Blog 4, Beneath the Surface, Underfloor Expertise for a Smart Retrofit Solution

Every home is different!

Every home is different, even from under the floor

In our last blog, we shared findings from the research conducted by Leeds Beckett University, based on underfloor data collected from thousands of homes fitted with the AirEx Floorvent system. The key conclusions were clear: underfloor humidity typically follows external humidity, and homes with Floorvent often experience lower overall humidity in the floor void compared with conventionally ventilated properties.

Those results were based on aggregated averages across a very large dataset. But, of course, averages only tell part of the story. When we look at individual homes, a much more detailed and nuanced picture emerges, one that helps us understand why no two properties behave quite the same, even when they’re on the same street.

Thanks to continuous monitoring from the smart air bricks, we can now analyse the conditions beneath individual floors in unprecedented detail. Each installation generates sensor data on temperature and humidity in the floor void, which we combine with external weather data and information about the state of the vents, how far open or closed they are at any given time. Together, this gives us a real-world view of how each home and Floorvent system is responding to its local environment.

Patterns that follow expectations

In many homes, we see the pattern we’d expect: humidity beneath the floor broadly follows external humidity. When it’s damp outside, it’s damp under the floor; when it’s drier, the void humidity drops too, especially following seasonal patterns. The Floorvent system adapts automatically to balance ventilation with energy efficiency, opening to purge moisture when humidity rises, and closing to retain heat when conditions are stable.

Within this majority group, there’s a smaller subset of homes where humidity levels are consistently higher than average, both inside and out. This appears to be driven largely by local weather. In areas with persistently high rainfall or coastal humidity, homes may experience elevated void moisture levels even with adequate ventilation. Identifying these patterns is useful, because while they may not indicate an issue, they do highlight properties that could be more vulnerable to damp or timber decay, making them prime candidates for closer monitoring or inspection.

When the void behaves differently

While most homes fit the general trend, a significant number do not. In some properties, humidity in the floor void remains consistently lower than the external environment throughout the year. This is an interesting finding, as it suggests the ground and subfloor conditions themselves are the driving force influencing the moisture balance.

Many of these homes are located on well-drained soils or sloping ground. In such cases, the underfloor environment may actually be drier than the outdoor air, meaning that additional ventilation could, paradoxically, introduce humidity rather than remove it. The Floorvent system’s ability to close automatically during these conditions becomes particularly valuable, maximising energy efficiency without compromising ventilation where it’s needed.

At the other end of the spectrum, some homes show consistently higher humidity inside the floor void than outside. In these cases, our data shows that the vents are open almost continuously, yet high humidity persists. This suggests a potential issue, possibly inadequate crossflow, insufficient vent numbers, or even external moisture sources such as leaks or rising groundwater.

For surveyors and housing teams, these are the homes that merit a site visit. Persistent underfloor humidity could point to structural, plumbing or drainage problems, and being able to identify them from data allows for targeted maintenance before damage occurs.

What the soil can tell us

Then there are the outliers, homes that don’t fit neatly into either category. Some show unusually high humidity in winter, followed by much lower humidity in summer, relative to outdoor conditions. When we mapped these locations, a pattern emerged: many of them sit on clay soils.

Clay is known to absorb and hold water during wet periods, then dry and contract during warm, dry weather. This shrink-swell behaviour can cause seasonal shifts in both moisture and ground stability. The data suggests that this dynamic is being mirrored in the underfloor environment, as the ground beneath expands and contracts with the seasons.

In these cases, the implications extend beyond moisture management. Homes built on shrink-swell soils may also be at greater risk of structural movement or subsidence. Identifying these through data gives housing providers an early indicator to investigate further, potentially before any visible signs appear above ground.

Turning data into action

What this growing body of data shows is that every home tells its own story. By combining environmental readings, local weather and soil information, we’re starting to see how local factors, from drainage and ground type to rainfall and construction, influence the conditions under a suspended floor.

For housing teams and supporting  professionals, this level of visibility represents a step change. It means issues can be spotted earlier, targeted surveys can be prioritised, and interventions can be more precisely planned. In short, it turns underfloor spaces, once invisible and unpredictable, into measurable, manageable parts of the building fabric.

As our dataset continues to grow, the goal is to refine this understanding further: identifying clusters of similar homes, developing predictive models of risk, and ultimately supporting housing providers to focus their efforts where they’re needed most.

Because if there’s one clear conclusion from all this data, it’s that every home behaves differently, and knowing how and why makes all the difference in keeping them healthy, efficient and resilient for the future.