LED is a very sustainable light source due to its high efficacy and long life potential, with the efficacy of LED chips continuing to increase dramatically. Well-established LED sources, commonplace in the market today, can deliver products with a system efficacy of more than 60 lumens per watt in a high quality warm white light (including losses accrued through the driver and thermal management). 

Furthermore, their directionality means far greater optical efficiency than traditional sources when combined with optics such as lenses or reflectors. The required light effect can therefore be achieved with a lower source efficacy. LEDs with cooler white light are even more efficient and can be used when this light is deemed acceptable for the application (refrigerated display lighting is a good example of this). In addition, LED products are capable of extremely long lives when engineered correctly.
The above numbers represent today’s state-of-the-art from commercially available products. LED technology continues to develop quickly however, and laboratory figures of >200 lumens per watt are now being quoted from some of the major manufacturers. These LEDs are not currently commercialised. 

One note of caution is that the benefits of LED, with respect to sustainability, are only achievable if proper attention is paid to how the LED is embodied and engineered into the product and application in which it is to be used. To do this, a good understanding is needed into how a given LED package performs under different conditions. 

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