New Build Bungalow,Bishopston
A timber frame annex conversion at the end of the garden using existing garage as part of the 40m2 construction to provide a future dwelling for the owner's mother. The timber structure has been highly insulated resulting in an airtight envelope.
Construction: New Build Timber Frame
Age: New Build
This 40 square meter timber framed annex is being built at the end of the owner’s garden using the existing garage as part of the construction, providing a main living area with kitchen, bed room and en-suite shower room with a separate toilet.
As an engineer, David wanted to create an environmentally high spec dwelling and has achieved AECB silver standard. He is aiming to build as close to Passivhaus as possible, while acknowledging there will have to be some compromises due to budget. That said, the only real compromise David feels he has had to make is on the level of glazing.
Otherwise, the unit has been insulated to the highest standard and precise care taken to ensure airtightness at every stage.
Particularly interesting is the trade-off between getting the envelope of the building sealed to the highest standard, without sacrificing too much internal floor space and height.
This is particularly challenging as the design includes a ‘service area’ in the walls, with pipes and cables running behind the membrane to ensure no heat is lost through the gaps.
To save space David has carefully planned the layout of the house, ensuring appliances are installed in such a way that the heat recovery system can store and retain as much heat as possible. Careful research also goes in to sourcing materials that can save space, including the discovery of flat ducting for the MVHR system – saving valuable inches of ceiling height.
With the project still in progress this is a valuable opportunity to take a look inside the walls at the many layers and stages involved. In particular the level of care and detail that can go into taping the house thoroughly.
In January 2018, David started the project of constructing this timber frame at the end of his garden: “The goal was to create a dwelling for my mum, she is 90 and still fully independent, but we are planning for future circumstances.”
“I’m an engineer and interested in modern construction so have taken this on as a project and learning curve to make and environmentally high spec home.”
He worked with an architect to draw up the blue prints and set about planning and researching how to get the build as close to passivhaus standard as possible.
With so much information and conflicting opinions about best practices online, David found a vital resource in Timber Frame Construction: Designing for High Performance, by Robin Lancashire & Lewis Taylor, which he couldn’t recommend more highly.
Having undertaken almost all of the build himself, David’s key recommendation is: “Get builders in to help with construction, but do the airtightness and taping part yourself. That way you can take your time, it’s well worth investing as much care as you can in ensuring the membrane and tape are sealed and tight.”
To some this may seem a huge undertaking alongside his full time job, but David has enjoyed the project so far: “Building the stairs was a highlight and adding the timber cladding was particularly satisfying!”
Although he does admit it wasn’t quite as fun when excavating the hole for the 100L macerating waste tank in the garden.
I’ve discovered just how many layers there are between outside and inHomeowner, 2015
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How this house performs
The chart for 2019 case studies shows the household’s annual energy consumption and generation data compared to Ofgem’s Typical Domestic Consumption Values - industry standard values for the annual gas and electricity usage of a typical domestic consumer. For more info click here.
With the project still in construction it’s too early to project the energy usage for the house.
David hopes to be complete by Christmas 2019. Meanwhile, work is ongoing, with the attention now turning to installation of the Mechanical Ventialtion with Heat Recovery system.
David's vital resource: Timber Frame Construction: Designing for High Performance, by Robin Lancashire & Lewis Taylor, which he couldn’t recommend more can be found here highly.https://bookshop.trada.co.uk/bookshop/view/8245D2F0-B0D4-468C-B166-B4910...