Down to earth
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Philippa Ward previews the best sustainable builds, starting with an earth-sheltered development designed to break new ground
Long Sutton earth-sheltered social housing
Location Lincolnshire
What Three three-bed and three two-bed earth-sheltered houses
Social landlord Lincolnshire Rural Housing Association
Architect SEARCH – Sustainable Ecological Architecture Ltd
Code level Pre-assessment rating is level 5
Funding Social housing grant
Jerry Harrall, the architect behind the Long Sutton project, has some dramatic claims to make for this scheme. ‘It will revolutionise social housing management,’ he enthuses. ‘It will be the first time that any social housing scheme has achieved autonomy — the tenants could even make money.’
The aim is to release tenants from being dependent on the vagaries of the economy, allowing them to generate and manage their own energy and water — even sewage will be treated onsite. The houses will have their own gardens and allotments so that residents can grow their own food.
Mr Harrall is developing the theories he worked on in the Honingham sheltered earth scheme, which was the first of its kind in the UK and cut tenants’ bills to 20 per cent of the UK average.
These houses should not need heating and should generate a net surplus of electricity annually. The initial standard assessment procedure rating is an extraordinary 105a. ‘The assessors didn’t know that you could get over 100 — it has generated a negative carbon dioxide figure,’ says Mr Harrall.
But the architect doesn’t recognise the concept of ‘zero carbon’, as contained in the code for sustainable homes. ‘The code encourages the use of mechanical space heating and fossil fuels in central heating: it is carbon offsetting.’ In this scheme, he has gone for zero heating, natural ventilation and 100 per cent renewable energy to create a community of the future.
Proving fruitful
Virtually all the plants on the site are fruit-bearing, which is good for both humans and wildlife. The sewage discharge is almost potable and goes into a balancing pond which is fringed with plants, creating another ecosystem. The planting on the earth bundling will make the buildings net absorbers of carbon dioxide.
Passive designs
Each building is oriented south, with large areas of glazing on that side. Each dwelling will be insulated with earth on the east, west and north elevations. The south elevation will have a timber screen with no cavity wall. There will be no earth cover on the roof. Passive stacks in the kitchens and bathrooms cut out the need for mechanical ventilation.
Material change
Some external areas will be exposed and rendered with hemp. The earth bundling around the homes will be planted with English ivy. Windows will be made from softwood and painted with linseed oil-based paint.
Play area
The private drive is designed around the concept of living streets – there are no lines, no kerbstones, no gullies and no metal surfaces. Pinchpoints slow traffic and the central island, with its vertical wind turbine, is lozenge-shaped – meaning it won’t used as a roundabout.
‘Everything is geared to make the drivers question their manoeuvres,’ says architect Jerry Harrall.
Hot stuff
A combination of passive solar gain, human occupation and secondary heat from household appliances will provide most of the heat required.
Heat is stored in super-insulated roofs and walls – 300mm of Styrofoam, which is a thick extruded polystyrene made by Dow – and emitted to make sure the room temperatures are constant. A back-up underfloor heating system is embedded in the concrete slab floor. Water will be heated with 5 m2 of flat-plate solar thermal panels.
The wind turbine is a Skyrota made by the Limavady Gear Company in Northern Ireland. The photovoltaic panels are Uni-Solar’s amorphous-silicon system.
New ideas
Lessons learned from the Honingham sheltered earth project have led to some changes. There is extra insulation; renewable energy in each building; rainwater harvesting; extra heating from wood burners; an onsite 6kw wind turbine; an onsite communal sewage treatment plant; and passive cross and stack ventilation.
St Austell Urban Village — phase two
Location Cornwall
What 19 homebuy units for shared ownership: six houses and 13 flats
Social landlord Devon & Cornwall Housing Association
Architect/developer Swan Country Homes, working with NBT Consult, Jewell & Co Architects, and Atkins Global
Cost £2.5 million
Code level Ecohomes excellent
Funding Land sold to DCHA by Restormel Council for £1; £660,000 from the Housing Corporation; £190,000 from DCHA’s recycled grant fund; the rest from shared ownership sales
This ambitious low carbon scheme was nearly a TV star. Lined up as part of a series for a Grand Designs TV special on sustainable building, plans for filming fell through at the last minute. But Restormel Council decided to go ahead anyway and opened up a competition for developers to build phase two of the St Austell Urban Village.
Phil Randall, regeneration manager at the council, explains the need for practical solutions: ‘It was a developer-based and not an architect-based competition — we didn’t want fancy designs.’ This was reflected in the final plan by competition winner
Swan Country Homes. ‘It isn’t focused on tons of technical kit — it is down to the building, because if there is a lot of innovation, there may be people living there who don’t operate things properly,’ Mr Randall says. Swan, a small developer based in Devon, impressed with its enthusiasm for the sustainability agenda and its existing contacts.
‘We selected them partly because of their attitude, even though they could be viewed as a bit risky as they are a small developer,’ adds Mr Randall.
It looks like a gamble that will pay off: Swan has looked at the whole life of the products going into the building and has chosen low-key workable solutions rather than experimenting on the future occupants.
The land was sold by the council to Devon & Cornwall Housing Association for £1, with planning approval given subject to the sustainability criteria being fulfilled. Work started onsite in the summer and is expected to be completed by March.
The association is keen to use the knowhow it gathers for other schemes. ‘This is a pilot across the different departments — for example, the asset management department will look at how to set up contracts for the wood pellets and for servicing the boilers, so the arrangements can be rolled out,’ says Richard Connolly, group director of development at DCHA.
No toxins
A key feature is a healthy internal atmosphere, so the development has a breathable construction design. Non-chemical-based paints will be used throughout and the buildings are formaldehyde and PVC-free.
Water world
Low-flush toilets and a rainwater flow system help to minimise water-use.
Plant life
‘We’re looking at a communal allotment area. We’re also installing a brown roof system using local seeds and soil, which will be good for indigenous wildlife,’ says Swan’s Mr Massey.
Keeping track
Swan Country Homes will monitor the houses for 12 months to help residents track their energy and water use.
Feel the heat
The whole block has a combined heat and power biomass boiler, which will be fired with locally sourced wood pellets. ‘We haven’t nominated a preferred supplier yet — we’re spending a lot of time looking at the after-sales support’, says Jonathan Massey, design and construction manager at Swan Country Homes. As well as scrutinising the availability of servicing and parts, Swan is looking at the type of fuel that can be burned – whether wood chip or pellet – and the maximum moisture content in the fuel that the system can take.
Walls
The houses are single-skin construction, which means there is no cavity in the walls. They use a German system of fired clay blocks called Thermoplan, which Swan sourced from Natural Building Technologies. The blocks are honeycombed, which helps them to breathe. ‘They give excellent thermal performance and airtightness but are also a modern method of construction and go up quickly,’ says Mr Massey.
Insulation
The insulation is via Pavatherm, also from Natural Building Technologies. ‘We looked at the whole picture — raw materials, waste implications, transport, usage onsite. We also thought about the future: the longevity of materials is important, since a lot perform well on day one but their performance drops considerably 10 years later,’ explains Mr Massey.
‘Then there is the question of what happens at the end of the building’s life. There isn’t a perfect solution — you have to weigh things up.’
Local materials
Swan has tried to use local trade and local materials, such as sustainable larch timber, grown in Devon and Cornwall and sourced from a local merchant. It has also used reclaimed Cornish slate.
Toxteth Street
Location The New East Manchester pathfinder area
What Plans to refurbish 500+ terraced houses
Architect Mark Hines Architects
Cost £70,000 plus VAT per house
Code level Possible to reach level 4 to 5, depending on investment
There is no question that refurbishment is preferable to demolition when it comes to cutting carbon dioxide emissions. A report by the Empty Homes Agency found that reusing empty homes could save 35 tonnes of carbon dioxide per property immediately, by stopping the need to use more resources for new build.
This is one reason that architect Mark Hines and the Save Britain’s Heritage pressure group have joined together to oppose the demolition and development of Toxteth Street, a typical terraced street in the New East Manchester pathfinder area.
Building new houses is the pathfinder’s favoured solution. It wants Lovell Partnerships to construct 432 new dwellings to level 3 of the code for sustainable homes. The competing visions of new build and refurbishment have sparked some fierce local campaigning, leading to a public consultation in mid-September to consider a compulsory purchase order.
Mr Hines has come up with plans to overhaul the houses with green extensions — an idea that could be used elsewhere as house building grinds to a halt. Among his ideas are tackling the need for family-sized housing by allowing residents to knock through between houses and to choose their own extensions.
‘Save Britain’s Heritage says the terrace houses in Toxteth Street could be saved by spending tens of thousands on each one, but we believe the only way to turn the area into one where people will choose to live, stay and bring up their families requires more significant change regeneration,’ says Eddie Smith, chief executive of New East Manchester, in response.
Will Palin of Save Britain’s Heritage thinks the ideas generated here can have wider lessons. ‘We hope that some of Mark’s ideas can find a place in this or other schemes.’
The proposals
First steps
- Insulate roof, walls and floors
- Fit energy efficient light fittings
- Seal air gaps to eliminate drafts and improve air tightness as much as possible
- Fit replacement windows or install secondary glazing
- Fit an energy efficient boiler — combined heat and power or biomass a Install energy monitoring devices
- Install external clothes drying lines a Ensure external space for recycling, composting, and bicycle storage
Next stage
- Solar thermal panels on south-facing roofs
- Ground source heat pumps in the rear yards
- New concrete floor slabs with underfloor heating
- Photovoltaic panels on south-facing roofs
- Energy efficient appliances
- Low flush toilets and aerated taps
- Grey water or rainwater harvesting system.
Strategy
The refurbishment plan focuses on extensions at the back of each house, which would provide extra space and create a thermal buffer zone. Residents could have input into the design process and pre-fabricated panels would reduce waste.
Power source
Removing poorer quality dwellings would allow space for a combined heat and power plant or biomass district heating system.
Building materials
Structure: Oriented strand board or SIP-clad in timber with hemp block infill to timber frame.
Triple-glazed glass with soft low e-coating with argon gas fill.
Sliding, fully glazed hardwood timber doors.
Friendly surroundings
The streetscape would be redesigned to a homezone plan, making it safer for children to play in the street.
Energy credentials
Based on initial calculations by architect Mark Hines the embodied energy – energy that has been used to make the building – locked into the materials of typical Toxteth Street house is around 35,000kwh/m.
The embodied energy in a new family house is about 90,000kwh. For comparison, a typical £40,000 refurbishment of a three-bedroom semi might use only 15,000kwh of embodied energy. Planting on the extension would absorb carbon dioxide, cutting emissions further.
Cheap thrills
Mark Hines argues that his solution is not only greener, it would also be cheaper than the alternative. Although New East Manchester and Lovell Partnerships, the pathfinder and developer behind the new build plans, will not release figures owing to commercial sensitivity, Mr Hines reckons that the plan to demolish and rebuild would cost £129,000 per house (taking an average new build cost of £1,500 per metre squared), as opposed to his estimate of £70,000 per house.
Childish dreams
Location Redditch, Worcestershire
What Two ‘child-designed’ eco-houses
Social landlord Accord Housing Association
Architect Accord Indesign
Code level Code for sustainable homes level 4/5
Funding Social housing grant, plus extra funds to be confirmed
Sometimes it takes a 10-year-old to come up with ideas to soothe ministerial headaches. How about combating obesity and cutting carbon emissions by powering people’s televisions using exercise bikes? If that sounds too dictatorial, schoolgirl Jennifer Brook has plenty of other suggestions to build the perfect green house, which she put forward for a competition run by Matrix Housing Partnership.
Accord Housing Association, a member of the Matrix group, will be building two homes based on Jennifer’s ideas, as part of an ‘exemplar terrace’ that will also include two ‘recycled houses’, built with 70 per cent reclaimed materials.
The housing association has committed to meeting level 4 of the code for sustainable homes wherever it can, a target which Jennifer’s homes will meet and may even exceed. ‘There is nothing you’d expect to see on a house like this that we won’t do,’ says John Bedford, head of project development at Accord. ‘It will be built to as high a code as we can manage.’
But one of the most amazing things about the house is that schoolchildren like Jennifer are aware of such things as cavity wall insulation, photovoltaic and solar thermal panels and rainwater harvesting — all of which were carefully drawn into her design with colouring pencils and will feature in the finished houses.
Victorian super-house
Location Camden, north London
What Refurbishment to reduce the emissions from a typical Victorian house by 90 per cent
Social landlord Camden Council
Funding Camden Council and Energy Centre for Sustainable Communities. Research funded by Urban Buzz
Research The Bartlett Faculty of the Built Environment, University College London
It sometimes seems that every university has its own refurbished house to monitor. University College London has just joined the fray with a tall, semi-detached Victorian house in a conservation area.
Its project has impressive aims: it wants to slash the property’s carbon dioxide emissions by 90 per cent while maintaining its heritage features.
The resulting data will be measured against a similar unmodified house around the corner, with results on temperature, humidity in the walls, pressure and co-heating and fuel use coming through until the end of winter. The fittings have been made as user-friendly as possible. (see table ‘The Super House’)
Other technologies were considered but rejected owing to:
- Cost: the benefits of triple-glazing or a 3,000 litre rainwater harvesting tank weren’t worth the extra pennies.
- Space: there wasn’t enough space for a ground source heat pump, and plans for low embodied carbon wood-wool insulation were abandoned to save space. a
- Planning and conservation regulations: the over-cladding of the side and rear of the house did not receive planning clearance.
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Readers' comments (1)
Brian lee | 11/12/2008 2:27 pm
A most interesting read, having been in social housing re-furb for the last twenty years its nice to know we are not standing still. I am sat here today pondering if i can afford to put the gas heating on again, its been on once for half an hour to lift my social housing abode above 50 degrees, two hours later and its back to 49. My house is only ten years old with a large North facing rear garden, pretty useless for heatpump technology and i dont think my housing association will let me stick Stryrofoam on the front, back and side. I would like to know though at what depth the temps are above 50 in Mid Devon, i may just dig myself a hole. :)
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