Taken to the cleaners

Abseilers, mountain climbers and robots. Just three ways to tackle that perennial building-maintenance problem - how do you keep all that glass clean?

Since windows became stretched into entire facades and those facades stretch hundreds of feet skywards, window-cleaning has become a boom industry. The question everyone always asks when a new building goes up is, how will they clean it? And now that all lottery- funded applications have to demonstrate the economy of running costs, architects have to come up with some answers. None of them like anything that ruins the facade. Even a lightweight aluminium cradle on ropes is seen as a blot. It is said that the steel rim around Norman Foster's Sainsbury Centre was only added after safety regulations on window cleaning specified it.

But this is not window cleaning as we know it but a whole new wall game. Men - there are no women in the industry yet - and robots can be tidied away to leave the facade squeaky clean for a photocall.

Hi-tech gives you a robot like the one Ian Ritchie developed with students of Magdeburg University in Germany to clean the world's largest glass palace at Leipzig, which he designed.

Schussing along 1,240 metres of glass, its windscreen-wiper arms gliding along its 80-metre-wide facade, the robot cleans the really tricky part at the apex of the curved roof, 30 metres up in the air. In fact, the entire building surface has a watering system, which provides evaporative cooling in the summer, as well as water for cleaning. And to clean the inside, doors into the glass house are wide enough for cherry pickers to roll inside once every two or three years.

Low-tech gives you abseilers, hitching themselves to the parapets and swinging down with just narrow hoses and a lightweight aluminium cradle providing water supplies. "Never look down," says Bill Wintrip, the managing director of CAN civil engineers, who put their ads for window cleaners and engineers in mountaineering and pot-holing magazines. It's easier to teach adventure sportsmen cleaning and painting and on-site inspection than it is to get engineers with vertigo to step off a tall building.

For years, maintenance was the unfashionable side of the construction industry. But since the 1994 Cleaning, Design and Maintenance regulations were introduced, it has been boom time. The glazing industry has been slow to catch on. In the guide for architects and designers Glass in Building there is everything you need to know about glass, including how smart skins change from clear to opaque at the flick of a switch. It explains how glass insulates, why it is bullet-proof, person-proof, security conscious, and responsive to electrical impulses or changes in the weather, which can darken or lighten it. Yet nowhere does it tell the architect and design professional - to whom it is dedicated - how to clean it. Pilkington, the UK glass manufacturers who helped to compile the tome, were sorry but they thought that the Glass and Glazing Federation would have all the answers. But their helpful hints were worthy of Mrs Beeton - soapy water and a chamois leather. And in obstinate cases, methylated spirits. Very useful 100 years ago, but hardly likely to hack it on the glass canopy which Richard Rogers Partnership has designed to protect - like cling film - the so-called "Sixties" buildings on the South Bank - the Hayward Gallery, the Queen Elizabeth Hall and the Purcell Room.

First, the existing buildings have to be hosed down to get rid of that cigarette-ash-grey pallor. Then the grounds around will be landscaped so that trees will grow under the glass. There will be 260 per cent more space beneath its protective canopy for arts but the Arts Council has been dragging its heels for eight months over giving it the go-ahead - and pounds 115m. Richard Rogers Partnership architect Ivan Harbour is on auto- pilot as he answers the inevitable question: "How will it be cleaned?"

"A combination of low-tech methods that comply with CDM (Cleaning, Design and Maintenance) regulations that are more akin to the methods at the Museum of Hamburg than to the pyramid in the Louvre, which requires specialist abseiling techniques." In other words, men with mops will walk all over the gently undulating roof made of specially toughened glass - a stroll that the vertiginous slopes of the Louvre pyramid rule out.

In the courtyard of the Louvre, two abseilers have to be lifted up to its apex to clean its slopes with soapy water. IM Pei, the architect, insisted upon this method of cleaning. The inverted pyramid below ground in the Carousel du Louvre, which beams in light, has special air filters fitted to stop the dust settling but they haven't been entirely successful.

However grimy glass gets, at least it repels graffiti. At the Building Research Establishment near Watford, Matthew Murray has been working out how to clean off spray- paint slogans on the historic buildings of Scotland. It's the kind of place that Q from the Bond films hung about in - big hangars where they recreate the Channel Tunnel fire to test fireproofing, or build walls only to blow them up again. Borrowing a tip from plastic surgery, the BRE team are testing lasers to give facelifts to sandstone facades. The pounds 50,000 laser emits a pulse of light onto walls to break off unwanted material but leave the masonry intact.

Daniel Libeskind, the architect of the controversial proposed spiral extension to the Victoria and Albert Museum, showed his blueprint to the museum cleaners before anyone else. They influenced his decision to clad the building in ceramic tiles, the material of the past and the future. He admits it is a nod to the applied arts of Ruskin and Morris a century ago. His tiles are designed like fractals, those randomly repeating patterns created by computers; they symbolise the way in which digital electronics has replaced steam and moving mechanical parts in the modern age.

Most of all, they exemplify the way modern materials assist in the maintenance of structures, helping them remain in as-new conditionn