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The U.K.'s most venerable mansions to get low-carbon face-lifts

LONDON -- A handful of Britain's most treasured old buildings are soon to get low-carbon makeovers as part of plans by the National Trust, the charity that owns them. The effort is to help the nation cut its carbon footprint, and more elderly structures could swiftly follow if the trial projects prove successful.

The National Trust runs some 29,000 buildings across the United Kingdom. About 300 are old mansions and 88 are castles. The trust has already taken some major steps toward its target of getting half its energy from renewable sources and halving its fossil fuel use by 2020 by installing large quantities of solar photovoltaic panels and insulating heat-leaking attics.

But the five pilot projects now underway -- two biomass power plants, two 100-kilowatt hydroelectric schemes and the country's first medium-scale marine source heat pump -- could open the way for many more if they prove a success.

"We have already done about 190 various projects over the years, and the five pilots are essentially leading on from them in a much more focused way into a much larger investment. It is much more than simple kilowatts," said Keith Jones, an environmental practices adviser for the National Trust.

"It is less about the technology than a new approach to development -- how the big themes of the trust's day-to-day business fit in. We would rather be putting the £6.5 million a year ($10.2 million) we are spending on energy into our core business, which is conservation. But what we are doing is all lowering costs to enable us to do our core business," he explained.

Among the more ambitious of the five projects is work at Plas Newydd, the sprightly 300-year-old former ancestral home of the Marquess of Anglesey on the small island of the same name just off the coast of north Wales.

Taming heating-oil guzzlers

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The National Trust has already insulated 21,528 square feet of the attic, thereby cutting energy use by 22 percent, switched all lighting to special light-emitting diodes (LEDs) of its own design, and installed half an acre of solar photovoltaic panels in a nearby field. It is in the process of installing discreet insulated windows in key parts of the house.

But there is still a major problem. At the height of winter, the mansion's oil-fired furnace can burn through 1,500 liters of fuel a day -- not only making it the biggest consumer of fossil fuel in the trust's portfolio of properties but also contributing significantly to carbon emissions.

So the National Trust plans to install a large heat pump that will be powered by the solar array. "I am hoping that by the time we are finished, we will see an 80 percent cut in the mansion's carbon emissions," Jones said.

If the five pilot projects prove a success, they will be swiftly followed by many more, all of which will be at houses chosen because they are oil guzzlers. "If we deliver the five and we keep the targets we have set ourselves, then that releases resources for a further 33 biomass projects, and around 12 decent-scale hydros [hydroelectric dams] -- we have got a couple around a megawatt. It is all about the learning process," Jones said.

"Most of our energy use goes on heat. We have some really old infrastructure using mostly oil. We want to get off oil as quickly as we can, so there is a heavy focus on heating within this programme," he added.

While solar photovoltaic panels are an integral part of the trust's plans to slash its carbon footprint, very few are actually fitted on the buildings. This is simply because not all have roofs facing the optimum way, which is south, and because the difficulty and costs involved in fitting and rewiring make it more economical to put larger arrays nearby and send the power to the building.

Introducing massive chandeliers to LEDs

Applying insulation and insulated windows also play important roles in the carbon makeovers of ancient castles and mansions, with the emphasis being on doing what is appropriate in each case rather than applying one solution for all.

"The important thing is to understand your building and what you are asking of it. It is not a matter of going out and putting secondary glazing [insulated windows] on everything. We put secondary glazing on what we call sitting targets. If you have got residential or offices, it is much more effective targeting those areas than areas where we just heat for conservation to maintain the fabric. We don't heat those to the same level, so the heat loss is less," Jones explained.

Lighting is also crucial. Across the trust's properties, there are tens of thousands of light bulbs in conservation areas, many in giant chandeliers with very old light fittings.

The new bulbs do not emit ultraviolet light, which can harm antique fabrics, and generate little heat to avoid damaging old fittings. They must also give out the right quality of light, have a long life and also look good even when they are not turned on.

After much frustrating trial, error and failure of commercially available low-energy light bulbs, the trust teamed up with an outside company to develop its own conservation-grade candle-like LEDs that it says not only look good but cut energy use by 85 percent.

"The new LED bulbs are half the price of the bulbs we were using, which had to be special low-UV emitters," Jones said. "The new bulbs also have a much longer life, which is very important, because if you need to change a bulb in a huge chandelier, it is not the bulb that costs but all the scaffolding time that is required."

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