UK first oak frame eco-home to meet rigorous Passivhaus standards

Oak Frame Building Costs

Area: Yorkshire
House Type: Oak frame Passivhaus
House Size: 188m2
Build Route: Oakwrights and self-managed
Build Cost: £450,000

In 2016, Phil and Yvonne Garnett set about realising their ambitions for an oak frame, traditionally styled eco-home self-build in Yorkshire. Upon developing their understanding of sustainable construction, their vision evolved into an ambitious project to construct the UK’s first ever oak frame Passivhaus new build home.

Why build a Passivhaus?

There is no actual definition of an ‘eco-home’ apart from a build that includes something that might be considered to be a sustainable feature. What appealed to Phil and Yvonne about Passivhaus is that it is a rigorous, evidence-based energy standard that guarantees low energy usage and a high level of user comfort.  Passivhaus projects are assessed through a calculation package called PHPP (Passivhaus Planning Package) which, in incredibly simple terms, assesses all elements of the build in complete balance with the ultimate aim of achieving a building with a heating (and cooling) demand of less than 15 kWh/(m²yr).  This roughly equates to an average heating bill in the region of £90 per year for a typical 3 bed house, and can then be further reduced by the addition of renewable energy generation but this is not necessarily part of achieving the standard.

When Phil and Yvonne had always admired green oak for self-build but it wasn’t until they appointed Achitect, Andrew Yeats of Eco Arc that their dreams became reality and they embarked on what some may have said was near impossible, building a green oak frame PassivHaus.

A false perception

The benefits of having a Passivhaus are clear, however, there is often stigma attached to Passivhaus homes that they are limited to being unattractive or clunky in their detailing.  The reality is a Passivhaus home can be created in just about any style, and nowhere better demonstrates this than Phil and Yvonne’s traditionally designed oak frame Passivhaus in Yorkshire. This home expresses all the elegance and proportions of a traditionally detailed, crafted oak frame home while achieving the rigorous sustainability standard.

Andrew Yeats, was very aware that airtightness in a PassivHaus was paramount but with the shrinkage of an oak frame over time his design had to allow for this. The solution was to create an internal green oak frame with the columns sitting within the rooms of the house as opposed to them being placed within the insulation layer. The encapsulation panel then wrapped around the outside of the oak frame with an allowance for movement between the two. The main structural load of the upper floor and roof was taken by the frame while the timber panels were self-supporting.

With responsibility for the construction of Phil and Yvonne’s home, we worked with Andrew of Eco Arc to realise the couple’s dream of an oak frame PassivHaus. Although a regular builder of oak frame houses we had never built to Passivhaus standards before but could appreciate the importance of the continuation of insulation for airtightness purposes. We followed Andrew’s design to the letter, following a checklist of Passivhaus features while incorporating the oak frame which proved extremely successful.

The oak frame and Passivhaus

The oak frame itself complimented the approach required to achieve Passivhaus as the internal structural frame resulted in less structure within the external walls, virtually eliminating thermal bridges and improving performance further.  In terms of embodied carbon, timber frame buildings have the least impact on the environment and at the same time allow for a reduced construction time on site. In addition, Passivhaus construction requires an exacting attention to detail and being able to pre-fabricate the frame and wall panels in our controlled workshop environment, had huge benefits to the overall quality of the build.

A Passivhaus home is so much more than an ‘eco-home’. It is one that guarantees low energy usage, it limits overheating risks, and the high level of insulation and triple glazing reduce noise impact from outside (again opening windows aren’t essential for fresh air for much of the year).  Through a constant supply of fresh air (which has been reported to reduce instances of Asthma and hay fever because of the filters in the ventilation system) there is an increase in comfort for occupants.

Phil explains, “Now we are living in a home that is maintained at a constant optimal temperature with a continual supply of filtered fresh air from the MVHR,” Phil Garnett says. 

Phil and Yvonne’s oak frame Passivhaus took 12 months to construct and may be the first of its kind in the UK but very much demonstrates the possibilities of both oak frame and Passivhaus construction working together.

Combine with this the subtle smell of wood, the visual appeal of the exposed oak frame, and the peace and quiet created by the exceptional soundproofing of the passive house construction, and you have an environment that is perfect for all the senses, generating a fantastic feeling of wellbeing.

Phil Garnett

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The UK’s first oak frame Passivhaus

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