Lights Up, Costs Down

13 November 2008

London’s Mayor recently announced plans to make the capital’s theatres more energy efficient. Philips has been working with London’s National Theatre for the past 15 months to develop a programme to upgrade its lighting technology to an energy saving future

IN THE SUMMER OF 2007 THE NATIONAL THEATRE ENTERED into a partnership with Philips Lighting with the objective of reducing the Theatre’s very considerable electricity use. Nearly 15 months into the five year period of the agreement progress has been made in a number of areas but there is still much to do. The key to the success of the project is the collaborative nature of the relationship between both parties.

The whole project began with a closer look at all the lighting installed in what is one of the largest theatre complexes in the world. The variety of light sources and applications used in the building crosses virtually all existing lighting technologies and most of the functional requirements. The majority of the lighting was, by this time, over ten years old. It was an opportunity to examine the solutions used in the ‘90s and test these against the latest technology. Add to this the fact that the Theatre is a listed building and all visible changes would need to meet the criteria set by English Heritage and Lambeth Conservation. This presented real challenges to all those working on the project at both the National and at Philips.

Hit list
A number of potential areas where energy savings might be made without compromising the quality and ambiance of the existing were identified and a target list was drawn up. The initial focus fell on the external lighting where it was thought that the latest colour changing LED luminaires could effectively replace the existing conventional fittings, which relied on efficiency draining filters to achieve their colour effects.

Using the National’s considerable lighting application experience, it was decided to apply LED lighting to significant parts of the exterior. Philips identified and supplied the requisite fittings and these were then installed by the NT team under the partnership. The new lighting was switched ON formally on the 23rd October 2007 and showed an 80 per cent saving compared to the lighting it had replaced.

However, the initial exterior lighting scheme covered only part of the building; there remained areas that the LED fittings available in 2007 could not reach. However, in August 2008 the Theatre kindly hosted the trial of a prototype of a new generation of colour changing floodlights and this test suggests that, when these fittings are available it will be possible to replace more of the old luminaires.

It is this facility to work together on innovation by allowing tests in real places that Philips values in the relationship. The outcome suggests that – on a typical fly-tower face – four 1200W projectors might be replaced by five 300W units. Something like a 70 percent saving is possible if all three colours on the LED fitting are running flat out; if only green is being used then the saving is closer to 90 percent! Hopefully these changes can be realised as soon as the new product becomes available.

Another benefit delivered by the LED lighting is the fact that even though they were installed last August, so far there has been no need to return to the fittings for maintenance purposes. Previously regular lamp changes were required and these powerful flood lighting lamps are not exactly cheap.

Not all the projects involved the supply of equipment. Saving energy sometimes only requires a little lateral thinking. For years the lighting rigs for the stage productions have been ‘proved’ sometime in the afternoon and then left running until the show in the evening. After taking advice from their stage lighting suppliers, Martin Professional, the National Theatre began to turn OFF the discharge element of the lighting rigs after the tests and then back ON half an hour before the curtain went up. Result – no failures and many hours of unnecessary use avoided, while maintaining the artistic integrity of the lighting rig. This ‘no cost’ approach to reducing lighting electricity use also helps to reinforce a good housekeeping policy towards all energy use, which can be extended to any lighting load – turn it OFF if it is not needed! It is calculated that no more than 15 percent of the lighting electricity is actually used in the performance; that leaves 85 percent employed to light workshops, rehearsal rooms and all the front and back of house.

In the National Theatre the public areas front of house are an important part of the building where all are welcome and there are cafes and, at times, entertainment to enjoy. The lighting of this space is, therefore, important and one of the major elements comprises 180 qty. Source 4 Projectors used to provide ambient lighting. Until recently these were fitted with either 150W metal halide or 575W tungsten halogen sources. Today all of these luminaires have been rebuilt to contain 70W CDM T Elite ceramic metal halide lamps with a colour rendering index (Ra) of 90. The National Theatre believes this has reduced their lighting electricity consumption by at least 90,000kWhs – or at least 39 tonnes of CO2 – every year! Of course the most important part of this exercise has been the preservation of the lighting quality and levels.

Other benefits arising from the re-lamping of the foyer lighting has been the retention of the luminaire bodies, which means that they can continue to give service for many more years. Retaining these fittings also avoided any need to seek approval from conservation bodies for ensuring the NT retains its design integrity. Additionally, the new lamps have a rated life of 12,000 hours, which should mean a considerable reduction in maintenance time and the expense of providing an access tower for electricians.

The National Theatre has now equipped all the lavatories with Occuswitch movement sensors to ensure the lights are only ON when they are needed. This confirms the importance of recognising that lighting is only using electricity when it is switched ON; it is the kWhs of use that really costs money and emits the carbon and NOT the connected load. However the connected load is still a very useful measure when it comes to analysing electricity use. If you know the approximate lighting loads it is often possible to spot when they are being used by looking at demand over the day.

One of the challenges presented by any energy survey is the identification of the prime targets for reduction and then keeping track of progress. Fortunately the half-hourly consumption data from July 2006 forwards has been made available to Philips Lighting and this will present us with the opportunity to see which measures had what effect by discussing key events with the National Theatre staff. It does mean, however that there is a data matrix of 48 items on 759 lines – 36,432 individual values – that needs to be crunched and compared! However the end result, will provide the best indication of the most effective projects as each is completed. Two days have been reserved in the near future to look at these numbers while being on site and observing the lighting events that influence consumption.

As mentioned above, there is still much work to be done. Front of house and in the public areas there are a lot of different lighting solutions, ranging from lighting for safe circulation through to highlighting and effects. The National Theatre has already experimented with some internal LED lighting and some new solid state lighting products could allow them to make further savings in these areas; the challenge here will be applying them without affecting the appearance of the existing fittings.

Backstage
Back of house there is work in progress to introduce dimming controls on the staircases; at each landing a movement sensor is used to reduce lighting to a low, but safe, level and only offer full lighting when someone is present. Wherever there is no immediate, and appropriate, new technology available then a lamp replacement programme will produce some quick wins; simple changes like swapping 50 Watt dichroic lamps for 30 Watt MasterClassic versions that give the same light output. Simple but effective.

The experience of working in partnership with the National Theatre is a rewarding experience for Philips Lighting. There is probably no other building with such a wide variety of lighting applications and potential for case studies ranging from luminaire refurbishments to before and after calculations. This is a building that contains three world class stages, full support facilities including set building workshops, dressing rooms, and rehearsal spaces. Then there are restaurants, meeting rooms, offices and exhibition spaces. When you are looking for user insights into lighting equipment you would be hard pressed to find a better source! The coming months and years will be valuable to both partners.

● John Aston is Green Marketing Manager at Philips Lighting