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Building Products October 2017

RENEWABLES OCTOBER 2017 | BUILDING PRODUCTS 75 indoor living environment; with Building Regulations, BREEAM and other construction standards – including the still widely referenced Code for Sustainable Homes – all striving to address the issues. Shelter and warmth can be considered as basic physiological needs under Maslow’s famous hierarchy, but ever since central heating became the norm, people have craved far greater control over their comfort levels: with thermostats having been the first step in a series of technical advancements, which have now progressed to a state of sophistication which would have seemed like science fiction just a decade or two back in time. Conversely, it should also be borne in mind that continued emphasis from Government on cutting energy losses, has brought its own problems in the form of creating potentially stuffy, moisture laden or even harmful indoor atmospheres. Not only do we have increased insulation standards, but these have been coupled with measures to improve airtightness. As a result of this, natural air changes have been reduced to the point where heightened levels of water vapour or even carbon dioxide can make us feel uncomfortable or drowsy. Humid air also generally creates more favourable breeding conditions for germs, mould and dust mites. The UK’s Building Regulations and the Building Standards in Scotland include sections on ventilation but we can look to the German PassivHaus standard or the Canadian Super E approach to construction as guidance taking a more proactive approach through the adoption of mechanical ventilation with heat recovery (MVHR). The challenge for architects and their mechanical services engineers is to quite literally balance the requirement for achieving adequate air changes, without compromising the efforts made to reduce energy usage and to do so in a manner which does not over-complicate everyday life for the building owner or occupant. The best answer, then, is to specify heating and ventilation systems, which can operate in harmony, ideally utilising controls which are both intelligent and user-friendly. Many consultants now recognise that underfloor heating systems (UFH) can offer a solution that is both economic to run and comfortable to live with. Firstly, by operating at lower flow temperatures than wall radiators, they assist both condensing boilers and ground or air source heat pumps deliver optimum efficiency. Then they also help create a very even temperature within the occupied space, which is pleasant for people whether they are relaxing or involved in some activity. It is vital, of course, that the MVHR chosen not only operates quietly, but consumes the minimum amount of electricity in extracting the stale moist air which we inevitably produce, replacing it with sufficient pre-warmed, filtered fresh air to keep occupants comfortable, alert and healthy. It may also be the case, in higher specification residential or non-domestic properties, that the designer may also want to incorporate some level of comfort cooling, which can be cheaply and effectively achieved by using the borehole or ground array providing energy to the heat pump. In summer the ground temperature can be 15OC at just 2m below the surface, so the brine in the system can be circulated through the UFH to provide free cooling. To make all of these systems run efficiently and make the best use of the fuel or electricity supplied to any property, these systems must be linked not just to sensors, thermostats and timers, but to an integrated control network that will properly monitor and optimise the entire internal space. Darren Trivett is Managing Director of Omnie


Building Products October 2017
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