioned and maintained, and the only way to know what we have really delivered is to measure it in homes where people are living their ordinary lives, exactly what this study does. 

Looking beyond the EPC 

The starting point reframed something I think we too often forget. We spend around 90 per cent of our lives indoors, and a great deal of that at home, yet our attention and our policy have been trained on outdoor air. Tiffany showed how everyday activities like cooking and cleaning can send indoor pollution spiking far above what we breathe outside. Homes can shelter us from pollution, but they can also generate and trap it, and that becomes even more important when we start changing the fabric of a building. 

The promise and the trade-offs of retrofit 

Insulation and draught reduction should make homes warmer, cheaper to heat and kinder to health and to carbon. But Tiffany was clear that this is not the whole story. Insulate without ventilating properly and you can trap moisture and pollutants and invite damp and mould. Make a home cheaper to heat and some households will, quite reasonably, heat it more, which is good for their health but eats into the carbon savings we assumed we would bank. The point is not that retrofit is wrong. The point is that we have to understand these trade-offs if we want the co-benefits rather than the unintended consequences. 

Measuring what happens after the work is done 

The study built on a rare opportunity. Bradford's largest social landlord, Incommunities, is retrofitting just under 3,000 homes, and the research team has been able to monitor a large sample as the work happens rather than piecing the story together afterwards. They are following 384 properties with continuous sensors recording conditions every five minutes, across two winters and a summer, alongside questionnaires, energy meter readings, interviews and longer term linkage to NHS records. It is the kind of evidence the whole sector has been crying out for. 

What the early findings tell us 

What the early data shows is that as outdoor temperatures fall, the homes do not cool together. They fan apart, and around half of them cannot be kept above the 18 degrees that the World Health Organisation sets as a minimum. Underheating here is a common experience. On air quality, almost half of readings exceeded WHO guidelines, driven by a mix of what drifts in from outside and what is generated inside by cooking and daily life. And the residents themselves are a vulnerable group, older on average, often on benefits, many reporting food insecurity, energy arrears and poor general health well below the national average. 

Why resident experience matters 

Two things we should reflect on: 

1.  You can raise a home's EPC through measures that do nothing for the comfort or the air quality inside it. Remove some secondary heating, add solar panels, and a property can reach EPC C while the person living there is still cold and still breathing poor air. If we are serious about housing as health, we cannot keep treating a modelled rating as the finish line. 

2. Tiffany's team learned that residents needed to know the researchers were separate from the landlord and the contractors, that their data would not be passed back to their housing provider, and that they would hear about everything from a trusted source rather than an unexpected knock at the door. Residents helped shape the questionnaires, sit on the funding grant, and are being trained as peer researchers. That is co-production done properly, and it is a reminder that communication and trust are not soft extras. They sit at the centre of whether retrofit works. 

Connecting winter warmth and summer heat 

There was a lovely thread running through the day too. Tiffany noted that she had been in our overheating session earlier, and her own work has expanded to include a summer questionnaire on overheating, because keeping people warm in winter and safe in heat are now two halves of the same job. The themes of our Exchange were talking to each other. 

Social housing is a vulnerable group, living with cold homes and poor indoor air, who often do not fully understand what the retrofit they are about to receive will involve. The technical works matter, but they are not enough on their own. If we measure what really happens inside homes, design with residents rather than for them, and treat health and comfort as the goal rather than a rating on a certificate, then retrofit can do everything we hope it will. That is the home this sector should be building. 

#MakeHousingBetter