i 0/ it 7 \ 412
Contents
1. 236 68 B P eW Unoccupied 4 000 400 12 1976 Elder 235 92 CT 4 060 123 11 1977 Hoffman et al 165 11 18 Claims 9 Drawing Figures Flame Smoke lonization 20 m Room Heat Rel Heating 60 HZ Time Information Fire Detector Room Operation mperqfora Sensor Senex ME f 13 e To From 4 12 Othe Rooms Room 5 42 Control Hot Air Hot Water Automatic Telephone Steam Control Processor gt P Dialing Equipment Solenoid Valve mm System 2i Room Heating Tele Li Coping phone Lines System 5 Fuel Control Signal A C Power and Key Operated Delayed Alarm Set Reset Units 4l Disarm Signals 30 60 Sec Typical Delay U S Patent Oct 13 1981 Sheet 1 of 5 4 294 404 Temperature F T T2 Ts 14 Ts Te Time Flame Smoke lonizofion Roo Fig ai Fire Detector oom Operation Temperature Sensors Is id To From pE Othe Rooms 15 42 1 10 C ntrol Hot Air Hot Water Mobi Automatic Telephone E 1 1 Steam Control Processor Solenoid Valve Es System Dialing Equipment 20 f Relay Heating Room Heating Cooling i System 5 Coritroi Signal Telephone Lines Fuel Control Signal A C Power and 60 Hz Time Information Key Operated Delayed Alarm Set Reset Units 4i2. of heat flow in structures is not widely understood This is the probable cause of the fairly widely held misconception that allowing short term devations from steady state environmental conditions by reducing energy for a short term after which the structure or portion thereof is returned to the comfort zone level of environmental condition will not result in long term energy savings In fact the major phenome nom involved in heat flow in structures is conduction through exterior walls The typical structural wall has an extermely large value of thermal inertia The energy lost from the interior of a structure to the exterior oc curs at the surface of the structural wall The rate of heat flow at this surface is dependent upon the average value of the temperature differential between the inte rior and exterior of the structure Any reduction in 4 294 404 3 interior temperature therefore necessarily reduces the time average value of this differential and accordingly reduces the quantity of heat lost From this it follows although it has not generally realized that very substan tial energy savings may be realized by appropriately controlling energy consumption even over the short period of time so that energy for environmental modifi cation purpose is consumed only when the environmen tal modification is needed It is accordingly an object of this invention to pro vide a control system for environmental control systems emp
3. that there are very substantial areas 32 of con tinuously unoccupied condition for each room It is also apparent that as between the master bedroom and the family room there are no times during the typical day in which heating would be required in both rooms Thus in each case there exists a period during which recov ery of wall heat into the interior of the structure as discussed hereinabove with reference to FIG 1 is possi ble by the employment of this system It should also be noted that the unoccuplied period 32 of the master bedroom occurs during the portion of the day in which manual setback of thermostats as currently practiced would not be employed and that the utilization pattern for the family room is such that a large number of rela tively brief periods of time in which the room is unoccu pied 32 exist that the home owner would be unlikely to conserve energy by intentionally setting back a control FIG 4 illustrates in electrical schematic form one embodiment of circuitry useful in accordance with this invention for performing the temperature sensing logic and control functions of respectively block elements 11 15 and 16 as shown in FIG 2 In FIG 4 a the temperature sensing element is transistor 51 whose base emitter voltage varies linearly with temperature Tran sistor 51 is connected in series with resistor 53 to form 45 50 55 60 65 8 a first voltage divider A second voltage divider 52 compr
4. when necessary How ever in current practices in the expenditure of energy for environmental modification of building interiors systems are designed to perform their environmental modification function irrespective of necessity at a sig nificantly large number of times and places Taking the heating of a residential building as an example a typical structure consists of seven or eight rooms and serves as a dwelling place for four or five persons At any given time most of the rooms are unoccupied Nevertheless a substantial number if not all of the unutilized rooms are continuously heated The typical residential heating system is controlled by a thermostat which controls the furnace to maintain a preselected temperature within the structure Some improvement of efficiency in prior art systems has been provided by the use of a clock thermostat which maintains the interior of the building at one temperature during a portion of the day and at another temperature during the remainder of the day This permits some saving of energy by reducing the temperature maintained for a portion of each day The same effect may be provided by manually resetting the thermostat With some types of heating systems notea bly central heating systems employing circulating hot water as the heat transfer medium further efficiencies have been provided in the prior art by the utilization of zone systems in which the structure is divided into two or three zones e
5. Disarm Signals 30 6 O Sec Typical Delay U S Patent Oct 13 1981 Sheet 2 of 5 4 294 404 Fig 3 Dining Room l 32 3M 32 3 32 3 32 3 32 ouo a l UZ Living Room 7244 14 UA xkichen Guest Bedroom Bedroom 3 Bedroom 4 Bathroom 3l 32 3l DAT ceo 72 Matt Radon QA UE A ab u suas de 0 Typical Winter Weekday Usage for a Family of Four 294 404 9 4 Sheet 3 of 5 U S Patent Oct 13 1981 5 4 4 294 404 Sheet 4 of 5 U S Patent Oct 13 1981 UO DD V u p y 01 243 aduog amog proua oS u 004 Of vs M 2V vZ 044002 IDUNA OL SIOAIAG 4000 OL 405522044 OLN S808 84u 9 big u 004 D UI 200 E S4 n24 2 ADJIUNS 7 43440 wodd ANMIND 20 40 0 GG pg K2updn22Q UO ndino 40suasg ouodnooo z U S Patent Oct 13 1981 Sheet 5 of 5 4 294 404 Room Heating is Fig 7 4 294 404 1 ENVIRONMENTAL CONTROL SYSTEM This invention relates to systems for controlling the interior environment of structures such as heating and cooling systems More particularly this invention re lates to the employment of multiple sensors and control systems to so regulate the operation of environment modification apparatus to minimize undesired energy losses Many types of apparatus are known and used for controlling the interior environment of structures For exampl
6. United States Patent n 1 4 294 404 Gajjar 45 Oct 13 1981 54 ENVIRONMENTAL CONTROL SYSTEM 4 084 744 4 1978 Wilson Jr 236 49 Z 5 4 114 807 9 1978 Naseck 236 1 E 75 Inventor Jagdishchandra T Gaifar Clifton Park N Y Primary Examiner William E Wayner 73 Assignee Integrated Energy Systems Attorney Agent or Firm Paul I Edelson Schenectady N Y 57 ABSTRACT 21 Appl No 877 682 An environmental control system for improving the 1221 Filed Feb 14 1978 energy efficiency of structures is disclosed A structure having a heating and or cooling plant of any conven 51 Int F24F 7 00 tional type is improved by providing in each subdivi 52 US i hene eter 236 49 236 94 sion of the structure such as a room a temperature 165 11 A sensor and an occupancy sensor The outputs of the 58 Field of d 7 7 44 temperature and occupancy sensors are received by a 1 R 165 11 62 126 235 92 C control subsystem whose output is a composite function 56 References Cited of the output signals of the occupancy and temperature U S PATENT DOCUMENTS sensors and which controls the heating and or cooling mm system of the structure to maintain each room at a first 2 oerren et al riirii t h 1 4 3 181 791 5 1965 Axelrod 7236 44 C 25 7 ps 775 at a Second 3 352 490 11 1967 Dalzell et al
7. ach zone having its own thermostat each thermostat individually controling a valve for 10 20 25 30 35 40 45 55 60 65 2 regulating the circulation of heating water within its zone and the furnace being controled by the thermo stats disjunctively such that the furnace fires whenever any zone demands heat In the case of direct electrical heating each room may be conveniently provided with its own thermostat This is done in some direct electri cal heating installations but not in the majority proba bly because thermostats are relatively expensive de vices Furthermore to obtain maximum benefit in terms of energy conservation from the use of individual ther mostats in each room the persons occupying the dwell ing would be required to manually adjust the thermo stats upon entering a previously unoccupied room and upon leaving a room unoccupied Energy conservation in the environmental control systems for structures has also been hampered by a number of misconceptions which have gained a substan tial currency of belief It is now generally accepted that the energy used by a heating system for example may be conserved by lowering the temperature setting of the controlling thermostat for a substantial period of time for example overnight Until recently however there was a school of thought which held that maximum energy efficiency would be obtained by maintaining a constant environmental condition
8. be provided with heating and cooling registers The outer ring is typically divided into a large number of relatively small fully partitioned rooms These rooms are not continuously occupied during the work ing day have a substantial proportion of glazing and have a substantial proportion of the total heating and cooling registers of the building installed therein In view of the typical construction and utilization of com mercial buildings as described immediately herein above it should be clear to those skilled in the art that the utilization of a control system in accordance with this invention in the rooms of the outer ring will result in very substantial energy savings typically in excess of that which will be obtained in residential use 4 294 404 11 VVhile this invention has been described vvith refer ence to particular embodiments and examples other modifications and variations will occur to those skilled in the art in view of the above teachings Accordingly it should be understood that within the scope of the 5 appended claims the invention may be practiced other wise that is specifically described The invention claimed is 1 An environmental control system for a structure having a plurality of rooms and means for modifying an environmental parameter within said structure compris ing an occupancy sensor in each room of at least two rooms of said plurality of rooms providing exclu sively a first output
9. ccumulator receving an output of said bi direc tional counter means and a display device for receiving an output of said accu mulator and indicating the number of occupants of said room 18 The control system of claim 16 further including time delay means interposed between said bi directional counter means and said control means whereby said control means is prevented from receiving said first output signal until said room has been occupied contin uously for a preselected period of time
10. city is assumed to be a con stant 30 F Assuming that the desired interior tempera ture for an occupied room is 70 F a system in accor dance with this invention will provide that when the room becomes occupied at time T1 as shown in FIG 1 and the interior temperature of the room as indicated by a temperature sensor in the room is below say 68 F the heating system will be so controlled to provide heat to the room and the temperature in the room will begin to rise If it be assumed that the temperature in the room at the time occupancy commences was 57 F roughly ten to fifteen minutes will elapse between time T1 when the heating demand is initiated and time T2 at which the interior temperature of the room reaches 70 F At this point in time so long as the room remains occupied the system in accordance with this invention functions operationally analogously to prior art systems to main tain the interior temperature of the room within prese lected limits Because of the very high thermal inertia of the wall Curve 2 begins to rise at point Ti but very much more slowly than Curve 1 Also so long as Curve 1 is either rising or constant the vertical axis temperature value of Curve 2 cannot exceed that of Curve 1 At time T3 as shown in FIG 1 the room becomes unoccupied again At time T3 the control system in accordance with this invention senses the unoccupied condition of the room and the heating apparatus is shut do
11. d and at a second level of said environmental parameter when said room is unoccu pied and including means for setting said first and sec ond levels 7 An environmental control system as claimed in claim 1 wherein said control means includes addition ally means for actuating an emergency condition re sponse device 8 The control system of claim 7 wherein said envi ronmental parameter is temperature and wherein said means for actuating actuates said emergency condition response device when said output signal of said second sensor corresponds to a temperature in said room in excess of 135 Farenheit 9 The control system of claim 7 including addition ally a third sensor for providing an output signal respon sive to the presence of an emergency condition in at least one of said rooms said control means re ceiving additionally said output signal of said third sensor and an emergency conditon response device 10 The control system of claim 9 wherein said emer gency condition response device includes a telephone dialing device 11 The control system of claim 7 including addition ally means for providing a signal to said control means to indicate that said structure is intended to be unoccu pied said emergency condition responsive device in cluding an intrusion alarm actuated by said control means whenever said occupancy sensor provides said first output signal contemporaneously with an indica tion from said means for p
12. d room has an entryway and said occupancy sensor comprises first and second perimeter detectors disposed across 10 said entryway each said perimeter detector pro viding an output pulse when an object crosses said entry way said first and second perimeter detectors being disposed in spaced relation to each other such that the output pulse provided by said first perimeter detector preceeds the output pulse pro vided by said second perimeter detector when an object enters said room and the output pulse pro vided by said second perimeter detector preceeds the output pulse provided by said first perimeter 20 detector when an object leaves said room and bi directional counter means receiving said output pulse provided by said first and second perimeter detectors said bidirectional counter means count ing upwardly by one for each reception of an out 15 25 30 35 40 45 50 55 60 65 14 put pulse provided by said first perimeter detector followed by an output pulse provided by said sec ond perimeter detector and counting downwardly by one for each reception of an output pulse pro vided by said second perimeter detector followed by an output pulse provided by said first perimeter detector said bi directional counter means provid ing said second output signal when its net count is zero and said first output signal when its net count is positive 17 The control system of claim 16 including addi tionally an a
13. e central and room heating and air conditioning apparatus are known as well as humidifiers dehumidifi ers and air cleaners In the case of heating apparatus and air conditioners the prior art almost universally provides a quasi automatic control device in the form of a thermostat to control the operation of the appara tus to maintain the volume served by the apparatus at a desired temperature Many humidifiers and dehumidifi ers are similarly equiped with a humidistat to provide automatic or semiautomatic maintenance of a desired humidity level in the volume served For simplicity only a heating system will be discussed in detail herein but it should be understood that the characteristics of environmental control systems and the applicability of this invention thereto is general and is not restricted to heating systems alone A common characteristic of heating and other sys tems for modifying an attribute of the environment within a structure is that they consume substantial quan tities of energy Particularly in recent years energy conservation has become extremely important both in terms of the individual economic interest of a building owner and the general interest of society in the conser vation and allocation of scarce resources In addition energy conservation has the beneficial side effect of reducing air pollution and thermal pollution Obviously conservation of any resource is enhanced by expending the resource only
14. ent signal for the room corresponding to the switch activated thus allowing a person to cause a room to begin its environ mental parameter modification prior to being entered The foregoing descriptions have basically used a residential structure as the context in which to describe the operation of a system in accordance with this inven tion The applicability of this invention is by no means so limited As to the alarm functions described immedi ately herein above the applicablity to industrial and commercial structures is considered obvious With re spect to the environmental modification functions the applicability to commercial buildings is of even greater significance than to residential structures Typical com mercial structures are laid out with the space or each floor divided essentially into 3 concentric rings In the innermost ring are placed elevator and utility shafts conference rooms service functions such as rest rooms libraries file rooms cafeterias and the like This core is almost invariably not provided with heating or cooling registers but is allowed to equilibrate through ventila tion with the outer rings The core is very substantially insulated by the outer rings The middle ring is occu pied by work stations for support personnel performing clerical and administrative functions The middle ring is frequently not fully partitioned is typically continu ously occupied during the working day and may or may not
15. eration of the system is essentially identical with that heretofore described with respect to heating The control system of this invention further lends itself very simply to the performance of emergency alarm and reporting functions The very simplest emer gency alarm and reporting function to add to the envi ronmental control system is intrusion detection because each room in the structure is already provided with an occupancy sensor 12 for control of the environmental parameters as discussed above Therefore the only modification needed to the system of this invention as heretofore described to provide for intrusion alarm is the provision of means 41 whereby the proprietors of the structure may inform logic element 15 that the structure is being intentionally left unoccupied for a period of time Means 41 may be any simple double throw electrical switch but is preferrably a key switch for security purposes Such switch means are well known in present burglar alarms and perform their well known function as an element of this embodiment of this invention The advantage herein provided is that intrusion detection is performed without additional detectors over those used for environmental control When key switch 41 is set in the building occupied position the system functions as heretofore described for environmental control purposes When the switch means 41 which may for example advantageously be one of the M15 series of key switches as
16. ic element 15 cause a bell to ring to alert the occupants of the struc ture immediately upon detection of a hazard condition when switch means 41 is set to the structure occupied position and alternatively to activate an automatic telephone dialing device to call the fire department upon the existence of a fire hazard signal when switch member 41 is set to the structure unoccupied position Other alternative features may be incorporated into the system of this invention if desired The flexibility of the system is one of its major advantages and a wide range of modifications will occur to those skilled in the art A a first example of such modifications a very simple fire alarm may be incorporated into the system by merely programming logic element 15 to respond to first and second temperature thresholds for environ mental control purposes as discussed above and to re spond to a third temperature threshold at approximately 135 F as a fire alarm Thus by simply programming the logic the temperature sensor 11 already provided for environmental control sensing may be made to provide a fire hazard sensing function very economically As a second example of such modifications a residen tial structure may be provided at conveniently located positions with a plurality of manually operable switches connected in parallel with the occupancy sensors in the various rooms Activation of such switches would transmit a momentary room occupied equival
17. ility that an occu pant might choose to leave a room in a condition de manding maintenance of a higher temperature when leaving the room with the belief that he will return shortly and also allows the system to operate effec tively with very inexpensive temperature sensors Logic element 15 and control element 16 are illustrated as separate elements in the drawing to aid in an under standing of the system operation Their functions are logically described separately However it will be obvi ous to those skilled in the art that the separate functions 4 294 404 7 of logic element 15 and control element 16 may if de sired be performed by a unitary apparatus subsystem comprising for example relays Control element 16 provides two separate output control signals in the case of a system in accordance with this invention used in a structure having a central heating system One control signal controls the provi sion of fuel to the central heating apparatus such as a furnace The other output control signal controls the operation of a device associated with each room such as a solenoid valve 21 inserted in the conduit conveying the heating medium from the furnace to the room The first output control signal causes fuel to be provided to the furnace whenever the composite outputs of temper ature sensors and occupancy sensors in any room are such as to demand heat to that room The second output control signal opens the solenoid val
18. inafter or may be a commerically available micro processor such as Intel model 8085 as illustrated in FIG 6 with appropriate peripheral cir cuitry chips as are all fully described in MCS 85 User s Manual published June 1977 by Intel Corpora tion If the person remains in the room he must retrans mit the occupancy signal at 15 minute intervals in order to give a continuous room occupied signal If he fails to re transmit the signal the room will begin to cool down At some point the occupant will be prompted by the cooling of the room to give another room occupied signal This is the least expensive embodiment of an occupancy sensor and at a slight cost in occupant com fort also provides maximum energy conservation since the room will begin to cool down after each 15 minute period When this manual occupany sensor is used in a residential context a time based override is provided for bedrooms to maintain the desired sleeping tempera ture therein in the absence of the periodic switch clo sure room occupied signal In this connection the peri odic closure of the switch by the room occupant consti tutes the sensor room occupied output signal Another alternative occupancy sensor as shown in FIG 5 is a perimeter detector operating directionally as for exam ple by having first and second perimeter detectors 71 The logic element 15 of FIG 2 then includes a counter shown as 74 in FIG 5 which counts up and counts down It is well know
19. ises a potentiometer The voltage across the vari able elements of the two voltage dividers are compared in the logic element 15 of FIG 2 and more particularly shown in FIG 4 b as discussed hereinafter The tem perature sensing circuit of FIG 4 a receives an input signal at terminal 54 from occupancy sensor 12 of FIG 2 The signal received from the occupancy sensor biases transistors T14 T g and T either into conduction or cutoff depending upon its state thereby changing the total resistance in series with calibration resistor 61 of FIG 4 2 to vary the thermostatic threshold of the circuit of FIG 4 a The output signals taken from the first and second voltage dividers of FIG 4 a are transmitted to logic elements 15 as shown in FIG 2 and more particularly comprising differential amplifier 62 as shown in FIG 4 b by two conductors C and D of a four conductor shielded cable The elements shown in FIG 4 a may in accordance with the particular embodiment illus trated conveniently be co located in each room of the structure in the particular embodiment of FIG 4 the elements shown in FIG 4 6 may be conveniently co located centrally in the structure When the temper ature in a room drops below the thermostatic threshold determined by the potentiometer settings and state of input at terminal 54 discussed hereinabove the output of differential amplifier 62 drives transistor 63 into con duction which in turn dr
20. ives relay 64 The contacts of relay 64 control the operation of the environmental parameter modification system for example a furnace and distribution controls for example solenoid valves as heretofore described l FIG 4 also illustrates two features which may be optionally included in the apparatus of this invention if desired The first of these is a delay network comprising resistor 55 and capacitor 56 interposed between termi nal 54 and the base of transistor T14 so that brief changes in the occupancy of a room such as when a person merely passes through a room on the way from one part of the structure to another will not alter the thermostatic threshold of the system The second op tional feature shown is a thermal stabilizer subcircuit to prevent thermostatic overshoot as is known in the art In this embodiment the thermal stabilizer includes diode 65 and resistor 57 When relay 64 is activated a small current is passed through resistor 57 which is in close thermal proximity to transistor 51 T3 The description of the preferred embodiment of this invention to this point has been limited for the sake of simplicity to a discussion of a control system in accor dance with this invention for controlling residential heating apparatus The invention however is not so limited A wide variety of environmental conditions within structures may be monitored and controlled by systems in accordance with this invention and the con t
21. k elements included of the preferred counter cir cuit for use in the embodiment of FIG 5 FIG 6 is an electrical schematic and block diagram of an embodiment of environmental control system apparatus in accordance with this invention in which commercially available microprocessor elements are used in the performance of the control and logic func tions of the system FIG 7 is a block diagram of a structure environmen tal control system and apparatus similiar to that of FIG 2 and wherein like numerals identify identical elements to those shown in FIG 2 explicitly showing the inter connection between the system block elements and a plurality of rooms Taking for illustrative purposes the example of the heating of a room in a typical residential structure in the winter FIG 1 illustrates the temperature variations with time in the room the wall and exterior tempera ture and serves to illustrate the substantial energy sav ings which may be achieved by the employment of a system in accordance with this invention In FIG 1 the horizontal axis represents time and the vertical axis represents temperature Curve 1 represents the varia tion of room interior temperature with time this is the parameter which will actually be experienced by occu pants of the room Curve 2 represents the mean temper ature of the interior of the structural wall of the room Curve 3 represents the temperature exterior to the structure which for simpli
22. loyed in structures which will maximize energy conservation by modifying the parameters of the envi ronment interior to the structures only to the extent necessary It is another object of this invention to provide such a control system wherein the operation of the enviorn mental control systems is responsive to a composite function of factors consitituting a demand for environ mental modification It is another object of this invention to provide such a control system which is additionally adaptable to provide sensing and alarm functions with respect to a plurality of emergency conditions Yet another object of this invention is to provide such a control system which is inexpensive to manufacture install and operate in a structure Briefly and in accordance with one embodiment of this invention a control system for controlling an envi ronmental parameter modification system comprises a sensor for measuring the value of the environmental parameter to be modified within a volume of the struc ture and a sensor within such volume for determining whether the volume is occupied or vacant A comput ing device which may be a very simple logical device receives a signal from the two sensors and provides an output which controls the environmental modification apparatus to supply modifying energy to the volume only when the signals from the two sensors indicate that the volume is both occupied and the environmental paramenter is at a level
23. n that logic circuitry may be programmed to count bidirectionally The room is indi cated as vacant when the counter is at zero the pre ferred circuitry for counter 74 is illustrated in FIG 5a It should be noted that one of the advantages of this invention is that it permits the replacement of thermo stats by temperature sensing devices which have costs typically on the order of ten percent of that of the ther mostats which they replace Sensors 11 and 12 provide outputs to logic element 15 which in turn provides control outputs to control ele ment 16 which are a composite function of the signals received from sensing elements 11 and 12 Logic ele ment 15 is programmed to provide control signals to cause heat to be provided to room 10 when the signal from temperature sensor 11 falls below a first prese lected limit if but only if the signal from occupancy sensor 12 indicates that room 10 is occupied Otherwise logic element 15 provides a control signal to cause heat to be supplied to room 10 only if the output of tempera ture sensor 11 indicates that the temperature of room 10 has fallen below a second substantially lower tempera ture The use of automatic occupancy sensors 12 pro viding an output exclusively as a function of room occu pancy in each room of the structure relieves the occu pants of having to remember to make a manual readjust ment of heating demand apparatus enforces energy conservation by eliminating the possib
24. outside a preselected range which is desired to be maintained when the volume is occupied When the volume is unoccupied the environ mental modification system is operated only upon a 15 20 25 30 45 substantially greater variation in the environmental parameter The novel features of this invention sought to be patented are set forth with particularity in the appended claims The invention together with further objects and advantages thereof may be understood from a reading of the following specification and appended claims in view of the accompanying drawings in which FIG 1 is a Cartesian graph illustrating the thermody namic effects across a structure wall of short term varia tions in the temperature maintained in a volume within the structure FIG 2 is a block diagram of a structure environmen tal control system and apparatus for a structure includ ing a control system in accordance with one embodi ment of this invention FIG 3 is a bar chart illustrating room utilization in a typical residential structure FIG 4 is an electrical schematic diagram of one em bodiment of sensing logic and control circuitry useful in practicing this invention FIG 4 a shows a tempera ture sensor FIG 4 b shows logic and control ele ments 50 60 4 FIG 5 is a block diagram of one embodiment of occupancy sensor useful in practing this invention FIG 5a is an electrical schematic diagram with logic bloc
25. resulting in a steady state operation of the macro system comprising the structure and its environmental control apparatus and that system inertia would defeat any attempt to reduce energy consumption by varying the level at which an environmental parameter is maintained In fact the maintenance of a steady state environmental condition is not efficient from the point of view of energy conser vation when the utilization of the structure or portions thereof is such that the environmental condition need not be maintanined as for example when certain rooms are unoccupied Nevertheless the misconception that departure from maintenance of a steady state for Short periods of time is inefficient continues to be widely held and even with the most flexible of pres ently available control systems the short term reduc tion of energy consumption requires that the persons using the structure manually readjust the system control apparatus such as thermostats when entering unoccu plied rooms and when leaving rooms unoccupied Even if the value of doing so is appreciated it is unlikely that the persons using a structure will make the required adjustments with adequate regularlity This is expected because of normal forgetfulness of simple tasks and also because a person who might be planning to reenter a room might feel that his comfort required his not per mitting the room to depart from the comfort zone envi ronmental condition The dynamics
26. rol system of this invention is further easily adaptable to the performance of other functions of an alarm con trol and reporting nature by the addition of simple and inexpensive modifications to the control system Re turning to FIG 2 the environmental condition modifi cation apparatus 20 heretofore described as for exam ple a furnace in the heating example may comprise a combined heating and cooling apparatus such as a heat pump or may in fact comprise a plurality of indepen dent or quasi independent sub systems such as a heating plant an air conditioning subsystem a humidifier etc Such plural sub systems may be completely indepen 9 dent or may share any number of components such as duct work heat exchangers etc In the case of a control system for combined control of heating and cooling apparatus within a structure the same sensors 11 and 12 will cause control element 16 to provide an output con trolling the supply of energy to the appropriate environ mental modification system heating or cooling as ap propriate and a signal controlling the distribution of heat transfer medium among the various rooms If con trol of a parameter other than temperature for example humidity is desired an additional appropriate sensor 13 for example a transmitting hygrometer as are known in the art would be provided in each typical room 10 Beyond the provison of a sensor appropriate to each parameter to be controlled the op
27. roviding that said structure is intended to be unoccupied 12 The control system of claim 11 wherein said means for providing a signal includes a key operated electrical switch 13 The control system of claim 11 including addi tionally a third sensor for providing an output signal respon sive to the presence of an emergency condition other than intrusion in at least one of said rooms said control means receiving additionally said out put signal of said third sensor means within said control means for causing said emergency condition responsive device to provide a first response upon contemporaneous receipt of said first output signal of said occupancy sensor and said indication from said means for providing that said structure is intended to be unoccupied and a second response upon receipt of said output sig nal of said third sensor 14 A control system as claimed in claim 1 wherein said occupancy sensor comprises means for establishing an energy distribution pattern in said room and means for detecting an abberation in said energy distribution pattern 4 294 404 13 15 The control system of claim 14 further including time delay means interposed between said means for detecting and said control means whereby said control means is prevented from receiving said first output signal until said room has been occupied continuously 5 for a preselected period of time 16 A control system as claimed in claim 1 wherein sai
28. shown on page 45 of the Mountain West Alarm Supply Company Cata log A 78 is set to the building unoccupied position logic element 15 provides outputs to control the envi ronmental modification apparatus as heretofore de scribed in the room unoccupied mode and upon receiv ing an occupancy indicative output from an occupancy sensor 12 in any room instead of modifying the envi ronmental parameters as heretofore provides an output to alarm effector 42 Alarm effector 42 may be any effector such as known in art for example a loud bell or an automatic telephone dialing device which may for example be a telephone dialer as illustrated on page A 1 of Mountain West Alarm Supply Company Catalog A 78 to notify providers of emergency service or any combination of known alarm effectors Similarly by the provision of additional sensors 14 in each typical room 10 any other emergency or hazard condition desired to be detected niay be detected an a corresponding output to logic element 15 for activation of alarm mechanism 42 for example sensor 14 may bea smoke or ionization detector for fire hazard warning purposes The operation of logic element 15 upon the receipt of a hazard condition signal from detector 14 may be dependent or independent of the setting of switch means 41 as desired For example in the case of 4 294 404 0 20 25 30 35 40 45 55 60 65 10 a fire alarm it may be desired to have log
29. signal when said room is occu pied and a second output signal when said room is unoccupied a second sensor in each room of at least two rooms of said plurality of rooms for providing an output signal responsive to the level of said environmental parameter in said room control means for receiving the output signals of each and every of said occupancy sensors and said sec ond sensors and for controlling said means for modifying responsively to a composite function of 25 said output signals of said occupancy sensors and said sensors and wherein said control means more particularly in cludes means for receiving the output signals of said occupancy sensors and said second sensors and for providing a control output signal said control output signal being a composite function of said output signals of said occupancy sensor and said second sensor and means for receiving said control output signal and 35 controlling said means for modifying responsively to said control output signal and wherein further said environmental parameter is tem perature and said means for modifying comprises an energy conversion unit and means for convey ing a fluid from said energy conversion unit to said rooms 2 An environmental control system as claimed in claim 1 wherein said structure has means for modifying a plurality of environmental parameters and further 45 including at least one additonal sensor for providing an output signal responsive to
30. t the residential room heat ing control example alone will continue to be described with reference to FIG 2 Each room in the structure of which room 10 is typical is provided with a tempera ture sensing device 11 and an occupancy sensor 12 Temperature sensor 11 may be a thermistor thermo couple or the base emitter junction of a transistor with the transistor embodiment being preferred for reasons of cost and ease of calibration For a given collector current the base emitter voltage of a transistor is a linear function of temperature Therefore calibration is sim ply a matter of initial adjustment of the detector for a voltage at some preselected temperature As another advantage the transistor cost is approximately the cost of a thermistor Occupancy sensor 12 may be a volumet ric detector such as an ultrasonic occupancy detector such as Model D8 or D6 as shown respectively on page 6 and 19 of Mountain West Alarm Supply Co Catalog A 78 or a microwave doppler occupancy detector such as Model S22 as shown on page 9 of Mountain West Alarm Supply Co Catalog A 78 Another alternative Occupancy detector is a momentary contact button in each room whereby any person entering the room can 15 20 25 30 35 40 45 50 60 65 6 close the switch to demand heat whereupon an approxi mately 15 minute room occupied signal is sent to logic element 15 which may be constructed as shown in FIG 4 and described here
31. the level of one of said envi ronmental parameters said control means receiving additionally the output of said at least one additional sensor and control ling said means for modifying to modify one envi ronmental parameter responsively to a composite function of said output signals of said occupancy sensor and said second sensor and controlling said means for modifying to modify another environ mental parameter responsively to a composite function of said output signals of said occupancy sensor and said at least one additional sensor 3 The control system of claim 1 wherein said second sensor is a temperature sensor comprising the base emit ter junction of a transistor 4 The control system of claim 3 including additon ally thermal stabilizer means comprising a resistance heating element adjacent said transistor 5 The control system of claim 1 wherein said means for receiving said contro output signal and controlling said means for modifying comprises 15 20 30 40 50 55 65 12 means for starting and stopping operation of said energy conversion unit and valve means interposed in said means for conveying for controlling distribution of said fluid among said rooms 6 The control system of claim 1 wherein said com posite function is such that said control means controls said means for modifying to maintain each of said rooms at a first level of said environmental parameter when said room is occupie
32. ue of Curve 2 exceeds the temperature value of Curve 1 Time T6 represents the time at which the mean interior temperature of the wall will reach the preselected lower equilibrium tempera ture for unoccupied rooms It may therefore be seen that when a room controlled by a system in accordance with this invention is unoccupied for a period of many hours the wall is warmer than the room for a substan tial period of time and the direction of heat flow is accordingly reversed This is to say a portion of the energy used to heat the wall is recovered into the room The major advantage of a system in accordance with this invention however is the result of the fact that in terms of energy conservation the critical factor is the rate of heat loss from a building interior to a building exterior This is in turn a function of the average tem perature differential between the interior and exterior of the building Energy conservation only has meaning over the very long term and it is therefore appararent that any decrease in the time average temperature dif ferential between the interior and exterior of the build ing will provide a corresponding decrease in the net average rate of heat flow across the structural wall thus providing a net long term energy saving FIG 2 illustrates in block diagram form a control system in accordance with one embodiment of this invention including multiple functions will be discussed hereinafter For the momen
33. ve or equivalent controlling the delivery of heating medium to each individual room for example room 10 or 10a of FIG 7 if but only if the composite output of the occupation and temperature sensors of that particular room are such that heating is demanded for the individual room involved Obviously in a structure in which a central heating system is not employed for example in a base board electrical heating system the first output control signal from control element 16 is not required and there are no heating medium conduits to be controlled by solenoid valves In such cases control element 16 will provide a single output control signal controlling the provision of fuel as for example electrical current to the individual heating means in each room as demanded by the composite outputs of sensors 11 and 12 in accor dance with the above described algorithm The fact that substantial energy savings in heating may be achieved by the employment of a control system in accordance with this invention may be seen from FIG 3 in which typical usage of various rooms in a typical residential structure are displayed in bar chart form Taking as particular examples the master bed room and family room of a typical residential structure 10 20 25 30 35 40 the periods of occupancy are shown by hatched areas 31 on the chart of FIG 3 and the unoccupied times are shown by the unhatched areas 32 It is immediately apparent
34. wn and the room is allowed to cool down thus conserving en ergy The control system in accordance with this inven tion is so designed as more particularly set forth herein after to control the heating apparauts to maintain a temperature centered about say 70 F for occupied rooms and to maintain a substantially lower tempera ture say centered about 55 F in unoccupied rooms Assuming that the interval between times T2 and T3 is on the order of two hours and the initial mean interior 4 294 404 5 temperature of the wall at time T3 will be approxi mately 59 F At time T3 the room temperature will begin immediately to decline as shown in Curve 1 Curve 2 will continue to rise by a small amount so long as the temperature is reached or the room is again occupied and the hereinabove described operation is repeated At some time T5 as shown in FIG 1 approximately two hours after T3 the time at which the room became unoccupied the interior temperature of the room will have declined to its new equilibrium temperature to be maintained by the control system if the room has not been reoccupied in the interim A relatively minor ad vantage of this invention but one worth mentioning for its aid in understanding the invention as a whole is now immediately apparent from Curve 2 Because of the relatively high thermal inertia of the wall from time T4 until time T6 as shown in FIG 1 approximately ten hours the temperature val
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