WE PICKED UP SOME FREE END-OF-VEIN PORTLAND STONE AT THE QUARRY
Sutherland Lyall talks to Andy Francis and Phillip Naylor of RH Partnership, along with Taus Larsen of the Low Carbon Network, about how a lecture by a US eco-architect led to the revolutionary earthship housing scheme landing in Brighton.
First you have to know that an earthship is not a hi-tech capsule.
It is quite the reverse. A paraphrased official description from www. earthship. org runs: 'A completely independent dwelling unit made from materials that are indigenous to the entire planet? designed to reduce our impact? by utilising recycled and low-embodied-energy materials, passive solar heating and cooling, a photovoltaic power system, catchwater, solar hot-water, grey-water and black-water treatment systems.' If you add the earthship's aim to have zero-energy input, this sounds just the sort of house that the green wing of government wants us to build.
PRACTICAL Unlike proselytisers for many nice architectural ideas, the promoters of earthship do not make wild claims. They do not say earthships are going to solve the current housing shortage, although they would like to help. One good reason is that earthships take up quite a lot of land. Nor will earthships solve the first-time buyer problem because, despite appearances, they are not particularly cheap to build. In any case, the cost of land means that low construction costs tend to figure less in purchase prices than innovators might hope. Nor would earthships really make a serious dent in the used car-tyre mountain, even if each earthship does use as many as 1,500 tyres in its construction. In addition, there is probably always going to be, as at Brighton, a heavy reliance on volunteer labour to build earthships. Nevertheless, this first English example (the original is in Fife, Scotland) has potentially important lessons for the design of sustainable architecture in general: Brighton University has installed many probes in the construction to monitor its performance as part of a Europe-wide research study.
THE MODEL Earthship Brighton started with an inspirational public lecture in Brighton by US architect, Mike Reynolds, who has been practising biotecture, the architecture of sustainability, for 30 years in the New Mexico desert. At the meeting were a number of local people, including Andy Francis, who was then an architect with RH Partnership. Francis says: 'We had known about earthships for a while and at the meeting we were all asked if we were interested in starting one in Brighton.' Among a lot of people, he was, and the Low Carbon Network was soon inaugurated, with Francis as one of the directors.
The standard earthship design consists of a main room, fronted on its south side by a sloping-glass suntrap with a circular office to one side; earthship enthusiasts know these features respectively as the nest, the sun space and the hut. The latter would be a bedroom if this had been built as a house. The north and west sides of the building are wrapped by a berm whose inner, slightly sloping wall is constructed from used tyres, filled with local earth and heavily plastered. The hut/office has vertical walls of filled, used tyres and is plastered internally and outside. The various roofs are supported by timber trusses and rafters. As potable water is harvested from them, the architects had to choose a membrane rather than the sedum or turf you might have expected. The glazed suntrap has an internal garden bed at the base of a glazed wall which, like the nest/meeting room's south wall, has standard concrete footings. The floors have a thermal-mass function - particularly the floor of the suntrap - and so are made of concrete.
At Brighton, a variety of recycling measures has been or soon will be implemented, including four storage tanks donated by Polypipe, each containing five kilolitres of water, built into the berm at the back.
Architects may cavil at a used-tyre main structural element, especially when the tyres just sit on the local Brighton chalk, scraped back to an undisturbed layer. But we are too used to complicated and responsibility-proofed modern foundation systems. Something like this construction method (although not, naturally, with tyres) was used for most of our housing stock until perhaps the late 1930s. It turns out that earth/chalk-filled used tyres spread relatively light domestic loads very efficiently - a proposition which building control was not disposed to fault.
As the steep, internal side of the berm, they worked successfully as a retaining wall.
With local enthusiasm for an earthship at a pitch, there was a need for a site and a client. Both were at hand. The allotments in Brighton's Stanmer Park were operated by an umbrella organisation called Stanmer Organics. It needed an office, and somewhere to meet and to shelter from bad weather. Funding for the whole scheme was raised off the back of that: ú1.8 million came from the government's landfill tax credit scheme, administered by the Royal Society of Wildlife Trusts.
When you ask, it turns out that the contract between the client and the builders, Low Carbon Network, is based on a handshake. No surprise there because everybody was on the same side. It was slightly complicated by the fact that the Low Carbon Network, which received the major grant funding, was a member of the client Stanmer Organics collective. Low Carbon's first project manager was a Part 3 student, Taus Larsen. He and his successor since early 2004, Mischa Hewitt, have, like any main contractor, worked at sourcing materials from both the usual channels and, in the earthship's spirit of recycling, builders' skips.
Other traditional tasks included controlling costs and coordinating the workforce. The fact that the latter was largely unpaid complicated rather than simplified things. About ú25,000 of the ú85,000 materials budget represents donated products and the ú85,000 labour bill included the cost, for a week, of US guru Mike Reynolds, with ten of his earthship-savvy team.
ARCHITECT'S ROLE RH Partnership's involvement was mainly unpaid, but it was essential. As Phillip Naylor (Francis' successor at RH) points out: 'Mike Reynolds was not interested in British regs.' Although this was an experiment that was located on the edge of an allotment, it had to be built to the same standards as any other building - and had to make its passage through planning and visitations by BCOs and regulatory inspectors. Hewitt says: 'RH Partnership has held the bureaucratic processes together.' So the architect's role has been more that of a mother hen to the project: RH has provided gravitas and acted as both a backbone and a facilitator. It has also had help: this is a bog-standard earthship design produced by Reynolds and his team in the US. The structure has been checked by local structural engineers BEP, and the sustainable services by Uckfield-based services engineers John Packer Associates - and the power systems were largely specified by Howard John of main services supplier Southern Solar. When Francis moved on to another practice, Naylor took on the architectural oversight at RH. The cast for quite a small building has been large and changing.
HOW LONG IS A SPECIFICATION?
One of the architect's big tasks was to produce a formal specification which translated the US materials of Reynolds' design into available materials that were available in the UK.
However, it is in the nature of this kind of project that this was to be modified by exigent circumstances, such as the fact that firms decided to donate materials or that somebody discovered a new material. For example, Larsen came across eco-cement, the idea of Tasmanian John Harrison. He discovered that 30 per cent of the cement in concrete can be substituted by magnesium oxide which is abundantly available in Australia and which Larsen sourced as a manufacturing by-product from Hartlepool. He explains: 'We got some cubes tested and found we were getting high enough results to use it as a slab with a bit of steel in it.'
He points out its claimed virtues: higher tolerance of recycled aggregates such as y ash and self-plasticisation, so it is liked by builders because less water is involved. Also, as it is fired at a lower temperature than cement, it has less embodied energy. In practice, eco-cement was mostly used for non-structural -lling between the tyres and external rendering.
Another case was the roofing, which had to be suitable for potable water. Larsen says: 'We looked at a wide range [of roofing materials], such as EDPM rubber, used on US earthships, but did not go with it because we were not too sure about the quality of water coming off it. We talked to Sarnafil and they were keen, but they suddenly realised that we were serious about the rainwater bit.
They were not sure about whether you could use it for collecting drinking water. We took the view that it could - but then we found that the membrane we eventually used, a single-ply Flagon EP/PR TPO, happened to have WRAS (Water Regulations Advisory Scheme) certification.'
HERE AND THERE Larsen goes on to explain that: 'Sourcing was a really big issue.
I found this amazing fired-clay masonry block with an incredible U-value. It is German, but there is no source in England so you would have to get it from Bavaria, and you need certification.'
However, other masonry was donated to the project.
Larsen says: 'We got end-of-vein Portland stone free from Albion Stone, which were partial batches of high-quality Portland stone which were dif-cult to sell. We hired a lorry and picked them up from the quarry.' The team asked masons for broken worktops and headstones and used them as crazy paving in the sun trap.
Day-to-day circumstances provided lessons. The structural engineers originally specified a self-healing Bentonite clay/ geotextile sandwich from Rawell Environmental as a DPM for the slabs. Larsen says: 'It is a good material, but it is also expensive and difficult to look after on site it once it is laid. After a few weeks underfoot, the costs really hit. So, we had to have a dialogue with the building control officer and the engineer.' Eventually the polythene solution was agreed and three layers of Visqueen 1200 heavy gauge were substituted in the main room.
SERVICES There are three rather than two taps over basins, the third for drinking water. Water used for washing-up, baths and showers goes into the gravel of the grey-water planters inside the south-facing glass wall. It feeds the plants, which oxidise the water that goes back into a sump at the bottom of the planter, and is then pumped up to the ushing system to join other recycled grey water. So the water is used three times: for showers, plants and ushing. Instead of pumping all the water up to a header tank, it is pumped only when a tap is turned on - reducing overall energy use.
The DTI-accredited 900W H40 Whisper wind turbine will go next to the building, and will charge 40 deep discharging batteries, designed specifically for solar and wind sources. An array of photovoltaic cells along the back of the main roof are from Unisolar and have, according to Larsen, 'a matt non-glass and plastic finish'. He explains that: 'There is local vandalism [on this allotment/parkland site] so we went with something rugged - which also works well in diffuse light.' They power lighting but are supplemented by a mix of triple-glazed skylights and sun pipes which double as ventilation - gifts from, respectively, Ubbink and Monodraught. With a berm for a north elevation, overhead lighting at the back of the building is essential. The massive oor in the sun trap acts as a heat sink behind the double-glazed and argon-filled Low-E Solaglas panels, provided free by Saint-Gobain.
Hot water Filsol twin solar cells are twin-coil at-plate collectors and heating is backed up by an Extraf lame 15kW wood pellet stove. There is a catch here, Larsen explains: 'Pellet supply is a tricky one because, although there is a huge market in Europe, it is only emerging here. It is on the cusp of being a big thing but it is still chicken and egg. Our pellets come from Wales. They are about 1cm long by 5mm diameter. They ow like liquid.'