The Eco Refurbishment
The work started on 25th January 2006. The first step was to complete all the demolition, and to sort out all the structural elements of the building before we could start building up again.
Foundations had to be dug inside the house for the huge steel 'portal frames' required by the structural engineers.
The steelwork and reinforcement work around the building cost around £15,000. The Portal Frames were needed to give
the building stability, since it no longer had the rest of the terrace to hold it up.
Another big problem was damp. When the neighbouring house had been demolished, all the rubble was heaped up on the site and a bit of top-soil laid over the top. This became one of Heeley City Farm's fields, and it finished up being up to a metre above the floor level of the building. Which sucked up the water like a sponge. We couldn't drop the level of the ground outside (though we'd have really liked to) because the gable wall built when next-door was demolished wasn't sitting on very much...
So we had to 'tank' the ground floor. This keeps the water from outside from getting inside.
Once these works were done, the most important thing was to insulate it, to stop heat from escaping. This is the most important thing for any building. Before you think of how you're going to heat a building, sort out how you're going to keep that heat in.
Because we wanted to show lots of different ways of doing the same job, and some of the advantages and disadvantages of those different ways, we used 8 types of insulation through the building.
Four types were used on the solid external walls:
Gyproc Thermal Board, which consists of solid plastic foam insulation stuck on to plasterboard. This is stuck to the walls using
adhesive 'dabs'. You need about 50mm (2") to increase the wall's insulation value by four times.
Knauf mineral laminate, which consists of fibreglass insulation stuck on to plasterboard. This is fixed with 'dabs'
and screws. It has approximately the same insulation value as the same thickness of Gyproc Thermal Board.
Innotherm, which is a cotton insulation made from waste denim. This is fitted between timber 'studs' and topped
off with foil-backed plasterboard. You need about 100mm (4") to get the same insulation value as the 2 products
above, but on the plus side its embodied energy (the energy used to process and transport it) is far lower.
Thermafleece is processed sheep's wool. It is fitted in the same way as Innotherm and has approximately the
same insulation value.
Two types of insulation were used in the ground floors: Solid plastic foam, and a product based on
wood-chips.
Two types of insulation were used in the pitched roofs: Warmcel (recycled newspaper) and Innotherm (see above).
And finally, the cavity walls of the single-storey extension on the ground floor were filled with mineral wool (a generic term which refers to either fibreglass or rockwool) which is blown in under pressure. If you are lucky enough to have cavity walls (common after 1920) you can get cavity wall insulation done absurdly cheaply thanks to subsidy from energy companies.
We had decided to heat the building with a 'Ground Source Heat Pump', which draws heat from the ground,
'multiplies it', and uses it to heat the building. See the Ground Source Factsheet
for details of how they work.
Again, this required a huge amount of work, mainly in digging the trenches in which 240 metres of
'ground loop' would be laid.
As much use as possible was made of recycled materials. Up to 3 tonnes of timber from steelworks
pallets was used inside the house. These pallets would otherwise be used once only, then shredded and composted.
Where possible we avoided treated timber, so the pallet timber was used exactly as it stood. We strongly believe that if you remove the pre-conditions for rot (poor ventilation and relatively high moisture content), you won't get it, so you don't have to treat against it. (We don't give guarantees, though. Ask us in 25 years' time!).
For similar reasons we used untreated timber gutters. Usually it comes pressure treated with preservative. Again,
we believe that if you maintain timber gutters properly (regular maintenance with a paint-brush and bitumen paint),
you keep the moisture out of the timber completely, so you don't need anti-rot treatment. Time will tell, and it
will probably be Nick up the scaffolding each year!
For readers who don't come from the Yorkshire area, this talk of timber gutters may seem like complete nonsense. An architect colleague of my father's accepted that timber gutters might have existed in the 1800s, but refused to believe they were still made. I went down to my local Sheffield timber merchants, bought a piece and sent it to him. Tens of thousands of terraced houses still have timber gutters.
High performance timber windows were specified, using untreated timber. These are glazed and usually spray-painted at the factory, giving them a much better start in life than windows stored on a damp site for months. Painting intervals can be increased, and many of the arguments for plastic windows just fade away.
We settled for double-glazed units which just meet the Building Regulations, with a u-value of 2.0. See the U-Value factsheet for an explanation of u-values. We could have got a much better u-value by specifying units filled with an inert gas such as argon or crypton, or triple-glazing, but we wanted to show the performance of more 'off-the-shelf' products.
The majority of the windows are softwood. The Fire Officer insisted on window frames and glazing with a half-hour fire resistance where the wooden access deck ran underneath. It's possible that a softwood unit might have passed, but we'd have had to ask the manufacturer to burn one to find out! Reluctantly we used hardwood, requesting sustainable sourcing.
Rainwater from all the gutters runs, via galvanised Steel down-pipes, into a 1500 litre WILO rain harvesting unit, from which it is pumped on demand to serve the WCs and an outside tap.
Hot water will be pre-heated by a Schott evacuated tube solar collector mounted on the South-East-facing gable. When funding is available (at time of writing, we wait for the government's Low Carbon Buildings Programme to become fully operational) we will have a 2-kilowatt photovoltaic (solar electric) array on the South-West-facing front roof. This will produce approximately 1500 kilowatt-hours of electricity per year.
We have planning permission for the installation of a 'Windsave' building-mounted wind turbine, but sadly currently (May '06) these are not yet available on the non-domestic market. The company has just announced that it is taking orders for domestic installations on a first-come, first-served basis, for installation from Autumn 2006.
More recycling can be seen outside, where the fence is made from re-used steel and bicycle wheels, and a set of railings bought from the scrap merchant. We bought the sink from the same place!
The concrete block paving to the front drive was bought second-hand (if you must use concrete - which has very high embodied energy - use it second-hand if you can). The access deck will be made predominantly from reclaimed timber, treated with boron-based preservative.
Volunteers have been an invaluable part of the build.
There is a full (we hope) list in the Thanks section, but here are a few photos.
A number of long-standing volunteers have been involved right from the demolition stage to date,
and others (such as this team from Yorkshire Forward, who spent a day decorating) came more recently.
Update July 2006
The last entry (above) was made in early May 2006. Since then the Centre has come on in leaps and bounds. A lot of hard work from 'White Horse, Green People' landscaping and our dedicated team of regular volunteers, and a few visiting teams, means that most of the external paving work is complete.
While we were digging up the tarmac and concrete of the yard we discovered, underneath, the 1880's cobbles. These were re-laid where necessary, having been damaged by having a number of trenches dug through them, but wherever possible we left them in their original positions. That's our excuse for the undulating nature of the yard!
Structural engineer's requirements meant we had to lift 4 4.2m-long purlins up scaffolding and 'post' them into holes in the gable wall. Once fully positioned they will help to support the solar panels on the front roof.
Students of Sheffield Environmental and Horticultural Training built part of the new timber walkway, built 2 retaining walls and built a new fence at the end of the field where we had 'stolen' the corner for our new access to the building. The resulting small plot next to the Energy Centre will soon be home to an experimental solar wood-drying kiln.
A kind donation of recycled plastic section means that our cycle park will soon have a covered shelter with a green roof. Any water which does run off the roof will be collected in a water-butt and will be used to water the raised beds built of railway sleepers by volunteers from the Department for Education and Skills (DfES). More DfES volunteers took on painting, floor varnishing, barrowing tonnes of hardcore and sand, and helped to lay the block paving for the new front path.
Working parties which often stretched into the night have resulted in most of the internal paintwork being finished, including a fantastic wind turbine mural by Pete Dyal. Helen chose the internal colours which have received much favourable comment, and Giles' work with bicycle wheels and a welder has to be seen to be believed. Peter Conn's furniture made from recycled timber will be one of the first things to catch the eye as you enter the Centre.