Clearing the air

  • 28 Nov 2013

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Housing refurbishment projects are multiplying as local authorities strive to improve the condition and efficiency of their housing stock. Cutting energy bills for tenants is a pivotal part of these projects and often involves improving the airtightness of a property. However, this can result in reduced air quality and condensation forming.

An estimated 50% of buildings in the UK suffer from condensation and the damage it causes to the health of tenants and the fabric of homes is a big issue for social housing providers. Indeed, poor indoor air quality is responsible for two million healthy life years lost annually in the 26 European member states.

Andy Bruce from Fuimus Building Services, which specialises in the control of condensation and mould, explains: “In the past, houses had open flues to every room and plenty of air gaps, creating airflow which removed water. Today’s energy saving measures – double glazing, cavity wall insulation, loft insulation and draught proofing – create an airtight box where water vapour builds up as a result of cooking, bathing and showering until condensation occurs. This can lead to serious health problems caused by the growth of black mould.”

The dew point
Air normally contains water vapour and its capacity to do so is related to temperature – warm air holding more than cold air. Air is saturated when it cannot contain any more water vapour at its existing temperature. Under these conditions, it is said to have a relative humidity (RH) of 100%. If the temperature of the air falls until saturation point occurs, the air reaches the critical temperature at which it cannot hold any more water. This temperature is known as the dew point. Any further fall in temperature results in vapour being forced to condense out as water on non-absorbent surfaces – this is surface condensation.

Meanwhile, according to BRE research, mould spores can germinate at relative humidity rates of 80-85% and, if relative humidity levels exceed 70%, it is likely mould will grow. Due to the serious consequences mould can have on tenants’ health, including respiratory infections, skin irritation and nausea, the Landlord and Tenant Act 1985 puts the onus on landlords to ensure properties are designed and maintained to prevent condensation and mould.

Structural damage
Condensation can also occur within the fabric of a building. This is due to warm, internal air permeating through the structure due to its greater pressure. Eventually, the warm, moist air will cool below its dew point within the fabric of the building resulting in condensation.

This interstitial condensation presents a greater hazard than surface condensation because the resulting high moisture content can go undetected until structural damage, such as timber decay, occurs. Unchecked, it will cause unsightly damage to the fabric of a property and spiralling costs for the social housing provider.

Local authorities initially may be unsure about the cause of this structural damage and so it is wise to seek expert advice. Mr Bruce explains that Fuimus is often called out by local authorities to deal with damp found in social housing. However, when surveying a property Mr Bruce says it often becomes quite clear from condensation on the windows and walls in addition to black mould in the bathroom, that the real problem rather than damp is ineffective ventilation.

Improving ventilation therefore, offers a simple solution to condensation for local authorities. However, traditional intermittent ventilation brings with it another set of issues. Intermittent fans have tended to be noisy and, when they do operate, give the impression of consuming energy and costing money. It is not uncommon for fans to be disconnected because of these factors with the result of condensation flourishing.

Modern continuous ventilation solutions present a much better answer for local authorities. These work with the natural air infiltration into the home, controlling the air path to prevent the migration of damaging humidity and pollutants. This is achieved by using continuous, low speed running extract fans in wetrooms (bathrooms, kitchens and utility rooms) with a boost via the light switch, an integral pull cord, or sensor, when higher ventilation rates are required.

The extract system can run at a low rate resulting in energy efficient systems that cut heat loss and fuel bills. Lower speeds mean low noise levels and this means tenants will be unaware that fans are running and less likely to turn them off.

A near silent Decentralised Mechanical Extract Ventilation (dMEV) solution offers literal peace and quiet, but also the peace of mind that electricity bills won’t skyrocket. Suitable for retrofitting as low energy ventilation into bathrooms, this type of fan is virtually silent, fits discreetly in modern homes and is simple to install.

An extra dimension
Meanwhile, a single room heat recovery unit adds another dimension. This type of product sets a new standard in energy efficient performance and can be easily retrofitted through a 100mm diameter hole in the wall. This ensures that Local Authorities can easily replace fans with a discreet, low energy, continuously running alternative that provides up to 84% heat recovery. It enables standard bathroom, kitchen, toilet or utility room fans to be changed without the need to make a larger hole, saving significantly on installation time and cost.

For local authorities wanting to provide good comfort for tenants, continuous ventilation technology is now available that is energy efficient, near silent, simple to use and discreet. This type of solution offers them a clear route to better ventilation, leading to a good indoor environment for tenants, lower humidity levels, and reduced maintenance costs. In short, effective ventilation offers a simple way to combat condensation and mould.

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