Holy heat pumps! Inside Lambeth Palace’s £40m eco makeover

The next Archbishop of Canterbury will have heat pumps. Lambeth Palace, the 800-year-old London home of the Church of England’s spiritual leader, has had a top-to-bottom eco-restoration that got rid of its gas boilers.

It is hard enough to do this in a Victorian terrace, let alone a grade I listed palace at the heart of England’s history since the 12th century. These buildings played a central role in Henry VIII’s marriage to Anne Boleyn and split from the Catholic church; were bombed in the Second World War; and played host to visits from kings and queens, prime ministers and presidents, the Pope and the Dalai Lama.

Its £40 million restoration is the ultimate historic retrofit. Not only did the builders fit 160 double-glazed windows, 30 miles of cables, a mile of heating pipes and three giant air source heat pumps. They did so amid rehearsals for the King’s coronation, blessings to dispatch ghosts and the discovery of half a human body (more on which later).

“We’ve already eliminated gas from the main building and reduced the carbon emissions by 63 per cent,” says Michael Minta of the Church Commissioners, which manages the church’s historic assets and funded the project. Once gas is switched off in the site’s smaller buildings — now all connected to the new heat pump network — emissions will be down 71 per cent.


“It’s part of that wider message: the fact that it’s possible [to decarbonise] such a time-deep, historically complicated site. If we can do it here, we can do it anywhere,” says Emily Gee, the Church Commissioners’ director for church buildings.

Gee says this while standing on the palace roof as workers fit 24 solar panels around us in September 2024, during the first of two exclusive tours for The Sunday Times. We are kitted out in hard hats, hi-vis and steel-capped boots. The sound of a hundred builders digging and drilling fills the air. Trenches dissect the ground far beneath us.

Up here, the solar panels are invisible from the ground, hidden behind a parapet on a flat roof section. “These must be the solar panels with the best view in London,” I tell Gee. Big Ben, the London Eye and the Shard are visible around us.

The rooftop fitted with solar panels
AKIRA SUEMORI FOR THE SUNDAY TIMES


Directly across the Thames from Britain’s seat of government at the Palace of Westminster, this site has been home to the Archbishop of Canterbury — then one of the monarch’s chief counsellors — since 1197. Over the centuries buildings from different eras were added; then partly rebuilt after Second World War bomb damage. This project is Lambeth Palace’s first big refurbishment since then.

Its ageing plumbing, heating and electrics were at “a high risk of a catastrophic failure … with the potential to cause irreparable damage” to the buildings, Minta says. “It probably was an accident waiting to happen.”

Burst pipes had stained ornate ceilings. The historic halls were icy. Justin Welby, the previous archbishop, told how he would switch off lights in his study, only to hear someone shout downstairs that it plunged them into the dark.

Bomb damage from the Second World War

In November Welby became the first archbishop to resign over a scandal, after being accused of mishandling allegations against a prolific serial abuser in the church. He has since moved out, leaving the “flat above the shop” — as Rowan Williams, his predecessor, called it — vacant for the 106th archbishop, due to be announced by September.

The three-year renovation has gutted the palace, but the scars are nigh invisible when The Sunday Times returned this month to see it complete. “When you walk through it now, you should feel like we haven’t done any work. This project is about being honest to the heritage,” says Stephen Smith of Wright & Wright Architects, who oversaw it.

The studio’s conservation architect, Leanna Boxill, adds: “There’s so many lovely characteristics about the buildings that you don’t want to lose. [When] trying to improve sustainability, it’s a stewardship. You try to get that balance right.”

Architects at work during the restoration
ALISTAIR VERYARD PHOTOGRAPHY


First, they improved the fabric of the buildings, so they would need lighter energy systems to run. The most dramatic change was to upgrade all the leaky windows in the Blore building, which contains the archbishop’s flat, headquarters and state rooms. Single-glazed leaded windows, fitted after the war bombing, were swapped for double-glazed oak sashes — laser cut to their intricate original design by the 19th-century architect Edward Blore. “Technologically this wouldn’t have been possible five years ago,” Smith says. This change alone has increased the palace’s energy efficiency by 41 per cent, according to Arup, the project engineers.

The main stairwell ceiling
HUFTON AND CROW


They also insulated the loft and floor, but not the walls, which were already up to a metre thick. Overall, the annual heating bill is expected to fall by 42 per cent, from £52,000 to £30,000 a year. Hidden behind a metallic screen in one corner of the site are three 250kW air source heat pumps. Standing a few metres away, I cannot hear them hum. The street noise is far louder.

From here a “Tube map” of underground heating pipes runs to the buildings, where 140 radiators were upgraded, Smith says. Because the water flows through the heat pump system at 50C, which is 20C lower than the old gas boilers, the radiators “needed a bigger surface area to get the same heat out into the room”.

The heat pump centre
AKIRA SUEMORI FOR THE SUNDAY TIMES

One of the 140 upgraded radiators
AKIRA SUEMORI FOR THE SUNDAY TIMES


Amid the digging to bury all those pipes, archaeologists found the truncated leg bones of a human thought to be pre-Christian. The remains were unearthed about a metre below where the deep-fat fryer now is in the new industrial kitchen. “It was on its own, which is quite strange,” Boxhill says. The skeleton’s upper half is still missing.

Afraid of ghosts, some builders are understood to have refused to work in this area. Two blessings of the bones were performed.

On a site with evidence of Roman and Saxon settlement, archaeological finds were expected. “Every time we opened a hole, we’d find something,” Minta says. They also discovered a medieval cesspit, the remains of the medieval palace walls and Tudor paving — all captured on a detailed 3D scan and then reburied.

A 3D scan of archaeological finds

The kitchen where pre-Christian human remains were found
AKIRA SUEMORI FOR THE SUNDAY TIMES


Piecing together the original design of the buildings from historical documents was “probably the most fun bit of our job”, Smith says. “People think something’s always been one way. Then you look at an old photo or drawing and you say, ‘Oh, there used to be a door through here.’” Incidentally, off the archbishop’s study is a secret door disguised as a bookshelf where they can escape unseen.

At Lambeth, history is everywhere you look. Its great hall, built in the 13th century, has hosted many monarchs — including Henry VIII. Because the Tudor king’s first marriage did not give him a male heir to his throne, he wanted to annul it but the Pope refused. This led to Henry declaring himself head of the Church of England and breaking with Rome.

A portrait of Henry VIII and Anne Boleyn
ALAMY

The floorplan for Lambeth Palace from 1684


Archbishop Thomas Cranmer, who lived at Lambeth Palace, granted the King’s annulment and married him to Anne Boleyn. In Lambeth’s 14th-century guard room, the King’s confidant and chancellor Thomas More refused to swear an oath acknowledging Henry as head of the church, which led to More’s beheading.

In his Lambeth study Cranmer later wrote what became the Book of Common Prayer, bringing English instead of Latin into church services. Much of it is still used today. Cranmer was burnt at the stake after Mary I, Henry’s daughter, tried to return England to Catholicism. Ultimately the split from Rome shaped England as a Protestant country.

Cranmer’s successor and England’s last Catholic archbishop, Cardinal Reginald Pole, planted a fig tree from Italy at Lambeth that still bears fruit almost 500 years on. It now has an inconspicuous row of electric car chargers next to it.

Pope Benedict XVI and the Archbishop of Canterbury, Rowan Williams, at Lambeth Palace in 2010
MATT DUNHAM/GETTY IMAGES

The great hall in 1804; after renovation


In 2010 the Pope visited Lambeth Palace for the first time in history and spoke in its great hall. Now the hall has trench heating, newly powered by heat pumps. Bookshelves that lined its walls have been sensitively refashioned into wall panelling. The hall’s oak hammerbeam roof, built in 1660, has been painstakingly restored. One Sunday afternoon during the renovation, part of a beam fell and “smashed into two pieces on the floor”, Smith says. “We were, like, ‘The roof is caving in. What else are we going to have to deal with?’”

The palace remained open to visitors and staff throughout the project. In the guard room — where past archbishops’ private armies once gathered — Welby rehearsed for the King’s coronation. Staff stood in for the monarch as Welby practised handling the crown used in the Netflix series The Crown, which is just as heavy as the real thing.

King Charles crowned by the Archbishop of Canterbury, Justin Welby, during his coronation ceremony
VICTORIA JONES/GETTY IMAGES


Smith says the builders would “just be told, ‘Can you be quiet on that Friday?’” Work was also scheduled to pause during the daily prayer services in the chapels.

The team restored 800 sq m of historic stonework, replaced 1,450 sq m of floorboards and plastered or painted over 13,500 sq m — equivalent to two football pitches. They fitted rooftop rainwater harvesting, a mile of water pipes and 26 new lavatories.

Energy-efficient chandeliers now light the state rooms where archbishops have hosted the likes of Princess Diana, Queen Elizabeth II, the Dalai Lama and the US secretary of state Mike Pompeo.

Princess Diana and the Archbishop of Canterbury, George Carey, at Lambeth Palace in 1993
GETTY IMAGES/TIM GRAHAM PHOTO LIBRARY

A restored state room
AKIRA SUEMORI FOR THE SUNDAY TIMES



Guests in wheelchairs no longer have to use a winding back entrance, but have elegant stone ramps to the main doors, four new lifts and lavatories accessible to all.

The original aim was to modernise Lambeth’s infrastructure, but that expanded to cut emissions after the General Synod set a target for the church to be net zero by 2030. The climate crisis most acutely affects the world’s poorest, Minta says. Responding to it is essential to “safeguard God’s creation and achieve a just world”.

The lessons from Lambeth’s retrofit will be shared as the church works to cut emissions at all 32,000 buildings it owns, Minta adds. “It’s an example project — the biggest we’re going to have by a long shot in the Church of England, and a really good example of what we can do in a historic grade I listed building towards net zero.”