Open day 23rd September

After a long and challenging refurbishment the Barbrook Passivhaus project is now complete. The groundbreaking challenge to transform a pair of North Devon concrete semis in Barbrook, Lynton into two of the greenest homes in the UK began last year. North Devon Homes and Energy Action Devon won a share of £17 million from the Technology Strategy Board’s ‘Retrofit for the Future’ programme to carry out the project.

We would like to invite you along to an open event on Friday 23rd September at 11am to view the properties and learn about the technologies used. As the location has extremely limited parking and access we will be holding the event at a venue near to the site and shuttling guests to the properties in small groups.

Places are limited, if you would like to attend please contact Nicola Smith at North Devon Homes before 12pm on Friday 16th September.  Call 01271 312500 or email nicola.smith@ndh-ltd.co.uk.

This is a residential area with limited parking, please do not arrive without booking.

 

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It’s 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!

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

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scaffolding has come down!

The scaffolding has now come down to allow the digging out and construction for the boiler house. The boiler house will have its own electricity supply which will be billed directly to North Devon Homes who will apportion the cost based on the heat consumed by the tenants in each property. The apportioned cost of the electricity and the pellets will be charged to the tenants in a regular service charge.

No. 8 has now been painted and is not far from being finished. No. 7 however is further behind. Without the MVHR system to dry the properties out the plaster has taken longer to dry and delayed painting. The only electricity on site has been a petrol generator so it’s not been possible to run a dehumidifier over night, and the windows obviously need to be closed for security.

The result from the second air test was 1.4, which is still not low enough to reach the target for passivhaus. It is a big challenge, to achieve this in retrofit but it should be possible and we’ve taken great care design a belt and braces air barrier, which is in fact two layers. Our inital air test have shown some air coming in through the sockets which are all in the partition walls. This means that air is getting into the partition walls, and we don’t know where from. At the moment it seems our only option is to seal up the sockets themselves, but this is by no means an ideal solution. The partitions do have mineral fibre insulation in for sound deadening, which will help to restrict the air flow. These houses are built for the future so we wanted a long term solution, if only the sockets are sealed the air tightness can easily be compromised further by the tenants putting up picture hooks, or an electrician in a few years time… Hopefully we will have a better solution, but time is running out.

On the plus side the cedar cladding does look beautiful against the wooded backdrop, and the houses feel suprisingly light and airy inside despite their small size and deep window reveals. We’ve encouraged the tenants to choose light colours for the paint and carpets, which has really helped.

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kitchens going in

Now we’re nearing the end of the build things are happening very fast, the kitchens are going in, as are the skirting boards.

We brought in extra men to tile the roof to speed things up, now the roof is tiled and the building is weather tight it means we can take down the scaffolding. Once the scaffolding is down the boiler house can be built, then the Okofen pellet boiler can be installed, it isn’t on site yet as there is no secure space to store it, so it is being held at the warehouse.

 

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progress!

Things are moving on very quickly now, as you can see from the photos below, the internal plastering is nearing completion, windows are all in, timber cladding is being fitted, and we’re making preparations for the air test which will now be this Friday 24th June.

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Warmcel demo day

This week began with a long drive up to Lynton to meet Nigel Bosanko and Sarah Price from Excel Industries who manufacture the Warmcel insulation we are using at Barbrook. Sarah booked a room at the Lynton Cottage Hotel which had outstanding views, lovely food and was a great venue for a small meeting.

We were joined by John from North Devon Homes, and Paul and Nikki from Ecofill Insulation who are the BBA accredited installers of Warmcel in the area. Also Adam Dadaeby, PH designer, Paul Elliott, Sustainable Energy Officer at Plymouth City Council, and Richard Squire, Private Sector Housing Officer from North Devon DC.

Nigel gave an interesting presentation about how Warmcel is made, often when they insulate schools the collect the newspaper from the school in advance and then process it and use that to insulate the school. If there are any changes to the building many years later the material can be collected, reprocessed and reinstalled somewhere else.

The Warmcel is completely safe to touch, and made from a waste product, which could otherwise be sent to landfill.

The main reason we chose Warmcel is because it offers a complete void fill which is really important in passivhaus to prevent gaps in the insulation and avoid cold spots and condensation. Later this year we’ll be able to double check the coverage when BSRIA come and do the thermal imaging. It’s a lot easier to fit than batts of insulation which would require cutting and very careful fitting to avoid gaps.

Once on site we met Rob, who has been installing Warmcel for years, so it was reassuring to watch him methodically fill the timber frame, and then feel how densely the insulation filled the void. The pump which Ecofill use allows them to set the density of material based on the size void which requires filling.

Other developments:

Inside the houses, there are now electrics and plumbing. The triple glazed Ecopassiv windows and doors are in, and looking lovely. Ian and Ian from Southcombe Construction (our local sub-contractors) have been working really hard to make sure the air tightness details are carried out properly and our first air test is on Friday – so fingers crossed.

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external timber frame nearly complete

The timber frame which holds the insulation is well underway. The frame was designed to accomodate 350mm Warmcel insulation on the outside of the original concrete walls.

As we’ve become accustomed to, there were some challenges with this too! In the design stage, Clive our architect worked with Teploe Ties to design a brand new type of fixing so we could attach from the concrete wall to the timber frame. There is a photo in the gallery below.

At the rear of the building, the wall bows out where the concrete wall meets the concrete bank of the river, this means that the steel fixings have to be shaped on site one by one. The frame was designed with the fixings at 600 centres, but the concrete we need to drill into at 600 centres ranges from solid pebbles to empty voids between pebbles. We’ve consulted the structural engineer and managed to overcome this problem to get the frame up.

The asbestos shuttering on the houses formed horizontal channels all around, so these have been be filled in to prevent air circulation. We then fixed OSB onto the surface using grip fill and mechanical fixings. The grip fill was applied in a grid pattern so there are no large pockets of air behind the boards. Ideally the whole OSB should be covered, but we decided this was a suitable compromise given time and resources available. The OSB joints will then be taped.

The timber frame is then fixed onto the outside of this. Because there is asbestos in the walls, the drilling will be accompanied with a hoover. Dust is also minimised because the OSB is already fixed on the outside.

The scaffolding has been adjusted numerous times throughout the build, currently it is far enough away from the external walls to allow the timber frame to be built up between. This meant our H&S inspector requested we issue full arrest harnesses, and you can see the guys wearing them in the photo as they fix the OSB.

The window boxes need to be made specifically for each window. Elliot, our carpenter, has  measured all the windows and made up boxes for each one individually. Then the boxes will be trimmed in situ as the original walls are slightly irregular.

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Warmcel installation demo

Warmcel have organised an installation demo to take place at the Barbrook Passivhaus on 23rd May.

Warmcel have donated recycled newspaper insulation for the walls and roof, and we would like to invite you to come and see the insulation being installed and have an opportunity to hear more about Warmcel. The insulation will be blown into a custom designed timber frame attached to the building with specially adapted teploe ties. The roof structure is also new and designed to accommodate the depth of insulation required.

Due to the size of the site places are limited, we would be particularly glad to welcome architects, developers and other housing providers. Booking is essential, please do not turn up on the day without prior arrangement.

Click here to open the invitation, or contact Sarah Price at Warmcel on 01685 845 203 or email sarah.price@excelfibre.com

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Floor slab complete

The floor slab is now complete, we had to change the original spec because the partition wall was load bearing. The slab build up is now:

  • 22mm t & g chipboard flooring
  • polythene vapour barrier and separating membrane [and additional air tight layer]
  • 250 expanded polystyrene insulation
  • 150 rc slab
  • 1200g dpm
  • 150 sand blinded hard core
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Contractor training day

On Thursday 28th April we held a training day for all the contractors on our site. Having never worked on this type of project before they were all keen to learn more about passivhaus and how to make sure they achieve the air tightness target.

The day was organised by new company Passivhaus Homes, http://www.passivhaushomes.co.uk/ and held at the Totnes Passivhaus. The training was put together specifically for us at Barbrook, but anyone else interested in such training should contact Janet at PHH. We were lucky to have four experts on hand to present and answer questions:

  • Janet Cotterell, architect an PH designer
  • Jonathan Williams, experienced builder specialising in sustainable materials and now PH
  • Adam Dadeby, PH designer and client
  • Sally Godber, PH designer and M&E engineer

The day started looking at the principles of PH and hopefully gave the contractors a better understanding of the project and why we’re doing things the way we are. We then had opportunities to talk through specific details at Barbrook, with our architect Clive Jones, thinking about how to ensure continuous insulation and air tightness. There were a lots of samples of the specific materials that the contractors could look at, and Jonathan and his men had some great tips on using the tapes and grommets in practice.

The day was a great opportunity for the contractors to talk to each other, and ask the experts questions.

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