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JDDK’s visitor centre gives visitors a bird’s eye view of Hadrian’s Wall

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The Sill, a £9 million mixed-use complex in Northumberland, is the largest project undertaken by a national park

Named after the adjacent Great Whin Sill – the volcanic crag on which Hadrian’s Wall is partly built – the centre comprises an exhibition space, learning and events spaces, a café selling local produce, a rural business hub, an 86-bed youth hostel and a shop. The project, funded by a £7.8 million Heritage Lottery Fund grant, is the largest undertaken by any National Park in the country, and forms part of a seven-year investment plan to increase visitor numbers to the Northumberland National Park and Hadrian’s Wall World Heritage Sites.

The Sill’s accessible living roof, designed to replicate the surrounding grasslands, sweeps gently upwards, giving visitors a bird’s eye vantage point across the UNESCO World Heritage Site of Hadrian’s Wall. The environmental strategy involved orientation to maximise solar gain in some of the public spaces while offices are placed to the north to prevent overheating. A central atrium provides daylight into the heart of the building while allowing a summer-time natural ventilation strategy and mechanical ventilation with heat recovery in the winter. The project achieved a BREEAM Very Good rating.

The south-facing entrance canopy provides solar shading to the glazed frontages of the classrooms and main entrance while also supporting photovoltaics for generating electricity. Solar panels are incorporated on the youth hostel roof to provide hot water while the remaining whin sill vegetation roof increases biodiversity and reduces surface water run off. The building also incorporates high levels of insulation and airtightness, low embodied energy materials and enhanced ecology including habitats for bats and birds.

Ground floor plan

Ground floor plan

Ground floor plan

Architect’s view

The Sill is inspired by The Great Whin Sill, Northumberland’s internationally renowned geological feature, and grows from the landscape that surrounds it. An aerial view of the wider landscape shows these dramatic geological outcrops as diagonal ripples in the landscape. The building is developed as another ripple rising out of the landscape so that the diagonal flowing lines of the building echo the natural undulations and outcrops in the landscape.

We hosted a series of open events and workshops where we discussed site layout, materials and architectural style. The participative design process gave the local community a chance to get involved, voice their opinions and feel some ownership of the project. It also allowed us to draw on a vast wealth of local knowledge and expertise.

The whole team at JDDK are incredibly proud of what we achieved at The Sill. Our brief was for a landmark building which would become the hub of visitor activities, welcoming visitors and supporting communities throughout the Northumberland National Park. Sustainability and public consultation were at the core of the design process with the finished building inspired by the rugged Northumbrian countryside. 

Alison Thornton-Sykes, project architect, JDDK Architects

Sill 200

Sill 200

Client’s view

The unique concept and rural location of The Sill presented challenges which required experienced and high-quality architectural design services. JDDK took the building from a list of required uses through an extensive and detailed public engagement process, establishing a desire for a modern design response in this key heritage location. This has ultimately led to a building in and of the landscape, with its very fabric drawn from the land within which its sits. The Sill is the largest project of its kind undertaken by a national park anywhere in the country. Its opening weekend was a huge success and the first stepping stone towards achieving our vision to excite, inspire and enable people of all ages to understand and explore the landscapes, history, culture and heritage of Northumberland. I am incredibly proud of what has been achieved.

Tony Gates, chief executive, Northumberland National Park Authority

Project data

Start on site September 2015
Completion June 2017
Gross internal floor area 3,070m²
Form of contract Design and Build, two-stage tender
Construction cost £ 8.8 million
Construction cost per m² £ 2,866/m²
Architect JDDK Architects
Landscape architect Glen Kemp
Client Northumberland National Park Authority 
Structural engineer Patrick Parsons
M&E consultant Cad 21
Quantity surveyor/cost consultant Gardiner & Theobald
Other specialist consultants Bright 3D
Project manager Gardiner & Theobald
Principal designer Gardiner & Theobald
Approved building inspector 
Northumberland County Council
Main contractor Sir Robert McAlpine
CAD software used 
Estimated annual CO2 emissions 41kg/m²

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