When it comes to house building….the CAT knows best
by David Hoppit.
New homes built of mud or bales of straw, with a lawn on the roof, sheep fleeces for insulation and heat from the ground or a boiler fired with sawdust pellets – this is a vision of the future, not for some third world country but for our still green and pleasant land.
Profound changes to the way we build and then run our homes will have to be made – and made quickly – if Great Britain is to lift itself from the bottom of the European energy efficiency league; and house-builders are at the sharp end of this reality.
The bald truth is that we are squandering resources. Our houses use three and a half times as much energy as those in, for example, Germany and Denmark. Government ‘carbon-budgets’ seek a 50 percent reduction in carbon dioxide emissions by 2050, if we still have a planet to save by then..
Help is at hand in Wales, where for more than 30 years a team of dedicated scientists and volunteers has been exploring and developing, or eliminating, alternative building and energy methods. Many of the ideas thought to be radical years ago are now common practice.
The Centre for Alternative Technology (CAT) in Machynlleth, the ancient Welsh capital, opened its gates to the public back in 1975. I was impressed by the innovation and enthusiasm back in 1982, but was astounded by the progress made when I made a second visit recently.
The centre, in a former slate quarry, is blessed with mountain streams, which help fire up some of the energy projects and also power a water-balanced funicular-style cliff railway. The CAT, in Dovey Valley, is in the foothills of southern Snowdonia, close to Cardigan Bay, providing a fun and educational day out for the family.
Many of the techniques currently being explored are not new – indeed, much of the work at CAT revolves around materials and methods that have been used for centuries. It is often a case of ‘looking forward to the past’.
There’s nothing new about rammed earth walls, for example. Ancient cob cottages built by labourers trampling mud and straw have survived for hundreds of years, provided they had “a good hat and boots” (roof and footings). Visit Norway, as I did recently, and you will see plenty of grass-covered roofs.
Taking shape at the centre is WISE – the Wales Institute of Sustainable Education, a large conference hall that is being built using many of the materials and techniques developed at the centre. It will, of course, be orientated to take full advantage of solar gain from the southern sun and the main structure will be of timber frame with hemp and lime infill.
Foundations will use ‘limecrete’ rather than cement based concrete – cement now being known to account for more than five percent of global carbon dioxide emissions.
Some of the techniques being tested at CAT may at first sound bizarre, but the policy there is to leave no stone unturned in the quest for a more environmentally friendly lifestyle. These ‘stones’ include not just energy conservation and generation but also conservation of wildlife and a more organic approach to food production. Visitors can go underground to get up close and personal with worms and other micro-organisms.
Lucy Stone, a spokesman for the centre, is in no doubt that the world is at last listening to them.
“The government’s declared quest for zero carbon homes by 2016 must spur the construction industry to give greater priority to the energy performance of housing,” said Miss Stone.
She added: “Energy generation is considerably more expensive than energy conservation, so simple economics dictate that a more rigorous approach must be taken to energy efficiency.
“If and when total energy use is reduced, then the renewable element can be met by smaller, cheaper systems.”
Among the energy saving building techniques being developed and used in its public buildings are grass roofs and rammed earth bricks covered with hemp and lime render. These, unlike traditionally fired bricks and clay tiles, use hardly any energy in manufacture. To the visitors, of course, a wall is a wall and few realise that what they are looking at is a tidy heap of mud.
Bricks may be beautiful to behold, but a kiln uses huge amounts of energy in the baking process. So they may become museum items and house-builders will have to use other materials to give their houses what estate agents call ‘kerb appeal’.
To be fair to the house builders many are now singing from the same hymn sheet and paying rather more than lip service to conservation issues, partly because they are obliged to but partly, also, because it is seen as good marketing practice.
More emphasis is being put on gardens and estate design. Reed beds and ‘grey’ and rain water cisterns are being installed, as are bat and bird nesting boxes.
One enlightened house builder enlarged areas of wetland and woodland with a series of lagoons, streams and lakes, at a development in Essex, partly to control water dispersal but also to provide diverse habitats for wildlife.
Meanwhile, another has built an experimental eco-village near Chorley, where wind turbines, solar panels and geothermal technology are being tested. The seven so-called ‘eco-smart’ houses produce a staggering 16 tonnes of carbon emissions a year less than similar ones without them, but they cost as much as 10 percent more to build.
With annual savings of only about £270 the ‘pay-back’ period would be three score years, even if nothing went wrong with the ‘gizmos’ – so some form of government grant would have to be introduced before schemes such as this became commonplace. House buyers may want to save the planet, but they need to save money as well.
So the moral is to build with cheaper but more energy efficient materials. At CAT the boffins reckon they can build a well-insulated house that cuts the cost of heating by 80 percent. Careful orientation helps, as do conservatories capturing the sun’s energy.
So homes built of earth or waste materials such as straw bales, insulated with sheep fleeces and capped with soil, grass and flowers could soon be the norm. Then and only then we can start thinking of more economical ways of generating our electricity.
After all, as the CAT reminds us, a third of the world’s houses are built of earth and 30 square metres of vegetation on the roof would absorb carbon dioxide and enable one person to be self-sufficient in oxygen.
For more enlightenment write to the Centre for Alternative Technology, Machynlleth, Powys SY20 9AZ, phone 0845 330 8355 or visit www.cat.org.uk and prepare to be amazed.
