Is now the time to invest in LED lighting?

Rebecca Atkinson, 17.01.2011
LEDs are said to offer high-quality, energy-efficient lighting to museums. But is this relatively new technology up to scratch and when should museums jump on the bandwagon?
LIGHT EMITTING DIODES

Although LEDs have been around for some time, it’s only been in the past few years that the level of light quality has improved enough to make them (arguably) suitable for museum and gallery use.

There are several advantages of LEDs. The first is the long life-span. According to Paul Ruffles, principal of Lighting Design & Technology, they can last for about 50,000 hours, which translates to 17 years bearing in mind museum and gallery opening times. This long shelf-life means reduced maintenance costs for museums. “Replacing lamps is time consuming and expensive,” explains Ruffles. “Plus, changing lights has an impact on access to exhibitions and exposes objects to risk. LEDs go some way in helping with these problems.”

However, the life-span of LEDs is not set in stone. If a LED is enclosed and the heat is not able to escape, then its life-span will diminish. On the other hand, using dimmers to reduce the level of light will increase the life-span.

Another advantage of LEDs is that the light emitted contains little infra-red and no ultra-violet, meaning sensitive objects may not need to have additional filters. Bear in mind though that LEDs themselves generate heat and this needs to be managed properly.

There are now a wide range of LEDs available – recessed, linear, track, mounted spotlights, individual spotlights, retrofit and so on –  and Ruffles says most large manufacturers have various LED ranges in each style of product.

“At the Light+Build exhibition in Frankfurt in spring 2010 there were over 2,000 manufacturers exhibiting, most of which were showing a wide range of LED products,” he adds. “Since then the ranges have expanded and matured rapidly, with most manufacturers having ranges of spotlights now with interchangeable beam angles and all the favourite baffles, filters and lenses needed for the more tricky lighting jobs.”

ENERGY EFFICIENCY

The energy-efficiency argument for LED lighting is a strong one, and many museums have already installed this type of lighting in order to reduce their carbon footprint and at the same time save money. A Carbon Trust survey of Manchester Museum in 2008 found that lighting accounted for 50% of its total energy consumption. As well as introducing occupancy sensors and programmable lighting controls, the museum replaced fluorescent tubes and dichroic lamps with LED lamps. This upgrade cost £15,000 but, along with the new sensors and controls, is estimated to reduce energy consumption by 89% - giving it an 18-month payback period.

For many museums and galleries, the cost of installing LED lighting is prohibitive. However, this should be offset against the potential savings.

At Manchester Art Gallery, a scheme to introduce LED lighting is estimated to cost in the region of £98,000. However, this is offset against the potential savings - £26,000 in electricity and £15,000 in maintenance per year. In addition, by introducing a display lighting strategy to ensure full gallery lighting is only used when the spaces are open to the public could save a further £5,900 a year. These savings don’t include the potential reduction in air cooling consumption.

Despite the compelling figures, Kevan Shaw, of Kevan Shaw Lighting Design, warns that energy-saving figures might not tell the whole story because you can’t compare exactly like-for-like.

“There is a danger that people will switch over when they see the energy performance figures even though they’ve still got life left in their current lighting systems,” he told delegates at the Museum Association’s one-day conference on lighting in December. He also points out other ways museums can save energy (and money) through their lighting, such as using better lighting controls in exhibition design.

COLOUR

Many designers also harbour concerns about the quality of LED lights, especially when it comes to colour. The two chief criticisms are temperature, as LEDs tend to be bluer than halogen lights, and colour rendering (the accuracy of colour).

Stephen Cannon-Brookes, of Cannon-Brookes Lighting & Design, says that while LED lights can have the same levels of colour quality as halogen lights, this is complicated by the fact that manufacturers have introduced technology to achieve a better quality – but at the expense of efficiency.

“The irony is that lights with lower colour quality tend to have higher efficiency – so by making the light source look warmer (converting blue light into red) you actually make it less energy efficient and hotter,” says Cannon-Brookes. “So it becomes a pay off between colour quality and efficiency.”

This places museum in a dilemma – should they opt for quality or compromise for energy savings?

Cannon-Brookes says the answer depends on what objects a museum houses and what its overriding mission is. “Colour is very important for collections such as paintings, which suggests colour rendering should be the priority. To date, that means halogen lighting.”

Manufacturers tend to agree that museums that place colour rendering above everything else will probably be more satisfied with halogen lighting. However, Chris Tiernan, managing director of ERCO Lighting, says that the rising number of art galleries and museum installing LEDs suggests that colour quality is already at an acceptable level.

The National Portrait Gallery and the National Gallery, both in London, have installed LEDs in some of their galleries. Elsewhere, the new contemporary art galleries at National Museum Cardiff, which will open in July 2011, are being fitted with LED lighting.

Mark Richards, deputy director general at the National Museum Wales (Amgueddfa Cymru), says: “We have historically depended on tungsten lights like most other museums. However, the quality of LED lights now give us the opportunity to be more flexible in our approach and will potentially help us reduce our energy costs by around 50%.”

THE NATIONAL PORTRAIT GALLERY

In the case of the National Portrait Gallery in London, the cost of repairing lighting tracks and fittings in its third floor galleries were too high so it decided to update to LED lights. Erco Optec 14 watt spotlights were initially trialled in a small gallery before extending this into a larger space. The second gallery trial was particularly significant because the paintings hung in it contain a considerable level of red, which is hard to bring out under LED lights.

The whole process took time and included a considerable amount of discussion with curators, conservators and other museums and galleries. Despite concerns about colour rendering, Tim Knight, building services engineer at the National Portrait Gallery, says the general consensus is that an LED-lit painting looks no worse than under the old tungsten halogen lights.

Although the higher concentration of light in the blue end of the spectrum does mean LED lights give off a cooler feeling to the rooms, Knight adds that the warmness of tungsten halogen is also not ideal. He recommends museums take into account room colour if they plan to install LED lights as this can have a dramatic impact on the quality of light.

In addition, Knight says that LED lights are not suitable for all works. For example, Marc Quinn’s Self – a self-portrait cast of the artist's head made in 2006 from his own blood and then frozen – has proved particularly difficult to light because it is red. Initial feedback from staff also suggest that gold frames appear slightly washed out under LED lighting.

Installing LED lights fits into the National Portrait Gallery’s energy-saving agenda. Knight estimates that the new system could save 11,802 kWh and 6.7 tonnes of CO2 per annum. This does not take into account potential savings from the reduced air cooling load. 

As well as the energy savings, Knight says the new LED lights require virtually no maintenance and after a year there have been no bulb failures. However, he does harbour some concerns.

“Although overall the LED projects have been approved, initial capital cost is relatively high and therefore restricts the pace of conversion,” he explains. “Technology is also advancing at a fast pace and it’s hard to know when to jump on the bandwagon. Plus, while there is a vast range of LED lights on the market, these are not all of the same quality.”

JUMPING ON THE BANDWAGON

Despite the concerns about colour, most lighting experts agree that LEDs can’t be ignored; EU legislation means older, less energy-efficient lamps are being banned, making replacements harder (and more expensive) to get. “There will always be legislation that makes it harder to buy less efficient lamps in the future and so all museums and galleries are going to have to give newer technology consideration,” says ERCO’s Tiernan.

Trialling LEDs seems to be the popular approach, but any museum considering this is advised to look carefully at its options.

Paul Ruffles recommends that museums purchasing LEDs make sure that they choose a good quality driver – the electronic device that controls the flow of power into the LED – that has a similar shelf-life to the LED light itself. He also says that museums need to be careful when specifying LEDs that they are supplied from a single colour “bin” to ensure that their colours are the same. This is because the manufacturing process means that as LEDs can have quite wide colour variation.

Museums should also do their research to ensure they understand the system efficiency before they buy. “Most manufacturers tend to avoid quoting the system efficiency – the actual amount of light produced - and instead quote the output in laboratory conditions,” Cannon-Brookes explains.

Investing in upgradable systems is also important. Jean-Francois Hocquard, chief executive of light designer Luxam, is concerned that the LEDs being sold today might not exist in, say, 10 years' time. Despite their long shelf-life, the systems will need replacing eventually and Hocquard’s concern is that museums may find they have to pay for another complete upgrade. He adds: “Museums might also have to replace display cases, depending on how the lighting has been installed. The important thing to keep in mind when investing in lighting is that it is upgradable.”

So, should museums jump on the LED bandwagon now or wait until the technology improves further or the cost comes down? 

“I would advise museums to proceed with caution,” says Cannon-Brookes. “LED technology has increased very quickly but has still not reached the plateau that we are familiar with for tungsten halogen lighting.”

But Nick Wraith, managing director of LED lighting manufacturer Luminal, says that, while technology will continue to improve, museums that wait for this will miss out on the potential energy and cost savings over that period.

As with anything, museums are advised to weigh up the pros and cons of LED lighting and to consider the capital costs carefully, especially if their current lighting systems still have life in them. Taking an incremental approach and combining LED lighting with other lamp types can be good approaches.

ERCO’s Tiernan recommends that any museum looking to change its lighting should at least consider LEDs before automatically opting for halogens.

“Inevitably, colour rendering will improve but no one knows when – it could be two years, it could be 10,” he explains. “Should museums wait for it when what’s on offer now is acceptable? If a museum needs to upgrade lighting now, then it should buy LEDs, The potential energy savings are already there.”

Click here to have your say on the issues discussed in this article