Solid state lighting
Energy efficiency of light sources is typically measured in lumens per watt (lm/W), meaning the amount of light produced for each watt of electricity consumed by the light source.
Conventional incandescent light bulbs have a lifespan of around 500 hours, and convert electricity to light at an efficiency of around 10-18 lm/W. This means that most of the power is lost as excess heat.
Compact fluorescent lamps (CFLs), often called “energy saving” bulbs, have a lifespan of around 3,000 hours, and convert electricity to light at an efficiency of between 35 and 60 lm/W.
Quantum dot LEDs have a lifespan of between 25,000 and 50,000 hours (up to 20 years at typical rates of domestic usage) and convert electricity to light at between 30 and 70 lm/W. They turn on instantly, and can be tuned to produce any shade of white light (or any colour).
As well as domestic lighting, quantum dot LEDs have an enormous range of potential applications in the public domain where longevity, accessibility (or lack of it) and economy are significant issues, for example in street lighting, traffic lights, exterior signage or vehicular lighting.