You may be one of those who think Renzo Piano’s Shard in the City of London is just pie in the sky, but the architect himself has no doubts. Besides, he’s got friends in high places. By Dan Stewart

Renzo Piano’s head is in the clouds. He is daydreaming about the church he plans to build at the top of the Shard: “I always thought it would be nice to have a place of meditation up there. It would not need to be a church, as such, but somewhere to go and sit.”

Many “starchitects” come across as lofty, self-involved individuals in the flesh, so obsessed with the conceptual that it is difficult to engage them on a practical level. But for all his talk of places to go and sit in the sky, Piano is a down-to-earth pragmatist, more obsessed with materials than with meditation. He builds a small replica – a “mock-up”, in his own words – of each of his designs before construction begins to ensure the building turns out exactly the way he wants it to look.

“Sometimes I have to explain this to the client,” he says with a smile, “but when I explain, they understand. If you don’t explore, you don’t find new things.”

Born in Genoa in 1937, Piano remains true to his Italian roots and still has a home and office there. He trained at the Politecnico di Milano where he later taught, before going on to work alongside other architectural greats, including Louis Kahn and Richard Rogers, with whom he joined forces to design the Pompidou Centre in Paris in 1977.

Over the past 30 years Renzo and his practice, Renzo Piano Building Workshop, have designed a dizzying variety of projects. There are not many signature architects who can boast airports (Kensai in Japan), shopping centres (Bercy in Paris) and football stadiums (Bari in Italy) on their CVs.

In his 70th year, Piano is still going strong, with an increasing focus on buildings in the UK – the reason for his flying visit to London last month. He is designing not only Mace’s Shard in the City of London, but also a brightly coloured office scheme at Central St Giles in the shadow of Richard Seifert’s Centre Point tower. Here, in a rare free slot, he talks 9/11, the Shard and Ken Livingstone – though Boris Johnson still appears something of a mystery to him.

Stanhope development director Mike Knowles is working with Piano’s workshop on Legal & General and MEC’s Central St Giles development. “It’s a personal approach,” he says. “He’s a down-to-earth and engaging individual, who’s more than happy to talk to people, and he takes a detailed craft-based approach to developing the project. He doesn’t stick rigidly to his ideas, which can be the case with high-profile architects. We’ve really enjoyed the creative process with him.”

It’s a measure of this trust and respect that Piano was the first architect to be commissioned to build a tower in post-9/11 New York, the recently completed New York Times HQ. Amazingly, Piano was awarded that contract on 11 September 2001: “It was very emotional because it was such a tragedy. We had to rethink completely how we do tall buildings.”

Although work on the tower didn’t begin until New York felt confident enough to start to move on, which was two years after the attack, Piano says there was still plenty of opposition to the 52-storey scheme. “The real problem was that the people who wanted to rebuild the city thought it was the fault of the towers and not the terrorists,” he says. “People blamed the towers for collapsing.”

In London, there is a medieval tradition that needs to be understood. It is the British way

He rejects the idea that the threat of attack should affect the design of a signature building. “The temptation in circumstances like this is to design a self-defensive building,” he says. “But the only building that is resistant to a terrorist attack is, of course, a bunker, underground. The real big adventure was to escape from that thinking.”

The result is a building traditional in its ambition, but forward-looking in its treatment. Clad in white ceramic rods, the New York Times HQ is a beacon on the Manhattan skyline. Piano is pleased with the result. “The owners like it, the people love it. They trusted us to build a building that is safe, and yet transparent. It works very well.”

After such groundbreaking work in Manhattan, Piano now has his sights set on London, and perhaps his most famous commission in recent years – the Shard of Glass. The designs for the 310m tower had a frostier reception than the New York Times HQ, with English Heritage (EH) calling it in for a public inquiry. Although he once described EH as “perverse,” he now claims some kinship with the public body. “In Manhattan, you have a generation of people who know towers, who understand a landscape of tall buildings,” he says. “In London, there is a medieval tradition that needs to be understood. It is the British way.”

As regular readers of Building will know, doubts remain as to the Shard’s financial viability, with many commentators not believing it will ever see the light of day. But Piano is so sure it will be built he has already started to build a large mock-up of the facade in a field in Genoa; the idea is to examine how it reflects light. “The light will change from wherever you are,” Piano says.

Like many other tall buildings, the Shard has been labelled unsustainable. The energy footprint of the 66-storey tower will be huge, and it has long been recognised that glass buildings are difficult to make sustainable. But Piano is quick to defend the project: “The sustainability of this building is as much in its position as in its construction. There will be no car parking spaces here. I would not have designed it if it were not on top of a train station.”

And though he may be daydreaming today, Piano’s church will not remain just an idle concept. He and the Right Reverend Tom Butler, the Bishop of Southwark – “a good friend of mine” – are to make it an official submission. “The building will be a living city, with hotels, and apartments, and businesses. Why should it not have a church too?” he asks. “Ken Livingstone has been very supportive.”

That may be so, but Livingstone is no longer in charge of London. That responsibility now rests with Boris Johnson, whose attitude to tall buildings has been less than supportive. So what does Piano think of Boris? He looks bemused. “Who is this?” Boris Johnson? Blond hair? Buffoonish? Piano shrugs, and smiles again. “I don’t know him.”

It’s difficult to tell whether this is true, or whether perhaps Piano’s head is back in the clouds.