Updated March 8, 2016

“Downton Abbey” saw technological changes during its six glorious seasons on TV—and none appealed to perhaps its most memorable character, the Dowager Countess of Grantham, Violet Crawley.

"First electricity, now telephones. Sometimes I feel as if I were living in an H.G. Wells novel," says the inimitable Lady Violet, played by actress Maggie Smith. Bemused by how the telephone works, she asks: “Is this an instrument of communication or torture?”

Unlike the TV countess, grief-stricken fans bidding cheerio to the British blockbuster—its last episode aired Sunday in the United States—may console themselves knowing that the real-life Downton is planning for an eco-minded future.

Massive Highclere Castle, along with other historic homes in Europe and the U.S. that were once heated solely by fireplaces, is taking steps to save energy by installing efficient lights and nearby solar panels. Blimey, it’s turning a tad green.

“We have a program of going around the castle” and replacing incandescent lights with LEDs, says Lady Carnarvon in an interview, noting that light-emitting diodes use 90 cent less power. About five or six years ago, she says, “I started on a journey to do it, and I’ll continue.”

Renovating Highclere, though, isn’t always simple. Some of the Victorian castle’s 200 to 300 rooms, including its 50 to 80 (unheated) bedrooms, need rewiring.

“It’s not changing a light bulb,” says the Countess of Carnarvon, a best-selling author who married the man with the keys to the castle, George Herbert (“Geordie” to her), the 8th Earl of Carnarvon.

She says the couple is “prioritizing” projects. She’s added insulation and installed LEDs in the estate’s cottages, and her husband’s put solar panels on farm buildings a couple miles from the castle. She says the panels provide electricity for drying wheat and corn during summer harvests but don’t ruin the view of Highclere.

As one of England’s historic properties, the castle has aesthetics to consider. “Solar panels are not necessarily the way forward for us,” says the countess, noting her husband is looking at biomass options such as heating with wood chips.

“At the moment, they don’t make enough sense,” she says, citing the need to cut down trees to make the chips and find enough space to store them. “Over the next five years, some options will become clearer.”

Lady Carnarvon says the castle aims to cut its carbon footprint with sensible, forward-thinking measures. “Highclere has been at the forefront of technology,” she says, adding it was one of the first of its era to get electricity.

View Images England's Upton House, bequeathed by former Shell chairman Lord Bearsted to the National Trust, has stopped using oil for heating. Instead, It's using wood pellet boilers. Photograph by lovethephoto, Alamy

Shell Heir’s Estate Nixes Oil

Other grand homes throughout the United Kingdom are getting bold makeovers—some innovative and perhaps surprising.

Take Upton House, once owned by petroleum tycoon Lord Bearsted but now bequeathed to the nation via the U.K.-based charity National Trust. Bearsted’s father, shopkeeper Marcus Samuel, helped found Shell Transport and Trading Company, which later became part of the Royal Dutch Shell Group*.

The Warwickshire estate had been using 25,000 liters (157 barrels) of oil each year to heat its buildings, which are roughly the size of 11 average homes. In a recent renovation, its four oil boilers were replaced by two new wood pellet boilers, a swap that reduced energy bills. (See more about the U.K. love affair with wood pellets.)

“It’s a bit ironic” given Upton’s lineage, says Patrick Begg, rural enterprise director of the National Trust, which has received 30 million pounds ($4.2 million) to green 43 historic properties in part by eliminating their use of oil. The charity has already done so with several projects, and it aims to get half the power needed for all properties from renewable sources by 2020.

“Most people are intrigued. They’re impressed we can do this without making a mess,” Begg says of visitors who tour the mansions after renovation. “We’re very careful about fitting the right technology to the right place, at the right scale.”

So in the case of 16th century Hardwick Hall, that means no wind turbines. The National Trust supported a government decision not to allow the construction of six tall turbines on the Derbyshire estate. It generally favors less intrusive approaches.

At Croft Castle in the Herefordshire countryside, for example, it also removed the oil boilers. Biomass boilers now provide three-fourths of the property's heating. The boilers are powered by wood chips from local conifers, offering a benefit beyond reduced carbon emissions and heating costs.

“The woodlands are becoming healthier,” Begg says. The conifers had overrun parts of the Croft estate, so using them for fuel has opened up space for the ancient broadleaf woodland to thrive.

Some projects take a broad approach. On the coast of North Wales, the 18th century Plas Newydd mansion got not only smart meters to monitor energy use but also roof insulation, efficient lighting and, in a nearby sports field, solar panels. Most significantly, its oil boilers were replaced with the U.K.’s largest marine-source heat pump, powered by the tidal currents of the Menai Strait.

“It’s performing brilliantly,” Begg says, noting the heat pump didn’t require interior changes such as ripping out radiators. “It’s plug and play,” he says, of the boiler switch.

“There’s no one-size-fits-all solution” to renovating old homes, says Asa Foss, residential technical director of the private U.S. Green Building Council. He says it needs to be done carefully to avoid water or structural damage. He recommends air sealing and attic insulation, but “I’d leave the radiators alone and get a new boiler instead.”

“Lighting is a no-brainer,” he says, of switching out incandescent bulbs for LEDs—as Downton, er, Highclere, is doing.

View Images Scotland's Birkhall House, one of Prince Charles' private residences, has a biomass boiler that uses wood chips for heating. Photograph by Duncan Shaw, Alamy

Other TV-famous castles have done energy makeovers. Castle Howard, where the 1981 British show “Brideshead Revisited” was filmed, has installed a ground-source heat recovery system that uses heat from water in the estate’s lake.

The Prince and the President

Prince Charles, a decorated environmentalist whose Aston Martin runs on bio-ethanol made from wine wastage and a cheese by-product, also uses a ground-source heat pump at his Highgrove House.

The Prince of Wales says 84 percent of his household energy comes from renewable sources and 38 percent is generated on-site. Highgrove also has wood-chip boilers, as do two other of his residences, and solar panels, as does his Clarence House. His homes use insulation, smart meters, LEDs, and motion-sensitive lighting.

President Barack Obama, who has made climate change one of his signature issues, installed solar panels on the roof of the White House in May 2014. He wasn’t the first to do so. President Jimmy Carter put a solar array on the roof in the late 1970s, but President Ronald Reagan took it down.

View Images Presidenti Barack Obama had solar panels installed on the rooftop of the White House in May, 2014. Photograph by Martin Shields, Alamy

“Being at the White House, we do have some security concerns,” White House Usher James Doherty says in a video about the project. “We can’t cover the entire roof with panels.”

Highclere, too, has its limits. Its thick stone walls make adding some modern-day comforts impractical. “There’s no wi-fi,” says Lady Carnarvon. “I find guests hanging out the windows trying to get a signal.”

Also, “if you’re American you might find the castle cold,” she says. “There’s no heating in the bedrooms” though she has portable units for frigid nights. She believes in old-fashioned efficiency steps such as bundling up with sweaters and turning off lights when you leave a room.

She says the 5,000-acre Highclere estate has many virtues, including gardens and exquisite architecture. “Some of the rooms in the tower have extraordinary views,” she says. “It makes you realize how lucky you are.”