Thermostat system with remote data averaging

FIELD OF THE INVENTION

0001This invention relates to the art of thermostats and, more particularly, to a thermostat system incorporating a central control device receiving remote environmental sensing data from remote sensors.

BACKGROUND OF THE INVENTION

0002Thermostats have been used for many years as a temperature sensitive switch which controls heating and/or cooling equipment for conditioning a space in which the thermostat, or a temperature sensor connected to the thermostat, is placed. In the well known manner, a simple thermostat can be adjusted to establish a temperature set point such that, when the temperature in the conditioned space reaches the set point, the thermostat interacts with the heating and/or/cooling equipment to take suitable action to heat or cool the conditioned space as may be appropriate for the season.

0003Modern thermostat systems, which take advantage of the ongoing rapid advances in electronic technology and circuit integration, have many features which provide more precise supervision of the heating and/or cooling equipment to achieve more economical and more comfortable management of the temperature of a conditioned space. Many modern thermostat systems include a real time clock, a memory and a data processor to run a process control program stored in the memory to accurately measure the temperature of a temperature sensor disposed in the conditioned space and to send control signals to the heating and/or cooling equipment to closely control the temperature of the conditioned space. Modern thermostat systems permit anticipating and minimizing hysterisis or overshoot of the temperature in the conditioned space. In addition, the program can specify different set points at different times of the day and week and may also include a “vacation” mode which employs different set points when the conditioned space is not occupied for an extended period.

0004Many modern thermostat systems have a central control device or unit that receives environmental sensor data from sensors remote from the central control device. These sensors can detect temperature, humidity, or other parameters that may be used in a control program by the central control device to control environmental control equipment. The environmental control equipment (comprising HVAC equipment, among others) responds to signals from the central control device to affect the ambient comfort in rooms of a conditioned space. Typically, a remote sensor signal is received by the central control device and its value compared with that of a pre-set setpoint. If the sensor value is sufficiently different from the setpoint, environmental control equipment is activated or de-activated in response thereto. Remote sensors can be connected by wire directly to the central control device or by wireless connection so that the control program can store the output of each sensor and associate it with an identifier for the remote sensor where the output originated.

0005Modern programmable thermostat systems also may act to control temperature in some rooms of out of all those in a conditioned space as a “zone”. Unfortunately, zone control requires dedicated equipment for the zone or duct dampers or deflectors to direct conditioned air to the zone rooms. This requires complexity and additional cost to the system. One form of zone control uses storage in a central control device storing all the signals from multiple remote environmental sensors in the zone. The control program calculates an average value from the stored values of the remote sensors and uses that average value as a control value. The control value is compared with a setpoint, whereafter environmental control equipment is activated or de-activated. The control value established by prior art thermostat systems can easily over- or under-condition a room where a user most desires environmental control.

0006There is a need for zone control in a thermostat system where remote sensor values are averaged for occupied rooms at a central control device. The averaged sensor data establish a zone control value. This zone control value more accurately reflects environmental conditions of rooms where the user most desires control of those environmental conditions.

SUMMARY OF THE INVENTION

0007A thermostat system according to the invention includes: a central control device (typically a programmable thermostat with a processor having: a CPU, real time clock and a memory for storing a control program and data information), multiple rooms comprising a conditioned space, environmental control equipment, and multiple environmental sensors capable of sensing an environmental condition (such as temperature, humidity, or other condition). With exception of those provided within or close to a housing of the central control device, environmental sensors are located remote from the central control device. “Remote” as used herein means effectively remote from the central control device as to a sensed environmental condition. A remote sensor may be located in another room as compared with the central control device. Alternately, a remote sensor may be located some distance away from the central control device in a large room. A communications interface is adapted to establish reception of signals (via wired or wireless connections) between the processor and the environmental sensors.

0008In one embodiment, the sensors are associated with transmission means, which control transmission of sensor signals, and occupancy sensors. Each sensor measures a local environmental condition. Occupancy sensors comprise infrared or other motion sensors, light detection sensors, door opening sensors, and other such sensors that detect the presence of humans in a room of the conditioned space where its associated sensor is located.

0009In one form of the invention, transmission means enables transmission of environmental sensor signals to the central control device only upon input of signals from the occupancy detector. In another form of the invention, transmission means provide continuous transmissions from environmental sensor signals to a central control device, albeit where such signals are associated with indications of occupancy or non-occupancy of a room where the sensor is located sensing occupancy of a room or an area of a large room. Such remote sensor signals are transmitted to the central control device and stored in its memory as a table of data indicating environmental conditions only in occupied rooms. The values of this table are averaged in one of several selected modes to yield a control value. This control value more accurately reflects the desired environmental conditions of the rooms where user's are present. Alternately, all sensor data may be stored at the central control device and associated with indications of occupancy or non-occupancy of a room where the sensor is located and a time of the sensing of the environmental condition and occupancy status of the room.

0010In a second embodiment, remote sensors and occupancy detectors are associated as in the first embodiment. However, this second embodiment comprises transmission means that causes transmission of environmental sensor signals to the central control device with additional signals indicating whether the sensor signal originates from an occupied or non-occupied room. Transmission means may transmit continuously, periodically or upon the occurrence of a sensed event. The occupancy status of the room is determined by the input to the transmission means of the occupancy sensor. These remote sensor signals are transmitted to the central control device and stored in its memory as a table of data indicating environmental conditions of both occupied and un-occupied rooms. The values of this table are averaged in one of several selected modes to yield a control value. This control value more accurately reflects the overall desired environmental conditions of the rooms where user's are present.

0011A user may optionally select from one of several forms of averaging of sensor data to derive a control value. The control program may cause a display screen connected with the CPU to provide a user with a list of averaging options, where by the user can select one of the options through a user interface with touch sensitive buttons or other well known means.

0012Averaging of sensor data may be accomplished by one of several methods. The sensor data table may contain sensor data from sensors located at the central control devices as well as from remote sensors. Simple averaging of sensor data associated with room occupancy occurs when all environmental sensor data are added together and divided by the number of data items in the table.

0013A second form of averaging uses weighting depending on square footage of the room where the sensor is located. Greater weighting is assigned to sensor data associated with occupancy in rooms with greater relative square footage.

0014A third form of averaging uses sensor data from occupied and unoccupied rooms and assigns greater weight to sensor data from occupied rooms.

0015A fourth form of averaging uses historical data to determine rooms most heavily occupied over a pre-determined period (such as a week or month) and averages current sensor data only from those heavily occupied rooms to arrive at a control value regardless of current occupancy status.

0016Current thermostat systems can include mobile remote temperature sensors with wireless transmitters. These mobile temperature sensors send sensed, local temperature signals to a central control device and are usually battery powered and enclosed in a handheld housing. The mobile sensors can include a display of locally sensed temperature. In one form of the invention, mobile sensors detect room occupancy and also have means to detect motion of the device itself relative to its surroundings. Without such means, movement of the mobile sensor by a user would result in a false indication of occupancy to the occupancy sensor. For example, an infra-red motion detector in the mobile sensor would falsely interpret carrying the mobile sensor from one room to another as the presence of a person moving in a room. Instead, transmission means are connected to a device motion sensor. The device motion sensor in one form comprises a circuit that opens, closes or alternates between those states when the mobile sensor is picked up and moved. A set of fixed contacts for the circuit can be arranged so that rolling or sliding metallic pieces in an enclosed cavity break or complete the circuit when the device itself is picked up and carried to another room. The transmission means delays receipt of inputs from the occupancy sensor until the mobile sensor has come to rest and/or after a predetermined period of time. These adaptations allow the mobile sensor to come to rest before setting room occupancy and thereafter transmitting local environmental conditions.

0017It is a feature of some modern thermostat systems to control duct dampers or diverters so that conditioned air from air handlers and fans is directed only to certain rooms of a conditioned space. In the present invention, occupancy sensed in a room creates a signal via the occupancy sensor which is transmitted from a remote device to the central control device. The central control device can act to average temperatures to calculate a control value and at the same time divert substantially all conditioned air only to the occupied rooms.

0018In some situations, environmental conditions in separated but occupied rooms may be quite different. A side of a building with its wall receiving full sun can dramatically heat a room on that side. A room on the opposite side of the building may be quite cool and have a temperature close to a desired setpoint. Simple averaging of local temperatures in those rooms may result in a control value near a desired setpoint for the central control device. A fifth form of averaging would cause the data table values of sensed environmental conditions to be subtracted from the setpoint to calculate a table of differences, some positive and some negative depending on the relationship of a sensor value to the setpoint. Differences beyond the setpoint value at which environmental control equipment is activated (such as the setpoint temperature at which air conditioning equipment is turned on) would be averaged and given greater weight than an average of differences outside of that activation range. For example, temperature sensors might indicate degree Fahrenheit temperatures of 80, 79, 77 and 75. If the setpoint is 78 for air conditioning to be turned on, the differences would be 2, 1, −1 and −3. Simply averaging the sensor values would not result in the overheated rooms being cooled. In one scenario, the positive differences are weighted 70% and the negative differences at 30%. The resulting control value will be sufficient to activate the air conditioning at the cost of overcooling some occupied rooms.

0019It is an object of the invention to average sensed environment conditions only in occupied rooms in order to calculate a control value.

DESCRIPTION OF THE DRAWING

0020<figref idref="DRAWINGS">FIG. 1</figref> is a plan view of a conditioned space with several rooms, a central control device and remote environmental sensors arranged in the rooms.

0021<figref idref="DRAWINGS">FIG. 2</figref> is a block diagram of a central control device and its relationship to environmental control equipment, the conditioned space, and remote sensors.

0022<figref idref="DRAWINGS">FIG. 3</figref> is a block diagram of a remote sensor.

0023<figref idref="DRAWINGS">FIG. 4</figref> is a high level process flow chart describing the operation of the remote sensor in a first embodiment.

0024<figref idref="DRAWINGS">FIG. 5</figref> is a high level process flow chart describing the operation of the remote sensor in a second embodiment.

0025<figref idref="DRAWINGS">FIG. 6</figref> is a high level process flow chart describing the operation of the central control device in the invention thermostat system.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

0026Referring first to <figref idref="DRAWINGS">FIG. 1</figref>, a structure <b>10</b> defines within its walls conditioned space for a thermostat system. Structure <b>10</b> comprises sides <b>11</b> and <b>12</b>, rooms <b>13</b> through <b>18</b>, lighting fixture <b>19</b>, fireplace <b>20</b>, and exemplary doors <b>21</b> and <b>22</b>. The thermostat system includes central control device <b>23</b> and remote sensors <b>23</b>A through <b>23</b>F. Remote sensors <b>23</b>A through <b>23</b>F are located respectively in rooms <b>13</b> through <b>18</b>. Alternately, any of the remote sensors <b>23</b>A through <b>23</b>F may be mobile sensors capable of being moved to any room in structure <b>10</b>.

0027Referring now to <figref idref="DRAWINGS">FIG. 2</figref>, central control device <b>23</b> is shown in a block diagram form with a processor <b>30</b> connected to an environmental temperature sensor S<b>1</b> and an occupancy sensor S<b>2</b> which are disposed with access to conditioned space <b>38</b>. The processor <b>30</b> and the sensors S<b>1</b> and S<b>2</b> may be situated in a common housing (not shown) or separated, all as very well known in the art, so that said sensors have effective access to the room in which the housing for processor <b>30</b> is located.

0028The processor <b>30</b> includes a central processing unit (CPU) <b>31</b> in communication with a memory <b>32</b> which stores data and program information and also, via an input/output unit (I/O unit) <b>34</b>, an optional user interface <b>35</b> and a liquid crystal or other type display (LCD) <b>36</b>. The memory <b>32</b> may include a read-only part which is factory-programmed and a random-access part which stores data subject to change during operation. A settable real time clock <b>33</b> is used to keep time in the central control device to facilitate diverse operations, such as different temperature set points (desired temperatures), during different periods of the day cycle. The thermostat system may be suitably powered by a battery (not shown) and/or from equipment to which is connected. The I/O unit <b>34</b> includes a wired or wireless communications interface <b>41</b> for coordinating communications between the CPU <b>31</b> and one or more remote sensors.

0029Referring now to <figref idref="DRAWINGS">FIG. 3</figref>, remote sensors <b>23</b>A through <b>23</b>F are shown in a block diagram form with a processor <b>50</b> connected to an environmental temperature sensor S<b>3</b>, an occupancy sensor S<b>4</b>, and device motion sensor S<b>5</b> which are disposed with access to conditioned space <b>56</b>. The processor <b>50</b> and the sensors S<b>3</b>, S<b>4</b> and S<b>5</b> may be situated in a common housing (not shown) or separated, all as very well known in the art, so that said sensors have effective access to the room in which the housing for processor <b>50</b> is located.

0030The processor <b>50</b> includes a central processing unit (CPU) <b>51</b> in communication with a memory <b>52</b> which stores data and program information and also, via an input/output unit (I/O unit) <b>54</b>, and a liquid crystal or other type display (LCD) <b>55</b>. The memory <b>52</b> may include a read-only part which is factory-programmed and a random-access part which stores data subject to change during operation. A settable real time clock <b>53</b> is used to keep time in the remote sensor to facilitate diverse operations, such as receiving and transmitting sensor signals. The remote sensor may be suitably powered by a battery (not shown) and/or from power supply integral with structure <b>10</b>. The I/O unit <b>54</b> includes a wired or wireless communications interface <b>59</b> for coordinating communications between the CPU <b>50</b> and the central control device.

0031Thus, in the usual manner during normal operation, one or more environmental sensors send an electrical signal (e.g., if the sensor S<b>1</b> is a simple thermistor, a resistance value; several types of temperature sensors are widely used) representative of the temperature within its local conditioned space (i.e., the room) which the processor can average to calculate a control value to compare against a previously entered set point to determine if control signals need to be sent to the space conditioning equipment <b>37</b>. For example, if the control value temperature in the conditioned space is found to be too low when operation is in the heating mode, the processor <b>31</b> signals the space conditioning equipment <b>38</b> circulate, through ducts <b>39</b>/<b>40</b>, air from/to the conditioned space <b>38</b> which is heated by the space conditioning equipment before return to the conditioned space. This heating phase continues until the calculated control value indicates that the space is now too hot (or approaching too hot) with reference to the set point such that the processor <b>31</b> sends signal(s) to the space conditioning equipment <b>38</b> to cease the heating function, all as very well known in the art. In a cooling mode, a counterpart procedure is followed. Those skilled in the art will understand that the control process typically includes such refinements as anticipation, hysterisis accommodation, fan control, etc. which are acknowledged, but are not directly relevant to the invention.

0032Consider now a first embodiment of the invention referring to <figref idref="DRAWINGS">FIG. 4</figref> as well as <figref idref="DRAWINGS">FIGS. 1</figref>, <b>2</b> and <b>3</b>. Continuously or at one or more predetermined times of day (and/or on-demand if provided for in a sensor control program), occupancy sensor S<b>4</b> determines whether or not its local conditioned space (i.e., a room) is occupied. An occupancy sensor S<b>4</b> may detect motion in the room, the opening of doors <b>21</b> or <b>22</b>, or the turning on of a light fixture <b>19</b>, all of which indicate presence of a human occupant. Processor <b>50</b> comprises a sensor control program that determines whether occupancy sensor S<b>4</b> has detected occupancy in conditioned space <b>56</b>. If occupancy is not detected, the control program optionally waits a predetermined period of time before evaluating input from occupancy sensor S<b>4</b> again or monitors such inputs continuously. If occupancy is detected, the sensor control program inquires to determine if an optional device motion sensor S<b>5</b> has detected movement of the remote sensor from a resting or installation location. If remote sensor movement is detected, the control program optionally waits a predetermined period of time before evaluating input from occupancy sensor S<b>4</b> again. If remote sensor movement is not detected, the control program receives input from environmental sensor S<b>3</b> and transmits its signal (or value) to the central control device <b>23</b> for storage in memory of processor <b>30</b>. Each remote sensor has a known data communications “address” so that a control program of the central control device can determine which remote sensor has transmitted sensor signals or values.

0033Consider now a second embodiment of the invention referring to <figref idref="DRAWINGS">FIG. 5</figref> as well as <figref idref="DRAWINGS">FIGS. 1</figref>, <b>2</b> and <b>3</b>. Continuously or at one or more predetermined times of day (and/or on-demand if provided for in a sensor control program), occupancy sensor S<b>4</b> determines whether or not its local conditioned space (i.e., a room) is occupied. An occupancy sensor S<b>4</b> may detect motion in the room, the opening of doors <b>21</b> or <b>22</b>, or the turning on of a light fixture <b>19</b>, all of which indicate presence of a human occupant. Processor <b>50</b> comprises a sensor control program that determines whether occupancy sensor S<b>4</b> has detected occupancy in conditioned space <b>56</b>. If occupancy is not detected, the sensor control program receives and transmits to the central control device <b>23</b> the signals (or values) from environmental sensor S<b>3</b> with signals indicating that the sensor value is associated with a vacant room. The remote sensor optionally waits a predetermined period of time before evaluating input from occupancy sensor S<b>4</b> again. If occupancy is detected, the sensor control program inquires to determine if an optional device motion sensor S<b>5</b> has detected movement of the remote sensor from a resting or installation location. If remote sensor movement is detected, the control program optionally waits a predetermined period of time before evaluating input from occupancy sensor S<b>4</b> again. If remote sensor movement is not detected, the control program receives input from environmental sensor S<b>3</b> and transmits its signal (or value) to the central control device <b>23</b> for storage in memory of processor <b>30</b> with signals indicating that the sensor value is associated with occupied room. Each remote sensor has a known data communications “address” so that a control program of the central control device can determine which remote sensor has transmitted sensor signals or values.

0034Consider now the first and second embodiments of the invention referring to <figref idref="DRAWINGS">FIG. 6</figref> as well as <figref idref="DRAWINGS">FIGS. 1 through 5</figref>. At the start of a portion of a control program for the central control device <b>23</b>, a user may select one of a set of averaging methods for environmental sensor values stored in memory <b>32</b> to generate a control value to compare with a setpoint for control of equipment <b>38</b>. The control program determines whether or not a user has selected an averaging method. If no averaging method is selected, a default method is used for averaging said environmental sensor values. In one form, the default averaging method adds together all stored sensor values in a data table and divides them by the number of sensor values to arrive at a control value. This form of averaging is referred to herein as the simple form. After an averaging method is selected, previously stored sensor values in the data table are erased and new sensor values are received and stored in the data table. Alternately, previously stored values from the data table are stored with an associated current time and date so that historical occupancy and vacancy may be determined for a particular room of structure <b>10</b>. New values of sensors S<b>1</b> and/or S<b>3</b> are received into a data table in memory <b>32</b> of the central control device to be used for averaging environmental condition values detected in certain rooms of structure <b>10</b>. The averaging calculation results in a control value used in comparison with a previously input setpoint to control operation of equipment <b>38</b> for changing an environmental condition in the conditioned space of structure <b>10</b>.

0035If the central control device is programmable, the control program installed during manufacture will provide for user entry of above user input following conventional instructions similar to those used in user-programming the climate control operation of the thermostat system.

0036As used herein, a second form of averaging uses weighting of values of environmental conditions detected by environmental sensors S<b>1</b> and S<b>3</b> in occupied rooms depending on square footage of the room where the sensor is located. Greater weighting is assigned to sensor data in rooms with greater relative square footage. For an example using the environmental condition of temperature, assume that room <b>13</b> is four times the size of room <b>15</b> in structure <b>10</b>. If rooms <b>13</b> and <b>15</b> are the only ones occupied, the second form of averaging would divide the sensed temperature at central control device <b>23</b> by 0.80 and the sensed temperature at remote sensor <b>23</b>C by 0.20 to arrive at the control value. The denominator in the divisions is arrived at by the pro rata amount of space or square footage of the rooms relative to each other.

0037For the second embodiment of the invention, a third form of averaging uses weighting of values of environmental conditions detected by environmental sensors S<b>1</b> and S<b>3</b> in occupied and unoccupied rooms and assigns greater weight to sensor data from occupied rooms. For an example using the environmental condition of temperature, assume that rooms <b>13</b> through <b>15</b> are occupied and the rest vacant. The third form of averaging would divide the sensed temperatures at central control device <b>23</b> and remote sensors <b>23</b>B and <b>23</b>C by 0.90 and the sensed temperatures at the remained of the remote sensors by 0.10 to arrive at the control value. The denominator in the divisions is arrived at determining the value of conditioning the air in the unoccupied rooms.

0038A fourth form of averaging uses historical data to determine rooms most heavily occupied over a pre-determined period (such as a week or month) and averages current sensor data only from those heavily occupied rooms to arrive at a control value that may or may not depend on current occupancy. Historical data would indicate that, for example, rooms <b>13</b>, <b>15</b> and <b>17</b> are occupied above a predetermined threshold level, i.e., three times per week or fifteen times per week. For those rooms where historical data indicated frequent occupancy and in the second embodiment of the invention, the environmental sensor data used to determine a control value would be those environmental conditions from occupied rooms and those environmental conditions from rooms where there is frequent occupancy regardless of current occupancy status. This form of averaging anticipates actual occupancy of a room. However, if a mobile environmental sensor it moved from one room to another and such motion is detected as above, historical environmental data for the moved sensor will be erased for the purposes of averaging in this embodiment of the invention. Environmental sensor data must begin anew with respect to room occupancy for a moved environmental sensor.

0039While the principles of the invention have now been made clear in an illustrative embodiment, there will be immediately obvious to those skilled in the art many modifications of structure, arrangements, proportions, the elements, materials, and components, used in the practice of the invention which are particularly adapted for specific environments and operating requirements without departing from those principles.