- Jul 21, 2017 -
The use of automatic light dimming is an aspect of smart lighting that serves to reduce energy consumption.Manual light dimming also has the same effect of reducing energy use.
In the paper "Energy savings due to occupancy sensors and personal controls: a pilot field study", Galasiu, A.D. and Newsham, G.R have confirmed that automatic lighting systems including occupancy sensors and individual (personal) controls are suitable for open-plan office environments and can save a significant amount of energy (about 32%) when compared to a conventional lighting system, even when the installed lighting power density of the automatic lighting system is ~50% higher than that of the conventional system.
A complete sensor consists of a motion detector, an electronic control unit, and a controllable switch/relay. The detector senses motion and determines whether there are occupants in the space.It also has a timer that signals the electronic control unit after a set period of inactivity. The control unit uses this signal to activate the switch/relay to turn equipment on or off. For lighting applications, there are three main sensor types: passive infrared, ultrasonic, and hybrid.
In response to daylighting technology, daylight-linked automated response systems have been developed to further reduce energy consumption. These technologies are helpful, but they do have their downfalls. Many times, rapid and frequent switching of the lights on and off can occur, particularly during unstable weather conditions or when daylight levels are changing around the switching illuminance. Not only does this disturb occupants, it can also reduce lamp life. A variation of this technology is the 'differential switching' or 'dead-band' photoelectric control which has multiple illuminances it switches from to reduce occupants being disturbed.
Smart lighting that utilizes occupancy sensors can work in unison with other lighting connected to the same network to adjust lighting per various conditions. The table below shows potential electricity savings from using occupancy sensors to control lighting in various types of spaces.
The advantages of ultrasonic devices are that they are sensitive to all types of motion and generally there are zero coverage gaps, since they can detect movements not within the line of sight.
Motion-detecting (microwave), heating-sensing (infrared), and sound-sensing; optical cameras, infrared motion, optical trip wires, door contact sensors, thermal cameras, micro radars,daylight sensors.