Plas Newydd mansion powered by sea energy

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We marked a good energy milestone after completing one of the biggest marine source heat pumps in the UK, which will warm up a 300-year-old mansion on the North Wales coast.

This project at Plas Newydd House and Gardens was the first of five schemes to be completed in a £3.5 million pilot phase of our Renewable Energy Investment Programme, which was launched in 2013 in partnership with Good Energy.

Swapping oil fuel for sea energy

The marine source heat pump provides 100 per cent of the heating needed by Plas Newydd in Anglesey. The 18th-century mansion used to be our biggest oil user and on some winter days would consume 1,500 litres of oil a day – the same as a typical house would use in ten months.

Now Plas Newydd is heated with a local and clean energy system, which pumps a small amount of sea water from the Menai Strait in Anglesey, through pipes to and from a heat exchanger on the shore, and then up 30 metres of cliff face to the mansion’s boiler house.

The 300kW marine source heat pump – one of the first and the biggest in the UK – cost £600k to install in total and is expected to save us around £40,000 a year in operating costs. That money can be reinvested back into the conservation of this elegant mansion, from its military uniform collection to a cricket pavilion on the estate.

Challenges and champions

'With the Irish Sea right on the doorstep of Plas Newydd, a marine source heat pump was the best option for us,’ said Keith Jones, our environmental practice advisor in Wales.

'However, being a pioneer is never easy. There are very few marine source heat pumps and few of this size in the UK, so it was a challenging project but a very exciting one.

'From the start, we worked closely with SEACAMS (Sustainable Expansion of the Applied Coastal and Marine Sectors), led by the School of Ocean Sciences at Bangor University, and conservation experts to make sure we got the best from the technology while protecting the site’s fragile environment and archaeology. We’re very keen to share what we’ve learned with others.'

Backing British energy

'This project shows that cutting-edge British renewable technology can transform the energy use of some our oldest buildings,’ said Juliet Davenport OBE, founder and CEO of Good Energy.

'It’s a pleasure to be part of this project with the National Trust and we look forward to seeing what the next step in their renewable energy journey will be.'

Find out more about how we’re producing our own green energy.

You can help us on our journey

Our energy partner, Good Energy, has worked alongside us to help us develop our renewable strategy and inspire others to think about their energy use. You can play your part by switching to a dual fuel tariff with Good Energy – they’ll give us up to £40 a year for each new customer who quotes ‘National Trust’ when switching.