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National Trust - Plas Newydd Energy efficiency

18th century mansion makes exemplary steps towards reducing its carbon emissions

National Trust Plas Newydd

Plas Newydd is an 18th century mansion set on the edge of the Menai Strait on the Isle of Anglesey. The mansion was identified as the largest consumer of oil out of the National Trust’s extensive estate, requiring 128,000 litres of oil each year to heat the building, which is responsible for 350 tonnes of carbon emissions a year and £76,000 in cost.

Getting the house in order

The National Trust worked with the Carbon Trust and a number of other organisations to develop and deliver the energy efficiency improvements at Plas Newydd. An initial opportunities assessment took place in 2009 to identify what short term and long term improvements could be implemented. The simple improvements included installing smart meters to monitor energy use, insulating the roof, replacing inefficient lighting, ensuring that all doors and windows were draftproofed, installing secondary glazing, and implementing staff energy management training. Through making these small alterations, energy use at Plas Newydd was reduced by a third in just two years.

Renewable electricity generation

In 2011, 50 kW of solar PV panels were installed in a nearby sports field which has been producing around 45,000 kWh per year. This electricity goes directly towards meeting demand within the Plas Newydd mansion. As a result of installing the solar panels the field has now been repurposed into a wildflower meadow, with the growth of 150,000 orchids.

National Trust Plas Newydd solar panels orchids

Renewable heat generation

The National Trust is currently making substantial investments in its historic properties with the aim of generating 50% of its energy from renewable sources by 2020. £3.5 million has already been put into developing five pilot renewable energy projects, making use of hydropower, biomass and heat pumps.

In providing low carbon heating at Plas Newydd, a marine source heat pump was determined to be the best option after an in-depth feasibility study which found that it would enable an 80% reduction in carbon emissions as well as providing perfect conservation-grade heat for the historic museum accredited building. Plas Newydd was the National Trust’s first project to be completed, using a marine source heat pump, a comparatively rarely used technology that draws heat from seawater.

The 300 kW marine sourced heat pump was commissioned on the 21st of May 2014 and it is one of the first and largest marine source heat pumps in the UK. In total it cost £600,000 to install and to date, seven months in, it has saved £18,000 in operational costs, which will be reinvested into the conservation of the beautiful mansion.

National Trust Plas Newydd marine source heat pump

What next?

The National Trust will be closely monitoring the progress of the new heating system for its durability, serviceability and efficiency in comparison to the old oil system. Money saved will be reinvested in additional energy efficiency measures and directly into conservation of the Plas Newydd building to ensure that it is protected for future generations to enjoy. 

Plas Newydd has made significant improvements in its energy production and usage. Considering it was the single biggest user of oil on the National Trust’s entire estate, it can now boast that it is the first large building that is heated by a marine source heat pump in the UK, and the new system is working superbly.

Paul Southall, Renewable Energy Programme Heat Lead at The National Trust

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