Pretty much any big city I travelled to London, Seattle, San Francisco just to name a few...walk in the streets of the city by night and you will see what I mea

Pretty much any big city I travelled to London, Seattle, San Francisco just to name a few...walk in the streets of the city by night and you will see what I mean. Sure, power efficient lighting is great and so are sensors but why are the lights on at night? Why are the motion-sensors that are so widespread (most offices you say?) not working to switch the lights off?