MMC 5542 48 Feb '16 cc

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Cross code project nears completion Technical Editor Bruce Meechan reviews a highly energy conscious, mixed tenure social housing development down near the Bristol Channel which is drawing on two of the industry’s best proven design standards. The continuing relevance of the Code for Sustainable Homes to the social housing sector has been demonstrated by the development of 25 new homes near to Minehead on the Bristol Channel, which is making use of both the points based system and the even more energy sensitive PassivHaus Standard.. Known as Townsend Farm, the project for Hastoe Housing is seeing Halsall Construction Limited build a total of 20 houses to full PassivHaus requirements, while a further five for market sales also offer excellent energy performance. Significantly, the project team which includes Bristol based architectural consultant, gcp and WARM Associates as the PassivHaus certification specialist, is also being specified to meet Code Level 4 in order to address wider sustainability issues. Beyond this site by the Bristol Channel, Hastoe is constructing all of its new housing to Code for Sustainable Homes Level 4 as a minimum standard, while 20 per cent of its developments are set to achieve the PassivHaus Standard. Design and Sustainability Manager at Halsall, Nicola Thorogood has been involved with the Townsend Farm project from early on and commented: “It’s a site that has been identified for a long time for housing and has been a challenge to get to this point, but pleased we are now moving forward providing high quality, low maintenance, low energy cost homes for local people in and around Carhampton. “This design and build project is an exciting challenge for Halsall building on the knowledge and experience of low energynear PassivHaus design, Code for Sustainable Homes levels 5 and 6 housing the company has successfully completed over the past few years.” The construction, while featuring a highly insulated timber frame system from Taylor Lane, brings together a selection of other products in order to achieve the required standards of airtightness and insulation across the building envelope. For example, at the critical floor/wall junction the designers have incorporated a course of Thermoblocks; manufactured by Marmox. These feature miniature columns of concrete encapsulated within high performance XPS insulation. They can be used at upper floor levels and other locations as well as around the perimeter to the oversite. The Site Agent for Halsall Construction Limited, John Gray, explained: “The PassivHaus properties feature the use of 150 mm wide Celcon aircrete blocks up to floor level then the course of Marmox Thermoblocks and another single course of blocks above, which ultimately carries the timber frame. The elevations to the buildings then features either local stone or render outside a further 200 mm thickness of insulation. The Thermoblock is employed to help achieve the very low U-value, while the airtightness figure required is 0.6 (m 3 / m 2 /hr)”. In fact the 140 mm timber frame is factory insulated with Kingspan Kooltherm insulation and then encased externally by 200 mm of Rockwool. The latter has the twin benefits of offering very good fire protection and sound reduction while remaining vapour permeable. Internally the frame has an Intello Smart air barrier to restrict movement of moisture vapour into the structure where it could cause interstitial condensation. Then there is also a batten cavity for the routing of building services. Although gcp Chartered Architects has designed past PassivHaus projects with slabs of high density polystyrene beneath the oversite, the challenging ground conditions on the former farmland did not lend themselves to a raft solution. As a result, the mix of one, two and three bedroom homes are raised on conventional footings spanned by a beam and block ground floor. This then has substantial insulation over and is protected against cold-bridging by the Thermoblocks and very energy efficient wall construction. Project Architect Colin Powell commented: “In order to maintain the very good airtightness and insulation offered by the fabric of the walls, roof and floor, the contract to supply the windows was awarded to TRC, an eastern European manufacturer. These are timber to respect the village setting of the development and triple glazed to keep heat loss within PassivHaus guidelines. The entrance doors were supplied by IG. “Then the properties all feature Zehnder mechanical ventilation with heat recovery systems which are ideal for PassivHaus requirements. In terms of the overall primary energy the places are heated with a couple of convector radiators in the bathroom and hall; while Baxi solar thermal systems will provide the domestic hot water through much of the year. “Overall the aim of the project was to design it to be as conventional as possible – adapting standard materials and techniques to keep the cost down and the appearance traditional. “Then of course the PassivHaus performance gives you a very good starting point in terms of energy standards to go onto achieve Code for Sustainable Homes Level 4, where the houses will be provided with facilities such as bike stores and water butts.” As well as the private market sale properties, the homes at Townsend Farm will offer the opportunity for both shared equity and affordable rent. The project is expected to be completed before the summer. 16
“Marmox Thermoblock is being used to break the thermal bridge between the sub-structure blockwork and the superstructure above - achieving a psi value of 0.007 W/mK”. “Overall the aim of the project was to design it to be as conventional as possible – adapting standard materials and techniques to keep the cost down and the appearance traditional.” The type of MVHR unit from Zehnder chosen for Hastoe’s PassivHaus project Colin Powell, Project Architect, gcp Chartered Architects. MMC February 2016 17
Page 1 and 2: MODERN METHODS OF CONSTRUCTION > is
Page 3 and 4: CONTENTS issue 5542 | Feb | 2016 De
Page 5 and 6: empowered by Achilles empowered by
Page 8 and 9: Whatever the exposure - EJOT ® has
Page 10 and 11: Sweat equity Technical Editor, Bruc
Page 12 and 13: How off-site construction can beat
Page 14 and 15: Exeter campus contract for Lowfield
Page 18: Could offsite construction attract
Page 21 and 22: Permanent buildings constructed usi
Page 23 and 24: The versatility of the SureClad ®
Page 25 and 26: Article > Precast Concrete Modular
Page 27 and 28: an nge han ndrail LED illuminat ted
Page 29 and 30: “A big thing for us at the minute
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Page 35 and 36: HTC The industry leader HTC Sweden
Page 37 and 38: Relieve the pain of rising patient
Page 40 and 41: Article > EOS Facades on a roll! On
Page 42: Smartply offers sustainable solutio
Page 45 and 46: Concrete considerations for offsite
Page 47 and 48: The Problem Delivering the right am

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