sustainability BELOWWienerberger’s Porotherm blocks
BOTTOM H+H aircrete: The cake mix is loaded into an autoclave that applies steam at high pressure
RIGHT BELOWLaying H+H aircrete blocks
RIGHT BOTTOM The main constituent of H+H aircrete is pulverised fuel ash (PFA). The PFA is mixed to a slurry with water, prior to being fed through a mixer where cement and aluminium powder are added
Haxted Estates’ scheme on Sandbanks Road in Poole –the Silver winner in the Best Luxury Development category at the recent What House? Awards – is an example of this thinking. From the outset, the designer, Black Architecture, made the decision to expose as much thermal mass to the interior as possible to avoid the need for the comfort cooling or air conditioning normally demanded in the luxury market. “We had quite large amounts of glazing to the
south-west, designed to enjoy the views, and it was hard to shade because it’s set on a series of terraces for various apartments,” explains Paul Hinkin, managing director of Black Architecture. “We developed a construction philosophy where we placed all of the masonry mass of the wall on the inside surface, we then insulated that on the outside and then clad beyond that.” The construction uses a concrete frame and concrete floors with the inner leaf of the walls of 150mm medium density blockwork. This is clad externally with a layer of ‘super’ insulation and external finishes of zinc, render and brick. “It wasn’t a brick and block heavyweight construction; it was heavy getting lighter, having less embodied energy the further away from the interior it is,” says Hinkin. “We coupled that with traditional two-coat, thick plaster finishes on the inside.” Hinkin believes there has been a trend of ever-
lighter construction, particularly in the residential sector. “This is beginning to cause real problems in terms of indoor environment conditioning with overheating, particularly on westerly facing elevations. There are real benefits in being able
to even out diurnal swings and usefully store thermal energy for reuse by having an element of mass in the interior. Like all these things it has to be incorporated with sensible passive solar design and must incorporate a proper external solar control strategy.” Sofie Pelsmakers acknowledges that benefits such as increased comfort may result from thermal mass but her analysis indicates that high thermal capacity materials, particularly brick and block, significantly increase embodied energy. “The additional embodied carbon is estimated at three
to five tonnes of CO² for a 100m² house, which would take around 19-25 years to pay back from operational heating energy savings alone.”
sh
The Environmental Design Pocketbook by Sofie Pelsmakers is published by RIBA Publishing, £25
CONTACTS
Black Architecture
www.black-architecture.com Brick Development Association
www.brick.org.uk Forticrete
www.forticrete.co.uk H+H
www.hhcelcon.co.uk Lignacite
www.lignacite.co.uk Wienerberger
www.wienerberger.co.uk
Read Roger Hunt’s blog:
www.huntwriter.com or follow him:
www.twitter.com/huntwriter
38| January 2014 showhouse
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