For more than a hundred years ‘artificial light’ has almost exclusively meant incandescent lamps. However, the relatively low output of incandescent lamps has been criticized and has ultimately led to their being banned in the EU. Low-energy fluorescent lamps are certainly more efficient, but they do not work well when turned on and off frequently, and they contain not exactly ecologically-friendly quantities of mercury. As LED lamps become cheaper to buy it seems that semiconductor-based lighting is the ideal replacement. So that’s all good then. Or is it?