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Barratt builds a green house
Sri Carmichael, Evening Standard16.10.07
Building work begins this week on a new generation of zero-carbon homes.
The prototype of the "green house" has been designed to produce the smallest carbon footprint.
Solar panels will heat the water, pumps will extract heat from the air to warm the house and lavatories will use rainwater to flush.
The floors and walls will be insulated with concrete to keep the building's temperature stable.
The family house is being built by Barratt Homes and will be scientifically tested to ensure it meets the strict credentials set out by the Government to make it zero carbon. If it is given the allclear, a range of properties will be introduced on to the mainstream market by 2010.
The house, developed at the BRE Innovation Park in Hertfordshire, comes two weeks after the exemption from stamp duty of zero-carbon homes worth less than £500,000.
The prototype was designed by London architects Gaunt Francis; and the National Centre for Excellence in Housing, based at the BRE complex, is collaborating on the project.
Mark Clare, chief executive of Barratt Developments, said: "The most exciting aspect of the 'green house' is it's not designed as a one-off - we will take what works and apply it to house building across the country."
Reader views (8)
Earth building is the solution.
- L, GVA, Switzerland
Andy is partly correct but the conclusions he has drawn are incorrect. Cement forms about 10% by mass of concrete, the rest is mainly aggregates, much now recycled from, for example, demolished concrete. But contrary to what many commentators believe, the embodied environmental impacts of construction materials have only a relatively minor importance in overall terms. The operational (in use) environmental impacts of buildings are 10X higher than embodied impacts taken over the life of the building. The benefit of concrete, and other heavyweight construction, is that its high thermal mass maintains stable internal temperatures throughout the year even in a warming (global warming) climate. Conversely, lightweight insulated constructions will, almost certainly, require energy intensive, high carbon footprint, air-conditioning to be fitted/retro-fitted to them for operation during increasingly hot summers. In this way, heavyweight constructions minimise the operational impacts over the life of the building.
But on the subject of embodied impacts, concrete has a carbon footprint of about 100kg/tonne. Cement is about 8X higher but cement is not the construction material, concrete is.
Hydraulic lime does have a lower embodied impact than cement but not a great deal lower because limestone still has to be heated. However, hydraulic limes are much weaker than Portland cements, so replacing cement by hydraulic lime in (heavyweight) concrete is unlikely to happen.
- Michael G Taylor, High Wycombe England
Andy is correct, cement is energy intensive. Lime is a much better product to use.
- Paul Bradford, Monflanquin, France
Under £500,000, well within my budget, not! Yet again only the rich can afford these new designs, and at that price not only would it take an eternity to rebuild all the homes in Britian, but the normal people wouldn't be able to afford them, it's too little too late again, why didn't the government do something in the 70s when they new this would be happening.
- Suki, South Yorks
From a building green website:
"But cement production is very energy intensive—cement is among the most energy-intensive materials used in the construction industry and a major contributor to CO 2 in the atmosphere. To minimize environmental impact, therefore, we should try to reduce the quantity of concrete used in buildings, use alternative types of concrete (with fly ash, for example), and use that concrete wisely. "
- Andy Fitter, London
I thought that they had built 'green' houses in Milton Keynes 25 years ago? I remember visiting the area and looking round the houses all of which had various degrees of efficiency.
- Robert Appleson, London, UK
What's so unfriendly to the environment about concrete? It's no worse than building with brick or other materials! I applaud this initiative and I certainly don't consider myself "weak minded and stupid"!
- Headhunter, London
How can concrete be enviromentally friendly?
This house will be very un-green before it has even been put up. More marketing spin for the weak minded and stupid.
- Mike, Sussex
