In 2014, Shuji Nakamura, Isamu Akasaki and Hiroshi Amano won the Nobel Prize (in Physics) for inventing diodes that emit blue light. What transpired was that their invention subsequently led to the development of bright and energy-saving white light sources for commercial use.
Although LED can no longer be called a new technology, its application in the development of lighting in commercial and residential sectors may be seen as revolutionary, for making (the use of) fluorescent fittings obsolete.
According to many academics, significant reduction in power consumption could be achieved worldwide with LEDs, which can have efficiencies 20 times as those of conventional lamps. Professor Dr Wolfgang Schnick, chair of inorganic chemistry at the Ludwig-Maximilian University of Munich, believes the development “cannot be estimated too highly” and that it will “help save up to 20% of the global electricity consumption”.
This, in turn, would result in reduction of fossil fuel consumption and a corresponding reduction in the release of carbon into the atmosphere. LED lighting design and products are at the forefront of energy-efficient design, reducing carbon emissions and contributing to high performance green building standards. But there are challenges, and here are some of the technical observations of the same.
It’s not true but most believe that lumens per watt for LED is very close to the fluorescent’s efficacy. Typically, fluorescent are below 100 lumens per watt at source. Taking into account the way they work with an optic in the luminaire, this value will reduce further because it has a 360° light distribution, light being lost bouncing within the luminaire. Meanwhile, LED offers more than 150 lumens per watt, and as the light is emitted in a single direction, it is fully used or directly distributed.
An LED lamp usually has a life of 50,000 hours and possibly more, compared to fluorescents’ 10,000 hours. Lumen value decreases over time as a fluorescent lamp is operated; it’s called lumen depreciation and is around 70% of the rated life of the lamp. So, for a lamp rated at a 1,000 hours, the light output would drop off at 700 hours.
Another myth is that if a fault occurs in an LED fitting, the whole unit must be replaced. This may be true for cheap imports. However, most leading manufacturers use Zhaga-compliant LED engines that allow for lamp replacement. Moreover, LED is inherently more reliable than fluorescent, providing savings on maintenance costs.
At present, LED costs are higher by about 20-30% on a product comparable basis. Although, clever layout and design shows that for each square metre (sq-m) of space, the number of LED fittings required is one per nine sq-m, compared with fluorescent at one per six sq-m.
It is imperative to choose lighting solutions for buildings that are fit for purpose, and design engineers and manufacturers have an obligation to look at options and impacts. We experience our environment through our eyes, which emphasises the need for appropriate lighting design and knowledge of its working methods, open-plan and cellular configurations.