| 摘要 |
<p>A sensor (15) detects when a room or other area is occupied. Whenever the room has been unoccupied for say two minutes a controlling CPU (11) and ROM (12) turn off the lights by way of a relay (21). The lights are turned on manually by operation of a switch (13), which will also turn off the lights when they are already on. Alternatively the on/off state of the lights when the room is occupied is determined by the light level sensed by another sensor (23). At the end of a two minute period the CPU also selects a low set point for temperature control by way of a temperature sensor and heat control device (19). Thus, when the room is occupied it is maintained at a comfort temperature; when unoccupied it is maintained only at a reduced temperature from which recovery to comfort can be achieved reasonably quickly. The system saves substantial energy. The components are contained in a unit (10) occupying the place of a conventional wall switch just inside the door of the room. The unit (10) also provides for fire detection by way of a smoke detector (20) and signalling to a central fire control station (17) which is informed also of the precise room in which the fire has been detected. The unit can also be switched to an intuder alarm mode, warning of an intruder when a person is sensed by the sensor (15).</p> |
