Patent Publication Number: US-2020300491-A1

Title: Controlling an hvac system in association with a demand-response event

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/805,312, filed Nov. 7, 2017, which is incorporated here by reference. U.S. application Ser. No. 15/805,312 is a continuation of U.S. application Ser. No. 13/866,635, filed Apr. 19, 2013, which is incorporated here by reference. U.S. application Ser. No. 13/866,635 is a continuation-in-part of U.S. application Ser. No. 13/842,213, filed Mar. 15, 2013, which is incorporated here by reference. 
    
    
     FIELD 
     This patent specification relates to systems, apparatus, methods, and related computer program products for controlling an HVAC system during a demand-response event. More particularly, this patent specification relates to techniques for intelligently selecting and/or optimizing a control trajectory of an HVAC system during a demand-response event. 
     BACKGROUND 
     Utility companies face ongoing challenges with consistently satisfying the demand for electricity. Facilities for generating electricity are typically well-suited for supplying constant amounts of electricity. However, consumers&#39; demand for electricity is often quite the opposite in that the aggregate electricity demand varies significantly over the course of the delay. The daily variance results in one or more ‘peak’ demand times or periods in which demand on the utility company is greatest, and ‘non-peak’ demand times or periods in which demand on the utility company is reduced. 
     The variance in demand over the course of a day may be impacted by a number of factors such as weather and living patterns. For example, during the summertime, demand generally tends to increase as the outside temperature increases to levels considered uncomfortable as consumers increase their usage of high consumption appliances such as air conditioning systems. Demand also generally tends to vary based on work habits, where demand peaks when people leave for work and again when people return from work. During some points in the year, such as during extremely hot days, demand may reach extreme peaks. 
     Utility companies have a variety of options for dealing with the variable demand for energy. They may, for example, increase their ability to satisfy higher peak demands by building additional power plants. However, the costs of doing so are often prohibitive and building such plants is often inefficient as the added capacity is used for only short durations throughout the year. They may buy additional capacity from other utility company&#39;s or energy providers, but doing so is also costly as such company&#39;s may charge a premium and the energy transfer from those other companies is often less efficient. Instead of increasing supply, utility companies may also address peak demands by reducing the demand via load shedding. 
     Load shedding is a technique in which the utility company reduces the amount of energy demanded by its consumers during a period of peak demand. A variety of load shedding techniques are in use today, most of which are based on the utility company directly controlling the cooling systems of its consumers. During such peak demand periods the utility company controls the cooling systems to reduce their energy demand. Such events, which most often take place on very hot days in the mid-to-late afternoon and have a duration in the general range of two to six hours, are referenced in the literature by a variety of different names such as load shedding events, load shifting events, and demand response events. The goal of the utility company in carrying out such events is not necessarily to reduce the total amount of energy consumed over the whole day, but rather to reduce the peak demand during that particular two-to-six hour interval, i.e., during the load shedding interval or demand-response interval. Typically, the end result is that the energy that would have been consumed during the load shedding interval is instead consumed in the hours subsequent to the load shedding interval, as the cooling systems of the participating homes work to regain their cooler normal setpoint temperature. Such control, of course, often creates an inconvenience to the consumers who sign up to participate in such a ‘demand response program’ as their cooling system may not cool their residence as expected. However, in return for this inconvenience the consumer is often granted certain benefits, such as more favorable rates for energy consumed outside of the peak demand period. 
     One common load shedding technique, often referred to as direct load control, involves the periodic on-and-off cycling of power to the cooling system of each participating customer under the direct control of the utility during the load shedding period. In such a method, a remotely controllable switch is installed on the cooling system of each customer and is operable to disconnect power to the cooling system under the direct control of the utility company. The power to the cooling system may then be directly controlled by the utility company such that it is turned off for regular, fixed time intervals during a peak demand period. Consumers may express some degree of animosity towards such a technique, however, as direct load control results in a lack of control by the consumer of their cooling system, and often results in inside temperatures that are found to be uncomfortable by the consumer. Deficiencies in the communication link between the utility company and the switch can worsen the problem, with lost commands from the utility company to the switch to reconnect power to the cooling system resulting in the cooling system undesirably remaining in a disconnected state. Such problems have resulted in some consumers attempting to obviate the control on their cooling system while still attaining the benefits of participating in the demand response program by bypassing the remotely controlled switch. As a result, while such “cheaters” may acquire their desired individual cooling system control, the effectiveness of the overall demand response program can be undermined. 
     Another known load shedding technique involves remote control of the setpoint temperature of the thermostat of each participating customer by the utility, wherein the utility sends a common setback value to the thermostats of the participating customers. During the load shedding period, the participating thermostats will control the indoor temperature to a temperature setpoint value that is higher than the normally scheduled temperature setpoint value by the setback amount. This control by the utility company will typically result in an ambient temperature that is less comfortable than what the consumers would have otherwise experienced, but provides the benefit of both energy and cost savings. While providing the potential for increased comfort and acceptance over direct on/off cycling of the power to the cooling system by the utility, this technique can have disadvantages including lack of control by the consumer and the utility company&#39;s ability to set the setback value to any value the utility company deems suitable. Moreover, the use of a single setback value for all consumers fails to recognize differences in perceptions in comfort, differences in thermal characteristics of residences, differences in cooling capacities of the cooling systems, and other differences among the base of participating customers. 
     U.S. Patent Publication No. 2012/0053745 to Howard Ng discusses a system and method for establishing load control during a load shedding event. Specifically, Ng discusses a technique that allows a customer or utility to control a maximum temperature rise under a direct load control program. The customer may set a comfort range on their thermostat that indicates a range of temperatures from a desired temperature that the customer is comfortable with. During a load shedding event, in a hot weather example, a switch on a space conditioning load is activated so that the space conditioning load undergoes direct load control (i.e., fixed-width duty cycling). The space conditioning load undergoes direct load control until the indoor temperature exceeds the upper value of the comfort range, at which point control will be transferred from direct load control to temperature setback control. One or more issues arise in relation to each of the above-described load shedding methods that is at least partially addressed by one or more of the embodiments described herein. By way of example, although the above described methods of direct load control, temperature setback control, and direct load control followed by temperature setback control will generally result in some amount of reduced energy use during the load shedding event across the base of participating customers, such “one-size-fits-all” approaches to the customer base can result in substantial missed opportunities for more effective load shifting and reduced customer inconvenience. By way of example and not by way of limitation, such issues and/or missed opportunities can arise with respect to one or more of: predicting with greater certainty the impact of a particular load shedding strategy for certain groups or subgroups of participating customers; increasing the tolerability and acceptance of load shedding programs such that more customers will be willing to participate; optimizing the load shedding strategy for particular groups or subgroups of customers in a manner that (i) reduces the amount of customer discomfort per unit of shifted energy demand, and/or (ii) increases the amount of shifted energy demand per “unit” of customer discomfort for those groups or subgroups; more readily identifying the groups or subgroups of customers who would be the best candidates for participation in any particular load shedding event; and more readily assessing the effectiveness of preceding load shifting event strategies for particular groups or subgroups of customers such that future load shifting events are better optimized. Other issues arise as would be apparent to one skilled in the art upon reading the present disclosure. 
     BRIEF SUMMARY 
     Various methods for carrying out demand response (DR) events are disclosed. According to one embodiment, a method for carrying out a DR event via an intelligent, network-connected thermostat associated with a structure, includes a variety of operations. Such operations include identifying a DR event that defines a DR event period, and determining an optimized control trajectory of a heating, ventilation, and air conditioning (HVAC) system to be in effect during the DR event period that minimizes a cost function. The cost function may be a combination of a variety of factors, such as a first factor representative of a total energy consumption during the DR event period, a second factor representative of a metric of occupant discomfort, and a third factor representative of deviations of a rate of energy consumption over the DR event period. The operations may further include controlling the HVAC system in accordance with the determined optimized control trajectory. 
     In some embodiments, the disclosed methods may further include operations such as determining a setpoint temperature profile over the DR event period. Such a determination may include a variety of sub-operations, such as calculating a setpoint temperature profile over the DR event period based on an expected indoor temperature trajectory, and identifying peaks and troughs of the calculated setpoint temperature profile. In some embodiments, methods may also include causing setpoint temperatures defined by the setpoint temperature profile to be displayed to a user of the HVAC system. 
     In some embodiments, determining an optimized control trajectory may include a variety of operations. For example, such a determination may include generating a plurality of candidate parameter sets, each parameter set characterizing an associated candidate setpoint schedule for the DR event. Such a determination may also include identifying an optimal one of the plurality of candidate parameter set, the optimal parameter set being optimal in that it minimizes the cost function when the associated optimal setpoint schedule is applied as an input to a predictive model-based simulation of the HVAC system. 
     A variety of thermostats are also disclosed. According to some embodiments, an intelligent network-connected thermostat for controlling an operation of an HVAC system in a smart home environment is disclosed. The thermostat may include a variety of components. For example, the thermostat may include HVAC control circuitry operable to actuate one or more elements of the HVAC system, and one or more sensors for measuring characteristics of the smart home environment. The thermostat may also include a processor coupled to the HVAC control circuitry and the one or more sensors, which may be operable to cause the thermostat to perform a variety of operations. Such operations may include, for example, identifying a DR event that defines a DR event period, and determining an optimized control trajectory of an HVAC system to be in effect during the DR event period that minimizes a cost function. The cost function may be a combination of factors, such as a first factor representative of a total energy consumption during the DR event period, a second factor representative of a metric of occupant discomfort, and a third factor representative of deviations of a rate of energy consumption over the DR event period. The operations may also include controlling the HVAC system in accordance with the determined optimized control trajectory. 
     In some embodiments, the processor may be further operable to cause the thermostat to perform additional operations. Such operations may include determining whether the HVAC system should be controlled in accordance with a different control trajectory, and upon determining that the HVAC system should be controlled in accordance with a different control trajectory: identifying a subsequent control trajectory, and controlling the HVAC system in accordance with the subsequent control trajectory. 
     Such operations may also include monitoring an indoor temperature of the structure, comparing the monitored indoor temperature of the structure to a predicted indoor temperature of the structure, and performing a variety of operations upon determining that the monitored indoor temperature is different from the predicted indoor temperature of the structure by at least a certain amount. Such operations may include, for example, determining a default control trajectory, and controlling the HVAC system in accordance with the default control trajectory. 
     Such operations may also include monitoring a state of the HVAC system, comparing the monitored state of the HVAC system to a predicted state of the HVAC system, and performing a variety of operations upon determining that the monitored indoor temperature is different from the predicted indoor temperature of the structure by at least a certain amount. Such operations may include, for example, determining a newly optimized control trajectory that minimizes the cost function, and controlling the HVAC system in accordance with the newly optimized control trajectory. 
     Computer-readable storage mediums are also disclosed. According to some embodiments, a tangible non-transitory computer-readable storage medium including instructions that, when executed by a computer processor, cause the computer processor to perform operations is disclosed. Such operations may include identifying a DR event that defines a DR event period, and determining an optimized control trajectory of a heating, ventilation, and air conditioning (HVAC) system to be in effect during the DR event period that minimizes a cost function. The cost function may include, for example, a first factor representative of a total energy consumption during the DR event period, a second factor representative of a metric of occupant discomfort, and a third factor representative of deviations of a rate of energy consumption over the DR event period. The operations may also include controlling the HVAC system in accordance with the determined optimized control trajectory. 
     In some embodiments, the instructions also cause the computer processor to perform additional operations. Such additional operations may include determining an original control trajectory of the HVAC system, comparing the optimized control trajectory to the original control trajectory, identifying similarities between the optimized control trajectory and the original control trajectory based on the comparison, and for portions of the optimized control trajectory that are similar to the original control trajectory, causing temperature setpoints defined by the original control trajectory to be displayed to a user of the HVAC system. 
     For a more complete understanding of the nature and advantages of embodiments of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. Other aspects, objects and advantages of the invention will be apparent from the drawings and detailed description that follows. However, the scope of the invention will be fully apparent from the recitations of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a system for implementing demand-response programs and event management according to an embodiment. 
         FIG. 2  illustrates an example of a smart home environment within which a portion of the system for implementing demand-response programs and event management may be implemented according to an embodiment. 
         FIG. 3A  illustrates an example of general device components which can be included in an intelligent, network-connected device according to an embodiment. 
         FIG. 3B  illustrates an intelligent, network-connected device having a replaceable module and a docking station according to an embodiment. 
         FIG. 3C  illustrates connection ports and wire insertion sensing circuitry of an intelligent, network-connected device according to an embodiment. 
         FIG. 4  illustrates a network-level view of an extensible devices and services platform with which a smart home environment and systems for implementing demand-response programs and event management can be integrated according to an embodiment. 
         FIG. 5  illustrates an abstracted functional view of the extensible devices and services platform of  FIG. 4 . 
         FIG. 6  is a block diagram of a special-purpose computer system according to an embodiment. 
         FIG. 7  illustrates a process for controlling an HVAC system during a demand-response event according to an embodiment. 
         FIG. 8  illustrates a process for determining an optimized control trajectory according to an embodiment. 
         FIG. 9A  illustrates a schedule of original setpoint temperatures that are scheduled setpoint temperatures defined prior to determining an optimized control trajectory according to an embodiment. 
         FIG. 9B  illustrates a schedule of candidate setpoint temperatures characterized by a parameter set according to an embodiment. 
         FIG. 9C  illustrates a relationship between the first parameter, the second parameter, and a linear sequence of temperature setpoints according to an embodiment. 
         FIG. 9D  illustrates a candidate duty cycle schedule that corresponds to the schedule of candidate setpoint temperatures according to an embodiment. 
         FIG. 10A  illustrates a predicted HVAC duty cycle resulting from implementation of an optimal setpoint schedule according to an embodiment. 
         FIG. 10B  illustrates a predicted HVAC duty cycle resulting from implementation of an original setpoint schedule according to an embodiment. 
         FIG. 11A  illustrates an expected indoor temperature profile resulting from implementation of the optimal schedule according to an embodiment. 
         FIG. 11B  illustrates effective setpoint temperatures relative to the expected indoor temperature profile according to an embodiment. 
         FIGS. 12A and 12B  illustrate a simplified graphical user interface (GUI) that may be presented to an energy consumer according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention generally relate to techniques for controlling an HVAC system during a demand-response event. The entities in a system for controlling an HVAC system during a demand-response event typically include a utility provider that provides electrical or other forms of energy from a power source (e.g., an electrical generator) to individuals&#39; homes or businesses. The individuals typically pay for the amount of energy they consume on a periodic, e.g., monthly, basis. In many embodiments an energy management system is disposed between the utility provider and the individuals. The energy management system operates to intelligently and effectively shift energy consumption of the individuals from one particular time period to other time periods. Such energy shifting is usually performed so as to shift energy consumption from a high energy cost period to a low energy cost period. In the case of DR events, energy is shifted from the DR event period to time periods outside of the DR event period. In some cases, such energy shifting may be motivated by an effort to reduce peak loads on the power grid. In other cases, such energy shifting may be motivated by a utility company&#39;s desire to sell energy supply to another utility company during a particular (e.g., high cost) period rather than to that utility company&#39;s own customers. 
     In either case, in many embodiments the end user (i.e., energy consumer) may be provided with an unprecedented level of control as to how their energy consumption devices (e.g., their HVAC system) are controlled during a DR event period. The energy consumer may select minimum disturbances to occupant discomfort which may result in minimal reductions in energy consumption, or may select maximum reductions in energy consumption which may result in greater disturbances to occupant discomfort, or may select something in between. Such a choice may be made prior to the DR event beginning, or during the DR event period, and in some cases may be modified during the DR event. Based on the user&#39;s choice, the most suitable HVAC control trajectory may be generated to attain such user defined objectives. Further, in many embodiments, the most suitable HVAC control trajectory may optimize a variety of HVAC control characteristics, such as the duration of a pre-cooling period, an amount of temperature setback applicable throughout the DR event period, and a maximum duty cycle of the HVAC. The independent and combined control of such HVAC control characteristics is further described in commonly assigned U.S. Ser. No. 13/842,213 (Ref. No. NES0253-US), filed Mar. 15, 2013, the entire contents of which are incorporate by reference herein in their entirety for all purposes, where embodiments described herein include techniques for determining the optimum selection of such HVAC control characteristics based on a plethora of data including but not limited to user preferences of reductions in energy consumption vs. comfort. 
     The energy management system according to many embodiments includes an intelligent, network-connected thermostat located at an individual&#39;s home(s) or business(es). Such a thermostat can acquire various information about the residence, such as a thermal retention characteristic of the residence, a capacity of an HVAC associated with the residence to cool or heat the residence, a likelihood of the residence being occupied (via occupancy sensors that, over time, can build an occupancy probability profile), a forecasted weather, a real-time weather, a real-time occupancy, etc. Moreover, the thermostat can be programmed by its users or may learn, over time, the preferences and habits of its users to set scheduled temperature setpoints. In exemplary embodiments, a population of such network-connected thermostats associated with a respective population of individual homes and businesses is configured to communicate with one or more central servers managed by one or more cloud service providers. Each network-connected thermostat is associated with one or more accounts managed by the cloud service provider(s), and data is sent back and forth as needed between each network-connected thermostat and the central server(s) for providing a variety of advantageous functionalities such as facilitating remote control, reporting weather data, reporting HVAC control data and status information, and providing the centralized and/or partially centralized control and data communications useful for carrying out the DR-related, time-of-use (TOU)-related, and/or real-time pricing functionalities described herein. 
     It is to be appreciated that although some embodiments herein may be particularly suitable and advantageous for commercial scenarios in which (i) the cloud service provider(s) associated with the population of network-connected thermostats is/are also the provider(s) of the described energy management system, (ii) the provider(s) of the energy management system are separate and distinct business entities from the utilities themselves, and (iii) the energy management system is provided as a value-added service to the utilities, the scope of the present description is in no way limited to such scenarios. In other applicable scenarios, for example, all of the elements can be provided by the utility. In other applicable scenarios, some of the elements can be provided by the utility while other elements can be provided by a governmental entity or by miscellaneous combinations of disparate cooperating businesses or consortia. Prior to a DR event, based on a wealth of information the energy management system possesses regarding the residences it is managing, the energy management system can effectively predict how much energy a residence is likely to consume over an given period, such as over a DR event. Moreover, given the wealth of information regarding the residences, the energy management system may also generate variations to the residence&#39;s original thermostat setpoints that can be implemented during the DR event period. The variations can be made so that that the residence consumes less energy over the DR event period. Further yet, because of this wealth of information the energy management system has regarding the residences, the energy management system may also accurately predict the amount of energy likely to be reduced over the DR event period or, in other words, shifted from the DR event period to one or more time periods outside (e.g., shouldering) the DR event period. 
     The described provisions for such energy consumption prediction and management bring about many advantages as described further herein. For example, not only do they allow the energy management system to effectively manage the energy consumption of a number of connected residences, but they also allow the energy management system to intelligently select a subset of residences from a large pool for participation in DR programs or events. The physical characteristics of residences, geographical characteristics of residences, and habitual tendencies of occupants of those residents vary widely across regions, and thus the potential energy savings/shifting also varies widely. The energy management system disclosed herein may intelligently choose the participants in an energy savings program to maximize efficiency and minimize costs. Various energy management systems are further described in commonly assigned U.S. Ser. No. 13/842,213, supra. 
     As the energy management system disclosed herein provides advantageous insight into energy-related characteristics of various residences on both individual and aggregate levels, the energy management system may also provide portals so that other interested parties, such as utility companies, may similarly have access to such information. As it is generally in the interests of the utility company to reduce energy consumption over a particular time period, the utility company similarly has interests in accessing such energy-related characteristics of the various residences individually and in the aggregate so as to more efficiently and effectively generate and manage DR events. Accordingly, in some embodiments, a utility portal may be provided that enables the utility provider access to consumer-level energy-related information at a variety of levels of detail and complexity, for facilitating both economically smart and environmentally responsible decision making on resource planning and utilization. Various utility portals are further described in commonly assigned and concurrently filed U.S. Ser. No. 13/866,199, titled “Utility Portals For Managing Demand-Response Events”, the entire contents of which are incorporate by reference herein in their entirety for all purposes, and U.S. Ser. No. 13/842,213, supra. 
     It should also be appreciated that while many embodiments described herein refer to an energy management system including an intelligent, network-connected thermostat that is operable to reduce (during a certain time period) or otherwise shift (from one time period to another time period) energy consumption during a period identified as a “demand-response event period”, similar techniques may also be applied during a “supply-response event period”, where a supply-response event period is indicative of a period of excess energy supply (in contrast to insufficient supply) during which it is desired to increase energy consumption (in contrast to decrease energy consumption). During such an event period, instead of optimizing control trajectories to minimize energy consumption, the opposite may be implemented whereby control trajectories are optimized to maximize energy consumption. In some embodiments, excess energy supply may include energy supplied by an energy consumer by one or more energy generating elements, such as solar panels, wind turbines, gas-powered electric generators, or other source(s) of electrical power. In situations where energy is supplied by the energy consumer (e.g., during a sunny period), such a period may be considered a “supply-response event period”. 
     The specifics of these and other embodiments are further disclosed herein, and a further understanding of which can be appreciated with reference to the figures. Turning now then to the Figures,  FIG. 1  depicts a system  100  for managing demand-response programs and events according to an embodiment. System  100  includes a plurality of electrical power generators  110 A- 110 N, a utility provider computing system  120 , an energy management system  130 , a communication network  140 , a plurality of energy consumer residences  150 A- 150 N, and a power distribution network  160 . 
     Electrical power generators  110 A- 110 N are operable to generate electricity or other type of energy (e.g., gas) using one or more of a variety of techniques known in the art. For example, electrical power generators  110 A- 110 N may include hydroelectric systems, nuclear power plants, fossil-fuel based power plants, solar plants, wind plants, gas processing plants, etc. The amount of electricity that may be generated at any given time may limited to some maximum energy supplied that is determined by the generators  110 A- 110 N. Further, the electrical power generators  110 A- 110 N may be owned and managed by a utility provider implementing the utility provider computing system  120 , or may be owned and/or managed by one or more third party entities that contract with the utility provider to provide source energy to customers of the utility provider. 
     Utility provider computing system  120  is a computing system operable to communicate with one or more of the electrical power generators  110 A- 110 N, the energy management system  130 , and in some embodiments electronic systems in one or more of the residences  150 A- 150 N. The utility provider associated with the utility provider company system  120  typically manages the distribution of electricity from the electrical power generators  110 A- 110 N to energy consumers at the residences  150 A- 150 N. This management includes ensuring the electricity is successfully communicated from the power generators  110 A- 110 N to the residences  150 A- 150 N, monitoring the amount of energy consumption at each of the residences  150 A- 150 N, and collecting fees from occupants of the residences  150 A- 150 N in accordance with the their respective monitored amount of energy consumption. The utility provider computing system  120  may perform one or more of the operations described herein, and may include a variety of computer processors, storage elements, communications mechanisms, etc. as further described herein and as necessary to facilitate the described operations. 
     Energy management system  130  is a computing system operable to intelligently and efficiently manage the energy consumption at one or more of the residences  150 A- 150 N while optionally providing reporting and control mechanisms to the utility provider computing system  120 . The energy management system  130  may be operable to engage in real-time two-way communications with electronic devices associated with the residences  150 A- 150 N via the network  140 , as well as in engage in real-time two-way communications with the utility provider computing system  120 . In one particular embodiment, the energy management system  130  may be operable to reduce the aggregate amount of energy consumed at the residences  150 A- 150 N so that the aggregate energy demand does not exceed the maximum energy supply limits of the power generators  110 A- 110 N. Such reductions may be achieved during any suitable time period through the day. For example, such reductions may be achieved during a demand-response (DR) event communicated by the utility provider computing system  120 . The energy management system  130  may perform one or more of the operations described herein, and may include a variety of computer processors, storage elements, communications mechanisms, etc. as further described herein and as necessary to facilitate the described operations. 
     Network  140  is any suitable network for enabling communications between various entities, such as between one or more components of the energy management system  130  and one or more electronic devices associated with one or more of the residences  150 A- 150 N. Such a network may include, for example, a local area network, a wide-area network, a virtual private network, the Internet, an intranet, an extranet, a public switched telephone network, an infrared network, a wireless network, a wireless data network, a cellular network, or any other such wired or wireless network(s) or combination(s) thereof. The network  140  may, furthermore, incorporate any suitable network topology. Network  140  may utilize any suitable protocol, and communication over the network  140  may be enabled by wired or wireless connections, and combinations thereof. 
     Residences  150 A- 150 N are a variety of structures or enclosures that are associated with energy consumption. The structures may span a variety of structure types, such as private residences, houses, apartments, condominiums, schools, commercial properties, single or multi-level office buildings, and/or manufacturing facilities. A number of examples described herein refer to the structure as being a private residence in the form of a house, but embodiments are not so limited as one skilled in the art would understand that the techniques described herein could equally be applicable to other types of structures. It is to be appreciated that, while some embodiments may be particularly advantageous for residential living scenarios, the scope of the present teachings is not so limited and may equally be advantageous for business environments, school environments, government building environments, sports or entertainment arenas, and so forth. Thus, while many of the descriptions below are set forth in residential living context, it is to be appreciated that this is for purposes of clarity of description and not by way of limitation. 
     The residences  150 A- 150 N typically include one or more energy consumption devices, which could be electrical energy consumption devices such as televisions, microwaves, home audio equipment, heating/cooling systems, laundry machines, dishwashers, etc. Similarly, energy consumption devices could include one or more other types of energy consumption devices such as gas consumption devices. For example, the residences  150 A- 150 N may include a natural gas (air/water/etc.) heater, stove, fireplace, etc. The residences  150 A- 150 N in many embodiments include one or more control devices that control energy consumption by one or more of the aforementioned energy consumption devices. For example, they may include an intelligent, network connected thermostat that is operable to control the thermal environment of the residence. The thermostats may be considered to be part of the energy management system  130  in that much of the processing subsequently described herein may be performed by computing systems at the energy management system  130  or by the thermostats themselves. Alternatively, the thermostats may be considered to be separate from the energy management system  130  due to their remote geographical location with respect to other components of the energy management system  130 . In either case, electronic devices associated with the residences  150 A- 150 N may perform one or more of the operations described herein, and may include a variety of computer processors, storage elements, communications mechanisms, etc. as further described herein and as necessary to facilitate the described operations. While most embodiments are described in the context of situations where it is desired to reduce the temperature inside of the structure (e.g., during a hot summer), similar principles apply (just applied in the opposite) in situations where it is desired to increase the temperature inside of the structure (e.g., during a cold winter). For some embodiments, some or all of the intelligent, network-connected thermostats may be the same as or similar in functionality to the NEST LEARNING THERMOSTAT® available from Nest Labs, Inc. of Palo Alto , Calif. 
     Power distribution network  160  is any suitable network for transferring energy from one or more of the electrical power generators  110 A- 110 N to one or more of the residences  150 A- 150 N. In an electrical distribution network, power distribution network  160  may include a variety of power lines, substations, pole-mounted transformers, and the like as known in art the for carrying electricity from the electrical power generators  110 A- 110 N to the residences  150 A- 150 N. In a gas distribution network, power distribution network  160  may include a variety of compressor stations, storage elements, pipes, and the like for transporting natural or other types of energy producing gas from the power generators  110 A- 110 N (in this embodiment, gas wells and/or processing plants) to the residences  150 A- 150 N. 
     System  100  in certain embodiments is a distributed system for managing demand-response programs and events utilizing several computer systems and components that are interconnected via communication links using one or more computer networks or direct connections. However, it will be appreciated by those skilled in the art that such a system could operate equally well in a system having fewer or a greater number of components than are illustrated in  FIG. 1 . Thus, the depiction of system  100  in  FIG. 1  should be taken as being illustrative in nature, and not as limiting the scope of the present teachings. 
       FIG. 2  illustrates an example of a smart home environment  200  within which one or more of the devices, methods, systems, services, and/or computer program products described further herein can be applicable. The depicted smart home environment includes a structure  250 , which can include, e.g., a house, office building, garage, or mobile home. In some embodiments, the structure  250  may correspond to one of structures  150 A- 150 N described with reference to  FIG. 1 . In addition to the structure  250 , the smart home environment  200  also includes a network  262  and remote server  264  which, in one embodiment, respectively correspond to network  140  and energy management system  130  ( FIG. 1 ). While the structure  250  as depicted includes a variety of components and devices as further described herein, a number of components and devices, such as pool heater  214 , irrigation system  216 , and access device  266  may also be associated with (e.g., powered at) the structure  250  without being physically attached or disposed within or on the structure  250 . 
     The smart home environment  200  includes a plurality of rooms  252  separated at least partly from each other via walls  254 . The walls  254  can include interior walls or exterior walls. Each room can further include a floor  256  and a ceiling  258 . Devices can be mounted on, integrated with and/or supported by a wall  254 , floor  256  or ceiling  258 . The various devices that may be incorporated within the smart home environment  200  include intelligent, multi-sensing, network-connected devices that can integrate seamlessly with each other and/or with cloud-based server systems to provide any of a variety of useful smart home objectives. An intelligent, multi-sensing, network-connected thermostat  202  can detect ambient climate characteristics (e.g., temperature and/or humidity) and control a heating, ventilation and air-conditioning (HVAC) system  203 . It should be recognized that while control of an HVAC system is described herein, similar principles can equally be applied to controlling other temperature/humidity control systems, such as a heating system, an air conditioning system, a humidity control system, or any combination thereof. One or more intelligent, network-connected, multi-sensing hazard detection units  204  can detect the presence of a hazardous substance and/or a hazardous condition in the home environment (e.g., smoke, fire, or carbon monoxide). One or more intelligent, multi-sensing, network-connected entryway interface devices  206 , which can be termed a “smart doorbell”, can detect a person&#39;s approach to or departure from a location, control audible functionality, announce a person&#39;s approach or departure via audio or visual means, or control settings on a security system (e.g., to activate or deactivate the security system). 
     In some embodiments, the smart home may include at least one energy consumption meter  218  such as a smart meter. The energy consumption meter  218  monitors some or all energy (electricity, gas, etc.) consumed by the devices in and around the structure  250 . The energy consumption meter  218  may display the amount of energy consumed over a given period of time on a surface of the meter  218 . The given period may be, e.g., a second, a minute, an hour, a day, a month, a time span less than one second, a time span greater than a month, or a time span between one second and one month. In some embodiments, the energy consumption meter  218  may include communication capabilities (wired or wireless) that enable the meter  218  to communicate various information, e.g., the amount of energy consumed over one or more given periods, the price of energy at any particular time or during any particular period of time, etc. The communication capabilities may also enable the meter to receive various information. For example, the meter may receive instructions for controlling one or more devices in the smart home such as the HVAC system  203 , the price of energy at any particular time or during any particular period of time, etc. To facilitate control of devices in and around the structure  250 , the meter  218  may be wired or wirelessly connected to such devices. 
     Each of a plurality of intelligent, multi-sensing, network-connected wall light switches  208  can detect ambient lighting conditions, detect room-occupancy states and control a power and/or dim state of one or more lights. In some instances, light switches  208  can further or alternatively control a power state or speed of a fan, such as a ceiling fan. Each of a plurality of intelligent, multi-sensing, network-connected wall plug interfaces  210  can detect occupancy of a room or enclosure and control supply of power to one or more wall plugs (e.g., such that power is not supplied to the plug if nobody is at home). The smart home may further include a plurality of intelligent, multi-sensing, network-connected appliances  212 , such as refrigerators, stoves and/or ovens, televisions, washers, dryers, lights (inside and/or outside the structure  250 ), stereos, intercom systems, garage-door openers, floor fans, ceiling fans, whole-house fans, wall air conditioners, pool heaters  214 , irrigation systems  216 , security systems, and so forth. While descriptions of  FIG. 2  can identify specific sensors and functionalities associated with specific devices, it will be appreciated that any of a variety of sensors and functionalities (such as those described throughout the specification) can be integrated into the device. 
     In addition to containing processing and sensing capabilities, each of the devices within the smart home environment  200  can be capable of data communications and information sharing with any other devices within the smart home environment  200 , as well as to any devices outside the smart home environment  240  such as the access device  266  and/or remote server  264 . The devices can send and receive communications via any of a variety of custom or standard wireless protocols (Wi-Fi, ZigBee, 6LoWPAN, IR, IEEE 802.11, IEEE 802.15.4, etc.) and/or any of a variety of custom or standard wired protocols (CAT6 Ethernet, HomePlug, etc.). The wall plug interfaces  210  can serve as wireless or wired repeaters, and/or can function as bridges between (i) devices plugged into AC outlets and communicating using Homeplug or other power line protocol, and (ii) devices that are not plugged into AC outlets. 
     For example, a first device can communicate with a second device via a wireless router  260 . A device can further communicate with remote devices via a connection to a network, such as the network  262 . Through the network  262 , the device can communicate with a central (i.e., remote) server or a cloud-computing system  264 . The remote server or cloud-computing system  264  can be associated with a manufacturer, support entity or service provider associated with the device. In one embodiment, a user may be able to contact customer support using a device itself rather than needing to use other communication means such as a telephone or Internet-connected computer. 
     Devices&#39; network connections can further allow a user to interact with the device even if the user is not proximate to the device. For example, a user can communicate with a device (e.g., thermostat  202 ) using a computer (e.g., a desktop computer, laptop computer, or tablet) or other portable electronic device (e.g., a smartphone)  266 . A webpage or software application can be configured to receive communications from the user and control the device based on the communications and/or to present information about the device&#39;s operation to the user. For example, when the portable electronic device  266  is being used to interact with the thermostat  202 , the user can view a current setpoint temperature for a thermostat and adjust it using the portable electronic device  266 . The user can be in the structure during this remote communication or outside the structure. The communications between the portable electronic device  266  and the thermostat  202  may be routed via the remote server  264  (e.g., when the portable electronic device  266  is remote from structure  250 ) or, in some embodiments, may be routed exclusive of the remote server  264 . 
     The smart home environment  200  also can include a variety of non-communicating legacy appliances  240 , such as old conventional washer/dryers, refrigerators, and the like which can be controlled, albeit coarsely (ON/OFF), by virtue of the wall plug interfaces  210 . The smart home can further include a variety of partially communicating legacy appliances  242 , such as IR-controlled wall air conditioners or other IR-controlled devices, which can be controlled by IR signals provided by the hazard detection units  204  or the light switches  208  or, in some embodiments, by using socket-based communication protocol such as powerline to communicate via a wall plug interface  210 . 
     It should be recognized that some or all of the components located inside and outside of structure  250  may be considered part of energy management system  130  depending on the embodiment. In general, devices or components which facilitate control of other energy consumption devices may be considered to be part of energy management system  130 . For example, thermostat  202  and access device  266  may be part of energy management system  130  while energy consuming components such as HVAC  203 , pool heater  214 , and legacy appliances  240  may be considered external to energy management system  130  as they comprise energy consuming elements that are controllable by the thermostat  202  and access device  266 . In other examples, however, additional or alternative components of smart home environment  200  may be considered part of energy management system  130 , such as hazard detection units  204 , entryway interface devices  206 , light switches  208 , plug interface  210 , etc., as they may provide monitoring (and/or control) functionality for the energy management system  130  to assist the system  130  in making intelligent energy management decisions. In yet other examples, none of the devices of the smart home environment (except for remote server  264 ) may be part of energy management system  130 , but rather one or more of the devices of the smart home environment  200  may be submissive devices that are remotely controlled by energy management system  130  to perform monitoring and/or energy consumption tasks. 
     Smart home  200  in certain embodiments is an environment including a number of client devices and access devices all operable to communicate with one another as well as with devices or systems external to the smart home  200  such as remote server  264 . However, it will be appreciated by those skilled in the art that such an environment could operate equally well having fewer or a greater number of components than are illustrated in  FIG. 2 . One particular example of a smart-home environment including various elements having differing functionality is described in detail in U.S. Provisional Ser. No. 61/704,437, filed Sep. 21, 2012, the entire contents of which are incorporated by reference herein in their entirety for all purposes. Thus, the depiction of the smart home environment  200  in  FIG. 2  should be taken as being illustrative in nature, and not limiting to the scope of the present teachings. 
       FIG. 3A  illustrates an example of general device components which can be included in an intelligent, network-connected device  300  (i.e., “device”). Device  300  may be implemented as one or more of the various devices discussed with reference to  FIG. 2 , such as thermostat  202 , hazard detection unit  204 , entryway interface device  206 , wall light switch  208 , wall plug interface  210 , etc. Much of the following discussion presents the device  300  as being a thermostat  202 , but it should be recognized that embodiments are not so limited. Each of one, more or all devices  300  within a system of devices can include one or more sensors  302 , a user-interface component  304 , a power supply (e.g., including a power connection  306  and/or battery  308 ), a communications component  310 , a modularity unit (e.g., including a docking station  312  and replaceable module  314 ), intelligence components  316 , and tamper detection circuitry  318 . Particular sensors  302 , user-interface components  304 , power-supply configurations, communications components  310 , modularity units, intelligence components  316 , and/or wire tamper detection circuitry  318  can be the same or similar across devices  300  or can vary depending on device type or model. 
     By way of example and not by way of limitation, one or more sensors  302  in a device  300  may be able to, e.g., detect acceleration, temperature, humidity, water, supplied power, proximity, external motion, device motion, sound signals, ultrasound signals, light signals, fire, smoke, carbon monoxide, global-positioning-satellite (GPS) signals, or radio-frequency (RF) or other electromagnetic signals or fields. Thus, for example, sensors  302  can include temperature sensor(s), humidity sensor(s), hazard-related sensor(s) or other environmental sensor(s), accelerometer(s), microphone(s), optical sensor(s) up to and including camera(s) (e.g., charged-coupled-device or video cameras), active or passive radiation sensor(s), GPS receiver(s) or radio-frequency identification detector(s). While  FIG. 3A  illustrates an embodiment with a single sensor, many embodiments will include multiple sensors. In some instances, device  300  includes one or more primary sensors and one or more secondary sensors. The primary sensor(s) can sense data central to the core operation of the device (e.g., sensing a temperature in a thermostat or sensing smoke in a smoke detector). The secondary sensor(s) can sense other types of data (e.g., motion, light or sound), which can be used for energy-efficiency objectives or smart-operation objectives. In some instances, an average user may even be unaware of an existence of a secondary sensor. 
     One or more user-interface components  304  in device  300  may be configured to present information to a user via a visual display (e.g., a thin-film-transistor display or organic light-emitting-diode display) and/or an audio speaker and/or some other communication medium. User-interface component  304  can also include one or more user-input components to receive information from a user, such as a touchscreen, buttons, scroll component (e.g., a movable or virtual ring component), microphone or camera (e.g., to detect gestures). In one embodiment, user-interface component  304  includes a click-and-rotate annular ring component, wherein a user can interact with the component by rotating the ring (e.g., to adjust a setting) and/or by clicking the ring inwards (e.g., to select an adjusted setting or to select an option). In another embodiment, user-input component  304  includes a camera, such that gestures can be detected (e.g., to indicate that a power or alarm state of a device is to be changed). 
     A power-supply component in device  300  may include a power connection  306  and/or local battery  308 . For example, power connection  306  can connect device  300  to a power source such as a line voltage source. In some instances, connection  306  to an AC power source can be used to repeatedly charge a (e.g., rechargeable) local battery  308 , such that battery  308  can later be used to supply power if needed in the event of an AC power disconnection or other power deficiency scenario. 
     A communications component  310  in device  300  can include a component that enables device  300  to communicate with a central server, such as remote server  264 , or a remote device, such as another device  300  described herein or a portable user device. Communications component  310  can allow device  300  to communicate using one or more wired or wireless communication techniques, either simultaneously or sequentially, such as Wi-Fi, ZigBee, 3G/4G wireless, IEEE 802.11, IEEE 802.15.4, 6-LO-PAN, Bluetooth, CAT6 wired Ethernet, HomePlug or other powerline communications method, telephone, or optical fiber, by way of non-limiting examples. Communications component  310  can include one or more wireless cards, Ethernet plugs, or other transceiver connections. In some embodiments, the communications component  310  facilitates communication with a central server to synchronize information between device  300 , the central server, and in some cases additional devices. Techniques for synchronizing data between such devices are further described in the commonly assigned U.S. Ser. No. 13/624,892 (Ref. No. NES0231-US), filed Sep. 22, 2012, the contents of which are incorporated by reference herein in their entirety for all purposes. 
     A modularity unit in device  300  can include a static physical connection, and a replaceable module  314 . Thus, the modularity unit can provide the capability to upgrade replaceable module  314  without completely reinstalling device  300  (e.g., to preserve wiring). The static physical connection can include a docking station  312  (which may also be termed an interface box) that can attach to a building structure. For example, docking station  312  could be mounted to a wall via screws or stuck onto a ceiling via adhesive. Docking station  312  can, in some instances, extend through part of the building structure. For example, docking station  312  can connect to wiring (e.g., to 120V line voltage wires) behind the wall via a hole made through a wall&#39;s sheetrock. Docking station  312  can include circuitry such as power-connection circuitry  306  and/or AC-to-DC powering circuitry and can prevent the user from being exposed to high-voltage wires. Docking station  312  may also or alternatively include control circuitry for actuating (i.e., turning on and off) elements of an HVAC system, such as a heating unit (for heating the building structure), an air-condition unit (for cooling the building structure), and/or a ventilation unit (for circulating air throughout the building structure). In some instances, docking stations  312  are specific to a type or model of device, such that, e.g., a thermostat device includes a different docking station than a smoke detector device. In some instances, docking stations  312  can be shared across multiple types and/or models of devices  300 . 
     Replaceable module  314  of the modularity unit can include some or all sensors  302 , processors, user-interface components  304 , batteries  308 , communications components  310 , intelligence components  316  and so forth of the device. Replaceable module  314  can be configured to attach to (e.g., plug into or connect to) docking station  312 . In some instances, a set of replaceable modules  314  are produced with the capabilities, hardware and/or software, varying across the replaceable modules  314 . Users can therefore easily upgrade or replace their replaceable module  314  without having to replace all device components or to completely reinstall device  300 . For example, a user can begin with an inexpensive device including a first replaceable module with limited intelligence and software capabilities. The user can then easily upgrade the device to include a more capable replaceable module. As another example, if a user has a Model #1 device in their basement, a Model #2 device in their living room, and upgrades their living-room device to include a Model #3 replaceable module, the user can move the Model #2 replaceable module into the basement to connect to the existing docking station. The Model #2 replaceable module may then, e.g., begin an initiation process in order to identify its new location (e.g., by requesting information from a user via a user interface). 
     Intelligence components  316  of the device can support one or more of a variety of different device functionalities. Intelligence components  316  generally include one or more processors configured and programmed to carry out and/or cause to be carried out one or more of the advantageous functionalities described herein. The intelligence components  316  can be implemented in the form of general-purpose processors carrying out computer code stored in local memory (e.g., flash memory, hard drive, random access memory), special-purpose processors or application-specific integrated circuits, combinations thereof, and/or using other types of hardware/firmware/software processing platforms. The intelligence components  316  can furthermore be implemented as localized versions or counterparts of algorithms carried out or governed remotely by central servers or cloud-based systems, such as by virtue of running a Java virtual machine (JVM) that executes instructions provided from a cloud server using Asynchronous Javascript and XML (AJAX) or similar protocols. By way of example, intelligence components  316  can be configured to detect when a location (e.g., a house or room) is occupied, up to and including whether it is occupied by a specific person or is occupied by a specific number and/or set of people (e.g., relative to one or more thresholds). Such detection can occur, e.g., by analyzing microphone signals, detecting user movements (e.g., in front of a device), detecting openings and closings of doors or garage doors, detecting wireless signals, detecting an IP address of a received signal, or detecting operation of one or more devices within a time window. Intelligence components  316  may include image-recognition technology to identify particular occupants or objects. 
     In some instances, intelligence components  316  can be configured to predict desirable settings and/or to implement those settings. For example, based on the presence detection, intelligence components  316  can adjust device settings to, e.g., conserve power when nobody is home or in a particular room or to accord with user preferences (e.g., general at-home preferences or user-specific preferences). As another example, based on the detection of a particular person, animal or object (e.g., a child, pet or lost object), intelligence components  316  can initiate an audio or visual indicator of where the person, animal or object is or can initiate an alarm or security feature if an unrecognized person is detected under certain conditions (e.g., at night or when lights are out). As yet another example, intelligence components  316  can detect hourly, weekly or even seasonal trends in user settings and adjust settings accordingly. For example, intelligence components  316  can detect that a particular device is turned on every week day at 6:30 am, or that a device setting is gradually adjusted from a high setting to lower settings over the last three hours. Intelligence components  316  can then predict that the device is to be turned on every week day at 6:30 am or that the setting should continue to gradually lower its setting over a longer time period. 
     In some instances, devices can interact with each other such that events detected by a first device influence actions of a second device. For example, a first device can detect that a user has pulled into a garage (e.g., by detecting motion in the garage, detecting a change in light in the garage or detecting opening of the garage door). The first device can transmit this information to a second device, such that the second device can, e.g., adjust a home temperature setting, a light setting, a music setting, and/or a security-alarm setting. As another example, a first device can detect a user approaching a front door (e.g., by detecting motion or sudden light-pattern changes). The first device can, e.g., cause a general audio or visual signal to be presented (e.g., such as sounding of a doorbell) or cause a location-specific audio or visual signal to be presented (e.g., to announce the visitor&#39;s presence within a room that a user is occupying). 
     Tamper detection circuitry  318  may be part or separate from intelligence components  316 . Tamper detection circuitry  318  may include software and/or hardware operable to detect tampering of the device  300 . Tampering may include, e.g., a disconnect between the device  300  and the HVAC indicative of a user attempt to obviate HVAC control by the remote server during a DR event, a change in impedance or power consumption by the HVAC indicative of a user attempt to obviate HVAC control by the remote server during a DR event, etc. 
       FIG. 3B  illustrates an intelligent, network-connected device  300  having a replaceable module  314  (e.g., a head unit) and a docking station  312  (e.g., a back plate) for ease of installation, configuration, and upgrading according to some embodiments. As described hereinabove, device  300  may be wall mounted, have a circular shape, and have an outer rotatable ring  320  (that may be, e.g., part of user interface  304 ) for receiving user input. Outer rotatable ring  320  allows the user to make adjustments, such as selecting a new target temperature. For example, by rotating outer ring  320  clockwise, a target setpoint temperature can be increased, and by rotating the outer ring  320  counter-clockwise, the target setpoint temperature can be decreased. Changes to an existing setpoint temperature that reflect a desire for the temperature in the structure to be immediately changed to that setpoint temperature may herein be referred to as changes to an “immediate setpoint temperature” or a “current setpoint temperature”. This is in contrast to setpoint temperatures that may be provided in a hourly, daily, weekly, monthly, or other schedule in which setpoint temperatures may reflect a desire for future temperatures in the structure. Such setpoint temperatures may herein be referred as “scheduled setpoint temperature” or as a “schedule of setpoint temperatures”. 
     Device  300  has a cover  322  that includes a display  324  (that may be, e.g., part of user interface  304 ). Head unit  314  slides onto back plate  312 . Display  324  may display a variety of information depending on, e.g., a current operational state of the device  300 , direct user interaction with the device via ring  320 , sensed presence of the user via, e.g., a proximity sensor  302  (such as a passive infrared motion sensor), remote user interaction with the device via a remote access device, etc. For example, display  324  may display central numerals that are representative of a current setpoint temperature. 
     According to some embodiments the connection of the head unit  314  to back plate  312  can be accomplished using magnets, bayonet, latches and catches, tabs or ribs with matching indentations, or simply friction on mating portions of the head unit  314  and back plate  312 . According to some embodiments, the head unit  314  includes battery  308 , communications component  310 , intelligence components  316 , and a display driver  326  (that may be, e.g., part of user interface  304 ). Battery  308  may be recharged using recharging circuitry (that may be, e.g., part of intelligence components  316  and/or may be included in the back plate  312 ) that uses power from the back plate  312  that is either obtained via power harvesting (also referred to as power stealing and/or power sharing) from the HVAC system control circuit(s) or from a common wire, if available, as described in further detail in commonly assigned co-pending U.S. Ser. Nos. 13/034,674 (Ref. No. NES0006-US) and 13/034,678 (Ref. No. NES0007-US), both filed Feb. 24, 2011, and commonly assigned U.S. Ser. No. 13/267,871 (Ref. No. NES0158-US), filed Oct. 6, 2011, all of which are incorporated by reference herein in their entirety for all purposes. According to some embodiments, battery  308  is a rechargeable single cell lithium-ion, or a lithium-polymer battery. 
     Back plate  312  includes electronics  330  and a temperature sensor  332  (that may be, e.g., one of sensors  302 ) in housing  334 , which are ventilated via vents  336 . Temperature sensor  332  allows the back plate  312  to operate as a fully functional thermostat even when not connected to the head unit  314 . Wire connectors  338  are provided to allow for connection to HVAC system wires, such as connection to wires for actuating components of the HVAC system, wires for receiving power from the HVAC system, etc. Connection terminal  340  is a male or female plug connector that provides electrical connections between the head unit  314  and back plate  312 . Various arrangements for connecting to and controlling an HVAC system are further described in U.S. Ser. Nos. 13/034,674 and 13/034,678, supra. 
     In some embodiments, the back plate electronics  330  includes an MCU processor, and driver circuitry for opening and closing the HVAC control circuits, thereby turning on and turning off the one or more HVAC functions such as heating and cooling. The electronics  330  also includes flash memory which is used to store a series of programmed settings that take effect at different times of the day, such that programmed setpoint (i.e., desired temperature) changes can be carried out even when the head unit  314  is not attached to the back plate  312 . According to some embodiments, the electronics  330  also includes power harvesting circuitry (that may be in addition or alternatively to that provided in head unit  314 ) to obtain power from the HVAC control circuit(s) even when an HVAC common power wire is not available. In various embodiments, tamper detection circuitry  318  ( FIG. 3A ) may also be incorporated in one or more of the head unit  314  and back plate  312  such that tampering may be detected regardless of whether the head unit  314  is coupled to the back plate  312 . 
       FIG. 3C  illustrates a conceptual diagram of the device  300  with particular reference to the wire connectors  338  and tamper detection circuitry  318 . It is to be appreciated that the wire connectors  338  and tamper detection circuitry  318  can, in whole or in part, be separably or inseparably integral with the main body of the device  300  without departing from the scope of the present teachings. Thus, for example, for one embodiment the wire connectors  338  and tamper detection circuitry  318  can be inseparably integral with the main body of the device  300 , with the HVAC wires being inserted directly into the back before placement on the wall as a single monolithic unit. In another embodiment, the wire connectors  338  and tamper detection circuitry  318  can be located in a wall plate unit to which the main body of the thermostat attaches, it being understood that references herein to the insertion of wires into the thermostat encompass embodiments in which the wires are inserted into the wall plate and the main body is attached to the wall plate to form the completed device  300 . 
     As illustrated in  FIG. 3C , each wire connector  338  is associated with a predetermined HVAC signal type. For one embodiment that has been found to provide an optimal balance between simplicity of installation for do-it-yourselfers and a reasonably broad retrofit applicability for a large number of homes, there are eight (8) wire connectors  338  provided, which are dedicated respectively to a selected group of HVAC signal types consisting of heating call power (Rh), heating call (W 1 ), cooling call (Y 1 ), fan call (G), common (C), heat pump (O/B), auxiliary (AUX), and heating call power (Rh). Preferably, the device  300  is of a “jumperless” type according to the commonly assigned U.S. Ser. No. 13/034,674, supra, such that (i) the Rh and Rc connection ports automatically remain shunted together for cases in which there is a single call power wire provided by the HVAC system, one or the other connection port receiving a single call power wire (which might be labeled R, V, Rh, or Rc depending on the particular HVAC installation), and (ii) the Rh and Rc connection ports are automatically electrically segregated for cases in which there are dual call power wires provided by the HVAC system that are inserted. 
     According to one embodiment, tamper detection circuitry  318  includes, for each wire connector  338 , a port sensing circuit  342  that communicates with the back plate electronics  330  over a pair of electrical leads  344 . Although the port sensing circuit  342  can operate in a variety of different ways without departing from the scope of the present teachings, in one embodiment the control port sensing circuit  342  comprises a two-position switch (not shown) coupled to the electrical leads  344 , the two-position switch being closed to short the electrical leads  344  together when no wire has been inserted into the associated wire connector  338 , the two-position switch being mechanically urged into an open position to electrically segregate the electrical leads  344  when a wire is inserted into the associated wire connector  338 . The back plate electronics  330  thereby is able to readily sense when a wire is inserted into the connection port by virtue of the shorted or open state of the electrical leads  344 . One particularly advantageous configuration that implements the combined functionality of the wire connector  338  and the port sensing circuit  342  is described in the commonly assigned U.S. Ser. No. 13/034,666 (Ref. No. NES0035-US), filed Feb. 24, 2011, the contents of which are incorporated by reference in their entirety for all purposes. 
     Device  300  in certain embodiments is an intelligent, network-connected learning thermostat that includes various components such as a head unit, a back plate, a user interface, communications components, intelligent components, etc. However, it will be appreciated by those skilled in the art that devices that perform the various operations described herein could operate equally well with fewer or a greater number of components than are illustrated in  FIGS. 3A through 3C . For example, the device  300  may be formed as a single unit rather than multiple modules, and may include more or fewer components than described with reference to  FIGS. 3A to 3C . For example, the device  300  may be formed as described in U.S. Ser. No. 13/624,878, filed Sep. 21, 2012, and/or as described in U.S. Ser. No. 13/632,148, filed Sep. 30, 2012, both of which are incorporated herein by reference in their entirety for all purposes. Thus, the depiction of device  300  in  FIGS. 3A through 3C  should be taken as being illustrative in nature, and not limiting to the scope of the present teachings. 
       FIG. 4  illustrates a network-level view of an extensible devices and services platform with which the smart home of  FIGS. 1 and/or 2  and/or the device of  FIGS. 3A through 3C  can be integrated. Each of the intelligent, network-connected devices discussed previously with reference to structure  250  can communicate with one or more remote servers or cloud computing systems  264 . The communication can be enabled by establishing connection to the network  262  either directly (for example, using 3G/4G connectivity to a wireless carrier), through a hubbed network (which can be a scheme ranging from a simple wireless router, for example, up to and including an intelligent, dedicated whole-home control node), or through any combination thereof. 
     The remote server or cloud-computing system  264  can collect operation data  402  from the smart home devices. For example, the devices can routinely transmit operation data or can transmit operation data in specific instances (e.g., when requesting customer support). The remote server or cloud-computing architecture  264  can further provide one or more services  404 . The services  404  can include, e.g., software updates, customer support, sensor data collection/logging, remote access, remote or distributed control, or use suggestions (e.g., based on collected operation data  402  to improve performance, reduce utility cost, etc.). Data associated with the services  404  can be stored at the remote server or cloud-computing system  264  and the remote server or cloud-computing system  264  can retrieve and transmit the data at an appropriate time (e.g., at regular intervals, upon receiving request from a user, etc.). 
     One salient feature of the described extensible devices and services platform, as illustrated in  FIG. 4 , is a processing engine  406 , which can be concentrated at a single data processing server  407  (which may be included in or separate from remote server  264 ) or distributed among several different computing entities without limitation. Processing engine  406  can include engines configured to receive data from a set of devices (e.g., via the Internet or a hubbed network), to index the data, to analyze the data and/or to generate statistics based on the analysis or as part of the analysis. The analyzed data can be stored as derived data  408 . Results of the analysis or statistics can thereafter be transmitted back to a device providing ops data used to derive the results, to other devices, to a server providing a webpage to a user of the device, or to other non-device entities. For example, use statistics, use statistics relative to use of other devices, use patterns, and/or statistics summarizing sensor readings can be transmitted. The results or statistics can be provided via the network  262 . In this manner, processing engine  406  can be configured and programmed to derive a variety of useful information from the operational data obtained from the smart home. A single server can include one or more engines. 
     The derived data can be highly beneficial at a variety of different granularities for a variety of useful purposes, ranging from explicit programmed control of the devices on a per-home, per-neighborhood, or per-region basis (for example, demand-response programs for electrical utilities), to the generation of inferential abstractions that can assist on a per-home basis (for example, an inference can be drawn that the homeowner has left for vacation and so security detection equipment can be put on heightened sensitivity), to the generation of statistics and associated inferential abstractions that can be used for government or charitable purposes. For example, the processing engine  406  can generate statistics about device usage across a population of devices and send the statistics to device users, service providers or other entities (e.g., that have requested or may have provided monetary compensation for the statistics). As specific illustrations, statistics can be transmitted to charities  422 , governmental entities  424  (e.g., the Food and Drug Administration or the Environmental Protection Agency), academic institutions  426  (e.g., university researchers), businesses  428  (e.g., providing device warranties or service to related equipment), or utility companies  430 . These entities can use the data to form programs to reduce energy usage, to preemptively service faulty equipment, to prepare for high service demands, to track past service performance, etc., or to perform any of a variety of beneficial functions or tasks now known or hereinafter developed. 
       FIG. 5  illustrates an abstracted functional view of the extensible devices and services platform of  FIG. 4 , with particular reference to the processing engine  406  as well as the devices of the smart home environment, according to an embodiment. Even though the devices situated in the smart home environment have an endless variety of different individual capabilities and limitations, they can all be thought of as sharing common characteristics in that each of them is a data consumer  502  (DC), a data source  504  (DS), a services consumer  506  (SC), and/or a services source  508  (SS). Advantageously, in addition to providing the essential control information needed for the devices to achieve their local and immediate objectives, the extensible devices and services platform can also be configured to harness the large amount of data that is flowing out of these devices. In addition to enhancing or optimizing the actual operation of the devices themselves with respect to their immediate functions, the extensible devices and services platform can also be directed to “repurposing” that data in a variety of automated, extensible, flexible, and/or scalable ways to achieve a variety of useful objectives. These objectives may be predefined or adaptively identified based on, e.g., usage patterns, device efficiency, and/or user input (e.g., requesting specific functionality). 
     For example,  FIG. 5  shows processing engine  406  as including a number of paradigms  510 . Processing engine  406  can include a managed services paradigm  510   a  that monitors and manages primary or secondary device functions. The device functions can include ensuring proper operation of a device given user inputs, estimating that (e.g., and responding to) an intruder is or is attempting to be in a dwelling, detecting a failure of equipment coupled to the device (e.g., a light bulb having burned out), implementing or otherwise responding to energy demand response events, or alerting a user of a current or predicted future event or characteristic. Processing engine  406  can further include an advertising/communication paradigm  510   b  that estimates characteristics (e.g., demographic information), desires and/or products of interest of a user based on device usage. Services, promotions, products or upgrades can then be offered or automatically provided to the user. Processing engine  406  can further include a social paradigm  510   c  that uses information from a social network, provides information to a social network (for example, based on device usage), and/or processes data associated with user and/or device interactions with the social network platform. For example, a user&#39;s status as reported to their trusted contacts on the social network could be updated to indicate when they are home based on light detection, security system inactivation or device usage detectors. As another example, a user may be able to share device-usage statistics with other users. Processing engine  406  can include a challenges/rules/compliance/rewards paradigm  510   d  that informs a user of challenges, rules, compliance regulations and/or rewards and/or that uses operation data to determine whether a challenge has been met, a rule or regulation has been complied with and/or a reward has been earned. The challenges, rules or regulations can relate to efforts to conserve energy, to live safely (e.g., reducing exposure to toxins or carcinogens), to conserve money and/or equipment life, to improve health, etc. 
     Processing engine  406  can integrate or otherwise utilize extrinsic information  516  from extrinsic sources to improve the functioning of one or more processing paradigms. Extrinsic information  516  can be used to interpret operational data received from a device, to determine a characteristic of the environment near the device (e.g., outside a structure that the device is enclosed in), to determine services or products available to the user, to identify a social network or social-network information, to determine contact information of entities (e.g., public-service entities such as an emergency-response team, the police or a hospital) near the device, etc., to identify statistical or environmental conditions, trends or other information associated with a home or neighborhood, and so forth. 
     An extraordinary range and variety of benefits can be brought about by, and fit within the scope of, the described extensible devices and services platform, ranging from the ordinary to the profound. Thus, in one “ordinary” example, each bedroom of the smart home can be provided with a smoke/fire/CO alarm that includes an occupancy sensor, wherein the occupancy sensor is also capable of inferring (e.g., by virtue of motion detection, facial recognition, audible sound patterns, etc.) whether the occupant is asleep or awake. If a serious fire event is sensed, the remote security/monitoring service or fire department is advised of how many occupants there are in each bedroom, and whether those occupants are still asleep (or immobile) or whether they have properly evacuated the bedroom. While this is, of course, a very advantageous capability accommodated by the described extensible devices and services platform, there can be substantially more “profound” examples that can truly illustrate the potential of a larger “intelligence” that can be made available. By way of perhaps a more “profound” example, the same data bedroom occupancy data that is being used for fire safety can also be “repurposed” by the processing engine  406  in the context of a social paradigm of neighborhood child development and education. Thus, for example, the same bedroom occupancy and motion data discussed in the “ordinary” example can be collected and made available for processing (properly anonymized) in which the sleep patterns of schoolchildren in a particular ZIP code can be identified and tracked. Localized variations in the sleeping patterns of the schoolchildren may be identified and correlated, for example, to different nutrition programs in local schools. 
       FIG. 6  is a block diagram of a special-purpose computer system  600  according to an embodiment. For example, one or more of a utility provider computing system  120 , energy management system  130 , elements of smart home environment  200 , remote server  264 , client device  300 , processing engine  406 , data processing server  407 , or other electronic components described herein may be implemented as a special-purpose computer system  600 . The methods and processes described herein may similarly be implemented by tangible, non-transitory computer readable storage mediums and/or computer-program products that direct a computer system to perform the actions of the methods and processes described herein. Each such computer-program product may comprise sets of instructions (e.g., codes) embodied on a computer-readable medium that directs the processor of a computer system to perform corresponding operations. The instructions may be configured to run in sequential order, or in parallel (such as under different processing threads), or in a combination thereof 
     Special-purpose computer system  600  comprises a computer  602 , a monitor  604  coupled to computer  602 , one or more additional user output devices  606  (optional) coupled to computer  602 , one or more user input devices  608  (e.g., keyboard, mouse, track ball, touch screen) coupled to computer  602 , an optional communications interface  610  coupled to computer  602 , and a computer-program product including a tangible computer-readable storage medium  612  in or accessible to computer  602 . Instructions stored on computer-readable storage medium  612  may direct system  600  to perform the methods and processes described herein. Computer  602  may include one or more processors  614  that communicate with a number of peripheral devices via a bus subsystem  616 . These peripheral devices may include user output device(s)  606 , user input device(s)  608 , communications interface  610 , and a storage subsystem, such as random access memory (RAM)  618  and non-volatile storage drive  620  (e.g., disk drive, optical drive, solid state drive), which are forms of tangible computer-readable memory. 
     Computer-readable medium  612  may be loaded into random access memory  618 , stored in non-volatile storage drive  620 , or otherwise accessible to one or more components of computer  602 . Each processor  614  may comprise a microprocessor, such as a microprocessor from Intel® or Advanced Micro Devices, Inc.®, or the like. To support computer-readable medium  612 , the computer  602  runs an operating system that handles the communications between computer-readable medium  612  and the above-noted components, as well as the communications between the above-noted components in support of the computer-readable medium  612 . Exemplary operating systems include Windows® or the like from Microsoft Corporation, Solaris® from Sun Microsystems, LINUX, UNIX, and the like. In many embodiments and as described herein, the computer-program product may be an apparatus (e.g., a hard drive including case, read/write head, etc., a computer disc including case, a memory card including connector, case, etc.) that includes a computer-readable medium (e.g., a disk, a memory chip, etc.). In other embodiments, a computer-program product may comprise the instruction sets, or code modules, themselves, and be embodied on a computer-readable medium. 
     User input devices  608  include all possible types of devices and mechanisms to input information to computer system  602 . These may include a keyboard, a keypad, a mouse, a scanner, a digital drawing pad, a touch screen incorporated into the display, audio input devices such as voice recognition systems, microphones, and other types of input devices. In various embodiments, user input devices  608  are typically embodied as a computer mouse, a trackball, a track pad, a joystick, wireless remote, a drawing tablet, a voice command system. User input devices  608  typically allow a user to select objects, icons, text and the like that appear on the monitor  604  via a command such as a click of a button or the like. User output devices  606  include all possible types of devices and mechanisms to output information from computer  602 . These may include a display (e.g., monitor  604 ), printers, non-visual displays such as audio output devices, etc. 
     Communications interface  610  provides an interface to other communication networks and devices and may serve as an interface to receive data from and transmit data to other systems, WANs and/or the Internet, via a wired or wireless communication network  622 . Embodiments of communications interface  610  typically include an Ethernet card, a modem (telephone, satellite, cable, ISDN), a (asynchronous) digital subscriber line (DSL) unit, a FireWire® interface, a USB® interface, a wireless network adapter, and the like. For example, communications interface  610  may be coupled to a computer network, to a FireWire® bus, or the like. In other embodiments, communications interface  610  may be physically integrated on the motherboard of computer  602 , and/or may be a software program, or the like. 
     RAM  618  and non-volatile storage drive  620  are examples of tangible computer-readable media configured to store data such as computer-program product embodiments of the present invention, including executable computer code, human-readable code, or the like. Other types of tangible computer-readable media include floppy disks, removable hard disks, optical storage media such as CD-ROMs, DVDs, bar codes, semiconductor memories such as flash memories, read-only-memories (ROMs), battery-backed volatile memories, networked storage devices, and the like. RAM  618  and non-volatile storage drive  620  may be configured to store the basic programming and data constructs that provide the functionality of various embodiments of the present invention, as described above. 
     Software instruction sets that provide the functionality of the present invention may be stored in computer-readable medium  612 , RAM  618 , and/or non-volatile storage drive  620 . These instruction sets or code may be executed by the processor(s)  614 . Computer-readable medium  612 , RAM  618 , and/or non-volatile storage drive  620  may also provide a repository to store data and data structures used in accordance with the present invention. RAM  618  and non-volatile storage drive  620  may include a number of memories including a main random access memory (RAM) to store of instructions and data during program execution and a read-only memory (ROM) in which fixed instructions are stored. RAM  618  and non-volatile storage drive  620  may include a file storage subsystem providing persistent (non-volatile) storage of program and/or data files. RAM  618  and non-volatile storage drive  620  may also include removable storage systems, such as removable flash memory. 
     Bus subsystem  616  provides a mechanism to allow the various components and subsystems of computer  602  communicate with each other as intended. Although bus subsystem  616  is shown schematically as a single bus, alternative embodiments of the bus subsystem may utilize multiple busses or communication paths within the computer  602 . 
     For a firmware and/or software implementation, the methodologies may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. Any machine-readable medium tangibly embodying instructions may be used in implementing the methodologies described herein. For example, software codes may be stored in a memory. Memory may be implemented within the processor or external to the processor. As used herein the term “memory” refers to any type of long term, short term, volatile, nonvolatile, or other storage medium and is not to be limited to any particular type of memory or number of memories, or type of media upon which memory is stored. 
     Moreover, as disclosed herein, the term “storage medium” may represent one or more memories for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other machine readable mediums for storing information. The term “machine-readable medium” includes, but is not limited to portable or fixed storage devices, optical storage devices, wireless channels, and/or various other storage mediums capable of storing that contain or carry instruction(s) and/or data. 
       FIG. 7  illustrates a process  700  for controlling an HVAC system during a demand-response event according to an embodiment. To facilitate understanding, the process  700  is described with reference to  FIGS. 1, 2, 8, 9A to 9D, 10A to 10B, and 11A to 11B , although it should be understood that embodiments of the process  700  are not limited to those described with reference to  FIGS. 1, 2, 8, 9A to 9D, 10A to 10B, and 11A to 11B . 
     In operation  702  a DR event having a DR event period is identified. A DR event is a time period over which energy reduction mechanisms are to be actively engaged. The DR event is defined by a DR event profile which includes information identifying a DR event period which defines the time period over which energy reduction mechanisms are to be actively engaged. The time period may be on the order of minutes, tens of minutes, hours, tens of hours, or other suitable time period for which energy shifting is desired. In at least one embodiment, a DR event period may be on the order of a few minutes and referred to as an ‘instantaneous DR event’, which is an event narrowly tailored to an expected peak in aggregate energy demand. In such instances the peak in energy demand may be identified a few minutes (or a few hours) prior to the expected peak time, and in some embodiments the duration of the peak energy demand (i.e., the duration during which expected demand exceeds supply) may last only a few minutes. 
     In some embodiments, a DR event may be part of a DR program. A DR program is a program that attempts to reduce load on the electrical grid supplying the energy consumer residences  150 A- 150 N during certain critical times which are generally times when demand gets close to or is expected to exceed supply. The DR program often allows for participation in the program by the energy consumers to be voluntary, although in some embodiments participation may be mandatory. In exchange for participation, the energy consumers are often rewarded monetary incentives, reward-based incentives, or other types of incentives to garner increased participation, but in some embodiments the energy consumers may not be provided such incentives. A DR program may run for set periods, such as for a certain number of months, days, years, may be seasonal (e.g., implemented in seasons such as summer when energy demand is expected to increase substantially), may be perpetual, and/or may be executed over any suitable period of time. In its efforts to reduce energy consumption over specifically defined periods, a DR program may define one or more DR events. 
     The DR event, in addition to having a time period, may also include other information suitable for effectively managing energy consumption over the DR event period. For example, the DR event may also include information identifying a DR event magnitude which defines a magnitude of the desired energy reduction (either on a per-consumer basis, a group basis, an aggregate basis, or other basis). For another example, the DR event may include information identifying a geographical scope of the DR event, where the geographical scope may describe a region that relates to one or more electrical grids from which load shedding is desired. The region may be defined using any suitable parameters such as state, county, zip code, address, or the like, or may identify one or more particular electrical grids from which such addresses of residences may subsequently be inferred. In some embodiments, the DR program may also identify costs per unit of energy over the course of the DR program, DR events, etc. In other embodiments, consumers may be grouped according to characteristics other than geographical characteristics. For example, consumers may be grouped based on similar (or different) characteristics regarding their structures (e.g., thermal retention), their affluency (e.g., absolute wealth, annual income, etc.), their tendency to participate in DR events and/or programs, the amount of energy shifting likely achieved by their participation in a DR event and/or program, etc. 
     A particular DR event may be identified by a device, such as thermostat  202 , in any one or more of a variety of fashions. For example, information identifying a DR event may be communicated from remote server  264 , or other computing element of energy management system  130  and/or utility provider computing system  120 , to thermostat  202 . For another example, thermostat  202  may generate and/or define a DR event based on sensed information. For example, thermostat  202  may monitor outdoor temperature or otherwise receive information regarding outdoor temperature, and based on the outdoor temperature define a DR event (e.g., thermostat  202  may generate a DR event when the outdoor temperature exceeds some value). For another example, thermostat  202  may monitor grid conditions (e.g., variations or other characteristics in power supplied via power distribution network  160 ), and based on those grid conditions define a DR event. For yet another example, thermostat  202  may be in communication with other thermostats arranged in the same or different structures in a similar geographical area as thermostat  202 , and may receive information indicative of a DR event from those other thermostats. 
     In operation  704  an optimized control trajectory of an HVAC system is determined to be in effect during the DR event period, where the optimized control trajectory minimizes a cost function. The control trajectory indicates how the HVAC system should be controlled over a period of time, such as the DR event period. The control trajectory may include one or more of a variety of tangible control sequences for controlling the HVAC system, such as a schedule of setpoint temperatures, an HVAC duty cycle schedule, etc. Based at least in part on an original control trajectory (e.g., a schedule of setpoint temperatures initially defined by a user to be implemented during the DR event period, and perhaps over a regular periodic interval), a space of possible control trajectories may be searched to find an optimal control trajectory that is optimal in some sense. In many embodiments, the optimal control trajectory is optimal in that it minimizes a cost function. 
     The cost function, in determining a cost of a particular control trajectory, may incorporate one or more of a variety of factors. For example, the cost function may include a factor representative of a total energy consumption during the DR event period. This factor may indicate, for example, the total energy (kW), or a value ($) of the total energy likely to be consumed by the HVAC system during the DR event period in the event the HVAC system is controlled in accordance with the particular control trajectory. In some cases the value of the total energy may be determined based on real-time energy pricing. For example, in time-of-use environments, wherein the price of energy may vary over the course of the day, the factor representative of total energy consumption may indicate a value of the energy consumed over a period of the day (e.g., the DR event period), where the value of the energy consumed is determined based on both the magnitude of energy consumed at a number of time instances over the period and a cost of energy at those time instances. 
     The cost function may additionally or alternatively include a factor representative of a metric of occupant discomfort. This factor may indicate, for example, a level of discomfort likely to be experienced by one or more of the occupants of the structure in the event the HVAC system is controlled in accordance with the particular control trajectory. In some embodiments, such a factor may be indicative of discomfort of any arbitrary occupant of the structure. In other embodiments, the occupant(s) likely to be present during a DR event period may be specifically identified, and the discomfort factor may be specifically tailored to that/those specific individual(s). 
     The cost function may additionally or alternatively include a factor representative of deviations of a rate of energy consumption over the DR event period. During a DR event period, an HVAC system may consume high amounts of energy during a first portion of the event period, and low amounts of energy during a last portion of the event period, or vice versa. In some embodiments, the HVAC system energy consumption may be distributed or otherwise equalized across the DR event period such that the rate of consumption over the DR event period is substantially constant. 
     In a variety of embodiments, the factors used by the cost function may be weighted the same or differently, such that they are all given equal consideration in determining a cost of a particular control trajectory, or one factor may be given more weight than another. The weightings may be determined based on one or more of a variety of information, such as a user input indicative of a user amenability to DR load shifting, occupant characteristics (e.g., age, income, net worth, health, spending habits, energy-management habits, lifestyle, occupancy times as defined, for example, by an occupancy probability profile, etc.), structure characteristics (size, number of rooms/bathrooms/etc., type of windows, type of insulation, type of electronic devices of structure, whether windows and/or doors are open/closed, etc.), or other characteristics indicative of a users&#39; tendency to prefer energy-savings over comfort or vice versa. 
     For example, an occupancy probability profile may be used to determine a likelihood of the structure being occupied during the DR event period, where a greater likelihood results in a greater weighting of likely discomfort. For another example, if a user had refused to participate in a previous DR event, such information may result in a greater weighting of likely discomfort and/or a lower weighting of energy consumption savings. For another example, the factors may be weighted based on the age of occupants, where if the occupants include children or elderly, such information may result in a greater weighting of likely discomfort. For another example, the factors may be weighted based on the health of the occupants, where if occupants recently went to the hospital, such information may result in a greater weighting of likely discomfort. For yet another example, the factors may be weighted based on characteristics of other devices in the structure, or even the structure itself, where if other devices are energy-saving devices (e.g., Energy Star® compliant), or the structure includes energy-saving features (e.g., includes cavity-wall insulation, multipane windows, etc.), such information may correspond to an increased weighting on energy consumption savings. For yet another example, the factors may be weighted based on user interaction with a control trajectory during the DR event period, where if a user modifies the temperature to consume less energy, such information may correspond to an increased weighting on energy consumption savings. 
     Turning briefly to  FIG. 8 ,  FIG. 8  illustrates a process for determining an optimized control trajectory according to an embodiment which, according to some embodiments, may be a process for determining an optimized control trajectory as described with reference to operation  704 . To facilitate understanding, the process  704  is described with reference to  FIGS. 1, 2, 9A to 9D, and 10A to 10B , although it should be understood that embodiments of the process  704  are not limited to those described with reference to  FIGS. 1, 2, 9A to 9D, and 10A to 10B . 
     In operation  704 A, a plurality of candidate parameter sets are generated, where each parameter set characterizes an associated candidate setpoint schedule for a DR event. Each parameter set includes a plurality of parameters each having a parameter value, where the parameters in the set, and their corresponding parameter values, characterize a specific setpoint schedule. For example, turning briefly to  FIG. 9A ,  FIG. 9A  illustrates a schedule of original setpoint temperatures  800  that are scheduled setpoint temperatures defined prior to determining an optimized control trajectory according to an embodiment. The original schedule may have been generated in one or more of a variety of fashions. For example, the schedule may be set by a user of thermostat  202 , and may be input for storage in thermostat  202  via a user interface of thermostat  202 , access device  266 , and/or another computing device of smart home environment  200 . The schedule may be generated by an entity of smart home environment  200 , such as the thermostat  202  itself, by learning the tendencies and preferences of the occupants of the structure associated with the thermostat  202 . The original schedule may be generated by an entity of system  100  other than smart-home environment  200 , such as by remote server  264 , energy management system  130 , or another entity of system  100 , and either pre-programmed in the thermostat  202  prior to installation of the thermostat  202  or communicated to the thermostat  202  post-installation. In some embodiments, the original schedule of setpoint temperatures may be generated based on a combination of one or more of the above. For example, the original schedule may initially be defined by the energy consumer, and subsequently tailored via learning. 
     The schedule of original setpoint temperatures  800  is defined over a period of time (in this example, from before noon until after 7 pm) including a DR event period extending between a DR event period begin time  802  and a DR event period end time  804 . In some embodiments, the DR event period may also include a pre-event period extending between a pre-event period begin time  806  to the DR event period begin time  802 . In some embodiments, the DR event period may also include a post-event period extending between the DR event period end time  804  and a post-event period end time that is sometime after the DR event period end time (not shown). In some embodiments, the DR event period may include one or both of a pre-event period and a post-event period. 
       FIG. 9B  illustrates a schedule of candidate setpoint temperatures  808  characterized by a parameter set according to an embodiment. The parameter set in this particular embodiment includes a first parameter  810  that indicates a temperature-wise offset from a first temperature setpoint of the schedule of original setpoint temperatures  800  (i.e., a temperature setpoint defined at the beginning of the pre-event period  806 ). In this particular example, the offset is 2° F. in a direction of increased energy consumption with respect to the corresponding original setpoint. That is, in this particular example, the outdoor temperature is greater than the indoor temperature and an air conditioning system is actuated to reduce the indoor temperature in accordance with the original and/or candidate schedule. The optimized schedule of setpoint temperatures should ultimately reduce the amount of energy consumed during the DR event period. To assist in such a reduction, a pre-cooling is performed during the pre-event period. In this particular example, pre-cooling is performed over the course of the pre-event period (i.e., from 1 pm to 2 pm), at a temperature offset defined by the first parameter  810 . 
     The parameter set also includes a second parameter  812  that indicates a temperature-wise offset from a last temperature setpoint of the schedule of original setpoint temperatures  800  (i.e., a temperature setpoint defined at the end of the DR event period  804 ). In this particular example, the offset is 3° F. in a direction of decreased energy consumption with respect to the corresponding original setpoint. That is, in this particular example, the indoor temperature is allowed to rise 3° F. by the end of the DR event period as compared to the schedule of original setpoint temperatures. 
     The first parameter  810  and the second parameter  812  can be used to define a slope of a linear sequence of temperature setpoints that may be used to determine the candidate schedule. For example, turning to  FIG. 9C ,  FIG. 9C  illustrates a relationship between the first parameter  810 , the second parameter  812 , and a linear sequence  814  of temperature setpoints according to an embodiment. The first  810  and second parameter  812  indicate a magnitude of maximum temperature change over a time period with respect to an arbitrary reference temperature. In this particular example, the time period is the DR event period (i.e., between the DR event period begin time  802  and the DR event period end time  804 ), and the arbitrary reference temperature is 73° F. Linear sequence  814  is then the linear sequence of temperature setpoints that increase from the reference temperature to the combined magnitude of the first and second parameters over the DR event period, and has a slope defined by the DR event period and the combined magnitude of the first and second parameters. 
     Turning back to  FIG. 9B , the slope defined by the DR event period and the combined magnitude of the first and second parameters may be used to determine the candidate schedule of setpoint temperatures  808  such that deviations in the rate of energy consumption over the DR event period are reduced. In this particular example, the candidate setpoint temperatures  808 , after being offset by a magnitude defined by the first parameter  810  from the pre-event period begin time  806  to the DR event period begin time  802 , begin to increase linearly at a rate of change defined by the slope of the linear sequence  814 . In cases where the original schedule of setpoint temperatures transitions from one temperature to another temperature, such as the temperature change from 75° F. to 70° F. at 5 pm, the candidate setpoint temperatures  808  continue to increase linearly, from the newly transitioned setpoint temperature, at the rate of change defined by the slope of the linear sequence  814 . In other words, a change in temperature magnitude in the original schedule (e.g., a drop of 5° F. in the original schedule  808  at 5 pm) is similarly reflected as a corresponding change in temperature in the candidate schedule  808  (e.g., a drop of 5° F. in the original schedule  808  at 5 pm). 
     While this particular embodiment is described with reference to a first parameter  810  that indicates a temperature-wise offset from a first temperature setpoint of the schedule of original setpoint temperatures  800 , and a second parameter  812  that indicates a temperature-wise offset from a last temperature setpoint of the schedule of original setpoint temperatures  800 , embodiments are not so limited. For example, in some embodiments a first parameter may indicate a temperature-wise offset from any setpoint of the original schedule  800 . This may be an offset at the pre-event period begin time  806 , the DR event period begin time  802 , the DR event period end time  804 , somewhere in-between any of those times, or somewhere outside of those times. For example, with reference to  FIG. 9B , this may be an offset of 0° F. from the 4 pm temperature setpoint of 75° F. defined by the original schedule  800 . A second parameter may then indicate a slope of a linear sequence of temperature setpoints passing through a point at the temperature-wise offset from the temperature setpoint of the original setpoint schedule. For example, the second parameter may indicate a slope of a linear sequence of temperature setpoints passing through the setpoint temperature of 75° F. at 4 pm, where the slope is an increase in temperature of 1° F. per hour. These two factors may then be used to determine the schedule of candidate setpoint temperatures  808 , where the original schedule  800  is modified to have a slope of 1° F. per hour with a 0° F. at 4 pm. 
     It should be recognized that the original schedule  800  and modified schedule  808  as described with reference to  FIGS. 9A and 9B  are merely used for explanation purposes and the scope of the embodiments are not intended to be so limited. For example, the aforementioned slope could be greater or less than 1° F. per hour, could be positive (as shown) or negative, and could be constant (as shown) or variable over the DR event period. The modified schedule  808  may include a temperature setpoint over the pre-event period that is constant (as shown) or variable (e.g., it may have a slope the same as or different than the aforementioned slope), and may have a duration of 1 hr (as shown) or a duration greater or less than 1 hr. Further, the slope may be defined based on a time period extending between the DR event period begin time  802  and the DR event period end time  804  (as described), or between other periods (e.g., between the pre-event period begin time  806  and the DR event period end time  804 ). Further yet, the schedule of candidate setpoint temperatures  808  may begin changing linearly from a setpoint temperature other than that associated with a temperature offset during the pre-event period. For example, with reference to  FIG. 9B , at 2 pm, instead of beginning a linear change from 73° F. (which is the same temperature as defined for the pre-event period between 1 pm and 2 pm), the schedule at 2 pm may begin a linear change from 74° F., 75° F., 76° F., or some other temperature that is different than that defined for the pre-event period. 
     In some embodiments, and with reference to  FIG. 9B , a third parameter  816  is indicative of a duration of the pre-event period. For example, the third parameter  816  may extend between the pre-event period begin time  806  and the DR event period begin time  802 , thereby defining a duration of the pre-event period. The third parameter may also or alternatively extend between other periods of time, such as over the post-event period. That is, the third parameter may also or alternatively extend between the DR event period end time  804  and the post-event period end time (not shown). 
     Turning briefly to  FIG. 9D ,  FIG. 9D  illustrates a candidate duty cycle schedule that corresponds to the schedule of candidate setpoint temperatures  808  according to an embodiment. That is, the candidate duty cycle schedule indicates a sequence of ON/OFF states that the HVAC system is expected to be controlled in upon implementation of the candidate schedule  808 . The candidate duty cycle schedule includes a number of HVAC system ON periods  818 , where the HVAC system is controlled to be in an ON state during those periods and in an OFF state outside of those periods. In some embodiments, a fourth parameter  820  is indicative of a maximum HVAC duty cycle period. For example, the maximum HVAC duty cycle period may indicate a maximum ON time of 45 minutes for every 60 minute period. The fourth parameter  820  need not be indicative of a maximum ON time, but similarly could also or alternatively indicate a minimum HVAC OFF time for a given period (e.g., 15 minutes for every 60 minute period). 
     By defining and optimizing a number of parameters such as the setback temperatures at the beginning and end of the DR event period, the duration of the pre-event period (during which, e.g., pre-cooling may be performed), the maximum duty cycle length, etc., the benefits of up to or more than three energy shifting strategies (setback, pre-cooling, and duty cycle modulation) may be realized while the drawbacks associated with such strategies may be reduced on a home-by-home basis. Further, by optimizing based on a user&#39;s preference for energy consumption vs. comfort, an optimal control trajectory may be realized where the control trajectory is optimal for the user&#39;s particular preference. 
     Returning now to  FIG. 8 , as mentioned, in operation  704 A a plurality of candidate parameter sets are generated. For example, a first parameter set may include a first parameter  810  having a value of 2° F., and a second parameter  812  having a value of 3° F., where this particular parameter set characterizes an associated candidate setpoint schedule (e.g., candidate setpoint schedule  808  as shown in and described with reference to  FIG. 9B ). A second parameter set may include a first parameter  810  having a value of 2.5° F., and a second parameter  812  having a value of 3.5° F., where this particular parameter set characterizes a different candidate setpoint schedule (not shown). 
     In operation  704 B an optimal one of the parameter sets is identified that results in minimization of a cost function when the associated candidate setpoint schedule is applied as an input to a prediction model-based simulation of the HVAC system. That is, one of the parameter sets generated in operation  704 A may be identified as being optimal with respect to a cost function. 
     In performing such an identification, the candidate setpoint schedule for each candidate parameter set may be applied to a prediction model-based simulation of the HVAC system. A prediction model-based simulation of the HVAC system may include, and may continuously update, a model of the HVAC system that is operable to predict the thermodynamic behavior of a structure, for example the model may be operable to predict an indoor temperature profile and/or an HVAC duty cycle schedule for a schedule of setpoint temperatures. The model may be generated/updated using some or all of a variety of information, such as a history of indoor temperature, a history of outdoor temperature, a history of temperature of the structure, characteristics of the HVAC system (e.g., a carryover of a rate of indoor temperature change that was occurring immediately prior to a change in actuation state of the HVAC system), etc. Some particular models and their use in prediction model-based HVAC system simulations are described in commonly assigned and concurrently filed U.S. Ser. No. 13/866,602, entitled “Generating And Implementing Thermodynamic Models Of A Structure,” the entire contents of which are incorporated by reference herein in their entirety for all purposes. In some embodiments, rather than using a trained model that is generated based on a history of data as described, a default model may be used whereby the default model provides a default thermodynamic behavior of the structure; e.g., a default relationship between a given control trajectory and an indoor temperature profile. 
     In response to applying a candidate setpoint schedule to the prediction model-based simulation of the HVAC system, a predicted indoor temperature profile and/or HVAC duty cycle schedule for the candidate setpoint schedule may be generated. The predicted indoor temperature profile and/or HVAC duty cycle schedule for the candidate setpoint schedule may then be used in the cost function to determine a cost associated with the candidate setpoint schedule. For example, the predicted HVAC duty cycle schedule may be used to determine an amount of total HVAC usage and/or cost for the expected HVAC usage over the DR event period for the candidate setpoint schedule. For another example, the predicted indoor temperature profile may be used to determine a metric indicative of occupant discomfort were the candidate setpoint schedule implemented over the DR event period. 
     In some particular embodiments, in identifying an optimal parameter set the space of parameter sets may be searched to identify the parameter set that minimizes the aforementioned cost function. By searching a space of parameter sets, where each parameter set includes a limited number of parameters (e.g., an offset and a slope), rather than a space defined by each of the temperature setpoints of a candidate schedule (which may be numerous), the search for an optimal schedule may advantageously be significantly expedited. Such a search may thus be performed by relatively low-power devices (or devices having a relatively low computational complexity) such as a thermostat, and may be performed on a regular basis (e.g., every 15 minutes) without unduly burdening the device. 
     In operation  704 C it is determined whether identification of an optimal parameter set failed. The identification of an optimal parameter set may fail for any one or more of a variety of reasons. For example, the minimization algorithm may fail to identify a local or global minimum of the cost function. If the identification fails, processing may continue to operation  704 D where a default parameter set is selected as the optimal parameter set. The default parameter set may be a set of parameters that result in at least some energy reductions over the DR period as compared to the user&#39;s original schedule. For example, the first parameter  810  may be a 1° F. temperature offset in the direction of increased energy consumption while the second parameter  812  may be a 1° F. temperature offset in a direction of decreased energy consumption. Such a parameter set may result in less energy consumption over the DR event period as compared to the original schedule, but may not be optimal in terms of minimizing energy consumption, occupant discomfort, etc. 
     Otherwise, if identification of the optimal parameter set does not fail, processing may continue to operation  704 E. In operation  704 E it is determined whether the optimal parameter set is within a baseline set. A baseline parameter set may be a parameter set that corresponds to the original setpoint schedule. In determining whether the optimal parameter set is within the baseline set, it may be determined whether the duty cycle schedule characterized by the optimal parameter set is identical to, or within some tolerance of, the duty cycle schedule characterized by the original setpoint schedule. In other words, it may be determined whether the optimal schedule is expected to result in the HVAC system being controlled in a similar fashion as if the HVAC system was to be controlled in accordance with the original schedule. To make such a determination the predicted duty cycle schedule characterized by the optimal parameter set and the original setpoint schedule may be compared. If the duty cycle schedules are identical or similar to one another, then it may be determined that the optimal parameter set is within the baseline set. Otherwise, it may be determined that the optimal parameter set is not within the baseline set. 
     For example, turning briefly to  FIGS. 10A and 10B ,  FIG. 10A  illustrates a predicted HVAC duty cycle  900  resulting from implementation of an optimal setpoint schedule  808  according to an embodiment. The HVAC duty cycle  900  includes HVAC ON periods beginning at approximately 1 pm, 3 pm, 4 pm, and 5 pm, where the HVAC ON periods beginning at 1 pm and 5 pm each last for approximately 50 minutes, and the HVAC ON periods beginning at 3 pm and 4 pm each last for approximately 30 minutes.  FIG. 10B  illustrates a predicted HVAC duty cycle  902  resulting from implementation of the original setpoint schedule  800  according to an embodiment. The HVAC duty cycle  902  includes HVAC ON periods beginning at approximately 1 pm, 2:30 pm, and 3:50 pm, with durations ranging from 30 minutes to over 2 hours. 
     In this particular example, to facilitate operation  704 E, the HVAC duty cycle  900  may be compared to the HVAC duty cycle  902 . If the duty cycles are identical or similar, then the original setpoint schedule  800  may be used rather than optimal schedule  808 . A variety of characteristics of the duty cycles may be used in the comparison, such as the HVAC ON times, HVAC ON periods, HVAC OFF times, and HVAC OFF periods, where schedules within 5% (or some other threshold greater than or less than 5%) of one another may be considered similar. 
     Returning to  FIG. 8 , if it is determined that the optimal parameter set is within the baseline set, then processing may continue to operation  704 F where the baseline parameter set is selected as the optimal parameter set. That is, instead of using a setpoint schedule characterized by the optimal parameter set to subsequently control the HVAC system, the original setpoint schedule may be selected and used. In this fashion, the HVAC system may be advantageously controlled precisely as expected by the user, thereby increasing the likelihood of the original setpoint schedule, which in this particular case is substantially optimal, being accepted or otherwise not interfered with by the user for the duration of the DR event period. 
     It should be appreciated that the specific operations illustrated in  FIG. 8  provide a particular process for illustrates a process for determining an optimized control trajectory according to an embodiment. The various operations described with reference to  FIG. 8  may be implemented at and performed by one or more of a variety of electronic devices or components described herein. For example, they may be implemented at and performed by one or more electronic devices in the smart home environment  200  (e.g., thermostat  202 ), the energy management system  130  (e.g., remote server  264 ), etc. Other sequences of operations may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the operations outlined above in a different order. Moreover, the individual operations illustrated in  FIG. 8  may include multiple sub-operations that may be performed in various sequences as appropriate to the individual operations. Furthermore, additional operations may be added or existing operations removed depending on the particular applications. 
     Returning now to  FIG. 7 , once an optimized control trajectory has been determined, the DR event period may begin in operation  706 . Once the DR event period begins, processing may continue to operation  708 , where the HVAC system is controlled in accordance with the control trajectory. For example, where the HVAC control trajectory includes a schedule of setpoint temperatures, thermostat  202  may control HVAC  203  in an attempt to reach and/or maintain those temperatures within a particular error threshold. For another example, where the HVAC control trajectory includes an HVAC duty cycle schedule, thermostat  202  may control an ON/OFF state of HVAC  203  in accordance with the duty cycle schedule. The particular control trajectory used may be that determined as a result of operation  704 , and thus may be the control trajectory resulting from optimization of the cost function, a default control trajectory, and/or the original control trajectory. 
     In operation  710 , a setpoint temperature profile over the DR event period may be determined. The setpoint temperature profile may be determined based on the particular control trajectory being used. For example, if the original setpoint schedule is used, then the setpoint temperature profile may correspond to the setpoint temperatures defined by the original setpoint schedule. Similarly, if the default or optimal setpoint schedules are used, then the setpoint temperature profile may correspond to the setpoint temperatures defined by the default or optimal setpoint schedules. In embodiments where the implemented setpoint schedule includes setpoint temperatures with a high rate of change over the DR event period, for example, setpoint temperatures that change every 5, 10, or 15 minutes (see, e.g., candidate schedule  808  in  FIG. 9B , where the setpoint temperatures continuously change over the DR event period), it may be desirable to reduce the rate of change of setpoint temperatures displayed or otherwise communicated to the user. In some embodiments, this may be done by suppressing display of the actual setpoint temperature in exchange for effective temperature setpoints (i.e., temperature setpoints that, if used to control the HVAC system, would be expected to cause the HVAC system to be controlled as it is actually being controlled in accordance with the selected control trajectory). 
     For example, turning briefly to  FIGS. 11A and 11B ,  FIG. 11A  illustrates an expected indoor temperature profile  1002  resulting from implementation of the optimal schedule  808  according to an embodiment. The expected indoor temperature profile  1002  may be determined by applying the optimal setpoint schedule  808  to the prediction model-based simulation of the HVAC system.  FIG. 11B  illustrates effective setpoint temperatures  1004  relative to the expected indoor temperature profile  1002  according to an embodiment. The effective setpoint temperatures  1004  may be determined by identifying the peaks and troughs of the expected indoor temperature profile  1002 . For example, an effective temperature setpoint may be defined as a peak temperature (e.g., at 3 pm) for a duration extending from a previous trough (e.g., at 2 pm) to the time at which the peak temperature is located (i.e., at 3 pm). Similarly, an effective temperature setpoint may be defined as a trough temperature (e.g., at 3:30 pm) for a duration extending from a previous peak (e.g., at 3 pm) to the time at which the trough temperature is located (i.e., at 3:30 pm). The combination of effective setpoint temperatures  1004  may then be used as the setpoint temperature profile. That is, instead of using the (continuously changing) setpoint temperatures defined by the optimal schedule  808  as the setpoint temperature profile, the (relatively static) sequence of effective setpoint temperatures  1004  may be used. In such a fashion, when displayed to the user, the user is not presented with the appearance of a continuously changing schedule (e.g., schedule  808 ), but rather is presented with the appearance of a relatively static schedule (e.g., as defined by the combination of effective temperature setpoints  1004 ). The presentation of a relatively static schedule may advantageously reduce the likelihood of user interference with implementation of the optimal schedule. 
     Returning to  FIG. 7 , once the setpoint temperature profile is determined, the setpoint temperatures defined by the setpoint temperature profile may be displayed, or otherwise communicated to the user, during the DR event period in operation  712 . For example, the effective setpoint temperatures  1004  may be sequentially displayed on thermostat  202  as a current setpoint temperature over the course of the DR event period. 
     While the HVAC system is controlled in accordance with the determined control trajectory, processing may continue to operation  714  where it is determined whether there is a need to re-determine the control trajectory. There may be a variety of reasons for the control trajectory to be re-determined, such as the actual HVAC states and/or indoor temperatures being different than the expected HVAC states/indoor temperatures, a real-time occupancy of the structure changing, the indoor temperatures crossing some safety thresholds, etc. In some particular embodiments, the control trajectory may be re-determined when: (1) where an optimal schedule is implemented, the actual indoor temperature profile is different than the predicted indoor temperature profile; (2) where the original schedule is implemented as it&#39;s deemed to result in similar control as an optimal schedule, the actual indoor temperature profile crosses some safety thresholds; (3) a real-time occupancy of the structure changes; and/or (4) where an optimal or original schedule is implemented, the actual HVAC states are different than the predicted HVAC states. 
     In making such a determination, a variety of information may be monitored. For example, an actual indoor temperature of the structure may be monitored during the DR event period and compared to the expected indoor temperature profile. For another example, the actual HVAC states may be monitored and compared to the expected HVAC states defined by the expected HVAC duty cycle schedule. For yet another example, an occupancy status of the structure may be monitored. 
     If it is determined that the control trajectory needs to be re-determined, then processing may continue to operation  716 . In operation  716  it is determined whether the control trajectory should be re-optimized. In some cases, the control trajectory may be re-optimized as described with reference to operation  704 , whereas in other cases an alternative control trajectory, such as one characterized by the original setpoint schedule or the default setpoint schedule, may be used in place of an optimal schedule. For example, in situations where the occupancy status of the structure changed, then the control trajectory may be re-optimized. For another example, in situations where the current control trajectory is characterized by an optimal setpoint schedule or original setpoint schedule and the actual HVAC state differs from the expected HVAC state, then the control trajectory may be re-optimized. For another example, in situations where the current control trajectory is characterized by an optimal setpoint schedule and the actual indoor temperature profile differs from the expected indoor temperature profile, then the default control trajectory may be implemented. For yet another example, in situations where the current control trajectory is characterized by the original setpoint schedule and the some safety thresholds are exceeded (e.g., HVAC ON period exceeds a maximum duration), then the default control trajectory may be implemented. 
     If it is determined that the control trajectory should be re-optimized, processing may continue to operation  718  where the control trajectory is re-optimized. Re-optimization of the control trajectory may be similar to the original optimization described with reference to operation  704 , thus further description is omitted. Upon re-optimization of the control trajectory, processing may return to operation  708  where the HVAC system is then controlled in accordance with the re-optimized control trajectory. If, on the other hand, it is determined that the control trajectory should not be re-optimized but rather that an alternative control trajectory should be determined, then processing may continue to operation  720  where an alternative control trajectory, such as one characterized by the default schedule or the original schedule, is determined. Processing may then return to operation  708  where, in this case, the HVAC system is controlled in accordance with the alternative control trajectory. 
     Returning to operation  714 , if there is no need to re-determine the control trajectory, then processing may continue to operation  722  where it is determined whether the DR event period is complete. If it is not, processing may return to operation  708  where the HVAC system is controlled in accordance with the control trajectory. Otherwise, processing may continue to operation  724  where the DR event period is completed. 
     It should be appreciated that the specific operations illustrated in  FIG. 7  provide a particular process for controlling an HVAC system during a demand-response event according to an embodiment. The various operations described with reference to  FIG. 7  may be implemented at and performed by one or more of a variety of electronic devices or components described herein. For example, they may be implemented at and performed by one or more electronic devices in the smart home environment  200  (e.g., thermostat  202 ), the energy management system  130  (e.g., remote server  264 ), etc. Other sequences of operations may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the operations outlined above in a different order. Moreover, the individual operations illustrated in  FIG. 7  may include multiple sub-operations that may be performed in various sequences as appropriate to the individual operations. Furthermore, additional operations may be added or existing operations removed depending on the particular applications. 
     A user of a device involved in energy management during a DR event may be presented with one or more of a variety of graphical user interfaces (GUI) on one or more of their devices (e.g., thermostat  202 , access device  266 , etc.) associated with the energy management system. The GUI&#39;s, or other user interfaces, may notify the user that a DR event is ongoing, and in some cases may notify the user that their HVAC system is being controlled in accordance with one or more of the processes described herein. In some particular cases, if, during the DR event period, their HVAC system is no longer controlled in accordance with the aforementioned processes, the user may be notified of such a condition. 
     Turning briefly to the figures,  FIGS. 12A and 12B  illustrate a simplified GUI that may be presented to an energy consumer according to an embodiment. While the GUI is presented in the form of an interface that may be displayed on a circular-shaped device such as the device  300  discussed with reference to  FIGS. 3A through 3C , embodiments are not so limited as similar GUI&#39;s could be presented on other devices of other shapes. 
     Specifically,  FIG. 12A  illustrates GUI  1100  which may be, e.g., user interface  304  ( FIG. 3A ), output device  606  and/or input device  608  ( FIG. 6 ), or other GUI of an electronic device associated with an energy consumer. The GUI  1100  includes a current setpoint temperature  1102  displaying the immediate setpoint to the user. The GUI  1100  also includes a current temperature indicator  1104  indicating the current temperature inside of the structure, and in some cases a current setpoint temperature indicator  1106  indicating the immediate setpoint and graphically displayed relative to the current temperature indicator  1104 . 
     Turning to  FIG. 12B , upon beginning a DR event, the same information as described with reference to  FIG. 12A  may be displayed. Further, GUI  1100  may also include a DR event indicator  1108  indicating that a DR event is currently ongoing. In this particular example, the DR event indicator  1108  is a textual display of “RUSH HOUR”, but in other embodiments the DR event indicator  1108  may take other forms or textual sequences, such as “DR EVENT”. Such an indicator may be displayed during the DR event period, but may also be displayed during other time periods associated with the DR event period, such as during the pre-event period and/or post-event period. GUI  1100  may also include an HVAC state indicator  1110  indicating a current state of the HVAC system (e.g., cooling, heating, stage 1, stage 2, etc.). 
     GUI  1100  may also include a DR event management indicator  1112  that indicates the HVAC system is being controlled in accordance with a DR event optimization process (e.g., an optimal control trajectory is being used). The DR event management indicator  1112  in this particular embodiment is an image of a leaf embedded in a gear, but in other embodiments may assume different graphical forms or shapes. The DR event management indicator  1112 , in some embodiments, may indicate that the thermostat is being successfully controlled in accordance with the DR event optimization process (i.e., no user setpoint changes to those defined by the DR event optimization process). In some cases, the DR event management indicator  1112  may be displayed if the setpoint is not altered. For example, if the energy consumer does not alter the current setpoint, then the indicator  1112  may be displayed, but if the energy consumer alters the current setpoint (e.g., increases the temperature by 2° F.), then the indicator  1112  may be removed from the display. In other cases, the DR event management indicator  112  may be displayed even if the setpoint is altered but only if the change does not result in a reduction in energy shift from the DR event period to one or more periods outside of the DR event period. 
     It has been found especially useful and beneficial to automatically display an iconic symbol to the user during these times (i.e., during the time that the automated schedule adjustment processes described herein are taking place) in association with the user interface, wherein the iconic symbol is designed to simultaneously achieve multiple objectives including reassuring and/or notifying the user that there is an automated process taking place, and that this automated process is directed to achieving an environmentally beneficial objective. It has been found that one particularly useful iconic indicator comprises a symbol of a gear along with a symbol of a leaf embedded therein, the gear being found to connote in the mind of the user that there is an automated process of some sort taking place, and the leaf being found to connote in the mind of the user that this process has a beneficial impact on the environment. In addition to having one advantage that the leaf-in-gear symbol does not need translation into foreign languages, there is furthermore the advantage that the leaf-in-gear symbol is not alarming or threatening to the user, and has a positive connotation such that the user is mildly and subtly encouraged not to take any action that would remove the leaf-in-gear symbol from the user display. At the same time, because there is an associated with automation by virtue of the gear&#39;s connotation, the leaf-in-gear symbol is less likely to spur the user into any unnecessary manual interactions with the device. 
     It should be appreciated that the specific I/O interfaces illustrated in  FIGS. 12A and 12B  describe particular I/O interfaces according to certain embodiments. The I/O interfaces described with reference to  FIGS. 12A and 12B  may be implemented at one or more of a variety of electronic devices associated with an energy consumer. For example, they may be implemented at and performed by one or more of the a thermostat  202 , hazard detection unit  204 , entryway interface device  206 , wall light switch  208 , wall plug interface  210 , appliance  212 , access device  266 , or other electronic device associated with the identified energy consumer. 
     The various messages and input elements may not necessarily be displayed at different times, but rather some messages could be presented simultaneously on the same display. Similarly, although some messages and information are explained as being presented simultaneously, they be instead be displayed at different times. Some messages could be communicated using other communication mechanisms, and responses could similarly be received using other communication mechanisms. For example, audible, touch, or other input/output mechanisms could be used. Further, it should be recognized that additional or alternative information could be presented before, during, and/or after implementation of a schedule optimization process, and all of the information illustrated in and described with reference to  FIGS. 12A and 12B  need not be presented. One of ordinary skill in the art would recognize and appreciate many variations, modifications, and alternatives. 
     Specific details are given in the above description to provide a thorough understanding of the embodiments. However, it is understood that the embodiments may be practiced without these specific details. For example, circuits may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments. Further, embodiments may include some or all of the systems, methods, apparatus, etc. described in one or more of the following commonly assigned applications, each of which is incorporated by reference herein in its entirety for all purposes: U.S. Ser. No. 13/842,213, supra; U.S. Ser. No. 13/632,118 (Ref. No. NES0119-US) filed Sep. 30, 2012; U.S. Ser. No. 13/632,093 (Ref. No. NES0122-US) filed Sep. 30, 2012; U.S. Ser. No. 13/632,028 (Ref. No. NES0124-US) filed Sep. 30, 2012; U.S. Ser. No. 13/632,041 (Ref. No. NES0162-US) filed Sep. 30, 2012; U.S. Ser. No. 13/632,070 (Ref. No. NES0234-US) filed Sep. 30, 2012; U.S. Prov. Ser. No. 61/704,437, supra (Ref. No. NES0254-US); PCT Application No. PCT/US12/20026 (Ref. No. NES0185-PCT) filed Jan. 3, 2012; PCT Application No. PCT/US12/00007 (Ref. No. NES0190-PCT), filed Jan. 3, 2012; and U.S. Ser. No. 13/269,501 (Ref. No. NES0120-US) filed Oct. 7, 2011. 
     Implementation of the techniques, blocks, steps and means described above may be done in various ways. For example, these techniques, blocks, steps and means may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing units may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described above, and/or a combination thereof. 
     Also, it is noted that the embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed, but could have additional steps not included in the figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function. 
     Furthermore, embodiments may be implemented by hardware, software, scripting languages, firmware, middleware, microcode, hardware description languages, and/or any combination thereof. When implemented in software, firmware, middleware, scripting language, and/or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine readable medium such as a storage medium. A code segment or machine-executable instruction may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a script, a class, or any combination of instructions, data structures, and/or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, and/or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc. 
     While the principles of the disclosure have been described above in connection with specific apparatuses and methods, it is to be clearly understood that this description is made only by way of example and not as limitation on the scope of the present teachings.