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    LED lamps: why and where not to use them

    Nathan Johnson

    With peaking electricity prices and an increasing push towards sustainable building practices, building designers are seeking more efficient products to illuminate their buildings.

    Combine this with developments in LED technology, as well as a declining initial cost for LED lamps and light fittings, and we’re well on our way to a future brightened by LED lighting.

    Jess Perry, director of architectural lighting firm Electrolight, says with certainty that LEDs will be specified in the future for nearly all lighting applications, although there might be a few exceptions.

    “LEDs are undoubtedly the future of the lighting industry and they will eventually replace all traditional incandescent, halogen, fluorescent and metal halide lamps, particularly as their price continues to drop and light efficacy continues to improve,” he said.

    HIGH-POWERED SPOTLIGHTS

    Perry explained that although LEDs are used in high powered spotlight applications they often don’t perform as well as high wattage metal halide and the cost is considerably higher.

    In its basic form, a LED light is made up of a number of micro-chips that contain positive and negative semiconductors which combine to produce a photon of light.  

    “Higher powered LED spotlights often use multiple LEDs which results in in a series of overlapping beams which is not ideal if you are after a nice even beam,” said Perry.

    The lifespan and light efficiency of LEDs are shortened and decreased at temperatures above 60°C, making them less suitable for high-powered lamps in warm environments. Companies such as Switch Lighting are using liquid silicone to draw heat away from the LEDs to combat this.

    THEATRES
    Perry explained that halogen lamps will continue to have a place in theatre applications where a completely dimmable light is needed because LEDs are difficult to dim smoothly down to one per cent.

    Some LEDs experience a “dropout,” where they only dim part of the way down to zero light output — say, to 60 per cent of maximum — instead of all the way from 100 per cent down to one per cent. Additionally, some LEDs won’t dim at all and others may dim in an abrupt or “staircase” fashion, instead of dimming smoothly and continuously.

    Some LED manufacturers can produce a perfect dimming but Perry notes that they can get very expensive and eat into the energy-cost savings they produce. 

     RETROFITS AND RENOVATIONS

    Although LEDs are more energy efficient than halogen lighting, Perry says it's important to understand that it is not always a comparable one-for-one replacement.

    “LEDs are often sold and marketed on their wattage rather than their lumen output,” Perry explained.

    “Some packaging will say ‘replace your 50 Watt halogen with a 5 Watt LED’ but the problem is that the LED won’t necessarily have the same light output as the halogen and therefore you may need to use more light fittings and often you’ll need to change the transformers.”


    The Sydney Opera House – Concert Hall lighting upgrade recently received The Built Environment Sustainability - Heritage Buildings award at the 2014 Green Globe Awards. 355 custom-made LED lights were fitted for the project which is tipped to slash Concert Hall power bills by 75 per cent - or $70,000 a year - and Opera House management expected the project to pay for itself within six years. (Image: Jamie Williams)

    Claims about the life expectancy of LEDs aren’t always correct either and the 50,000 - 100,000 hour average life expectancy is in some cases based on an algorithm . This is because LED lamps haven't been around long enough for companies in the industry to have a good understanding of how their  products perform over time.

    This lack of physical testing and  the reliance on an algorithm is more common among cheaper manufactures and small companies, and some reputable brands have performed physical testing on their products.

    WHY LEDs

    French conceptual lighting artist, Yann Kersale lighting artwork at One Central Park comprises 2880 coloured, programmable LED lights, which are Xenian Philips ColorKinetics iColorFlex LMX. Image: Simon Wood Photography

    The overarching cultural shift towards sustainable building practices has increased the popularity of LEDs because they are perceived as producing less energy.

    The Building Code of Australia for one emphasised the importance of an efficient lighting design in 2010 when it introduced significant changes to the National Construction Code Volume 1.

    Changes to Section J6.2 ‘Artificial lighting’ for class 2-9 buildings were made, and subsequently so was the allowable illumination power density (wattage) of lighting per square metre of floor space within homes and commercial buildings.  

    Perry said these targets are becoming more difficult to meet and that LEDs are a great product for meeting these requirements.

    Besides their sustainability credentials, initial capital costs for LEDs, which was a real deterrent for building designers in the past, are dropping fast.

    “Especially in the past couple of years, LEDs are becoming a lot cheaper,” he explained.

     “Companies are no longer recovering their investment in research and development and can afford to drop their prices.”


    The 'Superlight Compact Rotationally Symmetrical' Metal Halide flood light from Meyer was chosen by Electrolight for the 171 Collins Street. Image: Peter Clarke.

    Director of Electrolight Paule Beale said that LEDs will also facilitate a new era where lighting design can meet innovative new geometrics in architecture.

    “With the advent of LED, fittings are becoming smaller, narrower and can bend around corners (unlike the fluoros of the olden days),” he explained.

    “This, and advances in 3D modelling with programmes like Revit, means that geometries in architecture are becoming more complex and lighting design is becoming more sophisticated and intricate in response.”

     

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