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Barbrook passivhaus project complete!
After a long and challenging refurbishment the Barbrook Passivhaus project is now complete, all that is left to do is for EDF to fit a new electricity meter!
The project was part of Retrofit for the Future to test different methods of cutting CO2 emissions from existing housing by 80%. We chose a particularly difficult site with two semi-detached houses and decided to aim for passivhaus standard because it offered the most holistic approach. The insulation levels are so high the fuel bills will be extremely low, making it an ideal solution for people on a low income.
We chose environmentally friendly materials wherever possible:
- The Western Red Cedar cladding is from sustainably managed forestry at the Crown Estate near Dunster, less than 40 miles away and also on Exmoor. The timber is processed by the Local Wood Shop based in Minehead (on the edge of Exmoor).
- All other timber on site is either FSC or PEFC certified.
- The insulation we chose is Warmcel which is made from recycled newspaper, across the Bristol channel in South Wales.
- The new triple glazed windows are made from sustainably sourced timber.
- Even the kitchens are PEFC timber!
- We used OSB boarding in the timber frame and several other types of woodfibre board, which all have low embodied energy.
- We reused as many of the roof tiles as we could, and these are all on the front roof.
Our aim was to create houses that are not only cheap and efficient to heat, but are also easy to use and provide a healthy and happy home environment for the tenants.
A summary of our key sustainability features is below:
- Continous insulation all around walls and roof with 350 mm Warmcel insulation blown into the purpose built timber frame.
- Dig up the ground floor slab and replace with a new slab including 200 mm insulation
- Digging a trench and fitting insulation below ground around the edge of the slab
- Retaining the existing concrete walls within the thermal envelope to act as thermal mass and regulate the temperature
- Removing the chimneys which acted as a thermal bridge
and conducted heat out of the building - Fitting new triple glazed windows and doors
- Making the houses air tight to prevent unwanted heat loss through draughts
- Installing mechanical ventilation with heat recovery to provide high quality air, at a controlled humidity level - ideal in a damp spot like Barbrook.
- Installing one wood pellet boiler to provide low carbon heating to both properties, installed by Eco-Exmoor based in Parracombe.
- There will be 2 years of in-depth monitoring to test all of the measures we've installed, including thermal imaging and independent interviews with the tenants and contractors.
The site was really difficult, and we faced a number of challenges:
- The site was small so there was hardly any storage space, much of the stock had to be stored off site.
- Access was not very good, particularly in the snow
- The steep bank down to the river posed health and safety challenges
- We knew from the beginning that the first stage of the project would be extensive structural reinforcement works. But when we stripped back the properties, we found the concrete was very rough and needed a lot of extra care and repair.
- We discovered asbestos throughout, and had to close down the site to allow safe removal by qualified personnel
- Although we dug at least three trial pits, there were some surprises below ground too, with unbelievably hard concrete and even large boulders.
So overall it has been an exciting and demanding project, but we have all learned a lot from the experience, and would certainly do it again. The contractors recieved training and one-to-one support on technical aspects to enable them to carry out similar work in the future.
If you have any questions on the project please do not hesitate to contact Sophie Phillips sophie@energyactiondevon.org.uk