The personalised passivhaus with a place for everything


With a refined barn-like form expressed in timber and locally sourced sandstone, the award-winning Godwit House feels at once agricultural and contemporary. Sitting on the plains of the Coquet Estuary in Northumbria, this bespoke home, designed by TDUK members Mawson Kerr Architects, claims its crown as (for now) the most northerly certified Passivhaus in England.

The light-filled home wraps snugly around a courtyard, with bedrooms on the ground floor and a spacious living area above, opening onto a raised terrace. The design was developed in close collaboration with the client, who first came to the Newcastle-based practice seeking a sustainable, low energy and holistic approach. From these core intentions grew the ambition to create a Passivhaus.

A conscientious dwelling

Images all © Jill Tate: the house has an ‘upside down’ layout, with the open plan living area on the first floor, and bedrooms beneath.

With the site located on the edge of an Area of Outstanding Natural Beauty, and the proposed design quite unusual for the area, there were some planning difficulties to attend to. The early decision, on the part of the client and architects, to make the house a Passivhaus, however, helped to secure the planner’s enthusiasm.

Sensitivity to the surrounding area and material vernacular were also appreciated, as the architects worked with the proportions of the building to create a slim profile oriented to minimize impact on neighbours’ views. High quality natural materials – vertical larch cladding and Northumberland sandstone – were chosen for the building’s shell, to reflect local agricultural elements.

Minimising carbon hungry materials

As well as designing a home that would be low energy to inhabit, it was equally important to both architects and client to use low embodied carbon materials. This led to the use of a prefabricated timber cassette panel system for the frame of the house, filled with wood fibre insulation. The panels were produced by Wales-based company PYC. They slot together onsite, one storey at a time, to create an entirely airtight frame.

The larch cladding is coated in SiOO:x – a treatment that protects the timber and helps it to weather evenly.

An insulated raft foundation system was used – a first for Mawson Kerr – whereby insulation creates a thermal former into which a thin layer of concrete is poured. The entire slab is therefore wrapped in insulation, minimising thermal bridges and significantly reducing the required thickness of the slab (to about 200mm). The insulation for the foundation was laid onto an engineered stone buildup, ensuring a suitable base to spread the loads without relying on excessive concrete.

Growing the local knowledge base

For contractors who haven’t completed a Passivhaus before, taking one on can be a risk because of the extreme levels of airtightness that have to be met in order to achieve certification. Godwit House was the first Passivhaus undertaken by main contractor True North Construction – a two-person outfit based in Newcastle.

But they were very proactive in their approach, attending a Passivhaus course on airtightness specifically for the project. By fastidiously applying their newly learnt skills to their existing craftsmanship, the contractors managed to ensure an exceptional airtightness of 0.15ACH
(Passivhaus maximum is 0.6ACH).

Repeatable quality

The architects also took steps to de-risk the project, including arranging for much of the envelope to be built off site and sourcing critical high-tech elements from reliable companies that they knew had delivered before. “An important approach is isolating the difficult areas, such as the frame, windows, MVHR, foundations system,” project architect Dan Kerr explains.

“These are then collated into 3D modelling software. And once that’s tidied up and you know the sizes, you’ve basically created a building that is standard in terms of fit out. Everything is lined in plasterboard, plumbing and electrics are put in, and it gets clad – but this is nothing out of the ordinary for a good contractor.”

Kind to the environment, low cost to run, and with a specially made place for all of the client’s belongings.

Since Godwit House, True North Construction have gone on to work on a number of jobs with sustainable features, including two timber-frame new builds with passive properties as well as another Passivhaus project together with Mawson Kerr.

Bringing joy with joinery

The contractors are both joiners by trade and, having developed a great working relationship with the architect and client during the construction of the house, they went on to complete the bespoke internal joinery too.

The design of the furniture and storage played an important part in the project. Over her career, the client had lived and worked abroad, collecting many art objects and souvenirs. A key part of the brief had been to create places for her collection and musical instruments. These were measured and incorporated into the interior design, particularly in the stairwell and the main living area.

“We were trying to capture the site and the area, but also the client’s personality,” explains associate architect Daniel Dyer. “It’s all these things coming together that make it a truly one-off house.”

The characterful interior employs a range of timbers, with engineered oak used for the flooring, spruce for the windows and birch ply for the furniture. The elegance and quality of the finishing and the exemplary performance of the completed house attest to the commitment and collaboration of all those involved, and set a new standard for sustainable, beautiful housing in the region.

This article is taken from issue 5 of Designing Timber magazine and find a case study of it here