Hill Top Passive House: The award winning first green oak framed Passivhaus in the country for Phil and Yvonne Garnett

When Yvonne’s parents suggested that one day Yvonne and her husband Phil might like to move into their Thirties’ bungalow, they were delighted. The location was idyllic – close to the village centre where they had lived for 40 years – with wide, open views to the sea from the garden. But there was just one snag. Ever since Phil and Yvonne had built a house of their own nearly 30 years ago, they had harboured dreams of building another. They were particularly keen to create a high-spec eco-house – and the Thirties dorma bungalow was anything but.

‘We agreed that we would love to live here, but only if we could knock down the old bungalow and build a new house in its place,’ says Phil. When Yvonne’s mum died, they started to look at the options more closely and agreed to see if they could actually get planning permission to demolish the old bungalow and replace it with a modern eco-home.

‘We discovered Eco Arc on the internet and invited architect Andrew Yeats to come and discuss our ideas,’ said Phil. ‘He liked our philosophy and plans and agreed to design a Passivhaus, which would be the first in this district.’

To view a U tube video of the passivhaus build and completed house please click the link below:

Andrew presented such a comprehensive and persuasive proposal that planning permission was approved without question by Scarborough council. Yvonne and Phil could finally start putting their plans into action, starting by sourcing a company that could supply a green oak frame which would meet high ecological standards. Andrew discovered Oakwrights Green Oak Frame Company which not only could supply a beautiful timber frame, but also their own bespoke, highly insulated encapsulation system.
‘We didn’t realise at the time that this would be the first oak frame Passivhaus in the UK,’ says Phil.

With the supplier of the main structure taken care of, work could begin on the demolition of the old bungalow. A geological survey carried out before the foundations were created, using an Isoquick raft system of insulated, interlocking slabs overlaid with reinforced concrete which would take the weight of the timber frame and block walls. ‘The foundations had to be as flat as a pancake, with just a 5mm tolerance,’ says Phil. The frame went up within a week but the roof, with its complex design of pitches and valleys, took a bit longer complete.

‘We considered having slate tiles but heard that they could come loose in strong winds and we are on a very open site at the back – right on the coast,’ says Phil. ‘We decided to use natural, handmade clay pantiles rather than concrete, and when we couldn’t decide on a colour we chose a mix of three. ‘We used local suppliers and trades people wherever possible ‘

Throughout the build, Yvonne and Phil aimed for the best quality they could afford. The result of their careful research, planning and appreciation of quality is a Passivhaus home which has achieved more than they could have dreamed of – but there was just one last minute hitch.

‘When it came to the day of the final tests to secure the coveted Passivhaus status everyone on site held their breath,’ recalls Phil. ‘A window was removed and replaced with a sealed fan to measure the negative pressure in the building. Any leaks of air are detected with a feather. We were expecting to pass the test and couldn’t believe it when the figures were way off the mark. Then we realised that someone had left a window open! We all breathed a collective sigh of relief when the window was closed and the tests confirmed its Passivhaus status.’

Creating Passivhaus standard:

The Passivhaus standard was developed in Germany in the early 1990s by Professors Bo Adamson of Sweden and Wolfgang Feist of Germany. The first dwellings to be completed to the Passivhaus Standard were constructed in Darmstadt in 1991. According to the Passivhaus Organisation, the heating requirement in a Passivhaus is reduced to the point where a traditional heating system is no longer considered essential.

Eco Architect Andrew Yeats of Eco Arc said Phil and Yvonne were motivated by the need to demonstrate alternative design and construction solutions that support the shift to Low Carbon lifestyles. ‘This house demonstrates that green homes do not need to be grand designs using expensive high- tech building design and construction technology,’ said Andrew, adding that it demonstrated Best Practice in home energy conservation, renewable energy use, water conservation, waste reduction and home food production. This included high levels of insulation, minimizing thermal bridging, excellent airtightness, natural lighting, passive solar gain and the use of recycled materials.

‘Much of our conventional traditional housing in the UK is very poorly designed in terms of energy conservation and ecological awareness. Most houses are poorly insulated and consume unnecessarily high levels of energy (usually from non-renewable sources) and at the same time produce high levels of waste and pollution,’ said Andrew. ‘This house is a low carbon, eco-dwelling – a low embodied energy, super insulated, Passive House construction. Most of the space heating will be from passive solar gain, heat generated by the occupants, domestic electrical appliances and heat recovered from the mechanical ventilation system.’

The house marks a ‘first’ for Oakwrights, who accepted the challenge of building a timber frame house encapsulated within a bespoke, high insulation construction. David Bryan, Architectural Designer and Passivhaus consultant from Oakwrights said: ‘The encapsulation surrounding the green oak frame at the heart of the house is a bespoke manufactured structure – not SIPS, which are something very different – designed specifically for the project to achieve the enhanced insulation values required to meet the Passivhaus criteria.’ He said the structure was particular complex for a Passivhaus as the building is a traditional shape and therefore more complex.

Working with Eco Arc we agreed ‘The oak frame takes on the role of the main skeleton of the building with the encapsulation being supported on this to create the shape of the house around it,’ said David. ‘To increase the performance of our standard WrightWall Natural panels, the outer panel holding the cellulose insulation in between the I-joists was replaced with thicker wood fibreboard to enhance the insulation value. It also eliminated any thermal bridging at external junctions, thus increasing the performance further still.’ He said the positioning of the oak structure, particularly at corners, could have made the continuous nature of the internal membrane difficult to achieve on site, so full size mock-ups were produced in the factory to work through ways it could be done effectively. The project was then created in 3D design software and the entire system manufactured at Oakwright’s production facility in Herefordshire.

‘This allowed us to consider the complete system holistically, not just by its constituent element, which may then be reliant on others to co-ordinate once on site,’ said David. ‘It gives us control over the superstructure of the house, ensuring the frame and encapsulation work harmoniously and effectively.’

Andrew & Phil said they had searched long and hard to find a company that was prepared to work to this level of detail, and be determination to achieve Passivhaus status for a timber framed building. ‘It posed many challenges as it hadn’t been done before,’ says Phil. ‘Oakwrights not only rose to the challenge but also, in doing so, became the first company with Eco Arc to build a timber frame Passivhaus in the UK.’

Client Testimonial

“When we got the opportunity to build our Green Oak Frame House, an ambition held for more than a decade, not only were we lucky enough to obtain a plot with panoramic views of the North Yorkshire coast but we also had the good fortune to find an architect and construction company with the ability to design and build a Green Oak Frame House that also achieved Passivhaus standard.

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, 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 Passivhaus construction and you have an environment that is perfect for all the senses generating a fantastic feeling of wellbeing.

We are looking forward to enjoying the changing seasons in the comfort of our new home in the knowledge that we will be utilising very little energy and reaping the subsequent environmental and financial rewards.”

Passive House Characteristics:

The Passivhaus standard adopted at Hilltop House is a successful International ultra-low energy standard for buildings. This oak framed timber frame house uses only a fraction of the energy for heating of those built to the standards required by current building regulations, and delivers a low carbon solution without needing excessive renewable energy. This Passivhaus approach adopted at Hilltop has three main strands: Minimise heat loss via super insulation, triple glazing, compact built form; Minimise ventilation heat loss via heat recovery ventilation and airtight construction & Optimise solar gain for winter heat. These factors combine to deliver a heating demand that can be met with a minimal heating system.
Space heating demand (PHPP): 17 kWh/m2/yr

Heat load (PHPP): 10 W/m2

Primary energy demand (PHPP): 88 kWh/m2/yr

Airtightness (at 50 Pascals): 0.43 ACH and 0.50m3/m2/hr

Windows: Internorm HF310 triple-glazed aluminium-clad wood windows (mix of fixed and tilt and turn). Argon filled Ug=0.5 W/m2K (Ug =0.6 W/m2K on South elevation) with overall installed average (all windows) of U-value of 0.91 W/m2K

Heating system: Worchester Boch Gas Condensing Boiler

MVHR Ventilation: Paul Novus heat recovery ventilation system — Passive House Institute certified to have heat recovery rate of 93%.

Passivhaus Certification WARM


Architect Andrew Yeats, Eco Arc, www.ecoarc.co.uk Tel 01539 822822
M&E Services Engineer & PHPP Alan Clarke email alan@arclarke.co.uk 01594 563356
Passivhaus Certification WARM www.peterwarm.co.uk 01752 542 546

Timber frame Oakrights Green Oak Frame Company www.Oakwrights.co.uk 01432 353353
Killerby Stained Glass Company www.stainedglasscentre.co.uk
Foundations Isoquick www.isoquick.co.uk 01202 600 64401202 600 644
Windows EcoHaus Internorm Glazing Solutions www.ecohausinternorm.com
Ventilation system HRS Green Building Store www.greenbuildingstore.co.uk 01484 461705
Kitchen and bedroom units Chapel Kitchens www.chapelkitchens.com 01423 331417
Roof tiles William Blythe www.williamblyth.co.uk 01652 632175
Bathrooms fittings Bathroom Supplies online, Hull www.bathroomsuppliesonline.com 01482 795165
Copper pipes and gutters Rain Guard via MKM www.mkmbs.co.uk 01482 345678
Staircase: Stairs & More, 01845 577200 www.stairsandmore.co.uk

Words Heather Dixon Photography Oakwrights & Dave Burton