Concrete and clay tackle lifetime cost equation in E4 House

// the building envelope

HA Magazine hears from George Pickard of Litecast about his company’s contribution to the construction of the E4 House, a project case study on which appears in this edition as the lead in our Sustainable Homes feature.

John Prescott may have been picked to carry out the official opening of Wienerberger’s E4 House at the BRE Innovation Park because of his having championed the £60K home initiative, but it was actually Yvette Cooper who – during her time as housing minister – highlighted the issue of overheating which can affect many of the modern lightweight designs.

Having been inside the new 3/4 bedroom property while the sun scorched down on the tape cutting ceremony, I can report that hot summers and  solar gain should not prove a problem; even though a lot of the glazing is full height. This is because masonry construction and thermal mass are an integral part of the system being offered to the industry: with not just brick elevations beneath a tiled roof, but a superstructure formed from Wienerberger’s Porotherm blocks and an oversite featuring Litecast’s highest performing XT floor system.

Speaking exclusively to HA Magazine, Litecast’s Sales Director, George Pickard commented: “Wienerberger’s Head of the Built Environment, Paul Surin was keen to use a flooring solution readily available in the UK, but from a manufacturer which shared his company’s moral ethics. They wanted to know that our flooring was not only efficient and good value for money, but that it produced little waste or other damage to the environment – that we had ISO 14001 - and that it would help contribute to keeping down the long term running cost of the property.

“Although there is a lot of debate about the difference in carbon footprint between say timber frame and masonry construction, the ultimate environmental cost of a building is the energy used to operate and particularly heat it.”

Interestingly the E4 House – one of three new cutting edge domiciles being erected on the Watford site this year – will be occupied as an office and its costs strictly monitored by both the manufacturer and the BRE. Annual heating costs are predicted to be £167 out of a total for utility bills of £230.

George Pickard continued: “The XT 0.1 system offers a U-value of 0.1 W/m2K and also a very good psi value; making use of a special perimeter detail. Importantly for customers Litecast offers a range of products that achieve U values from 0.2w/m2k to 0.08w/m2k with the confidence of BBA certification. Litecast sell the floor as a system and coordinate the delivery of the silver grey high performance EPS units through a manufacturing partner so that it is supplied as a system.”

George went on to point out that the installation of an underfloor heating system for the E4 House – installed within a 100 mm concrete topping – is actually common practice for developers employing Litecast’s XT flooring systems. He explained that underfloor heating is the most efficient way of delivering heat: either from a hybrid heat pump as has been done at the Innovation Park, or if the specifier chooses a condensing boiler or perhaps biomass. Especially when very high insulation levels are being targeted under a Fabric First approach, higher flow temperatures – typically required with radiators – are simply not necessary.

As was mentioned in the main overview article on pages 40 - 41, the Wienerberger concept is not just one offering a wide choice of unit size, but also future flexibility and further development.

So while this is a phase one prototype, phase two properties are expected to replace the engineered timber first floor beams with a far more robust construction which will combine Porotherm ‘pots’ with the Litecast beams. This will not only increase thermal mass still further, but should also help eliminate noise transmission between storeys.

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