I have come up with a new idea for an energy saving project for my course (which has a novel element - they're not expected actual ideas to take off) Having thought a few things over, I am now thinking of simply saving energy in office's, particularly where offices are divided up into sub-offices, each with their own lighting etc. I wish to install a sensor on top of a computer monitor (or somewhere approximately thereabouts), and a receiving 'pad' on the back of a chair (the side you sit against so the pad and sensor are facing). When a person sits on the chair i.e.; when the pad is blocked, the lights turn on. When the chair is empty i.e.; when the pad is exposed, a timer is started. After 30 seconds, the lights will start to dim. After another 30 seconds (thats 1:00 from initially beginning the timer), the lights will be at their dimmest point. I will also be proposing to use LED lighting to for their high efficiency, long lifetime and low cost. I am particularly concerned about what combination for the sensor and the pad to use, since I want humans to effectively block this connection. All help is greatly appreciated.