From the Dark Ages to the Green Revolution

PUBLISHED: 15:19 21 June 2008 | UPDATED: 15:17 20 February 2013

Starting with photovoltaic panels, Dunster Castle hopes to pave the way in energy conservation. Photo Guy Edwardes

Starting with photovoltaic panels, Dunster Castle hopes to pave the way in energy conservation. Photo Guy Edwardes

To the medieval builders of Dunster Castle energy management would have consisted of shutting the great oak doors and throwing a few more logs on the fire. They would be astonished if they could see what's happening to the place today. But, the Na...

Earlier this year, the National Trust brought in specialist contractors to install the latest design of solar panels on the roof of the castle. The 24 photovoltaic panels, installed during the winter at a cost of £55,000, are supplying the equivalent of the energy consumed by two ordinary family homes, demonstrating that you don't have to live in a modern house to take steps to reduce your carbon footprint. In sunny weather the panels are already supplying most of the castle's daily energy requirements.

The solar cells should reduce the power taken from the National Grid and save almost 3,000 kg of CO2 a year - the equivalent of cutting the mileage of a family car by 14,000 miles. Carbon payback of the overall project is expected in four years. The project has been carefully planned and executed to minimise the impact of the installation on the appearance and fabric of the castle. The panels are not visible from the ground or the surrounding hills, and if new energy-saving technology comes along some time in the future, the framework installed can be used to house the equipment of future technologies.

The panels are part of a project to turn Dunster into the greenest castle in Britain

The largest slice of the funding has come from Barclays Bank, which contributed 30,000. The Low Carbon Buildings Programme, administered by the Energy Saving Trust, gave 15,000, with the National Trust paying the balance.

It's the first time the National Trust has tried this approach to renewable energy with a Grade I Listed building - and it is only part of a much wider environmental project that is likely to have an impact on the conservation and management of historic buildings right across the UK.

The panels are part of a project to turn Dunster into the greenest castle in Britain. The Trust plans to save energy across the board, along with reducing water consumption, increasing recycling, promoting green transport and many other initiatives.

Stephen Hayes, Property Administrator at Dunster Castle and the leader of the planning work for the project, is delighted with the success of the solar panels. "We have now passed the 1,000 kWh mark," he says. "During the sunny weather in May we were generating 80% of our daytime electricity usage from the panels. We're looking forward to taking the project on to the next stage."

The project has its roots in a staff meeting in 2006 when the Dunster team learned about a visitor reception building at a Cornwall National Trust property that had been fitted with photovoltaic panels. The castle's roof was about to be shrouded in scaffolding for renovation, so it seemed the ideal opportunity to try something similar at Dunster.

"Neither of us had any experience or knowledge about environmental issues, so the prospect of trying to dramatically reduce the environmental impact of Grade I Listed buildings was quite daunting" says Stephen, who leads the project together with Emma Howe from the gardening team. "We had a lot to learn, but we have had excellent advice from others who have been exploring green alternatives."

It helped that green issues were already very firmly in the spotlight within Exmoor National Park - the Park Authority is committed to becoming carbon neutral by 2025.

They began with the 'easy' things, such as replacing old fridges with 'A'-rated energy-efficient units and installing compost caddies in the staff rooms. The caddies are supplying wormeries in the castle gardens with discarded teabags, banana skins and apple cores.

To save water, four rainwater butts with a combined capacity of 800 litres were installed, while a 'water hog' placed in the volunteers' lavatory cistern is expected to save 11,000 litres of water each year. Public toilets were already operating efficiently. All the castle's hot-water pipes were lagged and the temperatures of the tanks reduced to 60°C. A rigorously monitored 'switch-off' policy was introduced.

Getting planning permission for the photovoltaic panels was a demanding process - among the requirements was that they should form part of a wider environmental plan. To avoid affecting the fabric of the roof and to allow for any updating in the future, the panels are supported by a galvanised steel support frame fixed to the castellated walls so that they place no weight on the roof. The reroofed area was insulated with a 200mm layer of a natural recycled product called Isonat. This in turn meant installing a ventilation system to safeguard the fabric of the roof.

The project is very far from over. There are plans to install a new glass door to the shop in the stable block, so that the old oak doors - far too big and heavy to be opened and closed for each visitor - do not have to be left open, which allows enormous quantities of heat to escape on a winter's day. An energy-efficient shop refit and a newly insulated ceiling will contribute to a huge reduction in both carbon emissions and energy usage. In the future the team will be looking at more adventurous ideas, such as using Dunster's watermill to generate hydroelectric power.

"Against a background of increasing concern about sources of traditional energy and the predicted rise in carbon-dioxide emissions, we believe this project is of real importance," says Stephen Hayes. "We hope to set an example for many other managers of historic properties, and show that energy conservation technology is not just for modern buildings." BY CHRIS NEWTON

Dunster Castle is open daily (except Thursdays). For opening times call 01643 823004. Visit the National Trust website at and search for 'green living' to find out how you can reduce your carbon footprint. There are sections on house, garden and leisure activities.

What do you think of the National Trust's green project at Dunster Castle? Would you like to see this rolled out across the county or is it a step too far for our historic buildings? Have your say on the Forum.

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