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Can we beilive the hype?

Issue 40 Dec / Jan 2007/8

Kevin Theobald, IALD UK Regional Coordinator and Associate at NDYLIGHT, looks at the array of energy saving light sources that are currently available.

With the recent amendments to Part L of the building code and the increasing number of projects joining the BREEAM scheme the requirement for Lighting Designers to look for energy efficient solutions has come to the fore.

It should be noted that most lighting designers have for many years designed schemes which reduce the carbon impact by providing light when and where it is required - not always using the most efficient sources but by effective use of control not only offering the required reduction in CO2 emission but retaining a desirable and flexible visual environment.

In recent months the media has promoted ‘energy saving’ lamps as they refer to compact fluorescent lamps, but recently they seem to have changed their focus to LEDs which due to their low power consumption are widely touted as energy efficient, which I am sure that most readers know is not the whole story.

It is essential that we look at the broader picture and not end up focussing on small elements that will ultimately restrict what can be achieved in terms of design without contributing to solving the bigger issues of CO2 emissions.

So as lighting designers we need to look at the technologies available to us which will enable more efficient schemes without compromising design.

Compact fluorescent technology is ever improving and whilst these lamps provide an energy efficient way of delivering illumination there remain questions about the quality of the light they produce and it is worth considering the alternatives.

Miniature fluorescent lamps are starting to appear with lamp life previously only achieved by cold cathode lamps. Apart from the very short lamps they have a good lumen/watt output, can be easily dimmed and as an indirect light source make a very useful ambient lighting tool.
Unfortunately because the small size of the tube in relation to the output it tends to cause glare issues, and as it is very difficult to provide effective beam control without the fitting becoming huge.

We have seen the miniaturisation of metal halide sources and after early teething problems relating to breaking pins and pinch temperature issues there are a number of good optical solutions available which are small enough to consider in all but the most minimalist interior design.

However as always there is a downside and here it relates to control. Apart from a couple of exceptions in the larger lamps (upward of 300W) there is no effective way of dimming metal halide sources. There are a couple of examples of control gear which will dim 35W lamps to around 50%, before the colour becomes completely unstable but lamp manufacturers will not currently warrant their lamps if they are dimmed in this way.

If some agreement was achievable this would only be able to provide a 25% power saving which may be attractive but these sources would still not help to provide a traditional scene set solution such as may be desirable in a hotel, restaurant or bar.

Cold cathode technology has been around for a very long time but can still provide an efficient method of indirect lighting. We have seen the transition of the miniature tubes from the monitor industry and their extremely small profile makes them a good candidate for inclusion in furniture details.

A mention should be made of induction lamps as they are extremely efficient and have a very long life, however as they effectively ‘dump’ light and there have been few developments in luminaires to take them there is little place for them in the overall design process.

Maybe it is time to revisit fibre-optic solutions. A few years ago we were told that fibre-optics were the lighting solution for the future. However apart from museum, gallery and a few specialist solutions they seem to have been largely left behind.

In the past I have used fibres quite successfully using metal halide lamps to achieve the output and a fairly rudimentary mechanical dimming system, albeit using DMX control.

With the development of smaller MH sources it may be that with a bit of additional development fibres could provide a possible option for accent lighting. Indeed a 68W MH fibre optic system which delivers 45 luminaire lumens/circuit watt targeted as a replacement for downlight ‘sparkle’ applications in residential applications is now available.

LEDs are widely being hailed as the next big thing in energy saving. Unfortunately, at this time most LEDs are far from energy efficient with many products fairing little better than incandescent tungsten sources, in terms of efficiency.

Where LEDs do well is in terms of producing saturated colour as they produce light at a specific wavelength in the visible spectrum rather than the conventional method of filtering colour from a broad spectrum light source, which results in the case of deep blues where only 6-10% of the light being produced is actually transmitted.
Colour mixing and control are also interesting developments but the effective exterior floodlights are still likely to draw upwards of 150W per fixture and require elaborate thermal management.

The other big issue with LEDs, particularly from a lighting designers’ perspective, is the actual delivery of the light from source to subject.
Many of the early products we were shown were manufacturers putting LED sources in existing luminaires, this is still the case in much of the mass retail market, which led to overheating, early failure and poor output. To an extent the situation has improved slightly particularly with regard to thermal management but optically we have yet to witness any real breakthroughs.

Most manufacturers use cheap collimators to control the beam and up to a point these do work, but I have lost count of the number of fittings I have seen which claim a 60 or 10 degree distribution but there is inevitably spill light at 20 degree, 40 degree or even greater angles.
We have been used to seeing extremely good optics particularly in the discharge luminaire ranges and we need to see the same investment in the optical delivery of LEDs.

We should not of course overlook the most sustainable and efficient light source available to us all and that is DAYLIGHT.

As designers we need to work with architects and developers to ensure that wherever possible we don’t rely on artificial light during the hours of daylight.

There are a number of technologies that can aid in this process and although their cost is currently prohibitive, these are surely worth development.

If this were achieved we would see such an outstanding drop in energy consumption that legislators would not even need to consider the application of draconian measures with regard to lighting.

A final word...
It is important that all of us who practice lighting design in all of its aspects get our side of the story heard. If we don’t the world at large will continue to be provided misinformation and ultimately there will be no role for us as lighting designers. Lighting will become so proscriptive that we will not be needed.


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Kevin Theobald
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