The Museum of London: a fundamental clash as the City of London dreams on

<span>Photograph: Robert Evans/Alamy</span>
Photograph: Robert Evans/Alamy

Next Sunday, the Museum of London, which as the official text puts it “tells the ever-changing story of this great world city and its people, from 450,000BC to the present day”, closes the doors of the building it has occupied for the past 46 years. This is on the edge of the Barbican, the brutalist estate of apartment blocks built in the 1960s and 70s in the City of London, with an adjoining arts centre completed in 1982. The renamed London Museum is due to reopen in 2026 in larger, more impressive and more accessible premises formed out of buildings that once served the meat market at nearby Smithfield. The current facility is closing with a bit of a bang, with a music weekend, cinema festival and 24-hour opening scheduled for its final days.

The move raises the contentious question of what to do with the buildings on the site, by the elegant postwar modernists Powell and Moya, which include the old museum and a 17-storey office tower called Bastion House. The City of London – the local authority-cum-business enterprise that owns the site – wants to replace them with 780,000 square feet of offices and other uses. Residents of the Barbican and other objectors say this would be a wasteful and environmentally damaging overdevelopment of the site, contrary to the City’s own policies and proclamations about climate.

Feelings are heightened by the fact that a glorious concert hall was promised for this spot

Like the high-profile battle over the future of Marks & Spencer’s flagship store at Marble Arch, this is a test case for the argument that old buildings should be kept for the sake of the carbon embodied in their fabric, and to avoid the costs in energy and emissions that go with rebuilding. The greenest building is the one that already exists, as many architects now like to say. Which should mean that the property industry, especially in the City of London, will have to give up its decades-long addiction to rapid cycles of demolition and rebuilding.

Feelings are heightened by the fact that a glorious concert hall was promised for this spot, the Centre for Music, a 2,000-seat venue with immaculate acoustics of a kind that London doesn’t have, until it turned out that the funding for its £288m budget wasn’t all there. Early last year, Simon Rattle, music director of the London Symphony Orchestra and the driving force behind the project, announced that he would be leaving for Munich. So it’s a bit of a comedown to be offered a splurge of office space instead, as if you’d been promised a state-of-the-art sound system for Christmas but found only gift-wrapped filing cabinets around the tree.

They are, to be sure, fancy filing cabinets, bearing many pot plants. The project consists of three blocks, 17, 14 and five storeys high, designed by the British architects Sheppard Robson and the New York practice Diller Scofidio + Renfro, the latter forever esteemed for their work on the city’s High Line, and who also designed the cancelled concert hall. The idea of the new plan, carried over from that lost project, is to make a welcoming entrance to the Barbican complex, across what is now a forbidding traffic roundabout. You would ascend to a raised green space, bracketed by the two larger blocks, which would have leafy balconies rising their full height.

The proposed buildings twist and swoop, and have mushroom-shaped columns at their base, in the style of Thomas Heatherwick. Exhibition and auditorium spaces are also promised, in loving memory of the grander artistic plans. But the designs can’t hide the blocks’ bulk, nor the fact that Bastion House and the museum buildings, which underwent a £20m redevelopment that opened in 2010, would be destroyed.

The City of London says that it’s unviable to keep the old buildings; that Bastion House is too awkward for modern office users – its ceilings too low, its floors too narrow, its structure dangerous, its walls poorly insulated. Experts working for the objectors contest these claims. Simon Sturgis, an architect specialising in sustainability, argues that the City’s own figures show that “the retrofit option” – that of renovating the existing fabric – “produces less lifetime carbon emissions than new-build”. Bastion House, according to the engineer Bob Stagg, is not in fact unsafe.

The current designs have no particular rapport with the dignified order of the Barbican

At the heart of the matter is what Sturgis calls a “fundamental clash”: on the one hand there is “20th-century logic”, where “you max out development of site irrespective of what is there”. Developers, often encouraged by planners, seek to create the maximum possible volume of commercial space, built to the unyielding specifications that achieve the highest rents. On the other hand, says Sturgis, you take the attitude that a new building, whatever “green” claims may be made for it, can “never be as good as a proper refurbishment.

“It’s amazing what you can do with existing buildings,” he says, but keeping them requires flexibility and thought by both planners and developers. Wider ranges of uses need to be considered. Bastion House, for example, might work better as a hotel or apartments than as office space. The benefits of retention, such as quicker and cheaper development, should be taken into consideration.

The plans for the Museum of London site would benefit from such a close engagement with what is already there, of a kind that made the High Line – a park conjured out of an old elevated railway – an inspiring place. The current designs have no particular rapport with the dignified order of the Barbican, while displaying a high degree of optimism about the ability of plants to grow in unlikely places. Calmer and cleverer architecture would help the green spaces work as promised.

Behind the designs, of course, are questions of money, and the City says it needs the tens of millions that it hopes to make from this site to help fund the new, improved London Museum and some upgrades to the Barbican. But less extravagant-looking architecture would be cheaper. Savings might also be made on the rather vague cultural uses promised for the new development: the physical environment, local and global, matters more.