National Trust puts its trust in saving energy

National Trust, Ashden Awards, renewable energy, biomass, solar
Llanerchaeron mansion is one of properties of the National Trust in Wales that has been retrofitted to save energy and cut carbon emissions. (All Photos © Andrew Aitchison)

A major campaign by the National Trust in Wales to reduce the energy consumption of its properties is achieving spectacular results.

An organisation with some 300 properties spread across an entire country reducing its energy consumption by 41% over just two years is worthy of note. That reduction in energy consumption also cut CO2 emissions by 46% (about 1700 t) and fuel bills by 42%.

That feat was achieved by the National Trust for the 300 properties in Wales for which it has direct responsibility. They are all historic buildings of the kind that are regarded as hard to treat, but the lessons learned are applicable to other buildings — both historic and not historic.

Indeed, the work that the National Trust has piloted in Wales has been given board approval to be rolled out rapidly across all the other regions. The National Trust itself owns 29 000 buildings, most of which are historic and have listed status so they cannot be modified in ways that significantly alter their visible appearance.

Their energy use for heating and lighting is high because of poor insulation and inefficient equipment — giving them an annual energy bill of £6.5 million. In England and Wales as a whole, there are over 400 000 listed building, 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 the properties and also changing staff culture to promote energy saving.

The efforts and example of the National Trust have made the organisation the overall UK Gold Award winner in this year’s Ashden Awards, described by Ashden itself as the world’s leading green-energy awards. Characterising these awards is the availability of detailed case studies of the winning entries with valuable information for anyone wanting to emulate the success of the winners

The approach to reducing energy consumption and carbon emissions was systematic.

Nine solar PV systems have a combined capacity of 313 kW.

The first stage was a rigorous analysis of the energy used by buildings, appliances and staff to define what action to take to make savings. That preliminary detailed monitoring of energy and resource use enables the benefits of the work to be measured and used to inform future decisions.

The first energy-efficiency measures to be implemented were those with a very short payback period. They included insulation, secondary glazing and draught proofing.

Another measure was to upgrade lighting using low-energy LED lamps, some of them specially designed to meet the requirements of historic properties. Most rooms in properties that are open to the public are lit for the whole day, previously almost exclusively by incandescent bulbs with very low efficacy. Energy consumption was high, especially in rooms with chandeliers.

Following work with several manufacturers, the National Trust now makes extensive use of a new ‘candle’ dimmable LED bulb specially developed by Heritage Lighting and ideal for chandeliers. These bulbs enable the right atmosphere to be created and have the right colour and intensity of light.

Behaviour change to make better use of heating, lighting and appliance has also helped to reduce energy use. Energy issues are discussed in board meetings and in day-to-day operations meetings at individual properties. In addition to taking technological steps to save energy, the National Trust has worked with staff in Wales to change their behaviour and create a culture of saving energy. Energy savings are made by switching off lighting and electrical appliances when they are not in use, closing curtains and shutters at the end of the day, and making better use of water heaters. Staff are recognised and rewarded for their behaviour — or named and shamed. Examples of the energy that can be saved include a small water heater always left on wasting electricity equivalent to a National Trust membership fee.

The refurbishment or replacement of heating systems in buildings include the use of biomass boilers and heat pumps to provide low-carbon heating.

Biomass boilers have been a popular option as the National Trust owns and manages woodland and can therefore supply some of its own fuel. Its own estate in Wales is currently supplying 200 t a year, and the trust is investigating what the maximum sustainable yield is.

Heat pumps have also been used, both air-source and ground-source. A marine-source heat pump is being installed at Plas Newydd on the Menai Strait.

The renewable-energy theme continues with the installation of renewable sources of electricity — including several solar-PV and hydro systems.

Biomass heating systems have been installed in a number of properties.

Projects included 18 ground-source heat pumps, 18 biomass heating systems, three log heating systems and 12 solar-thermal water-heating systems.

The National Trust in Wales has also installed nine solar PV systems with a combined capacity of 313 kW and over 250 kW of hydro power.

The National Trust has the benefit of administering large areas of open countryside, making it possible to install substantial hydro-electric schemes. One under construction is a 650 kW site near Snowdon, which will generate 1900 MWh a year. The National Trust reckons that this scheme alone could generate enough electricity to run all its properties in Wales — including castle, mansions, gardens, 45 holiday cottages and 200 farms.

The 41% reduction in energy consumption achieved between 2009/10 and 2010/11 amounts to 3.3 GWh a year.

Electricity consumption was reduced by 42%, 1.5 GWh a year

The use of natural gas and LPG fell by 42%, 740 MWh a year.

There was a similar reduction in the use of heating oil, which fell by 43% — 1.1 GWh a year.

There are significant inputs from renewable energy. In particular solar PV installations generate about 270 MWh a year and existing hydro schemes 450 MWh a year.

CO2 emissions achieved by improving efficiency and behaviour change were reduced by 46%, amounting to about 1700 t. The generation of electricity from renewable sources reduced CO2 emissions by a further 380 t a year.

The overall cost benefit of all the measures is around £280 000 a year, or 42%.

So far the National Trust has spent about £250 000 on energy efficiency and behaviour change. The average payback on this work is under four years, and some measures have a payback of less than a year.

Investment in renewable-energy generation has a longer payback, on average eight years. £1.75 million has so far been spent on such schemes.

In its own small way the work of the National Trust in Wales has stimulated its own green economy.

The money invested in energy efficiency and renewable generation has created and supported jobs.

Heat pumps have been used to provide low-carbon heating in a range of properties, supported by the installation of solar PV and hydro schemes to generate electricity.

For example, a plumber was trained to install heat pumps in National Trust properties — after which he went on to win further contracts elsewhere.

Another development was the starting up of a new business selling LED lights specifically designed for historic properties as a direct result of working with the National Trust in Wales.

Not only have existing businesses been supported by the installation of biomass boilers, solar PV, insulation and secondary insulation, but the support continues through maintenance contracts for the equipment installed.

To help ensure that savings continue to be achieved in the long term, the effectiveness of energy-saving measures is monitored through meter readings. The National Trust has paid for the development of metering software that enables the managers of all its properties to enter monthly readings from all their meters. That information is presented in tables for regional manager to review the properties they are responsible for.

Energy use and CO2 emissions from different regions can be seen at a glance and compared to data from previous years and the target for the current year.

To ensure good-quality data for 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.

Such attention to on-going performance is the key to ensuring that the savings made by the National Trust in Wales continue.

This article is based on the case study summary for the Ashden Awards. There is more information on the web site below.

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