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Building Products March 2018

HEATING, VENTILATION AND AIR CONDITIONING A BREATH OF FRESH AIR FOR NEW BUILD Paul Croughan, head of sales – new build, at EnviroVent, looks at the ways of improving indoor air quality and meeting ventilation requirements in new homes. In its National Infrastructure Plan (2016), the government committed to doubling the housing budget from 2018-2019 to deliver 400,000 new homes. For any new home, it is vital that building materials are selected for their quality and sustainability in order to support the health and well-being of occupants. Increasingly stringent building regulations that affect energy efficiency and air tightness have led to a need to ensure that new homes have appropriate levels of indoor air quality and ventilation, while reducing the amount of energy used to heat a property. The new build sector is seeing mechanical ventilation with heat recovery (MVHR) as a practical way of meeting what at first appears to be the conflicting requirements of adequate ventilation and high levels of energy efficiency. Requirements for increased levels of air tightness and energy efficiency mean that around 25% of new homes are now being specified with MVHR systems, according to research by the National Housebuilding Council (NHBC). MVHR systems are situated in a central location, usually in the loft space of a house or a 42 BUILDING PRODUCTS | MARCH 2018 utility room in an apartment. They provide both supply and extract ventilation, extracting warm and moisture-laden air from the bathroom, kitchen, WC and utility room of a property which is drawn into the main system and passes over a heat exchange cell, before being ducted outside to the atmosphere. At the same time fresh air is drawn from outside into the system, the heat from the extract air is then transferred to the supply air through the heat exchanger. MVHR units can transfer more than 90% of the heat from the extracted air to the supply air as it passes through the heat exchange cell. This helps to reduce the overall energy requirement of the building, as well as its carbon footprint. This fresh, filtered and tempered air is then supplied into the living areas of the home, providing a good level of indoor air quality and preventing humidity which can lead to condensation and mould growth. Higher levels of air tightness Where greater levels of air tightness (of 3m3/h/m2@50Pa or below) are set to be achieved, MVHR is often specified to secure a larger percentage reduction between the dwelling emission rate (DER) and target emission rate (TER). A high performing MVHR system through standard assessment procedure (SAP) may lower the DER. For new homes, MVHR is helping to cost effectively contribute towards the improvements in CO2 emissions required by building regulations. With MVHR, the incoming air is filtered, improving internal air quality and it also negates the need for window trickle vents. In addition, MVHR is an attractive option for Humidity can lead to condensation and mould growth


Building Products March 2018
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