Abstract:
A sensor surrogate ( 120 ) for causing a heating, ventilating, and air conditioning (HVAC) system ( 110 ) to maintain a desired room temperature, contains a temperature sensor ( 122 ) for determining an actual room temperature and logic embodied on at least one non-transitory computer readable medium ( 130 ). The logic ( 130 ) is configured to perform the steps of: calculating a current low temperature that is lower than a pre-programmed HVAC system temperature and providing the HVAC system with a first signal that represents the calculated current low temperature, if the desired temperature is above the pre-programmed HVAC system temperature; and calculating a current high temperature that is above the pre-programmed HVAC system temperature and providing the HVAC system ( 110 ) with a second signal that represents the calculated current high temperature, if the desired room temperature is below the pre-programmed HVAC system temperature.

Description:
TECHNICAL FIELD 
       [0001]    The present invention is directed generally to control systems for heating, ventilating, and air conditioning (HVAC) systems. More particularly, various inventive methods and apparatus disclosed herein relate to providing supervisory control of an HVAC system without requiring a change to the HVAC system. 
       BACKGROUND 
       [0002]    HVAC systems provide much needed climate control in buildings. To reduce the cost and energy usage of heating, cooling, and ventilating a space in commercial buildings, it is sometime useful to add supervisory control to an existing HVAC system. The supervisory control may be used, for example, to cause the HVAC system to use more energy efficient setpoints at certain times of day or when the space is unoccupied. The supervisory control may also be used to sequence the activation of multiple HVAC units in applications where there are multiple units and it is useful to limit peak electrical loads. Among other things, supervisory controls may also be used to test the HVAC equipment by forcing it into heating, cooling, or ventilation modes, while measuring the airflow or temperature of the air entering the space. 
         [0003]    In many cases the existing HVAC system utilizes a simple temperature sensor to determine the temperature of the space. There are several common types of temperature sensors used including, but not limited to, devices whose: resistance varies with temperature, regardless of voltage and current; voltage varies with temperature, independent of current; and, current varies with temperature, independent of voltage. 
         [0004]    In many applications existing HVAC systems do not provide an interface to communicate with a supervisory control system, so the existing HVAC system has to be replaced and/or reprogrammed in order to gain the benefits of supervisory control. Unfortunately, modification of a controller of the HVAC system to add such supervisory control requires a certain skill level, knowledge of building specifics, and/or knowledge of the particular HVAC system. Such skill level and knowledge comes at a significant financial cost. 
         [0005]    Thus, there is a need in the art to provide a way to provide supervisory control of an HVAC system without requiring physical change to the HVAC control system or replacement of a current HVAC control system. 
       SUMMARY 
       [0006]    Embodiments of the present invention provide a system and method for providing supervisory control of an HVAC system. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system contains at least one sensor surrogate and at least one controller. The sensor surrogate contains a temperature sensor for determining an actual room temperature and logic embodied on at least one non-transitory computer readable medium. The logic is configured to function in a first mode or in a second mode, wherein the first mode is characterized by the logic being configured to perform the steps of: if the desired temperature is above a pre-programmed HVAC system temperature, calculating a current low temperature that is lower than the pre-programmed HVAC system temperature and providing the HVAC system with a first signal that represents the calculated current low temperature; and if the desired temperature is below the pre-programmed HVAC system temperature, calculating a current high temperature that is above the pre-programmed HVAC system temperature and providing the HVAC system with a second signal that represents the calculated current high temperature. The second mode is characterized by the logic being configured to perform the step of providing a third signal that represents the actual room temperature. The system also contains a controller for instructing the at least one sensor to run in either the first mode or the second mode. 
         [0007]    The present invention also provides a sensor surrogate for causing an HVAC system to maintain a desired room temperature. The sensor surrogate contains a temperature sensor for determining an actual room temperature and logic embodied on at least one non-transitory computer readable medium. The logic is configured to perform the steps of: if the desired room temperature is above a pre-programmed HVAC system temperature, calculating a current low temperature that is lower than the pre-programmed HVAC system temperature and providing the HVAC system with a first signal that represents the calculated current low temperature; and if the desired room temperature is below the pre-programmed HVAC system temperature, calculating a current high temperature that is above the pre-programmed HVAC system temperature and providing the HVAC system with a second signal that represents the calculated current high temperature. 
         [0008]    The method for providing supervisory control of an HVAC system, comprises the steps of: determining an actual room temperature; determining if a desired room temperature is above a pre-programmed HVAC system temperature; if the desired room temperature is above the pre-programmed HVAC system temperature, calculating a current low temperature that is lower than the pre-programmed HVAC system temperature and providing the HVAC system with a first signal that represents the calculated current low temperature; and if the desired room temperature is below the pre-programmed HVAC system temperature, calculating a current high temperature that is above the pre-programmed HVAC system temperature and providing the HVAC system with a second signal that represents the calculated current high temperature. 
         [0009]    The term “network” as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (e.g. for device control, data storage, data exchange, etc.) between any two or more devices and/or among multiple devices coupled to the network. As should be readily appreciated, various implementations of networks suitable for interconnecting multiple devices may include any of a variety of network topologies and employ any of a variety of communication protocols. Additionally, in various networks according to the present disclosure, any one connection between two devices may represent a dedicated connection between the two systems, or alternatively a non-dedicated connection. In addition to carrying information intended for the two devices, such a non-dedicated connection may carry information not necessarily intended for either of the two devices (e.g., an open network connection). Furthermore, it should be readily appreciated that various networks of devices as discussed herein may employ one or more wireless, wire/cable, and/or fiber optic links to facilitate information transport throughout the network. 
         [0010]    It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
           [0012]      FIG. 1  is a schematic diagram illustrating a general network in which the present system and method for providing supervisory control of the HVAC system may be provided. 
           [0013]      FIG. 2  is a block diagram illustrating an example of the control device of  FIG. 1 , wherein the control device is a general purpose computer. 
           [0014]      FIG. 3A  is a block diagram illustrating a resistance sensor surrogate. 
           [0015]      FIG. 3B  is a block diagram illustrating a voltage sensor surrogate. 
           [0016]      FIG. 3C  is a block diagram illustrating a current sensor surrogate. 
           [0017]      FIG. 4  is a block diagram providing an example of a surrogate module. 
           [0018]      FIG. 5  is a flow chart providing a detailed illustration of a process performed by the surrogate module of  FIG. 4  for creating a customized signal. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The present system and method provides for supervisory control of a previously installed HVAC system with minimal financial and labor cost, as well as without requiring modification of a controller of the HVAC system, without requiring reprogramming of the HVAC system, and without requiring replacement of the HVAC system. 
         [0020]    The present invention introduces a sensor surrogate that replaces the temperature sensor of a room. The sensor surrogate stimulates the HVAC system into performing a desired behavior. Specifically, the sensor surrogate provides supervisory control of the HVAC system by adding logic for acting upon a detected actual temperature of the room and providing to the HVAC system a signal that causes the HVAC system to adjust or maintain temperature. 
         [0021]      FIG. 1  is a schematic diagram illustrating a general network  100  in which the present system and method for providing supervisory control of the HVAC system may be provided. As shown by  FIG. 1 , the network  100  contains an HVAC system  110 , a sensor surrogate  120 , and a control device  150 . It should be noted that although  FIG. 1  illustrates a network  100  having a single HVAC system  110 , a single sensor surrogate  120 , and a single control device  150 , the network  100  may instead have multiple HVAC systems  110 , multiple sensor surrogates  120 , and/or multiple control devices  150 . 
         [0022]    The HVAC system  110  may be any known HVAC system for supplying a room with air at a selected temperature and humidity. Of course, the HVAC system  110  may instead provide only temperature maintenance or only humidity maintenance. In addition, the HVAC system  110  may be a single packaged unit with integral control or a collection of equipment that has an external controller. Since one having ordinary skill in the art would know components of an HVAC system and how an HVAC system functions, further description of an HVAC system  110  is not provided herein. It should be noted that while the present description is provided with regard to a room, the present invention is not limited to monitoring and modifying room temperature and/or humidity. Instead, the room may be any space or area requiring monitoring and/or modification in temperature and/or humidity. 
         [0023]    The sensor surrogate  120  is connected to the HVAC system  110  and simulates the actions of a room temperature sensor. There may be one or more sensor surrogates  120  within the network  100 . As an example, there may be one sensor surrogate  120  placed in each room of a building for assisting with regulation of temperature within respective rooms. It should be noted that sensor surrogates  120  are described in further detail with regard to the description of  FIG. 3  provided hereinafter. 
         [0024]    The control device  150  communicates with the sensor surrogate  120 , either through wired or wireless communication, providing a desired temperature to the sensor surrogate  120 . For instance, a programmer of the control device  150  may specify different temperatures for different sensor surrogates  120  within the network  100 . Such different temperatures may be for different periods of time as well, such as, but not limited to, per hour, per day, or per week. The control device  150  may be any device capable of allowing a user to program a temperature for each sensor surrogate  120  and capable of communicating the selected temperatures to the sensor surrogates  120 . As an example, the control device  150  may be a general purpose computer or any device having at least a memory and a processor. 
         [0025]      FIG. 2  is a block diagram illustrating an example of the control device  150  of  FIG. 1 , wherein the control device  150  is a general purpose computer. Generally, in terms of hardware architecture, as shown in  FIG. 2 , the control device  150  includes a processor  152 , memory  154 , and one or more input and/or output (I/O) devices  156  (or peripherals) that are communicatively coupled via a local interface  158 . The local interface  158  can be, for example but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface  158  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communications. Further, the local interface  158  may include address, control, and/or data connections to enable appropriate communications among the aforementioned components. 
         [0026]    The processor  152  is a hardware device for executing software  162 , particularly that stored in memory  154 . The processor  152  can be any custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the control device  150 , a semiconductor based microprocessor (in the form of a microchip or chip set), a macroprocessor, or generally any device for executing software instructions provided by the software  162 . 
         [0027]    The memory  154  can include any one or combination of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)) and nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, DVD, etc.). Moreover, the memory  154  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  154  can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processor  152 . 
         [0028]    The software  162  in the memory  154  may include one or more separate programs, each of which contains an ordered listing of executable instructions for implementing logical functions. In the example of  FIG. 2 , the software  162  in the memory  154  of the control device  150  provides capability for assigning temperatures to sensor surrogates  120  ( FIG. 1 ), in accordance with the present invention. As an example, the software  162  may define a graphical user interface (GUI) and associated functionality for allowing a user to designate specific sensor surrogates  120  and assign temperatures for each sensor surrogate  120 . 
         [0029]    A suitable operating system (O/S)  160  may also be provided within the memory  154 . As is known by those having ordinary skill in the art, the operating system  160  essentially controls the execution of other computer programs of the control device  150 , and provides scheduling, input-output control, file and data management, memory management, and communication control and related services. 
         [0030]    The I/O devices  156  may include input devices, for example but not limited to, a keyboard, mouse, scanner, microphone, etc. Furthermore, the I/O devices  156  may also include output devices, for example but not limited to, a printer, display, etc. Finally, the I/O devices  156  may further include devices that communicate both as inputs and outputs, for instance but not limited to, a modulator/demodulator (modem; for accessing another device, system, or network), a radio frequency (RF) or other transceiver, a telephonic interface, a bridge, a router, etc. 
         [0031]    When the control device  150  is in operation, the processor  152  is configured to execute software  162  stored within the memory  154 , to communicate data to and from the memory  154 , and to generally control operations of the control device  150  pursuant to the software  162 . The software  162  and O/S  160 , in whole or in part, but typically the latter, are read by the processor  152 , perhaps buffered within the processor  152 , and then executed. 
         [0032]    In an alternative embodiment, where the control device  150  is implemented in hardware, the control device  150  can be implemented with any or a combination of the following technologies, which are each well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA), etc. 
         [0033]    It should be noted that in accordance with an alternative embodiment of the invention, the network  100  may instead exclude use of a control device  150 . In such an embodiment, control features for the sensor surrogate  120  are instead provided by the sensor surrogate  120  itself. This alternative embodiment is described in further detail with regard to  FIG. 3 . 
         [0034]      FIGS. 3A ,  3 B, and  3 C (together referred to as  FIG. 3 ) are block diagrams further illustrating three examples of the sensor surrogate  120  of  FIG. 1 . Of course, one having ordinary skill in the art would appreciate that additional examples of the sensor surrogate  120  may be provided in accordance with the present description, based on the type of temperature sensor replaced by the sensor surrogate  120 . 
         [0035]    The present description provides for three exemplary embodiments of the present system and method. The first and second embodiments require knowledge of the temperature that the HVAC system  110  is pre-programmed to maintain, while the third embodiment of the sensor surrogate  120  does not require knowledge of the HVAC system  110  pre-programmed temperature. 
         [0036]      FIG. 3A  is a block diagram illustrating a resistance sensor surrogate  120 A, in accordance with the first exemplary embodiment of the invention. The resistance sensor surrogate  120 A replaces a temperature sensor in a room, where the temperature sensor being replaced has a resistance output vary with room temperature change. The resistance sensor surrogate  120 A contains a temperature sensor  122  for determining a temperature of a room in which the resistance sensor surrogate  120 A is located. The temperature sensor  122  provides a detected temperature to a surrogate module  130  located within the resistance sensor surrogate  120 A. The surrogate module  130  provides the functionality performed by the resistance sensor surrogate  120 A as is described in further detail hereinbelow with regard to  FIG. 5 . 
         [0037]    The surrogate module  130  may contain logic similar to a computer. An example of a surrogate module  130  is provided by the block diagram of  FIG. 4 . Referring to  FIG. 4 , the surrogate module  130  contains a memory  132  having software  134  therein, a processor  136 , a storage device  138 , and a local interface  140 . Input and/or output (I/O) devices  139  (or peripherals) may be connected to the surrogate module  130 , such as, for example, the temperature sensor  122 , which provides detected temperatures to the surrogate module  130 . 
         [0038]    In the example of  FIG. 4 , the software  134  in the memory  132  provides for either forwarding of a signal representing current room temperature or creating of a customized signal representing a modification to current room temperature, in accordance with the present invention. A detailed description of a process for creating the customized signal is provided by the flowchart of  FIG. 5 . 
         [0039]    Returning to  FIG. 3A , the resistance sensor surrogate  120 A also contains a network interface  124  for allowing communication between the surrogate module  130  and the control device  150  ( FIG. 2 ). A digitally controlled voltage source  126  may be located within the resistance sensor surrogate  120 A for receiving the signal from the surrogate module  130  and converting the signal from a digital signal to an analog signal. The analog signal from the digitally controlled voltage source  126  is received by a voltage controlled resistance source  128  for converting the analog signal into a resistance for outputting to the HVAC system  110 . 
         [0040]      FIG. 3B  is a block diagram illustrating a voltage sensor surrogate  120 B, in accordance with the first exemplary embodiment of the invention. The voltage sensor surrogate  120 B replaces a temperature sensor in a room, where the temperature sensor being replaced has a voltage output vary with room temperature change. The voltage sensor surrogate  120 B contains logic that is similar to the resistance sensor surrogate  120 A, wherein such similar logic is designated by the same numbers as such logic in  FIG. 3A . 
         [0041]    The voltage sensor surrogate  120 B contains a temperature sensor  122  for determining a temperature of a room in which the voltage sensor surrogate  120 B is located. The temperature sensor  122  provides a detected temperature to a surrogate module  130  located within the voltage sensor surrogate  120 B. The surrogate module  130  provides the functionality performed by the voltage sensor surrogate  120 B as is described in further detail hereinbelow with regard to  FIG. 5 . The surrogate module  130  may contain logic similar to a computer, an example which was provided by  FIG. 4 . 
         [0042]    The voltage sensor surrogate  120 B also contains a network interface  124  for allowing communication between the surrogate module  130  and the control device  150  ( FIG. 2 ). A digitally controlled voltage source  126  may be located within the voltage sensor surrogate  120 B for receiving the signal from the surrogate module  130  and converting the digital signal to an analog signal for outputting to the HVAC system  110 . 
         [0043]      FIG. 3C  is a block diagram illustrating a current sensor surrogate  120 C, in accordance with the first exemplary embodiment of the invention. The current sensor surrogate  120 C replaces a temperature sensor in a room, where the temperature sensor being replaced has a current output vary with room temperature change. The current sensor surrogate  120 C contains logic that is similar to the resistance sensor surrogate  120 A, wherein such similar logic is designated by the same numbers as such logic in  FIG. 3A . 
         [0044]    The current sensor surrogate  120 C contains a temperature sensor  122  for determining a temperature of a room in which the current sensor surrogate  120 C is located. The temperature sensor  122  provides a detected temperature to a surrogate module  130  located within the current sensor surrogate  120 C. The surrogate module  130  provides the functionality performed by the current sensor surrogate  120 C as is described in further detail hereinbelow with regard to  FIG. 5 . The surrogate module  130  may contain logic similar to a computer, an example which was provided by  FIG. 4 . 
         [0045]    The current sensor surrogate  120 C also contains a network interface  124  for allowing communication between the surrogate module  130  and the control device  150  ( FIG. 2 ). A digitally controlled voltage source  126  may be located within the current sensor surrogate  120 C for receiving the signal from the surrogate module  130  and converting the signal from a digital signal to an analog signal. The analog signal is received by a voltage controlled current source  129 , which converts the analog signal into a current for outputting to the HVAC system  110 . 
         [0046]    As shown by  FIGS. 3A ,  3 B, and  3 C, each sensor surrogate  120  also contains a power source  127 . The power source  127  may be one or more of many different categories of power sources. As an example, the power source  127  may be an internal power source, such as a battery power source. In addition, the power source  127  may be a remote source of power that provides power to the sensor surrogate  120  upon connection or communication with the power source  127 . Such a remote source of power may be power provided by an HVAC system interface or a power supply from a building. In addition, the power source  127  may scavenge power from the environment, such as receiving power from light, or another energy source. 
         [0047]    It should be noted that in accordance with the alternative embodiment of the invention in which the network does not contain a control device  150 , the sensor surrogate  120  may instead contain input and/or output devices. An input device provided on the sensor surrogate  120 , such as, for example, but not limited to, a key pad, would allow a user to program the sensor surrogate  120  with a desired temperature. In addition, an output device, such as, for example, but not limited to, a display, would allow a user to view the desired temperature entered. 
         [0048]      FIG. 5  is a flow chart  200  providing a detailed illustration of a process performed by the surrogate module  130  for creating the customized signal referred to in the description of  FIGS. 3A ,  3 B, and  3 C, in accordance with the first exemplary embodiment of the invention. It should be noted that any process descriptions or blocks in flow charts should be understood as representing modules, segments, portions of code, or steps that include one or more instructions for implementing specific logical functions in the process, and alternative implementations are included within the scope of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention. 
         [0049]    As shown by block  202 , the surrogate module  130  receives an HVAC system pre-programmed temperature, an actual room temperature, and a desired room temperature. In accordance with the first exemplary embodiment of the invention, the HVAC system pre-programmed temperature may be stored within the storage device  138  of the surrogate module  130 , while the desired room temperature may be received from the control device  150 . It should be noted that in accordance with an alternative embodiment of the invention, where the network  100  does not include a control device  150 , the desired room temperature may instead be programmed directly into the sensor surrogate  120  via, for example, touch entry buttons, or any other method of entering the desired temperature. 
         [0050]    As shown by block  204 , the surrogate module  130  determines if the desired temperature is higher, lower, or the same as the pre-programmed HVAC system temperature. If the desired room temperature is higher than the pre-programmed HVAC system temperature, the surrogate module  130  creates a signal representing an actual temperature that is lower than the pre-programmed HVAC system temperature (block  206 ). It should be noted that through the sensor surrogate  120  this signal is provided to the HVAC system  110 , causing the HVAC system  110  to function as if the actual temperature were below the pre-programmed HVAC system temperature. This process is continued until the actual temperature in the room is at or above the desired temperature (block  208 ). 
         [0051]    When the actual temperature of the room is the same as the desired temperature, the surrogate module  130  creates a signal representing an actual temperature that is the same as the pre-programmed HVAC system temperature. In addition, when the actual temperature of the room is above the desired temperature, the surrogate module  130  creates a signal representing an actual temperature that is above the pre-programmed HVAC system temperature. 
         [0052]    If the desired temperature is the same as the pre-programmed HVAC system temperature, the surrogate module  130  creates a single representing an actual temperature that is the same as the pre-programmed HVAC system temperature (block  210 ). Through the sensor surrogate  120  this signal is provided to the HVAC system  110 , causing the HVAC system  110  to function as if the actual temperature were the same as the pre-programmed HVAC system temperature. 
         [0053]    If the desired temperature is lower than the pre-programmed HVAC system temperature, the surrogate module  130  creates a signal representing an actual temperature that is higher than the pre-programmed HVAC system temperature (block  212 ). Through the sensor surrogate  120  this signal is provided to the HVAC system  110 , causing the HVAC system  110  to function as if the actual temperature were above the pre-programmed HVAC system temperature. This process is continued until the actual temperature in the room is at or below the desired temperature (block  214 ). 
         [0054]    When the actual temperature of the room is the same as the desired temperature, the surrogate module  130  creates a signal representing an actual temperature that is the same as the pre-programmed HVAC system temperature. In addition, when the actual temperature of the room is below the desired temperature, the surrogate module  130  creates a signal representing an actual temperature that is below the pre-programmed HVAC system temperature. 
         [0055]    In accordance with the second exemplary embodiment of the invention, the surrogate module  130  determines the difference in temperature between the desired temperature and the pre-defined HVAC system temperature. This difference in temperature is the amount higher or lower that the surrogate module  130  uses in creating a signal representing an actual temperature that is higher or lower than the pre-programmed HVAC signal temperature. As an example, if the desired temperature is lower than the pre-programmed HVAC system temperature, the surrogate module  130  determines the difference in temperature between the desired temperature and the pre-programmed HVAC system temperature. The surrogate module  130  then creates a signal representing an actual temperature that is higher than the pre-programmed HVAC system temperature by the determined difference. Through the sensor surrogate  120  this signal is provided to the HVAC system  110 , causing the HVAC system  110  to function as if the actual temperature were above the pre-programmed HVAC system temperature. 
         [0056]    In accordance with the third exemplary embodiment of the invention, the HVAC system temperature is learned by the surrogate sensor  120 . Specifically, there may be circumstances in which the pre-programmed HVAC system temperature is not known. In such instances, the temperature sensor  122  and surrogate module  130  of the surrogate sensor  120  may work together to learn the temperature maintained within the room in which the surrogate sensor  120  is located. Such learning may take place over any time period, such as, but not limited to, a week or a month. 
         [0057]    During the learning period, the surrogate module  130  receives temperature readings from the temperature sensor  122  and stores the same within the storage device  138  of the surrogate module  130 . After monitoring temperatures for the learning period, the surrogate module  130  uses the learned temperatures as the pre-programmed HVAC system temperatures. 
         [0058]    The following describes examples of modes of use in which the sensor surrogate  120  may be provided, namely, a night setback mode, a non-occupied setback mode, an equipment sequence management mode, and a demand response mode. 
         [0059]    Night Setback Mode 
         [0060]    One way of reducing energy use is to change the space temperature setpoint (desired temperature) during night hours. To accomplish this, the control device  150  instructs the sensor surrogates  120  to continuously provide an output that is offset from the actual temperature by the amount and direction of a desired setback, wherein the setback is the difference between the desired temperature and the pre-programmed HVAC system temperature. As previously mentioned, the HVAC system  110  uses the sensor surrogate  120  outputs to determine heating and cooling requirements so the result is a change in the actual room temperature with no change in the pre-programmed HVAC system temperature. For example, if the goal is to raise the setpoint on a summer evening from 72 degrees to 85 degrees, each sensor surrogate  120  is instructed to maintain its output at the actual room temperature minus 13 degrees. So, when the room temperature is 80 degrees, the HVAC system  110  will read the sensor surrogate  120  and interpret the result to mean that the room is only 67 degrees, and therefore will not activate the cooling. 
         [0061]    Non-Occupied Setback Mode 
         [0062]    Another way of reducing energy use is to change the room temperature setpoint (desired temperature) during times when the room is not occupied. To accomplish this, the control device  150  is provided with information regarding the occupied status of the room in which temperature is being monitored. This can be accomplished through occupancy sensors connected to the control device  150 . Information regarding occupancy sensors can be communicated from other devices connected to occupancy sensors or the control device  150  can receive information about schedule occupancy from some other applications. When the room is not occupied, or scheduled to be non-occupied, the control device  150  instructs the sensor surrogates  120  to continuously provide an output that is offset from the actual room temperature by the amount and direction of the desired setback, wherein the setback is the difference between the desired temperature and the pre-programmed HVAC system temperature. 
         [0063]    The HVAC system  110  uses the sensor surrogate outputs to determine the heating and cooling requirements so the result is a change in the actual room temperature with no change in the pre-defined HVAC system temperature. For example, if the goal is to lower the setpoint (desired temperature) from 68 degrees to 58 degrees on a winter afternoon when no classes are scheduled in a school room, each sensor surrogate  120  is instructed to maintain its output at the actual room temperature plus 10 degrees. So, when the room temperature is 60 degrees, the HVAC system  110  will read the sensor surrogate  120  and interpret the result to mean that the room is at 70 degrees and therefore will not activate the heating. 
         [0064]    Equipment Sequence Management 
         [0065]    To avoid energy utilization peaks it may be useful to sequence portions of the HVAC system  110  from one setpoint (desired temperature) to another such as when a building is going from non-occupied to occupied in the morning. The present system and method can accomplish this by instructing the sensor surrogates  120  to change from setback mode to normal mode in a timed sequence rather than all at once, effectively accomplishing the desired sequencing for the HVAC system  110 . 
         [0066]    Demand Response 
         [0067]    Another supervisory control function is to reduce energy utilization in response to a “demand response event” declared by the utility (or other grid related entity). This invention enables demand response functionality as long as the control device  150  has a means to determine the initiation and conclusion of a demand-response event. This can be accomplished by a direct communication link between the control device  150  and the utility, a user input to the control device  150  or a communication from some other device that has access to the demand response initiation and conclusion information. When the control device  150  is informed of the initiation of a demand response event it instructs the sensor surrogates to enter the setback mode with a temperature offset value consistent with the degree of energy saving desired. When the control device  150  is informed of the conclusion of a demand response event it instructs the sensor surrogates to enter the normal mode. 
         [0068]    It should be noted that for purposes of explanation, the abovementioned description refers to target temperatures, however, as is known by those having ordinary skill in the art, actual target temperatures are typically implemented as represented by ranges to provide a hysteresis. 
         [0069]    While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. 
         [0070]    All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
         [0071]    The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
         [0072]    The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
         [0073]    As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. 
         [0074]    As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
         [0075]    It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited. 
         [0076]    Reference numerals appearing in the claims between parentheses, if any, are provided merely for convenience and should not be construed as limiting in any way. 
         [0077]    In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively.