INDOOR AIR qUALITY mECHAnICAL vEnTILATIon unwelCoMe HOmE As dwellings are highly insulated and sealed to improve energy performance, effective ventilation becomes essential to ensure good indoor air quality. Mechanical systems can address the issue, but they must be used as designed, and be properly maintained and installed. Andrew Brister reports A re you sitting comfortably? If you are at home, then perhaps not. According to the My Health, My Home campaign, by the British Electrotechnical and Allied Manufacturers Association (Beama), indoor air can be 50 times more polluted than outdoor air and may contain more than 900 chemicals, particles and biological materials with potential health effects. A study by Prism and Waverton Analytics found a staggering 91% of homes tested for volatile organic compounds (VOCs) in the air were above the recommended level. VOCs are not the only problem. A recent YouGov consumer survey, conducted on behalf of Beama, showed that 58% of respondents have experienced mould or condensation in their homes and 19% of these have suffered respiratory or dermatological conditions. Beama estimates that 15.3m homes are at risk from what is being called Toxic Home Syndrome. Adequate ventilation is essential, yet according to Beama only 2% of UK homes have mechanical ventilation systems installed. Evidence shows that, if care is not taken to ensure adequate levels of ventilation in line with Part F of the Building Regulations high levels of humidity can lead to a growth in dust-mite populations, condensation and mould, resulting in health and comfort issues. Britain is busy upgrading its ageing building stock, improving insulation standards to drive up energy performance. Beamas recommended approach to a balanced refurbishment eor RmadE mvHr In uSE Persons Scheme similar to what you have with gas installation and we are looking at guidance on robust details around ventilation systems. Perhaps there is a need for a handbook on how it should be done, with dos and donts similar to whats available for walls and floors. Users need guidance, too. Carrie Behar is a PhD student at the UCL Energy Institute, and her research is examining occupant interaction with ventilation systems in low energy dwellings. Poor information provided to residents of new homes goes some way to explaining why they arent involving internal or external insulation improvements is to specify continuous ventilation equipment. There is no doubt that indoor air quality has an impact on health, with mould and condensation being key factors of poor indoor air quality and People living in fuel poverty, are unlikely to heat a building enough or ventilate it sufficiently to prevent the presence of damp and mould interacting with systems in the way we might hope, says Behar. The findings include a lack of awareness over the way the ventilation system is to be used, as well as no explanation of the need for maintenance, such as an annual filter cleaning. A research team at the University of Exeter Medical School has found that failure of residents to heat and ventilate retrofitted properties could lead to more people developing asthma. Working with social housing provider Coastline Housing, the team assessed data from the residents of 700 properties in Cornwall. We have found that adults living in energy-efficient social housing may have an increased risk of asthma, says researcher Richard Sharpe. Modern efficiency measures are vital to help curb energy use and prevent heat loss, through improved insulation and sealing. Yet some people, particularly those living infuel poverty, are unlikely to heat a building enough or ventilate it sufficiently to prevent the presence of damp and mould, factors that we know can contribute to asthma. Head of technical services at Coastline Housing, Mark England, says: health risk, says Lee Nurse, marketing director at Vent-Axia, and chair of Beamas ventilation committee. With many people spending the majority of their time indoors, improvements in indoor air quality must be seen as a priority. Continuous ventilation is a simple solution to air-quality problems. For new-build homes, more and more designers are turning to mechanical ventilation with heat recovery (MVHR) equipment. The National House Building Council (NHBC) says there has been a noticeable increase in the number of homes incorporating MVHR, with current estimates suggesting this could be around a quarter of new homes. A study conducted by the BRE for the NHBC sheds light on some of the issuessurrounding MVHR systems, namely the way they are installed, used and maintained (tap MVHR in use button below). Certainly, an MVHR system is a step up from a simple bathroom extract fan, for installers and users alike, andits no surprise that it takes time to get used to them. Beama is trying to establish a more integrated approach to competency when it comes to installation, says Nurse. We are looking at whether there is a requirement for a Competent This research has given us an invaluable insight into how the behaviour of people living in fuel-efficient homes can affect their health. As a result, were working to provide customers with better information on how to manage their indoor environment, including potential training of volunteer sustainability champions. Manufacturers are also addressing the installation and in-use issues. We offer installers free attendance on a BPEC-accredited training programme to make sure they are properly trained, says Andy Mudie, marketing director at Nuaire. We also offer a design service, so that the industry can get the robust detail issues right, and we always provide information for the installer and the end user about how the products work. There has to be a handover pack. Clearly, the public has yet to understand fully the crucial role their ventilation system plays in indoor air quality and health. Beamas My Health, My Home campaign is a step in the right direction. Perhaps, one day, getting the ventilation system serviced will be as commonplace as the annual boiler check-up. CJ mvHr In uSE The BREs study for the NHBC monitored 10 zero-carbon Code for Sustainable Homes Level6 properties at Scottish and Southern Energys (SSEs) Greenwatt Way development at Chalvey, near Slough, Berkshire both during construction and for almost two years post-occupancy. The research involved assessment and evaluation of MVHR systems, taking in design,procurement, installation, commissioning, performance, maintenance and occupant perceptions. After approximately one year of occupation, nine of the MVHR units were recommissioned and changes made to room inlet air valves andair filters. In one home, the MVHR fan unit was replaced, and changes made to sections ofductwork and its insulation. The main findings are: It is critical that the overall ventilation strategy is taken into consideration during the design stage when using MVHR systems During the procurement process, it is important to seek technical input from the supplier and installer of MVHR systems MVHR systems should be installed by trained and experienced ventilation system installers Commissioning of MVHR systems must be fit for purpose Factors likely to affect the power consumption by MVHR fan units adversely during operation must be considered Factors likely to affect the thermal performance of MVHR systems adversely in operation must be considered Successful measures may be taken to increase the performance of MVHR systems and to reduce noise levels associated with their operation. Occupant feedback has been mainly positive, with levels of satisfaction tending to increase over time as the homes and their MVHR systems became more familiar. Much of the negative feedback associated with ventilation, thermal comfort and internal noise could be attributed to MVHR systems, including issues with perceived lack of control, temperature differences between storeys, experiences of draughts from cool air dumping and levels of mechanical noise. Levels of occupant satisfaction on these particular issues generally improved as a result of the remedial works carried out on MVHR systems after one year of occupancy. However, the Greenwatt Way occupants will have been better informed than the average householder, and have benefited from the interventions carried out as part of this research project. In the wider world, there would be every possibility that, where MVHR systems are not designed, installed and operated correctly, occupants may take radical steps in response to problems such as turning off the MVHR system.