The likely LEDs: heritage lighting

11 July 2018

Renovating historic buildings is never easy, especially when it comes to the lighting. Place fittings incorrectly and designers risk wrecking what made the original architecture so impressive. Andrea Valentino examines some of the most successful heritage lighting projects of recent years, and how new technology can make change feel seamless.

From 1543, and on for nearly half a millennium, the German town of Ulm has housed the tallest church on earth. Climb to the top of its 163.5m steeple and you can see the Alps, nearly 200km away across the Swiss border. The view is just as impressive from the ground up. Long square windows, criss-crossed with delicate Gothic stonework, rise up until your neck gets stiff and you push your eyes down again.

The building is as majestic as it was in the 16th century, but modern architectural decisions have proved less successful.

Divine light

Lighting is a case in point. For decades, visitors were faced with a gaudy regime of overhanging lights that made prayer feel closer to an interrogation than a conversation with God.

Not that the church is alone: from India to Italy, careless lighting design can ruin the aesthetic qualities of old buildings. But the situation is far from hopeless. By respecting the history of a space, lighting designers can protect original design decisions, while reimagining sites in remarkable new ways. New technology is a huge part of this process, helping designers create dynamic displays in the most enormous of projects.

Though they ultimately won the Heritage Project of the Year at the 2018 Lighting Design Awards, Michael Bamberger and his colleagues at Ingenieure Bamberger (IB) did not have an easy job fixing the lighting at Ulm Minster. Just getting to grip with the enormity of the structure took a while. Its walls are so high that the distribution of natural light is affected, obscuring the aisles and their wonderful stained-glass windows. On cloudy days, the images can become completely invisible.

Past mistakes made things even harder. In the 1980s, the cathedral was fitted with cumbersome pendant luminaries that lit pews directly and proved inappropriate for the rest of the building. At night, the spectacular vaulted ceiling was completely enveloped in gloom. Projects elsewhere have faced similar problems; 40 years ago, a botched refurbishment of the Sistine Chapel made its Michelangelopainted ceiling famously difficult to see. Meanwhile, new lights at the Taj Mahal lured plagues of insects, quickly coating the marble in a layer of excrement.

For Afron Davies, director at Arup Lighting, these mishaps emphasise the need for careful planning, especially in heritage buildings with salient architectural features. “Lighting has such a fundamental connection to conservation and potential damage of objects that the briefing phase needs to be very detailed,” explains Davies. “If you get that stage wrong and expectations are not managed, you can build a project where the designer is happy but the clients – museum directors, curators and conservators – are not,” he adds.

IB believes in similar principles and approached Ulm Minster with the ‘historical development’ of the church in mind. This meant carefully referencing the original Renaissance features of the building. Its triptychs and paintings are delicately lit from below, while the pews are flanked by fluted arches framed by gold. More specifically, the IB team made the most of a process called ‘daylighting’, commissioning studies to determine how much light should be allowed into the church from outside.

“The visual connection to the outside is very important in many different ways,” says Davies. “For example, it can remind people where they are or what time of day it is, but it has to be very carefully considered because it can generate a whole array of lighting challenges.”

In practice, IB worked to preserve the directional light streaming in from the 40m-high nave windows at the front of the church, while new fittings were placed to mimic natural light – even during bad weather.

Overall, it is hard to disagree with the judges at the Lighting Design Awards: the new Ulm Minster is a marvel. Nor is it the only church to receive such thoughtful treatment. The cathedrals at Strasbourg, France, and Southwark in London have enjoyed gorgeous lighting makeovers in recent years. Also in the UK, Sutton Vane Associates won plaudits for its work at York Minster. Like Ulm, success has tended to hinge on emphasising the intrinsic beauty of the architecture. In York, for instance, Sutton Vane endeavoured to conceal new fittings, letting the gargoyles and carved medieval saints speak for themselves.

Heritage lighting in secular architecture has gone the same way. One of the most elegant examples comes courtesy of Lighting Design International (LDI), and a project it took on Oxford Street in London. By using soft-lit bulbs and louvres, the firm brilliantly restored a row of storefronts to its Victorian best. Like IB and Sutton Vane, the designers let the building do all the heavy lifting. LDI highlighted its elegant stone balustrades and pediments, while the lights themselves were hidden or painted to blend with the bricks.

Absolute LED

Technology is another crucial part of modern heritage lighting. Perhaps the biggest change in recent years involves using different light bulbs, explains Boris Pretzel, principal scientist at London’s Victoria and Albert Museum.

“Standard light sources come from halogen and tend not to have very long lives, so designers have a lot of time invested in replacing lamps,” Pretzel states. “But by swapping to more LED lights, we get far fewer problems.” These advantages are particularly useful to looming spaces like Ulm Minster, where fittings can sometimes hang several storeys above ground.

Davies agrees, but is more interested in the creative possibilities of LED lights. “The two most widely known and acknowledged benefits of LEDs are reduced cost of ownership and reduced energy consumption,” he says. “But some of the other opportunities of LED lighting are things like the ability to customise the spectral distribution of the light, which can change how objects appear when illuminated.”

None of this is straightforward. As Davies notes, the technical aspects of LEDs require a “very detailed, intimate knowledge”. No wonder IB worked with Tridonic, a Swedish lighting manufacturer, to develop a range of sophisticated LED drivers for Ulm Minster. Each lighting head is individually aligned with the correct optics, and the luminaries consist of vertical tubes that can accommodate 20 or 24 small LED lighting heads. Not that these details scrimp on flexibility: the cathedral lighting can easily be adjusted, depending on the event or time of day.

Sutton Vane adopted this versatile approach for its work at York Minster. Each bay is controlled by two separate control circuits, so that each part can be dimmed individually. Several preset displays mean the atmosphere can be changed at the flick of a switch, whether the cathedral is hosting a graduation ceremony or intimate concert. The system can even be linked up to an iPad, letting event organisers tweak the lights remotely.

As remarkable as all this is, not even IB can protect Ulm Minster from the passage of time. When it is finally completed in 2026, the Sagrada Familia in Spain will become the tallest cathedral in the world, robbing Ulm of a title it has held for 535 years. Parishioners should probably not be too upset, though. The church is still a masterpiece and its glow is more beautiful than Reformation Germans could ever have imagined

The lights at Ulm Minster needed extensive work to let the church really shine.
Sutton Vane Associates’ work at York Minster has been highly praised.
Ulm Minster’s lighting previously stopped visitors seeing its stunning stained-glass windows.

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