28 January 2010 – LED, or light-emitting diode lights, has been touted as the next big step in sustainable lighting to replace fluorescent tubes. The promise is a very long life span, improved efficiency and immediate full brightness when switched on.
However, a trial conducted by sustainability consultancy Carbonetix, with assistance from the Victorian Government and the City of Frankston in Victoria, finds the reality falls short.
CarbonetiX founder Bruce Rowse says the biggest problem is cost and exaggerated claims on performance.
“To date, high costs, exaggerated performance claims and uncertainty about light depreciation have held back LEDs from becoming a viable replacement for the familiar fluoro tube,” he said. There are three main barriers that needed to be overcome, he said.
One is high costs. LED tubes bought for the trial ranged from $50 to $120 per tube, with the best performing tube at the higher end. By comparison a good fluorescent tubes costs about $5.
However, Mr Rowse said industry expectations were that prices would soon fall significantly. By 2015, “a LED tube should set you back just $20 to $30 per tube”, he said.
LED lighting installation is also more expensive than fluorescent lighting, but this could be overcome by choosing LED lights designed for retrofitting.
There is also uncertainty about lumen depreciation and lamp life. Lumen depreciation is the loss of light that occurs from a lamp as it ages. For example, a fluorescent tube will typically produce between 15 per cent and 20 per cent less light at the end of its life, Mr Rowse said.
“LED manufacturers are claiming lamp lives in the order of 50,000 to 100,000 hours. However, the technology is developing so quickly that it is impossible for a manufacturer to test a lamp for this long before it is obsolete.
“A new testing standard now means lumen depreciation can be estimated to be 36,000 hours.
“As more manufacturers test to this standard, buyers will have greater certainty about the longer-term performance of their investment.”
The trial also reveals exaggerated performance claims.
“None of the six lamps we tested in our trial produced the amount of light their manufacturers claimed. The best performing lamp in our trial produced less than 80 per cent of light the manufacturer claimed,” Mr Rowse said.
“Fortunately there is a move towards certification. The development of standards gives confidence that LED tubes, as a fluorescent substitute, will eventually be subject to a standard, such as Energy Star.
“Notwithstanding exaggerated performance claims, lamp luminous efficacy is improving.”
Efficacy is a measure of the amount of light produced per watt of electricity consumed, Mr Rowse explained. New fluorescent lighting typically has an efficacy of 80 to 100 lumens per watt.
“Our experience in testing LEDs over the last two years has shown a great improvement in LED efficacy over that time.
“At current rates of improvement, it is reasonable to assume that an efficacy of 150 lumen per watt will be achieved before 2015, and that lamps will then be commonly available with an overall efficacy of at least 120 lumens per watt. This would mean that an 18 or 20 watt LED could be confidently used to substitute a 36 watt fluorescent with no loss of light output.”
Improve lighting performance now.
Mr Rowse suggested that building owners and managers had a range of options to improve lighting efficiency before major improvements in LEDs by:
- Upgrading to high performance T8 tubes of 100 lumens/watt;
- Fitting mirror-like reflectors in the light fittings to reflect light going upwards, sideways and downwards and thus make it useful;
- Refitting opaque diffusers with prismatic diffusers, if appropriate;
- Undertaking an illumination assessment using a lux meter and delamping so that the space is not over-illuminated.
“Building owners will save money and greenhouse gas emissions by installing these technologies now, as well as generating a positive return on investment,” Mr Rowse said.