The science behind mould and preventing it with underfloor heating

Whenever there is excess moisture present within a property, there is potential for mould growth. These unsightly microscopic fungi not only reduce indoor air quality and become a health risk for occupants but can also create expensive maintenance problems. Here, Ashley Cooper, Managing Director at WMS, answers questions about the science behind mould, why ventilation alone is insufficient to combat the issue and how radiant heating creates the perfect conditions to avoid mould growth.

What causes mould to develop within a property?

“There are a few areas within a home where mould can develop, particularly on cold surfaces in rooms with high moisture levels. In these damp areas, microscopic fungi breed on surfaces, typically in bathrooms, kitchens, and around windows where condensation may gather.

“There are many reasons why moisture levels can increase within a property, including everything from a leaky roof or poor indoor plumbing to resident activities such as showering, drying laundry, and even boiling water on the hob.

“Once mould has developed, it generates allergens, irritants, and on occasion, toxic substances. If a resident inhales or touches the mould spores, it may cause an allergic reaction, such as sneezing, a runny nose, sore eyes and a skin rash. Inhalation of the mould spores can also trigger asthma attacks and negatively affect a person’s immune system.”

Can extra ventilation reduce the risk of mould?

“Unfortunately not, because even during warmer months when it’s more likely for windows and doors to be open, warm air still carries more moisture than cold air so when it touches a cold surface, it cools down rapidly. As such, it’s still possible for condensation (and consequently, mould) to form when moisture-filled air hits a cold surface with the home that’s below the dew point.

“While ventilation will help to inhibit mould growth somewhat during the summer, during the colder months, it’s likely that residents will be resistant to having windows and doors open as it will negatively affect their energy bills.”

If cold surfaces are the issue, what’s the solution?

“The only system which can heat all surfaces in the room evenly is radiant heating, specifically hydronic (water-based) underfloor heating.

“This form of heating creates evenly warm spaces and because warm air holds more moisture than cool air, that room can hold more moisture rather than depositing it as condensation.

“Radiant heating operates by increasing the temperature of all surfaces rather than solely heating the air. Consequently, this leads to an increase in the air temperature upon contact with these warmed surfaces. In addition to establishing a pleasantly warm atmosphere, underfloor heating extends warmth uniformly across the entire floor surface, effectively eradicating any chilly areas within a room that might otherwise foster mould growth.

“The way underfloor beating is controlled differs from traditional radiator heating systems which are either on or off. Residents will benefit more when the underfloor heating system runs 24 hours a day, seven days a week and is turned down very slightly during the night. Crucially this also ensures that the fabric of the property doesn’t become too cold throughout the winter.

“This type of programming makes this low-temperature heating technology more cost-effective to run and up to 15-40% more efficient than an equivalent radiator system. For optimal energy efficiency, it’s also essential for the property to be insulated to a good standard and equipped with double glazing. This ensures that the wall surfaces can effectively retain the warmth radiated from the underfloor heating.

“A solution which meets the needs of today and the future, WMS offers a 75-year pipework warranty, making it possible for the system to outlive the life of the building itself. Plus, underfloor heating pipework, made from superior quality, sustainable five-layer PERT (polyethylene of raised temperature resistance) material, can also be melted down safely and reused, further reducing the building’s overall environmental impact. In contrast, radiators usually become a waste product after around 25 years.

“In summary, underfloor heating provides a low-temperature system that offers even heat distribution, eliminates cold surfaces and provides constant warm air. Together these factors provide the perfect conditions to avoid mould growth while ensuring residents can enjoy a healthy and comfortably warm indoor environment.”