Temperature control based on energy price

A system is disclosed comprising memory configured to store a temperature value based on a cost of a given energy resource, wherein the cost-based temperature value differs from a temperature value based on a temperature schedule. The system also comprises a controller operatively coupled to the memory and configured to compare the cost-based temperature value to the schedule-based temperature value, and to direct one of a cooling system and a heating system to maintain a temperature of an environment at the one of the cost-based temperature value and the schedule-based temperature value that results in an energy cost savings.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to energy management, and more particularly to energy management effectuated by controlling temperature levels associated with a heating, ventilation and air conditioning (HVAC) system based on energy prices.

Many utilities are currently experiencing a shortage of electric generating capacity due to increasing consumer demand for electricity. Traditionally, utilities generally charge a flat rate, but with increasing cost of fuel prices and high energy usage at certain parts of the day, utilities have to buy more energy to supply customers during peak demand. Consequently, utilities are charging higher rates during peak demand. If peak demand can be lowered, then a potential huge cost savings can be achieved and the peak load that the utility has to accommodate is lessened. In order to reduce high peak power demand, many utilities have instituted time of use metering and rates which include higher rates for energy usage during on-peak times and lower rates for energy usage during off-peak times. As a result, consumers are provided with an incentive to use electricity at off-peak times rather than on-peak times.

Traditionally, to take advantage of the lower cost of electricity during off-peak times, a consumer typically manually operates an HVAC system during the off-peak times. For example, during off-peak times the consumer in cool mode can decrease the setpoint temperature of the HVAC system and during on-peak times the consumer can increase the setpoint temperature of the HVAC system and/or turn the HVAC system off. Control of the setpoint temperature is typically through a thermostat or a user interface/display associated with the thermostat. This user-managed approach is undesirable because the consumer may not always be present in the home to operate the system during off-peak hours. This is also undesirable because the consumer is required to manually track the current time to determine what hours are off-peak and on-peak.

One proposed third party solution is to provide an energy management system where a controller “switches” the actual energy supply to the HVAC system on and off. However, there is no active control beyond the mere on/off switching. There are also currently different methods used to determine when variable electricity-pricing schemes go into effect. Also, different electrical utility companies can use different methods of communicating periods of high electrical demand to their consumer, for example, phone lines, schedules, and wireless signals sent by the electrical utility company. Other electrical utility companies simply have rate schedules for different times of day.

Unfortunately, these existing energy management approaches require some unacceptable degree of user interaction and/or, when more fully automated, can result in undesirable temperature levels in the environment being managed.

BRIEF DESCRIPTION OF THE INVENTION

As described herein, the exemplary embodiments of the present invention overcome one or more disadvantages known in the art.

One aspect of the present invention relates to a system comprising memory configured to store a temperature value based on a cost of a given energy resource, wherein the cost-based temperature value differs from a temperature value based on a temperature schedule. The system also comprises a controller operatively coupled to the memory and configured to compare the cost-based temperature value to the schedule-based temperature value, and to direct one of a cooling system and a heating system to maintain a temperature of an environment at the one of the cost-based temperature value and the schedule-based temperature value that results in an energy cost savings.

In another aspect of the present invention, the memory and controller are part of a heating and/or cooling system such as an HVAC system.

Advantageously, illustrative embodiments of the present invention provide for the HVAC system to maintain the temperature of an environment at a level that ensures energy cost savings but that is also tolerable based on user preferences.

These and other aspects and advantages of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

One or more of the embodiments of the invention will be described below in the context of energy management in the context of a residential environment. However, it is to be understood that embodiments of the invention are not intended to be limited to use in residential environments or with any particular environment. Rather, embodiments of the invention may be applied to and deployed in any other suitable environment in which it would be desirable to manage the energy consumption associated with an HVAC system, a standalone heating system, or a standalone cooling system.

It is to be further understood that the types of energy consumption that are being managed here may include, but are not limited to, electricity consumption, natural gas consumption, and oil consumption. That is, by efficiently managing the temperature levels in a residential or other environment, either natural gas or oil (depending on natural resource being used) is conserved, as well as the electricity otherwise needed to operate the HVAC system. Of course, one or more embodiments of the invention may be even more generally applied to any suitable forms of resource consumption.

As illustratively used herein, the phrase “user interface” is intended to refer to an area where interaction between a human and a machine occurs including, but not limited to, a user viewing or listening to some form of information presented by the machine and/or the user inputting one or more selections or commands to the machine. In at least some of the embodiments described herein, the machine is an HVAC system and the human is the user or consumer, and interaction between the user and the HVAC system is via a user interface such as a user interface that is associated with a thermostat. The user interface can be an integral part of the thermostat module, separate from the thermostat module, or some combination thereof.

Before describing illustrative temperature control embodiments of the invention, we describe an illustrative HVAC system (FIGS. 1 and 2) and an illustrative energy management system (FIG. 3) in which one or more of such temperature control embodiments may be implemented.

FIG. 1illustrates an HVAC system100for conditioning air of a room according to an embodiment of the invention. The HVAC system100comprises one or more power consuming features/functions including at least one temperature controlling element for one of heating and cooling air. A controller104is operatively connected to each of the power consuming features/functions. The controller104can, in one embodiment, include a microcomputer on a printed circuit board (including one or more processor devices and one or more memory devices) which is programmed (via one or more software programs stored thereon and executed thereby) to selectively control the energization of the power consuming features/functions.

The controller104is configured to receive and process a signal108indicative of a utility state, for example, availability and/or current cost of supplied energy. There are several ways to accomplish this communication, including but not limited to PLC (power line carrier, also known as power line communication), FM, AM SSB, WiFi, ZigBee, Radio Broadcast Data System, 802.11, 802.15.4, etc. The energy signal may be generated by a utility provider, such as a power company, and can be transmitted via a power line, as a radio frequency signal, or by any other means for transmitting a signal when the utility provider desires to reduce demand for its resources. The cost can be indicative of the state of the demand for the utility's energy, for example a relatively high price or cost of supplied energy is typically associated with a peak demand state or period and a relative low price or cost is typically associated with an off-peak demand state or period.

Note that the signal108provides the HVAC system100with the energy cost information for given time intervals over a time period (e.g., day, week, month, year, etc.). For example, this energy price information provided in accordance with the signal108is what is used by temperature control schedules described below in the context ofFIGS. 4-8to determine which temperature offset and/or temperature setpoint to apply. Note that the term “cost” with respect to energy as used herein includes, but is not limited to, specific cost tiers or levels (e.g., low, medium, high, critical, etc.), specific prices (e.g., $0.10 per kWH (kilowatt hour), etc.), or some combinations thereof.

The controller104can operate the HVAC system100in one of a plurality of operating modes, including a normal operating mode and an energy savings mode in response to the received signal. Specifically, the HVAC system100can be operated in the normal mode in response to a signal indicating an off-peak demand state or period and can be operated in an energy savings mode in response to a signal indicating a peak demand state or period. As will be discussed in greater detail below, the controller104is configured to selectively adjust and disable at least one of the one or more power consuming features/functions to reduce power consumption of the HVAC system100in the energy savings mode. It should be appreciated that the controller can be configured with default settings which govern normal mode and energy savings mode operation. Such settings in each mode can be fixed while others adjustable to user preference and to provide response to load shedding signals.

An exemplary embodiment of the HVAC system100is illustrated inFIG. 2. In this embodiment, the HVAC system100is a central air conditioning system110and the at least one temperature controlling element is a refrigeration system112including a setpoint temperature. The refrigeration system is a closed loop system defining passages for a refrigerant fluid to flow and includes a compressor120, a condenser122and an evaporator124in a refrigerant flow relationship. As is well known, the compressor120, which can be driven by electrical energy or other suitable power sources, compresses a low-pressure refrigerant vapor exiting the evaporator124into a high pressure and temperature vapor. This high pressure vapor refrigerant rejects heat to outdoor ambient air in the condenser122condensing into a liquid. As depicted, the condenser can comprise one or more coils or tubes adapted to receive the hot refrigerant from the compressor. An outdoor fan130blows ambient air across the condenser. The liquid refrigerant then passes through an expansion device132such as a thermostatic expansion valve or a fixed orifice device and becomes a low pressure two-phase refrigerant. The expansion valve132can be located on a conduit which is in communication with the evaporator124to meter the flow of liquid refrigerant entering the evaporator at a rate that matches the amount of refrigerant being boiled off in the evaporator. This refrigerant then enters the indoor coils of the evaporator124and absorbs heat from the indoor air circulated by an indoor fan or blower140. An air filter142is provided for filtering the air flowing through the blower and into the evaporator. Cool, dehumidified air is then blown through ductwork into rooms to be cooled. The evaporator124then discharges refrigerant to a conduit which is in communication with the compressor120. The refrigerant vapor then enters the compressor120and the cycle repeats. In effect, indoor air is cooled by absorbing heat from indoor air and rejecting the heat to outdoor air in a vapor compression based air-conditioning system.

A thermostat150controls the air conditioning system using dry bulb temperature alone. In the exemplary central air conditioning system110, the thermostat150is one module of the controller104which controls the operation of the system110. The controller104can also include a separate control module154which can be located on a blower housing; although, this is not required. As shown inFIG. 1, a sensing device160is operatively connected to the controller104. According to one aspect, the sensing device is integrated with the controller104; although, this is not required. The sensing device160has sensor inputs for indoor air dry-bulb temperature, indoor relative humidity, outdoor air temperature, outdoor relative humidity, supply air temperature and return air temperature. The output of the sensing device160is processed by the controller104. The controller, in response to the sensing device output and depending on a setpoint temperature of the refrigeration system, selectively actuates the refrigeration system112.

With reference again toFIG. 1, a control panel or user interface170is provided on the HVAC system100and is operatively connected to the controller104. The control panel170can include a display172and control buttons for making various operational selections, such as setting the setpoint temperature of a temperature controlling element. A light source can be provided for illuminating the user interface.

If the controller104receives and processes an energy signal indicative of a peak demand period at any time during operation of the HVAC system100, the controller makes a determination of whether one or more of the power consuming features/functions should be operated in the energy savings mode and if so, it signals the appropriate features/functions of the HVAC system100to begin operating in the energy savings mode in order to reduce the instantaneous amount of energy being consumed by the HVAC system. The controller104determines what features/functions should be operated at a lower consumption level and what that lower consumption level should be, rather than an uncontrolled immediate termination of the operation of specific features/functions.

In order to reduce the peak energy consumed by the HVAC system100, the controller104is configured to at least one of selectively adjust and disable at least one of the one or more above described power consuming features/functions to reduce power consumption of the HVAC system100in the energy savings mode. Reducing total energy consumed also encompasses reducing the energy consumed at peak times and/or reducing the overall electricity demands. Electricity demands can be defined as average watts over a short period of time, typically 5-60 minutes. Off peak demand periods correspond to periods during which lower cost energy is being supplied by the utility relative to peak demand periods.

As set forth above, the HVAC system100has a setpoint temperature in the normal operating mode. To reduce the power consumption of the HVAC system100in the energy savings mode, the controller104is configured to adjust (increase or decrease) the setpoint temperature of the HVAC system to precipitate less refrigeration system on time (i.e., compressor on time) in the energy savings mode. For example, if the HVAC system100is being used to cool the room air, the controller104can increase the setpoint temperature. If the HVAC system100includes a heat pump cycle to heat the room air, the controller104can decrease the setpoint temperature. To precipitate less compressor on time, according to one aspect, a duty cycle of the compressor120can be adjusted (for example, by time or by setpoint) in the energy savings mode. According to another aspect, to reduce the current draw of the compressor120in the energy savings mode, the speed and/or capacity of the compressor can be varied or reduced. A controllable expansion valve can also be implemented. According to yet another aspect, the refrigeration system112can be temporarily deactivated in the energy savings mode. In this instance, the fan140can continue to operate to limit discomfort to the consumer. The light source of the user interface170can also be dimmed or deactivated in the energy savings mode. The speed of the fan130and/or fan140can also be varied and/or reduced or the fan130and/or fan140can be deactivated in the energy savings mode.

Other power load reducing measures may include reducing before on-peak hours the setpoint temperature (pre-chilling) and increasing the setpoint temperature during on-peak rates. For example, shortly before peak rate time, the temperature setting of the central air conditioning system110could be decreased by 1-2 degrees (during off-peak rates). One skilled in the art of heat transfer will appreciate that this pre-chilling maneuver would need to occur a predetermined time prior to the peak demand period to allow enough time for the environs to reach the pre-chilled setpoint temperature. The system could “learn” the amount of time required for a given pre-chill at a specific ambient condition and then invoke the pre-chill accordingly. Some communication line with the utility including but not limited to the communication arrangements hereinbefore described could be established so that the utility can send a signal in advance to decrease the room temperature during off-peak rates as a pre-chill maneuver and, in turn, increase the setpoint temperature during on-peak rates.

The determination of which power consuming features/functions are operated in an energy savings mode may depend on whether the HVAC system100is currently operating in the cooling cycle or the heating cycle. In one embodiment, the controller104may include functionality to determine whether activation of the energy savings mode for any power consuming features/functions would potentially cause damage to any feature/function of the HVAC system100itself or would cause the HVAC system to fail to perform its intended function. If the controller104determines that an unacceptable consequence may occur by performing an energy saving action, such as deactivating or curtailing the operation of the refrigeration system112, the controller may opt-out of performing that specific energy saving action or may institute or extend other procedures.

Further, the controller104can be configured to monitor various parameters of the refrigeration system112as well as the home environs and alert a user of a fault condition of the HVAC system100. For example, the controller can be configured to monitor or extrapolate faults of at least one of the capacity of the compressor120, refrigerant charge level and air filter system and alert a user of a respective low capacity, low charge level and severely clogged air filter system. To this end, and as shown inFIGS. 1 and 2, the sensing device160can include a first sensing device180, a second sensing device182and a third sensing device184. The first sensing device180measures a temperature of the evaporator124. The second sensing device182measures a temperature of the condenser122. The third sensing device184measures outside ambient temperature. The thermostat of the HVAC system100is set to an indoor setpoint temperature by the user and senses the actual indoor ambient temperature. The controller104is configured to record the respective evaporator, condenser and outdoor ambient temperatures along with run times of the compressor120during operation of the HVAC system100. The controller104can then utilize the recorded temperatures and run times to identify a fault condition. The controller can be configured to compare the run times associated with an outdoor ambient temperature and setpoint or actual room temperature to identify a fault condition.

FIG. 3is an exemplary implementation of a home/premises energy management system300according to the present application. It is to be appreciated that the energy management system300can be deployed throughout the same environment as the HVAC system shown inFIGS. 1 and 2.

The main source of information flow for the home (or other environment in which system300may be deployed) is shown as smart electric meter302acting as trust center, coordinator, and/or and energy service portal (ESP), and which is configured in operative connection/communication with a home energy gateway (HEG)304. Note that the controller104of the HVAC system100inFIGS. 1 and 2may be part of the HEG304, separate from the HEG304, or some combination thereof.

It is well known that the functions of smart meter302may be separated into different devices. For example, if the home does not have a smart meter302, so the electric meter functions only as a meter to provide consumption information, other components can be used to provide the additional capabilities. For example, homes without a smart meter302can have the metering functionality of smart meter302replaced with a simple radio and current transformer (CT) configuration. Also, there are devices that can be placed on the outside of the meter to communicate consumption by reading pulse counts or the rotating disk of the meter. In this embodiment, smart meter302is shown with an IEEE 802.15.4 radio (such as in the configuration of a ZigBee type; where ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless home area networks (WHANs), but the meter could also communicate by a number of other standards such as IEEE 1901 (e.g., Home Plug Green Phy or Home Plug AV specifications), among others.

Computer306(such as a desktop, laptop of other computing device) is in operative attachment to modem/router308, a common manner of attaching computers to Internet310. InFIG. 3, computer306is connected to modem/router308by a wired IEEE 802.3 (Ethernet) connection311. However, it is to be appreciated the connection could be made by other known arrangements such as an IEEE 802.11 (Wi-Fi) connection, power line communication/power line carrier (PLC) connection, among others. In one embodiment, the PLC connection is made using an adaptor such as sold by Netgear Inc. of San Jose Calif. or other manufacturer for that purpose. Also, although a modem/router arrangement is shown in system300, it is not required, and the system would function for its primary purpose of monitoring and displaying energy consumption information without such an arrangement. In that case, computer306would connect directly to HEG304via a wired or wireless connection.

A Web/Internet enabled smart phone (or other smart hand-held device)312is configured to communicate with HEG304for displaying data and configuring accessories (such as home appliances314e-314k). Accessories314a-314kfall into two main categories: sensors and devices (where, depending on how the accessories are used, some will fall into both categories).

Examples of sensors include solar meters314a, gas meters314b, temperature sensors314c, motion sensors314d, and appliances reporting their power consumption (such as dishwashers314e, refrigerators314f, stoves314g, washers/dryers314h, etc.). Devices include thermostats314i, alarms314jand simple switches314k, along with the appliances (e.g., dishwashers314e, etc.), when performing their normal functions. The foregoing are just some examples of accessories to which the concepts of the present application will apply. Note that thermostat314ican be the same as thermostat150in the HVAC system100ofFIG. 1.

The HEG304is comprised of one or more processor devices and one or more memory devices. In one embodiment, the HEG304is constructed with computational capabilities and multiple communication technologies but without its own integral display screen, its audio visual display capability being limited to status indicators (although, this is not required). Rather, it is configured to communicate with remote devices having user interface displays, such as for example, personal computers, smart phones, web-enabled TV, etc., so as to communicate with the user via these displays. In contrast to existing controllers (such as a HEM) used in home energy systems, HEG304is significantly smaller, cheaper, and consumes less power. The HEG304also has the capability of operating over multiple communication networks which use different formats, protocols, and bandwidths. This allows HEG304to acquire and manipulate (e.g., reformat) data of one communication network (e.g., that which monitors/controls the home appliances) and to supply that manipulated data to another communication network (e.g., to the consumer electronics network, such as to a home computer, smart phone, web-enabled TV, etc.), even though these networks are not generally compatible. The manipulation or reformation includes putting the data in a format and/or location whereby it is accessible by the other communication networks. In some cases, the reformatting may only need to provide the data to a database accessible to the other communication networks, while in still other cases, the system translates the data from a protocol understandable by one communication into a protocol understandable by the other communication networks.

As another example, HEG304is connected to system loads (e.g., the home appliances, etc.) over one type of communication network, to the utility company over a different communication network, and to a display over a third different communication network. In one particular embodiment, connection to the display is via a Wi-Fi communication network, connection to the utility company (over the meter) is via a ZigBee communication network, and connection to the home accessory (sensor/device/appliance) network is over the third. Alternatively, in a home where the accessories and utility company's rules are different, the data could be structured differently. For example, the whole home consumption could be available over the Internet or via a ZigBee meter on the second network. Further, in addition to the display, several home automation accessories including pool controllers, emergency generators, and storage batteries are designed to be accessed over an Ethernet using an Internet Protocol (IP).

Given the above-described exemplary HVAC system100and exemplary energy management system300, we now describe various temperature control schedules, in the context ofFIGS. 4-8, that may be employed by either of the two systems to attempt to achieve energy savings (e.g., part of the energy savings mode of the HVAC system100mentioned above). It is to be appreciated that such schedules may be stored in memory and executed by controller104of HVAC system100, HEG304of system300, some other component(s) of the systems, or some combinations thereof. The systems allow for user input and selection of setpoints as will be seen, in response to user preferences and/or energy price information as may be provided to the systems via one or more signals received from one or more utility companies.

FIG. 4graphically depicts a temperature control schedule400for a thermostat based on the Energy Star schedule. As is known, Energy Star is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy that is intended to help energy consumers save money and to protect the environment through energy efficient products and practices. Thus, it is assumed that a thermostat is programmed (in accordance with controller104and/or HEG304) to follow the temperature schedule depicted in the graph ofFIG. 4over the course of the day in order to assist in maintaining energy-efficient temperature conditions in an environment in which the thermostat is deployed. As is known, such a thermostat is operatively coupled to an HVAC system and/or energy management system (HEG) which either activates/deactivates a heating subsystem of the HVAC system or a cooling subsystem thereof in order to maintain the temperature schedule programmed into the thermostat for the given environment. While this example shows the recommended Energy Star schedule, it is common to provide a user interface to a thermostat to allow a consumer to edit this schedule according to when they are home and away, and what temperature ranges they are willing to accept.

So as shown inFIG. 4, which assumes deployment in a residential environment such as a home, between 12:00 am and 6:00 am (time interval401), the thermostat schedule causes the temperature of the home to be maintained at 82 degrees (note that degrees are given in Fahrenheit unless otherwise specified). Then, between 6:00 am and 8:00 am (time interval402), the thermostat schedule causes the temperature of the home to decrease to 77 degrees, i.e., the cooling subsystem brings the temperature of the home down from 82 degrees to 77 degrees in response to the thermostat setting. This change in temperature between these two time intervals is based on the assumption that residents of the home will be sleeping during the first time interval and thus can tolerate a warmer temperature, but will be awake and getting ready for work or school during the second time interval and thus would prefer a cooler temperature. Then, in a third time interval403, i.e., between 8:00 am and 6:00 pm, the thermostat schedule causes the temperature of the home to be maintained at 85 degrees. This is when the residents are presumably not at home, and thus a warmer temperature is permissible. In time interval404, between 6:00 pm and 10:00 pm, the illustrated schedule dictates that the temperature of the home be maintained at 77 degrees (again, when residents are presumed to be home). Lastly, in time interval405, between 10:00 pm and 12:00 am when residents are presumable sleeping again, the temperature is maintained at 82 degrees (which then leads to a repeat of the schedule ofFIG. 4starting at 12:00 am the next day).

FIG. 5graphically depicts a temperature control schedule500for a thermostat based on the Energy Star schedule with temperature offsets that are a function of the price of energy (this is referred to in the figure as an Energy Star schedule with price offsets). That is, as compared to temperature control schedule400inFIG. 4with time intervals401through405, it is noted that schedule500adjusts the Energy Star recommended temperature in certain intervals based on the price of energy. More specifically, schedule500takes into account the price of energy to run the HVAC system at each hour interval of the day and applies an offset to the Energy Star recommended temperature. So assume that the price of energy over the course of the day can range from low (L), medium (M), high (H), to very high or critical (C). When the energy price is defined as low (L), then the schedule follows the Energy Star recommended temperature levels, as shown in time intervals501,502and the first part of503(i.e.,503-1) where temperature level is maintained at 82 degrees in time interval501, 77 degrees in time interval502, and 85 degrees in time interval503-1.

However, when the energy price is defined as medium (M), in time interval503-2, note that a two degree offset is applied via schedule500to the Energy Star recommended temperature for that time interval (85 degrees) such that a temperature level of 87 degrees is maintained by the HVAC system. Then, in interval503-3, when the energy price is high (H), a three degree offset is applied to the Energy Star recommended temperature for that time interval (85 degrees) such that a temperature level of 88 degrees is maintained. When the energy price goes to critical (C) in time interval503-4, a four degree offset is applied, raising the temperature to 89 degrees. In time interval503-5, when the price goes back down to high (H), the three degree offset is applied.

Similarly, it is evident that in the first part of time interval504, i.e., time interval504-1, a three degree offset is applied corresponding to a high energy price, and a two degree offset is applied in504-2corresponding to a medium energy price. Note then how no offset is applied in time interval504-3or time interval505since the energy price goes back down to the low level.

It would seem that there is only advantage in this application of offsets based on the price of energy, i.e., consumer uses less energy during times when the price of energy is relatively high. However, it is realized that certain offsets cause the temperature in the residence to be at an unacceptable level for pets and plants that remain in the home even when no people are present. Perhaps 89 degrees is too warm for certain plants and pets that are in the residence. Also, since the temperature was let rise to 89 degrees, the consumer may find that the home is not adequately cooled by the time he/she returns. So, to avoid these conditions, the consumer may manually decrease the base temperature, e.g., 85 degrees to 81 degrees, so that when the four degree offset is applied, the temperature will not go above the recommended level of 85 degrees. However, this requires the consumer to manually adjust the thermostat and remember to adjust in back during times when the energy prices may differ from those assumed in schedule500.

FIG. 6graphically depicts a temperature control schedule600for a thermostat based on the Energy Star schedule with price setpoints. That is, as compared with schedule500inFIG. 5, schedule600provides for a specific setpoint temperature for a given price of energy. As will be explained below, these price-sensitive setpoints can be entered (or selected as defaults) by the consumer on a thermostat. Alternatively, for maximum energy savings, they can be coded into the thermostat and not adjustable.

Thus, as shown inFIG. 6, when the price is at a low (L) level, i.e., time intervals601,602, and the first part of603(603-1), the temperature is maintained at the Energy Star recommended level. However, when the price goes to a medium (M) level, i.e., time interval603-2, the schedule calls for a setpoint of 80 degrees. Then, in time interval603-3, when the price is high (H), an 81 degree setpoint is employed. An 82 degree setpoint is employed in time interval603-4when the price is critical (C), and a setpoint of 81 degrees is employed in time interval603-5when the price returns to high. Time interval604-1has a setpoint of 81 degrees (H) and604-2is maintained at an 80 degree setpoint corresponding to a medium (M) price level, while time intervals604-3and605are maintained at the Energy Star recommended temperatures.

Note that setpoint-based schedule600inFIG. 6overcomes the issues raised above regarding the offset-based schedule500inFIG. 5by providing specific setpoint temperatures that are considered tolerable by the consumer (as opposed to the temperature offsets that raise the temperature to undesirable levels in schedule500) during time intervals when the price is medium, high or critical. However, note that some of these setpoint temperatures end up being lower than the Energy Star recommended temperatures for certain time intervals (i.e.,603-2,603-3,603-4and603-5), thus maintaining the temperature at a level lower than the consumer was willing to tolerate under the Energy Star schedule (85 degrees). This causes the consumer to have to unnecessarily pay more for energy consumption during those time intervals.

FIG. 7illustrates a temperature control schedule700, according to an embodiment of the invention, that overcomes the issues associated with schedule600inFIG. 6. Note that the same price-sensitive setpoints are selected in schedule700as in schedule600, and also that the temperatures that are maintained in time intervals701,702,704and705are the same as those maintained in time intervals601,602,604and605, respectively. The difference is in time interval703as compared to time interval603. Recall that, as pointed out above, the temperatures maintained in time intervals603-2,603-3,603-4and603-5are at a level lower than the consumer was willing to tolerate under the Energy Star schedule (85 degrees), thus causing the consumer to have to unnecessarily pay more for energy consumption. Advantageously, in accordance with schedule700, a comparison is performed between the setpoint temperature and the Energy Star recommended temperature, and the temperature that costs the consumer less (based on energy price) to maintain is selected as the actual temperature that is implemented by the HVAC system.

Thus, in this example shown inFIG. 4(which assumes that the HVAC system is performing a cooling function), note that the setpoint temperatures implemented in time interval703for prices ranging from medium (M) to critical (C) are ignored in favor of the Energy Star recommended temperature of 85 degrees. This is due to the comparison described above. Thus, the HVAC system will operate at the Energy Star recommended temperatures in time interval703despite the lower setpoint temperatures that were selected by the consumer for medium through critical pricing. Note also that the above-described comparison in time intervals704-1and704-2works in favor of the setpoint temperatures (81 and 80 degrees, respectively) since they are higher than the Energy Star recommended temperature (77 degrees), and thus would cost the consumer less to implement.

FIG. 8illustrates a temperature control schedule800, according to another embodiment of the invention, that implements the same comparison as described above for schedule700. Except, in schedule800, it is assumed that the consumer selected different setpoint temperatures for high (H) and critical (C) energy prices. So, time intervals801,802,803-1,803-3,804-2,804-3and805operate the same as time intervals701,702,703-1,703-3,704-2,704-3and705, as a result of the comparison operation. However, note that when the setpoint for the critical energy price (87 degrees) is higher than the Energy Star recommended temperature (85 degrees) in time interval803-2, the setpoint is selected. The same occurs in time interval804-1where setpoint of 84 degrees is selected over the Energy Star recommended temperature of 77 degrees.

FIG. 9is a diagram of a user interface900associated with the temperature control schedule ofFIG. 5. User interface900is where the consumer is able to select and enter temperature offsets based on energy price levels, as explained above. By way of example, user interface900can be part of one or more elements of HVAC system100(FIGS. 1 and 2) and/or energy management system300(FIG. 3), e.g., controller104, thermostat150, user interface170, display172, HEG304, computer306, thermostat314i, etc.

As shown, the user interface900comprises several features for presenting the consumer with options and information and for allowing the consumer to enter selections and other information. For example, user interface900has an information section902, a rate level section904, a cool adjustment section906, a heat adjustment section908, a cancel button910, and a done button912. Information section902indicates to the consumer that the thermostat can adjust the scheduled temperature based on the utility rate (energy price level), but such temperature adjustments will only occur if energy savings can be achieved, as explained above. Then, the consumer can view the rate levels (column904) and the default temperature offsets (column906for cooling system and column908for heating system), and decide to cancel (button910) or accept (button912) the settings. Note that, as implemented in the examples above, the low price level does not have an offset but rather implements a schedule (e.g., Energy Star recommended schedule). Features can be added to the user interface900to allow the consumer to enter other offsets. This can include, but is not limited to, increase/decrease icons and/or text entry fields.

FIG. 10is a diagram of a user interface1000, according to an embodiment of the invention. For example, user interface1000can be used in association with the temperature control schedules shown inFIGS. 7 and 8. User interface1000is an example of where the consumer is able to select and enter temperature setpoints based on energy price levels, as explained above. As with user interface900, user interface1000can be part of one or more elements of HVAC system100(FIGS. 1 and 2) and/or energy management system300(FIG. 3), e.g., controller104, thermostat150, user interface170, display172, HEG304, computer306, thermostat314i, etc.

As shown, the user interface1000comprises several features for presenting the consumer with options and information and for allowing the consumer to enter selections and other information. For example, user interface1000has an information section1002, a rate level section1004, a cool adjustment section1006, a heat adjustment section1008, an opt-out section1010, a cancel button1012, and a done button1014. Information section1002indicates to the consumer that the thermostat can adjust the scheduled temperature based on the utility rate (energy price level), but such temperature adjustments will only occur if energy savings can be achieved, as explained above. Also, the information section explains that the consumer can select one or more price levels for which they can opt out of the selected setpoint temperature and opt for a schedule (e.g., Energy Star recommended schedule). This is done by selecting one or more of the selection features in column1010. The consumer can view the rate levels (column1004) and the default temperature setpoints (column1006for cooling system and column1008for heating system), and decide to cancel (button1012) or accept (button1014) the settings. Note that, as implemented in the examples above, the low price level does not have an offset but rather implements a schedule (e.g., Energy Star recommended schedule). Also, note that selection features are provided to allow the consumer to enter other setpoints, e.g., increase/decrease icons as shown. However, text entry fields or other input features can be implemented as an alternative.

FIG. 11is a diagram of a temperature control methodology1100, in accordance with an embodiment of the invention. In this illustrative embodiment, it is assumed that the environment in which the temperature is being controlled includes an energy management system300(FIG. 3) including computer306which is in communication with HEG controller304. It is also assumed that the computer306is running an application that enables it to access and utilize energy management features and functions associated with HEG304. In one illustrative embodiment, the energy management application that is executed by the computer is referred to as a Nucleus™ application (a trademark of General Electric Corporation of Fairfield, Conn.). HEG304may also be referred to as a Nucleus™ or Nucleus™ Energy Manager.

The methodology begins at block1102. In step1104, the customer (consumer or user) opens the Nucleus™ application running on computer306. In step1106, the Nucleus™ application gets price/temperature settings (setpoints or offsets) which were stored in the memory of the thermostat150. In step1108, the customer reviews the price/temperature settings. If he/she is not satisfied with the settings (step1110), the customer modifies the settings in step1112. In step1114, the Nucleus™ application sends the modified settings to the thermostat150, and the methodology ends at block1116. If the customer is satisfied with the settings in step1110, then the methodology ends at block1116.

FIG. 12is a diagram of a temperature control methodology1200, in accordance with another embodiment of the invention. In this methodology, as compared to the one inFIG. 11, it is assumed that the customer uses the thermostat user interface170menu to access the price/temperature settings. Thus, the methodology begins at block1202. The customer displays the settings in step1204. In step1206, the customer reviews the price/temperature settings. If he/she is not satisfied with the settings (step1208), the customer modifies the settings in step1210. In step1212, the thermostat150sends the modified settings to the Nucleus™ application, and the methodology ends at block1214. If the customer is satisfied with the settings in step1208, then the methodology ends at block1214.

FIG. 13is a diagram of a temperature control methodology1300, in accordance with yet another embodiment of the invention. This methodology illustrates steps performed a controller in the HVAC system (e.g., controller104, HEG304, etc.) when there is a change to a setpoint temperature.

The methodology begins at block1302. Step1304detects whether or not there has been a price change (this may be determined from information received via signal108(FIG. 1). If not, step1306determines whether or not there has been a thermostat schedule change (i.e., if at this time, the schedule is supposed to change setpoints, for example, 8:00 inFIG. 11). If no, then step1308directs the system to maintain the current setpoint(s). However, if in step1304a price change has been detected, or in step1306a temperature schedule change has been detected, then a determination is made in step1310as to what mode the system is in, i.e., heating mode or cooling mode.

If in cooling mode, step1312determines whether the price temperature value (setpoint or offset) results in a temperature that is greater than a schedule temperature (e.g., Energy Star recommended temperature). If yes, then the price temperature value is used as the setpoint (rather than Energy Star recommended temperature) in step1314, else the schedule temperature is used in step1316. Returning to the decision step1310, if the system is in the heating mode, step1318determines whether the price temperature value (setpoint or offset) results in a temperature that is greater than a schedule temperature (e.g., Energy Star recommended temperature). If no, then the price temperature value is used as the setpoint (rather than Energy Star recommended temperature) in step1314, else the schedule temperature is used in step1316. The methodology then iterates for any subsequent price or thermostat schedule changes.