Modern Building Services

MODERN BUILDING SERVICES AUGUST 2022 13 How widespread is the issue? The English Housing Survey Headline Report 2020-21 stated that in 2020* 2% of homes had problems with condensation and mould (namely where there are extensive patches of mould growth on walls and ceilings and/or mildew on soft furnishings). When you consider there are an estimated 24 million households in England, that 2% equates to 480,000 homes suffering from serious condensation and mould. The problem is most prevalent in private rented dwellings where 6% had some type of damp problem, followed by 4% of social rented dwellings and 2% of owner- occupied dwellings. The good news is that all damp- related problems in housing have been on a downward trajectory since the 1960s. The bad news is that condensation and mould reduction have stalled, with only a slight reduction in the figures over the past decade. Condensation: who’s to blame? So, what can we do to reduce condensation in our homes? Over the years, the onus has been very much placed on residents to make lifestyle changes. These have included drying clothes outside when possible or using a tumble dryer, covering pans when cooking, shutting the bathroom door when showering or bathing, and ensuring extraction fans are switched on. However, for many low-income households that are struggling to adequately heat their homes, and therefore have a higher level of condensation, these measures are not always economically viable. Furthermore, recent research has verified that construction and external factors play more of a role in the development of these issues than residents’ behaviour: dampness and mould are directly linked to badly insulated and poorly ventilated houses. So, it’s time to stop laying the blame at the door of the resident and start making our homes more condensation proof. Ventilation: the way forward If we improve the ventilation in a home, we lower the humidity. It really is as simple as that. Circulating the air and extracting excess humid air outdoors can be accomplished through a number of different ventilation solutions, depending on the budget available, the nature of the property and the seriousness of the issue. For existing properties, the most cost-effective options are bathroom and kitchen intermittent extraction fans or single flow, continuous running decentralised mechanical ventilation fans, such as the new Domus Ventilation D-dMEV. Positive Input Ventilation (PIV) units can also be used which gently pressurise a dwelling to expel stale and humid air through natural ventilation points. For new builds, the options are more widespread and ultimately more effective. In addition to intermittently operating extract fans, Mechanical Extract Ventilation (MEV) units and Mechanical Ventilation with Heat Recovery (MVHR) can be deployed. MEV units, provide constant low-level ventilation by extracting waste, and damp air from a dwelling through a system of ducting. These are best suited to apartments and small to medium- sized houses. MVHR systems go one step further by combining extraction with supply. The extracted air is passed across a high-efficiency heat exchanger located inside the MVHR unit, to remove and transfer the otherwisewasted heat. The exhaust air is then expelled into the atmosphere. At the same time, fresh filtered supply air is drawn across the opposite side of the heat exchanger and pre- warmed before being distributed through ceiling-mounted grilles to habitable rooms. The new breed of MVHR units on the market is highly energy- efficient, with models available with integral humidity sensors. By accurately measuring air humidity, the extract speed automatically changes from background to boost as the level of humidity increases, thereby providing optimal ventilation performance. These mechanical systems provide a long-term and cost- effective solution rather than short-term problem ‘hiders’ such as dehumidifiers. Time to take action Our climate has changed over the last few years, with milder winters and wetter summers, but the issue of condensation in our homes remains and is not improving fast enough. Expecting people to change their lifestyle to prevent excess condensation is not realistic (it certainly hasn’t worked up until now, so it’s unlikely to work in the future), nor will it reduce condensation to comfortable levels. Building adequate ventilation into our homes is by far the more realistic and long-term solution. More information can be found at www.domusventilation.co.uk FEATURE AIR CONDITIONING, COOLING & VENTILATION