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National Trust / Conserving energy and our heritage

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Over 400,000 buildings in England and Wales have listed status, and, being of historic importance, have traditionally been viewed as difficult or impossible to retrofit for improved energy efficiency.

The National Trust has shown through its work in Wales that such properties can in fact be retrofitted, and is now expanding the work to its other regions.

Renewable electricity generation has been installed, including 313 kW of solar PV, and over 250 kW of hydro

 Cost savings of £280,000 per year 

Cut in annual CO2 emissions of about 1,400 tonnes

"We can’t operate in isolation from our environment – everyone has to do something to contribute to tackling climate change."

Patrick Begg, Rural Enterprises Director


The National Trust owns 29,000 buildings, most of which are historic and have listed status, and so cannot be modified in ways that significantly alter their visible appearance. Energy use for heating and lighting is high, because of poor insulation and inefficient equipment, and the energy cost of £6.5 million per year diverts funds from the core purpose of the Trust – to preserve heritage. However, in the past it has been assumed that nothing can be done to improve energy efficiency, due to the historic nature of the buildings. The National Trust is not alone in this situation – there are over 400,000 listed buildings in England and Wales, most of which are currently not energy efficient.

To tackle this problem, the Wales region of the National Trust has developed and implemented methods of improving energy efficiency without changing the character of its properties, and also changing staff culture to promote energy saving. These methods are now being rolled out across the whole Trust.

Specially-designed LED lights in use at Llanerchaeron

The organisation

The National Trust was founded in 1895, and works to preserve and protect the coastline, countryside and buildings of England, Wales and Northern Ireland. It owns 29,000 buildings in total, including 39 villages, 88 castles, 300 mansions, 61 pubs and two gold mines. It also manages over 700 miles of coast and 250,000ha of land, including 42,000ha of woodland. In addition to over 5,000 employees, volunteers contribute over 3 million hours of work a year. The National Trust’s income is from membership fees, investments and donations, which totalled £268m in 2010.

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The programme

The Wales region of the National Trust was selected to pilot the energy efficiency work for the whole organisation as it had already made progress in this area, and had developed significant expertise within its staff. The Wales region includes three castles, eight mansions, 55 holiday cottages and five farms under direct management, amongst other properties. The work is part of the National Trust’s ‘Fit for the future’ campaign, in which it aims to reduce its environmental impact while developing new business opportunities and empowering others to cut their impact too.

Before any changes were made to buildings or procedures, detailed monitoring of energy and resource use was implemented, so the benefits of the work could be measured and used to inform future decisions. The programme then moved on to analysis of the existing buildings, energy use, transport and methods of work, providing the information to make decisions about what steps could be taken to reduce environmental impact. Following the analysis, a range of technologies have been used, along with changes to the culture and behaviour of staff, to reduce energy demand and improve efficiency. Technology to generate energy from renewable sources has also been used.

We have an opportunity to lead, in terms of our buildings being ‘hard to treat’. We’ve proved you can look after old buildings while making them efficient at the same time.

Patrick Begg, Rural Enterprises Director


The National Trust carried out an environmental audit of its properties in Wales, and commissioned energy surveys of the properties which the audit identified as needing further technical investigation of energy use and sources of inefficiency. These surveys and audits formed part of the evidence the Trust used to prioritise resource allocation for cutting energy use. As expected, the main energy use in most buildings was for heating, due to their lack of insulation and poor draught-proofing. Thermal models identified where changes could be made, and thermal imaging was used to present the information in a visual way that could be easily understood and presented to non-technical staff.

The results of the recommendations were combined with energy costs to produce a business case for technical changes to be made, and compelling examples to help in driving behavioural change. The payback periods of the different options were important in justifying investing money to save energy.


Measures to improve efficiency were installed before those to generate renewable energy, as efficiency yields faster paybacks and saves more energy for a given investment. Heat loss has been dealt with through several methods; lofts have been insulated and secondary glazing installed, dramatically improving the airtightness of the buildings. Where secondary glazing is not appropriate for a historic building other measures have been taken, such as installing thick curtains or bringing existing shutters back into use, repairing them where necessary. Other appropriate draught proofing measures have also been taken for windows and doors.

Every window has been properly sealed and insulated at Llanerchaeron House

Significant efficiency improvements have also been possible for lighting, as when National Trust properties are open to the public the majority of the rooms in them are lit for the whole day. Existing lighting was almost exclusively incandescent bulbs, resulting in high energy consumption – especially in rooms with chandeliers. The requirements for lighting in historic buildings that are open to the public are stringent, as the right atmosphere needs to be created. The colour and intensity of the light and the appearance of the bulbs are important, and they must not be too heavy or generate too much heat. The National Trust has worked with several lighting manufacturers to find LED lights that meet their requirements and has made extensive use of a new ‘candle’ dimmable LED bulb, ideal for use in chandeliers, which was specially developed by Heritage Lighting.

Other improvements include more efficient hand dryers in public toilets, improved tamperproof time controls for heating in holiday rental cottages and voltage optimisation.

The National Trust made a huge difference, I’ve not got the time in my job to fully address the energy use in our properties so their advice was invaluable.

Andrew Muskett, Building Projects Officer, Pembrokeshire Coast National Park Authority

Heating systems have been improved as well, initially by more rigorous maintenance of boilers, and then by replacing gas or oil fired boilers with renewable sources of heat. Biomass boilers have been a popular option as the National Trust owns and manages woodland and can therefore supply some of its own fuel. It is currently using 200 tonnes a year from its own estate in Wales, and is investigating what the maximum sustainable yield is. Heat pumps have also been used, both air-source and ground-source, and a marinesource heat pump is currently under construction at Plas Newydd, on the Menai Straits. Renewable sources of electricity have been installed, including several solar PV and hydro power systems.

Behaviour change

Energy issues are discussed in both board-level meetings and in the day-to-day operations meetings at individual properties. In addition to taking technological steps to save energy, the National Trust has worked with its staff in Wales to change their behaviour and create a culture of energy saving. The actions staff are taking include switching off lights and electrical appliances when not in use, closing curtains and shutters at the end of the day, and making better use of water heaters. Behaviour change is encouraged through both ‘recognition and reward’ and ‘name and shame’, and relevant illustrations are used to motivate staff; for example, leaving a small water heater switched on 24 hours a day, 365 days a year, wastes electricity with a cost equivalent to a National Trust membership fee.

National Trust staff and wood stove at Llanerchaeron cafe

How much does it cost?

The National Trust has so far spent about £250,000 in Wales on energy efficiency and behaviour change. The average payback on this work is under four years – some measures can even pay back in a single year. Investment in renewable energy generation tends to have a longer payback, on average eight years, and £1.75 million has been spent so far on such schemes.

Monitoring and maintenance

The effectiveness of energy saving measures taken is monitored through meter readings. The National Trust has paid for the development of metering software that allows the managers of all its properties to enter monthly readings from all their meters, and presents this information in tables for regional managers to review the properties they are responsible for. This allows the energy use and CO2 emissions of different regions within the National Trust to be seen at a glance, and compared to data from previous years and the current year’s target. To ensure good quality data in this system, providing monthly meter readings is a key performance indicator for property managers. The metering system has been developed using open source software, and can be adapted by other organisations for their own use.

The clever bit is not using energy, the psychological stuff. The quick wins are good housekeeping, not throwing technology at it.

Keith Jones, Environmental Practices Advisor

Maintenance of heating equipment is usually outsourced by the National Trust, but the Wales region has reviewed maintenance contracts and added more detailed instructions to them, yielding improvements in efficiency. Day-to-day monitoring and maintenance of the measures installed to save energy is carried out by staff at individual properties.


By April 2012, the National Trust in Wales had carried out a range efficiency and renewable energy work in the 300 Welsh properties it has direct responsibility for. It had insulated 8 mansion properties and 95 smaller properties, and installed 18 ground-source heat pumps, 18 biomass heating systems, three log heating systems and 12 solar water heating systems. It had also installed nine solar PV systems with a combined capacity of 313 kW, and over 250 kW of hydro power. More solar PV and hydro schemes are under construction at present, including a 650kW hydro site near Snowdon, which will generate 1,900 MWh/ year. This work is benefitting the 5,500 National Trust employees and volunteers in Wales, and also the 2 million visitors their properties receive every year.

Environmental benefits

Between 2009/10 and 2010/11, the National Trust cut overall energy consumption at its Welsh properties by 3.3 GWh/year, or 41%. Breaking these figures down, electricity use was cut by 1,500 MWh/year (42%), natural gas and LPG were cut by 740 MWh/year (42%) and heating oil use was cut by 1,100 MWh/year (43%). Over the same period, the use of wood-fuel increased from zero to 160 MWh. The solar PV installations generate about 270 MWh/year, and the hydro 450 MWh/year.

Powis castle greenhouses

This equates to a cut in annual CO2 emissions of about 1,400 tonnes, or 46%, solely from efficiency and behaviour change, with a further 380 tonnes a year saved due to generation of electricity from renewable sources.

Social benefits

The main purpose of the National Trust is to preserve cultural and natural heritage, so money saved through energy efficiency and renewable energy can be diverted to furthering this work. Numerous tenants and holidaymakers in its properties have benefitted from insulation that has been installed.

The National Trust is also working to promote community use of its properties and land. One part of this is involving volunteers with the energy-saving projects, for example training them to carry out energy audits of holiday rental properties. In Wales it is also currently working to set up a community-owned hydro power scheme.

Economic and employment benefits

Based on current prices the National Trust pays for gas, electricity, heating oil, and woodfuel, the reductions it has made in consumption are saving about £280,000 a year, or 42%, which can now be spent on its core areas of work instead.

The money that has been invested in energy efficiency and renewable generation has created and supported jobs, such as two new posts within the National Trust Wales region. A plumber in Wales underwent training specifically to install heat pumps in Trust properties, after which he won further contracts elsewhere, and a new business selling LED lights specifically designed for historic properties has started up as a direct result of working with the Trust in Wales. Existing businesses have been supported through the Trust’s installation of biomass boilers, solar PV, insulation, secondary glazing and through maintenance contracts for the equipment installed.

Solar PV at Llanerchaeron

Potential for growth and replication

The work which the National Trust has piloted in Wales has recently been given board approval to be rolled out rapidly across all the other regions. The system for monthly meter readings is already in use in all regions, and included in staff key performance indicators. National Trust properties in Wales represent a small proportion of the total number, so the roll-out to other regions is expected to result in significant reductions in energy use and CO2 emissions.

The National Trust has also been taking action to replicate its work in other organisations. It has participated in numerous presentations and workshops on saving energy, involving the Society for the Protection of Ancient Buildings, the Historic Houses Association, Historic Scotland, the Prince’s Regeneration Trust, the Irish Historic House Association, the Museums and Libraries Association, Pembrokeshire National Park Authority and others.

The potential for replicating the National Trust’s work is significant; there are over 400,000 listed buildings in England and Wales, many of which could benefit from the same measures to save energy while preserving their historic nature. Widening the scope, there are 5.3 million homes in Great Britain that were built before 1918; these usually have solid walls and are considered ‘hard to treat’ when it comes to improving energy efficiency. These homes could also benefit from what the National Trust has learned about how to analyse energy use and implement measures to save energy while taking account of the age and construction of the building.

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