Teaching old buildings new tricks

17th September 2012


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The National Trust in Wales has halved its energy use and carbon dioxide emissions in just two years. the environmentalist reports

The National Trust scooped the top prize for UK-based organisations at the prestigious Ashden Awards earlier this year, recognising the conservation charity’s achievements in green energy across its Welsh estate.

The award judges were impressed by the charity’s dynamic, common-sense approach to improving energy efficiency and producing renewable energy in its continued drive to make the National Trust in Wales energy self-sufficient by 2020. The reductions in energy use are now saving the charity £280,000 a year, and have cut its annual CO₂ emissions by 1,700 tonnes.

Over the past two years, more than one hundred trust properties in Wales have been insulated and numerous solar, hydro and ground-source heat pump power systems have been installed, generating more than 700MWh a year.

According to Keith Jones, the trust’s environment adviser in Wales, it is a combination of efficiency measures and cultural change across its paid workforce and a band of 5,000-plus volunteers that will ensure the National Trust in Wales achieves energy self-sufficiency by the end of the decade.

Aiming high

A clear driver for the National Trust’s overall energy-efficiency strategy is to reduce its energy bill, which currently runs at £6.5 million a year. The trust’s headline target is to cut its use of fossil fuels through efficiency measures across England, Wales and Northern Ireland by 20% by 2020 and to generate 50% of its remaining energy needs from its own estate. Achieving both will cut carbon emissions from heating and electricity use by 59%.

In Wales, under its “Fit for the future” strategy, the charity has taken this goal to another level and has already reduced energy use by 41%. The range of energy efficiency and renewable energy initiatives launched by the trust in Wales requires a £3.5 million internal investment over the next 18 months, an amount that has to be paid back with interest in the next seven years.

Financial savings do not represent the only impetus for the trust’s work in this area. As it is a charity that exists to conserve cultural and natural heritage, Jones points out that it makes sense for the trust to want to lower its own environmental impact and “show what can be done”.

The Welsh region of the National Trust has become a centre of excellence on environmental issues: it was the first to pilot an environment management system and is now leading the way on energy efficiency. At the same time, regions elsewhere are at the forefront of developing other corporate initiatives – in this way, the trust’s different regions can learn from each other.

Winning the 2012 Ashden Award, which was announced in May, puts paid to the myth that historic buildings cannot be retrofitted and made more energy efficient. But the National Trust’s success so far does not mean that its ambitious energy-efficiency goals will be easily attained: the charity has more than 29,000 buildings across England and Wales, with many listed or designated.

Jones says that the trust has encountered a knowledge and experience deficit in the mainstream contractor world when it comes to introducing energy-efficient adaptations to old, sensitive buildings.

“The official data say that historic buildings are ‘hard to treat’ but really they are just hard to understand,” he explains. “Most housing stock is already built and it is always a challenge asking a building to do something it is not designed to do. It is not a case of everything everywhere but something somewhere.”

The National Trust in Wales, however, has been successful in installing energy-efficient and green technologies in historic properties. These include fitting air-to-heat pumps at Dan y Gyrn and a biomass boiler at Chirk Castle, as well as reducing energy wastage at holiday cottages in North Wales.

Renewable energy initiatives

As well as improving energy efficiency across its holiday cottages and historic buildings, the National Trust is committed to generating all of its own energy as part of its sustainability mission.

It now has eight medium-sized hydro-power systems operating in Wales, including one at Hafod y Llan, a trust campsite in the Nant Gwynant valley. “After much discussion, consultation and adjustment we now have our abstraction licence in place,” says Jones.

“This means we now have an agreement with the Environment Agency and the other statutory bodies involved on the volume of water we can take out of the river and how much to leave in the river to maintain ecological and aesthetic aspects. This licence then triggers the planning permission to be registered and processed,” he explains.

The hydro system at Hafod y Llan uses around 450 litres of water per second and the trust is aiming to complete the work on the 650kW system in 2013.

The trust is also generating power through solar photovoltaics, including several systems set up in the grounds of historic buildings, rather than on their roofs. “We didn’t bother with the roofs because of the scale we needed, and the mitigation costs on a listed building could result in us having fewer panels in place because of the extra cost,” says Jones. “And I’m not a fan of bolting green ‘bling’ on.”

Changing the culture …

The National Trust views employee engagement as a crucial precursor to achieving its energy-efficiency goals. Cottage managers, for example, were involved throughout the heating controls project.

As well as the trust benefiting from the managers’ knowledge of the buildings, their understanding of the installation now means that they are able to support the smooth running of the equipment. “Hearts and minds, and not technology, are key,” Jones comments. “We do not want just a couple of environmental experts in Wales – we want everyone to be specialists.”

Effective training and communication sits at the centre of the charity’s strategy for involving staff and volunteers, and there is also a lively environmental blog that is followed by a lot of employees.

But, Jones confirms, developing commitment to the charity’s energy-efficiency mission is ultimately a relationship issue and based on “never-ending, day-to-day interaction” with trust staff. “The number one indicator of employee engagement is how much the environment team are asked about the issues – and we get asked a lot,” he says.

… to shape the future

As if its current energy-efficiency achievements and goals aren’t enough, the National Trust has a longer-term vision to generate 400% more energy from its buildings and land than it uses in Wales.

Another part of its game plan is to set up a consultancy to help others save energy and look at appropriate renewable technologies for older buildings. The charity seems to be well on its way to energy self-sufficiency and beyond.

Heat pumps at Dan y Gyrn

Nestling in the Tarell Valley, at the foothills of the Brecon Beacons, is Dan y Gyrn, the National Trust’s countryside base, and its volunteer house Beili Gwennol. Keith Jones, environment adviser for the trust in Wales, describes the buildings as having been touched with the “sustainable energy wand”.

In addition to the 25kW biomass system installed at Beili Gwennol, a series of air-to-air heat pumps have been introduced. “We have become fans of air-to-air heat pumps – namely for their simplicity and cost, which is around £500–£1,000 each – and the fact that they take just four hours to fit,” says Jones.

The challenge with upgrading the heating in Dan y Gyrn was that there was no distribution system for hot water; any replacement for the very inefficient storage heaters that distributed heat throughout the building (often when there was nobody in it) would also need to include an expensive hot water system.

“In this situation we opted for a £3,500 spend on seven heat pumps rather than £25,000 for a biomass system,” explains Jones. “Budget, time and disruption were major factors. Air-based heat pumps have had a bit of a bad press, but that’s been more based on design and management than the technology.”

Jones says that when the temperature is well below freezing, the heat they emit may well be on a par with a convector heater, and for 95% of the time he expects good heating performance from them.

“It is essential that users are trained in how to operate the air-to-air heat pumps,” adds Jones. “Our staff are well aware of the need to manage the heat pumps and refrain from using the ‘sub-tropical’ setting on the controllers!”

Biomass boiler fit for a castle

The National Trust has more than 25 biomass energy systems in place across Wales. One of its larger examples is a 450kW biomass boiler system in Chirk Castle, a grade I listed building near Wrexham that was built in 1310.

Heating and hot water were previously provided by an electric and oil-fired boiler system that had been in operation for more than 30 years. At £39,000 a year, Chirk Castle had one of the highest demands for oil fuel in the National Trust estate, with the large oil tanks posing a particular environmental risk for the property.

The aim was to replace the old electric and oil heating system with a low-carbon equivalent. To meet the funding requirements, the new system needed to be entirely renewables-based. In 2009, two biomass boilers, one 150kW and the other 300kW, were installed, with just over one-third of their cost being met by NATHEN – “National Trust heat from nature”, a trust programme funded by the Big Lottery Fund as part of its bio-energy capital grants scheme.

Low labour and maintenance needs were deemed important when scoping the project. This requirement, combined with the lack of available wood and storage facilities on the property, resulted in the decision to install a wood-pellet boiler rather than a woodchip system.

A modular boiler system was selected to ensure the system could cope with the seasonal variations in demand. The boilers are supplemented by solar thermal technology that comprises two double sets of solar thermal panels with a third set due to be fitted when the castle roof is replaced. These panels complement the biomass boilers by providing hot water to the public toilets.

Keith Jones, the trust’s environment adviser in Wales, says that the new system now provides 90% of the heating and hot water supply to the castle. The cost of the wood pellets is estimated to be half the price of the fuel for the old system, saving the trust around £25,000 a year.

Energy for holiday cottages

The National Trust has several traditionally built holiday cottages in North Wales, with solid wall construction. Although they have high levels of sheep wool insulation in their loft spaces, the draught and air leakage, particularly from ill-fitting doors, were having a negative impact on the energy performance of the cottages. The trust has been piloting low-carbon heating solutions, such as heat pumps and biomass, as well as an initiative on better heating controls to cut energy use.

Heating for the cottages used to be provided by a mixture of storage heaters, oil panel heaters and fan heaters. When the cottages were occupied, the storage heaters could be switched to their maximum output by guests and left on for days or even weeks.

The trust fitted electrical panel heaters operated via a controller that works in much the same way as a boiler controller. The period of time that the heaters are on is timed. A manual boost control was also fitted to the existing fan heaters which times out after a predetermined period, preventing the guests from leaving them running. The hot water heating systems at these properties were also fitted with additional controls.

Energy usage over the course of a year has been closely monitored and has confirmed that one of the trust’s cottages near Betws-y-Coed has saved £1,123 in energy costs over the 12 months.


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