GB2192080A - Environmental control system eg for heating or lighting - Google Patents

Abstract

The control system is for controlling heating (but may be used for lighting and ventilation) in a room 6 and includes ultrasonic detectors 10 responsive to body movement within the room 6 and a timer actuated by an automatically resetting press button 9. The timer is preset and when actuated by manual depression of the button 9 by a person entering the room 6 permits heaters 7 to be energised for at least the preset period. If body movement is sensed by the detectors 10 the system is reset and maintained actuated for a further preset period. If no body movement is sensed by the detectors 10 during the preset period the system is de-actuated at the end of the period. Preferably two detectors 10 are provided which are arranged so that the system will only reset when both detectors sense movement simultaneously. A thermostat T1 maintains the heaters 7 operational to provide a minimum background temperature in the room 6 irrespective of whether or not the button 9 has been depressed to actuate the system. A thermostat T2 controls operation of the heaters 7 during actuation of the control system to provide a predetermined working temperature environment. <IMAGE>

Description

SPECIFICATION An environmental control system TECHNICAL FIELD & BACKGROUND ART This invention relates to an environmental control system and is primarily concerned with a system for conserving energy in the use of one or more devices for heating, lighting or ventilating a premises. The amount of energy used by heating, lighting and ventilation devices to provide a predetermined environment in a particular premises is, to a large extent, governed by the personal discipline of the occupants. At a basic level this discipline requires the devices to be switched off or turned down and windows closed when the premises are unoccupied. Energy is expensive and consequently many high energy users such as County Councils, public and national services organise campaigns to promote careful housekeeping to save energy on a day-today practice.However, the effect of such campaigns is generally far less than satisfactory as can frequently be observed when occupants often leave lighting or heating devices on after working hours or continuously on in a building subject to irregular use. Admittedly time switches can be used to control the operation period of heating, lighting or ventilation devices but even with such devices subject to the control of time switches, considerable energy can still be wasted if the premises are used irregularly and for much of the time the energy absorbing devices may be operational to maintain a predetermined environment in a room which has no occupants! This problem is particularly felt with hutted type buildings which are frequently employed as an inexpensive and rapid means of providing additional accommodation in schools, colleges, hospitals and the like where it is not unusual for some of the rooms to be unoccupied for fifty per cent of the normal working day (from which it can be appreciated that the energy which is wasted in continuously maintaining the heating, lighting or ventilation of such a room throughout the working day can be considerable).

It is an object of the present invention to provide an environmental control system which alleviates the problems discussed above and is relatively simple and economical to manufacture, instal, operate and maintain.

STATEMENT OF INVENTION & ADVANTAGES According to the present invention there is provided an environmental control system comprising at least one of heating, lighting and ventilation devices; intruder detector means responsive to body movement, and manually actuated timer means pre-set for a predetermined period; the system being actuated for energisation of said device or devices and for at least said pre-set period by manual actuation of the timer means and wherein during said period when the system is actuated, body movement detected by the detector means causes the system to re-set and be maintained actuated for an extended period comprising the or a further pre-set period from said detection and if no body movement is detected during said pre-set period or extended period, the system is de-actuated.

On entering a room fitted with a control system of the present invention, a person will make a decision whether to actuate the timer means which will, conveniently, be achieved by depressing an automatically re-setting push button at a convenient location near the entrance. Unless the timer means is actuated manually, the system will not function to provide the environmental characteristics of heating, lighting and/or ventilation which have been predetermined for that particular room.

Undoubtedly the greatest energy consumption is in room heating and, for convenience of description, we will hereinafter and in the main consider the present invention in relation to heating control; it is appreciated that persons having an understanding of the present invention will readily realise its applicability to lighting or ventilation control and any modifications necessry to achieve such control.

If the system is actuated on entering the room, say by pressing the push button as aforementioned, heaters can be energised for a pre-set period, say in the range of up to three to twelve minutes, to raise the temperature of the room to that which is required.

Once the room has been entered and occupied, and the push button operated, the control of the heaters is taken over by the intruder detector means which are responsive to body movement. The purpose of the detector means, which are preferably ultrasonic detectors or passive infrared detectors, is to sense body movement within the room and to reset the system each time such movement is detected so that following such a detection the heaters can continue to be heated during a further pre-set period (which will usualy be the same as the first pre-set period, say in the range of up to three to twelve minutes). In this way it is possible for the heaters to be energised solely during the basic pre-set period which may be as little as three minutes before the system shuts off (if say the push button is pressed and the person then immediately leaves the room).Alternatively the heaters can be energised during a much longer period comprising the whole time during which the room is occupied and then the further preset period (of say three minutes) after the last person has left the room. It will be appreciated therefore that, in the main, the beaters are only likely to be energised to an extent to raise the temperature in the room to that which may be required to provide a reasonable working environment for the period dur ing which the room is occupied; thereby considerable energy savings can be achieved by not so heating the room for the majority of the time when it is unoccupied. In practical trials of the control system of the present invention in typical hutted type classrooms having electrical convector heaters, savings on the cost of electricity in the order of 50% have been achieved.These savings indicate that, as far as heating control is concerned, it should be realistic to achieve a pay back on first cost of the system in under two years (and perhaps in less than twelve months if the system is installed in an infrequently used large classroom with several heaters).

The detector means must be very sensitive to body movement and as such it is possible, under certain conditions, that the detector means would react to "ghost bodies" such as the convection currents from the heaters themselves, draughts from windows and doors that may be left open and the like. To alleviate this possibility it is preferred that a particular room fitted with the control system has at least two detectors (preferably of the ultrasonic type) which are spaced from each other and are arranged so that for the system to reset both (or all) of the detectors must detect body movement simultaneously. It has been found that such use of two or more detectors alleviates the problem of the system being actuated for an extended period in response to extraneous signals from "ghost bodies".

From the above it will be seen that the combination in the system of the manually actuated timer means and the intruder detectors which are responsive to body movement has several advantages over an environmental control system in which the heating devices are actuated solely under control of the body movement detectors. For example, if the timer means is omitted it would be possible for the system to be actuated in response to spurious signals caused by doors being left open, draughts and the like whereas by the invention it may be ensured that the heating will not be actuated unless a person requires the facility and makes a positive decision to actuate the timer means.

Preferably the control system comprises setback means which overrides the timer means.

The purpose of the set-back means is to cause operation of the heating, lighting and/or ventilation devices and provide a predetermined low energy level environmental condition when the system is de-actuated and manual actuation of the timer means permits operation of the device or devices to provide a predetermined high energy level environmental condition. The set-back means is primarily applicable for heater devices to maintain a background temperature during periods when the room is unoccupied.In this way it may be ensured, particularly during winter with very low external temperatures, that the set-back means (which in this case would comprise a thermostat) maintains the temperature in a room at a reasonable but low level when the room is unoccupied so that when the room is occupied and the system actuated, the heaters will rapidly raise the temperature to that which is considered provide a reasonable working environment. Where the device is a heater as aforementioned, the thermostat or a further thermostat will normally be provided so that when the timer means is actuated and during the pre-set or extended period, operation of the heater will be such as to provide and maintain a predetermined temperature environment.

DRAWING One embodiment of an environmental control system of the present invention and as applied to a single storey hutted type classroom will now be described, by way of example only, with reference to the accompanying illustrative drawing which diagrammatically shows the classroom in plan and illustrates a typical layout of the system for control of temperature in the room.

DETAILED DESCRIPTION WITH REFERENCE TO DRAWING The accommodation shown in the drawing is a typical wooden hut type single storey building as is frequently employed by County Councils and education authorities for use as a classroom and comprises a main entrance 1 with swing doors leading to a lobby 2. A door 3 leads from the lobby to a storeroom 4 and swing doors 5 iead from the lobby into a main classroom 6. The room 6 is heated by an array of electric convector heaters 7 mounted around the walls of the room. The heaters 7 are electrically connected to a control unit 8 conveniently mounted in the storeroom 4.The unit 8 includes the electrical wiring, relays and other electrical and electronic components required to effect and control the operation of the heaters; however, for convenience the electric circuits and components in the control unit 8 will not be described as it is fully appreciated that such circuits and components will readily be apparant to persons skilled in the art and having an understanding of the control system of the present invention.

Included within the system of the unit 8 is a timer which is manually actuated by a push button 9 located on the wall of the classroom 6 at a convenient position near the door 5.

The push button 9 is spring loaded to reset automatically and when manually depressed actuates a relay which permits the heaters 7 to be heated for a period preset by the timer and at the end of which period the relay is broken and effectively the heaters are switched off. The preset period will usually be three to five minutes but for practical pur poses can be as long as twelve minutes.

Mounted high on the wall at one end of the room 6 and spaced from each other are two ultrasonic detectors located to direct their beams, approximately, at right angles to each other. The detectors 10 sense and respond to body movement within the room 6. Ultrasonic sensing is well known whereby disturbance of radiation emitted from the devices 10 by a moving body is detected using Copier principles so that a signal is transmitted to the control unit 8. If the detectors 10 sense body movement within the room 6 during the preset period after the push button 9 has been pressed to actuate the system, the timer is caused to be reset and the control system to be maintained actuated for an extended period which will again be preset in the range of three to twelve minutes from the moment that the body movement is detected.In practice a five minute preset period is considered adequate both for the initial period of operation of the system caused by actuation of the push button 9 and for an extension in the operational time of the system which may be achieved upon body movement being sensed by the detectors 10. Consequently, if no body movement is sensed by the detectors 10 for five minutes it is reasonable to assume that all occupants have left the room 6 and the heating of the room to an acceptable working temperature would be a waste of energy - as a result a relay within the control unit 8 is broken to ensure that the heaters 7 will not be energised to provide the working temperature until the push button 9 is again depressed manually to actuate the system and indicate that the room is occupied and that there is a requirement for heating.

Mounted on the wall of the classroom 6 are two thermostats T1 and T2 which are wired into the control system in the unit 8. The unit T1 forms a set-back thermostat and ensures that a minimum background temperature can be maintained within the classroom 6 irrespective of whether or not the control system is actuated by manual depression of the button 9. In effect therefore the set-back thermostat T1 can cause the heaters 7 to be energised so that the system overrides the timer means and body movement detectors.Typically the thermostat T1 would be set at 12"C. The thermostat T2 is set at what is considered an appropriate working temperature for the room 6 when occupied and typically would be set at 20"C. The thermostat T2 effectively determines whether the heaters 7 are energised once the system has been actuated by depression of the push button 9. Consequently, if the control system is actuated, say while the room 6 is occupied with many students for a long period, the heaters 7 will rapidly raise the temperature in the room to the required 20"C; when this is detected by the thermostat T2 the electrical supply to the heaters is cut off.However, during this latter state the detectors 10 will continue to sense body movement and cause the timer of the control system to reset so that should the temperature as sensed by the thermostat T2 fall below a permitted tolerance from 20 , the electrical supply will again be made available to the heaters 7.

By appropriate selection of the preset temperatures for the thermostats T1 and T2 at, say, 12" and 20"C it will be apparent that a temperature increase from the lower to the higher can rapidly be achieved within a reasonable time from actuation of the control system by pressing the button 9. This is of course likely to be of particular importance during freezing conditions, not only to ensure that some heat is maintained within the building to alleviate water pipes from becoming frozen but also to ensure that the temperature within the classroom 6 is tolerable to new entrants for at least the period during which the room is being heated to its acceptable working temperature.

It will be noted from the drawing that the two ultrasonic movement detectors 10 are arranged so that their respective rays 10a and 10b intersect over a predominant area of the room. As of necessity the detectors 10 are very sensitive to movement, it is possible for a detector to sense and react to convection currents from the heaters 7 or draughts from doors or windows which have been left open.

Consequently a preferred feature of the present embodiment is that the two detectors 10 are incorporated in the control system so that both detectors must sense movement simultaneously before the control system will cause the timer to reset for the extended period. It has been found that convection currents and draughts from windows and the like are unlikely to be sensed by both detectors simultaneously whereas the bulk of a person moving normally within the area of room 6 in which beams 10a and 10b intersect would certainly be sensed simultaneously by both detectors.

In a classroom or other public building environment the control unit 8 will usually be situated in a locked housing to restrain unauthorised access and normally a key operated override facility will be provided to permit a temporary by-pass of the controls so that the heaters 7 can be controlled manually in conventional manner should a malfunction occur in the control system. It will also be appreciated that the thermostats T1 and T2 are resistent to tampering so that they can only be set by authorised personnel.

Claims (12)

1. An environmental control system comprising at least one of heating, lighting and ventilation devices; intruder detectors means responsive to body movement, and manually actuated timer means preset for a predeter mined period; the system being actuated for energisation of said device or devices and for at least said pre-set period by manual actuation of the timer means and wherein during said period when the system is actuated, body movement detected by the detector means causes the system to re-set and be maintained actuated for an extended period comprising the or a further pre-set period from said detection and if no body movement is detected during said pre-set period or extended period, the system is de-actuated.

2. A system as claimed in claim 1 comprising ultrasonic detector means.

3. A system as claimed in either claim 1 or claim 2 comprising infrared detector means.

4. A system as claimed in any one of the preceding claims in which the detector means comprises at least two detectors spaced from each other and wherein, for the system to reset, said spaced detectors must simultaneously sense movement.

5. A system as claimed in any one of the preceding claims and comprising set-back means which overrides the timer means, the set-back means causing operation of the device or devices to provide a predetermined low energy level environmental condition when the system is de-actuated and manual actuation of the timer means permits operation of the device or devices to provide a predetermined high energy level environmental condition.

6. A system as claimed in claim 5 in which the device comprises a heater and the set-back means comprises a thermostat which causes operation of the heater to provide a predetermined minimum temperature environment when the system is de-actuated.

7. A system as claimed in either claim 5 or claim 6 in which the device comprises a heater and thermostat means is provided which on manual actuation af the timer means and during said preset period or extended period causes operation of the heater to provide a predetermined temperature environment.

8. A system as claimed in any one of the preceding claims in which the timer means is actuated in response to manual operation of a means which automatically resets during said predetermined period.

9. A control system as claimed in any one of the preceding claims in which the preset period or further preset period is in the range of three to twelve minutes.

10. A control system as claimed in claim 9 in which said period is in the range three to five minutes.

11. An environmental control system substantially as herein described with reference to the accompanying illustrative drawing.

12. A single storey hutted type building having a room, the temperature within which is controlled by a system as claimed in any one of the preceding claims.