System and method for performing building energy management

Abstract

A method for performing energy management for a building includes generating an energy load stack representing a plurality of building energy loads. The energy loads are prioritized from the highest priority energy load to the lowest priority energy load. The prioritized energy load is then compared to a building power threshold. The lowest priority energy load is switched off until the sum of the remaining energy loads is equal to or less than the building power threshold. And the remaining energy load is served. The processes of prioritizing the energy load, comparing the prioritized energy load to a building power threshold, and switching off the lowest priority energy load are repeated in response to a change in the situation affecting the building.

Description

[0001] This application is a divisional application of an application with a filing date of January 2, 2018, application number 201810002122.2, and invention name “System and method for performing building energy management”. Technical Field

[0002] The present application relates generally to energy management and, more particularly, but not exclusively, to systems and methods for performing building energy management. Background Art

[0003] Energy management of various types, such as building energy management, remains an interesting area. Some existing systems have various shortcomings, deficiencies, and weaknesses with respect to certain applications. For example, in some building energy management systems, a large amount of processing resources are required for implementation. Thus, further contributions are still needed in this area of ​​technology. Summary of the invention

[0004] One embodiment of the present invention is a unique method for performing energy management for a building. Another embodiment is a unique building energy management system for managing energy usage of a building. Other embodiments include devices, systems, equipment, hardware, methods and combinations for performing building energy management. Additional embodiments, forms, features, aspects, benefits and advantages of the present application will become apparent from the description and drawings provided herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The description herein is made with reference to the accompanying drawings, wherein like reference numerals refer to like parts throughout the several views, and wherein:

[0006] Figure 1 Some aspects of a non-limiting example of a building with electrical loads and a building energy management system according to embodiments of the present invention are schematically illustrated.

[0007] Figure 2 Some aspects of a non-limiting example of building loads arranged by priority in a stack at two different times in accordance with an embodiment of the present invention are illustrated.

[0008] Figure 3 Some aspects of a non-limiting example of building loads arranged by priority in a stack at two different times in accordance with an embodiment of the present invention are illustrated. DETAILED DESCRIPTION

[0009] For the purpose of promoting understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the accompanying drawings, and specific language will be used to describe these embodiments. However, it will be appreciated that it is not intended to limit the scope of the present invention thereby. Any changes and further modifications to the described embodiments and further applications of the principles of the present invention described herein are contemplated as those skilled in the art to which the present invention relates will generally be expected.

[0010] refer to Figure 1 , illustrates some aspects of a non-limiting example of a building energy management system 10 for managing energy usage of a building 12 having a plurality of electrical loads 14, according to embodiments of the present invention. In some embodiments, the building energy management system 10 may be part of a building automation system. The electrical loads 14 may be or include any electrical load associated with or controlled by a building or group of buildings, such as one or more lighting systems, appliances, computers, servers and related systems, HVAC systems, and / or any type of electric machine. Figure 1 The number and type of electrical loads 14 in the system may vary with the needs of the building and application. Each electrical load 14 may represent a single load or a cluster of loads.

[0011] The power flow to each electrical load 14 is controlled by a switch element 16. The switch element 16 may be, for example, a circuit breaker, a contactor, a relay and / or a thermostat or other HVAC (heating, ventilation and / or air conditioning) system control element. In various embodiments, the switch element may be, for example, juxtaposed in a common housing, or may be distributed at various locations. The switch element 16 is operable to control the power flow to the electrical load 14, for example, by turning the electrical load 14 on and off. In some embodiments, the building 12 may include one or more thermal zones or other HVAC zones 18, for example, a room or a group of rooms or other spaces / volumes within the building, where the temperature, humidity and / or ventilation is handled or supplied by the electrical load 14 in the form of an HVAC load, where the power flow to the HVAC system is controlled by adjusting the set point on the switch element 16 in the form of a thermostat, a humidistat and / or other HVAC control device from a normal setting to a reduced power setting. The normal setting or set point is the set point normally employed for an HVAC load when no attempt is made to reduce power to meet a building power threshold by shedding the HVAC load, while the reduced power setting or set point is the set point used when reducing power to meet a building power threshold by shedding the HVAC load. For example, HVAC loads may be shedding by lowering the temperature set point in winter months or raising the temperature set point in summer months. Some embodiments may include more than one reduced power set point level.

[0012] The system 10 includes a controller 20 and a memory 22 associated therewith. The controller 20 communicates with the electrical load 14, in particular with the switch element 16. In one form, the controller 20 communicates with the switch element 16 via a network 24. In other embodiments, the controller 20 can communicate directly or indirectly with the switch element 16 with or without the use of a network. In one form, the network 24 is a Wi-Fi network. In other embodiments, the network 24 can be a local area network, a control area network, the Internet, or any suitable wired and / or wireless network protocol and structure. In some embodiments, one or more switch elements 16 are constructed for direct network connection. Some embodiments may include one or more gateways 26 for coupling one or more switch elements to the network 24 and the controller 20.

[0013] refer to Figure 2 In some embodiments, the building loads 14 are arranged according to a priority list or stack 32, and power thresholds are defined, such as normal power thresholds used in the absence of a demand response signal (described below). Figure 2 The electrical load 14 and its characteristics illustrated in the drawings are by way of non-limiting example only and do not necessarily reflect Figure 1 An electrical load 14 is shown. Figure 2 The electrical loads 14 include critical loads, priority load 1, priority load 2, load 1, load 2, load 3, and optional loads. Figure 2 The loads at time T1 and time T2 are illustrated in FIG. In some embodiments, the vertical height of each particular load represents the size of the load, which may change over time. The loads are arranged in order of importance, with the most important and therefore highest priority loads at the bottom of the stack 32, and the lowest priority loads at the top of the stack, with the priority of a particular load being given by the relative position of the load in the stack, with the priority decreasing with height from the bottom of the stack. The assigned importance and therefore priority is in Figure 2 The power is gradually reduced in an upward direction to the least important and therefore lowest priority load at the top of the stack 32. According to some embodiments, loads above the power threshold are cut off or disconnected. It is understood that Figure 2 The stack depiction of is by way of example only, and other representations of the load stack may be employed in other embodiments.

[0014] Various embodiments include methods and systems for controlling a building energy management system, which in some embodiments includes responding to a demand response signal from a utility (e.g., a grid utility). The building energy management system 10 is operable to change a building power threshold based on a demand response signal received from an electric utility. For example, the building energy management system 10 can be coupled to a utility demand response program 28 via, for example, the Internet 30. One or more demand response signals can be received from a utility (e.g., a demand response program 28) that can be used to set a power threshold, for example, a power threshold that is reduced relative to a normal power threshold that is used in the absence of a demand response signal. Thus, some embodiments employ dynamic power thresholds based on demand response signals. Upon receiving a demand response event signal from a utility (e.g., from a demand response program 28), a new demand response power threshold is set, for example, based on a pre-programmed value provided by a user and negotiated with the utility. Any load that increases the total building power above the new threshold will cause one or more loads above the threshold to be cut off or disconnected based on priority, while during normal operation without a demand response signal, only loads above the normal threshold are cut off or disconnected. In various embodiments, when total building power consumption exceeds a threshold currently being supplied, loads are shelved in ascending order of priority (i.e., loads are shelved starting with the lowest priority loads). When building power consumption drops below a threshold (either because the threshold is raised or the power consumption level is reduced, or both), previously shelved loads are restored in descending order of priority (i.e., previously shelved loads that are most important or have the highest priority are restored first) in a manner complementary to load shedding. In some embodiments, in addition to or in lieu of electrical loads, other energy loads may be shelved and restored as described herein, for example, natural gas loads (e.g., natural gas powered systems and equipment) or loads powered by other energy sources such as oil or other liquid fuels.

[0015] Figure 2 Illustrated are power threshold 34 and power threshold 36. In one form, power threshold 34 is a normal power threshold and power threshold 36 is a reduced power threshold set in response to a request from demand response program 28. The normal power threshold is a power threshold that is typically adopted by, for example, an owner or operator of building 12, such as generally or, for example, based on an agreement with an electric utility regarding the average power consumption of building 12, in order to control the power consumption of building 12. Power threshold 36 is a reduced threshold relative to power threshold 34 that is used in response to demand response program 28.

[0016] If the power at the input to the building exceeds the power threshold, the loads are cut off or disconnected sequentially, e.g., from lowest priority to highest priority, until, for example, the power consumption of the remaining electrical loads is equal to or less than the power threshold. As described above, the building power threshold can be adjusted, for example, based on input from a utility. For example, the power threshold 34 can be reduced to one or more power values, e.g., power threshold 36, in response to a utility signal indicating a demand response event, which can enable a building owner or operator to participate in a demand response program to potentially improve the stability of the network during peak loads in some embodiments while minimizing discomfort experienced by building occupants, e.g., as described herein. After the demand response event ends, the power threshold can be restored to an initial value (e.g., power threshold 34) or other value.

[0017] Once the loads are prioritized, the energy usage of the building is managed by the application of a power threshold, such as power threshold 34 (or power threshold 36 when a demand response signal is received). In one non-limiting example, the building power is measured, and if the building power exceeds the threshold, the lowest priority load (e.g., the top-most load in the stack) is disconnected by opening the circuit breaker serving the load or by another disconnection procedure such as described herein, and the building power is measured again. If the power threshold is still exceeded, the next lowest priority load is disconnected, and the process is repeated until the building power no longer exceeds the threshold. In other embodiments, other methods may be used to disconnect loads to achieve building power usage at or below the power threshold.

[0018] refer to Figure 2 , at time T1, the power supplied to the electrical loads in the stack 32 is below the power threshold 34, and therefore, the application of the power threshold 34 does not result in the disconnection of any load. However, if the power threshold 36 is achieved in response to a signal received from the demand response program 28 at the controller 20, the electrical loads 14 labeled as load 2, load 3, and optional loads will have to be disconnected in order to maintain below the power threshold 36. At time T2, the power usage of the building is greater, and therefore load 3 and optional loads will have to be disconnected in order to maintain below the power threshold 34. However, if the power threshold 36 is achieved at time T2, for example, in response to a signal received from the demand response program 28 at the controller 20, the electrical loads 14 labeled as load 1, load 2, load 3, and optional loads will have to be disconnected in order to maintain below the power threshold 36.

[0019] In some embodiments, loads are dynamically prioritized, where the prioritization of a stack (e.g., stack 32) changes, for example, in response to a change in conditions affecting the building. Examples of changes in conditions affecting the building may include, for example, but are not limited to, changes in occupancy, such as a previously occupied HVAC zone 18 becoming unoccupied, or experiencing a decrease or increase in occupancy, or where a previously unoccupied HVAC zone 18 becomes occupied. For example, changes in occupancy may be indicated to the controller 20 via sensors located in different thermal zones, such as proximity sensors or temperature sensors (not shown), or may be indicated by an occupant turning on a light or computer or appliance, or may be indicated manually by a building manager or owner or operator. Changes in HVAC zone occupancy may affect the priority given to electrical loads 14 in the form of heat or other HVAC loads, and in some embodiments, may affect the priority given to other loads such as lighting loads. As another example, a critical or high priority machine or device may be turned on, thereby changing the current priority scheme. In some embodiments, the passage of time, such as a period of time, may be considered a change in conditions affecting the building.

[0020] In some embodiments, heat or other HVAC loads may be shut off by adjusting heat or other HVAC set points. For example, some of electrical loads 14 include HVAC loads for HVAC zones 18. Each HVAC zone is regulated by a thermostat, humidistat, and / or other HVAC control device that affects the HVAC heating, ventilation, and / or cooling of that zone. The effect may be, for example, in the following aspects: adjusting the state of a damper, increasing or decreasing a fan speed, or changing the temperature of a heating or cooling element, or changing the output of a humidifier or dehumidifier. Each HVAC zone may be considered a load in a load priority stack. These loads may be dynamically adjusted, for example, according to the process described herein.

[0021] In one form, the occupancy rate and historical temperature data of each HVAC zone 18 are measured. The historical temperature data is used to calculate the temperature change rate. The HVAC zone 18 is then divided into, for example, two bins: occupied and unoccupied. All occupied zones are assigned a higher priority than all unoccupied zones. If a previously unoccupied HVAC zone 18 becomes occupied, its priority is increased, and if a previously occupied HVAC zone 18 becomes unoccupied, its priority is reduced. In some embodiments, the priority can also vary with occupancy. For example, an HVAC zone 18 with a larger number of occupants may have a higher priority than an HVAC zone 18 with a smaller number of occupants, or its priority may increase when the occupancy rate increases, or decrease when the occupancy rate decreases. In each zone, the priority is determined by the rate of change of temperature or other comfort parameters, such as humidity or ventilation level. The priority assigned to a given electrical load for an HVAC zone 18 increases with the increase in the rate of change of temperature. For example, electrical loads 14 associated with an HVAC zone 18 having a higher rate of change of temperature (or other parameter, such as rate of change of humidity) are considered to have a higher priority than electrical loads 14 associated with an HVAC zone 18 having a lower rate of change of temperature. This is because if HVAC service to a zone with a lower rate of change is interrupted, the occupants of the zone with the lower rate of change are expected to experience less discomfort because the temperature or other parameter change in that zone will take longer. The higher rate of change may correspond to, for example, rooms on the side of a building that is exposed to sunlight in the summer, rooms with a larger number of occupants, or rooms with relatively few or weaker insulation. All of these conditions are associated with rooms where the occupants may be expected to optimize HVAC activity and ensure comfort.

[0022] Once the priorities of the thermal zones are determined, the priority stack is adjusted to reflect the new priorities. In some embodiments, the adjustment of the priority stack can be continuous in response to changes in the situation (e.g., occupancy, temperature change rate, or other parameters), for example, where the priorities change when the situation changes. In other embodiments, the priorities can be updated based on periodicity or otherwise. Unoccupied zones and zones with low temperature change rates or low another parameter are moved toward the top of the stack and are therefore cut off first when needed to meet a power threshold. The cutoff can be, for example, as described herein.

[0023] refer to Figure 3 , illustrates some aspects of a non-limiting example of a load stack 40 at times T3 and T4 according to an embodiment of the present invention. Figure 2In the manner described, the building loads 14 are arranged according to a priority list or stack 40 , with the highest priority loads at the bottom of the stack 40 and the lowest priority loads at the top of the stack 40 . Figure 3 The illustrated electrical loads 14 and their characteristics are by way of non-limiting example only and do not necessarily reflect Figure 1 and Figure 2 An electrical load 14 is shown.

[0024] Figure 3 The electrical loads 14 include critical loads, priority load 1, priority load 2, HVAC load 1, HVAC load 2, HVAC load 3, HVAC load 4, HVAC load 5, and HVAC load 6. In some embodiments, the vertical height of each load represents the size of the load. The loads are arranged according to importance, with the most important and therefore highest priority loads at the bottom of the stack 32. The assigned importance and therefore priority is in Figure 3 The loads are gradually reduced in an upward direction to the least important and therefore lowest priority loads at the top of the stack 40. According to some embodiments, loads above a power threshold are switched off or disconnected. Figure 3 Power threshold 42 and power threshold 44 are illustrated. In one form, power threshold 42 is a normal power threshold, e.g., a power threshold normally used for the building in the absence of a demand response signal; and power threshold 44 is a reduced power threshold set in response to a demand response signal from demand response program 28.

[0025] At time T3, application of power threshold 42 will result in the shutoff of HVAC loads 6, portions of which are above threshold 42. If power threshold 44 is achieved in response to a signal received from demand response program 28 at controller 20, electrical loads 14 labeled HVAC load 4, HVAC load 5, and HVAC load 6 will have to be shut off in order to remain below power threshold 44. At time T4, the power usage of the building is slightly greater than at time T3, and is still greater than power threshold 42. At time T4, the HVAC loads have been prioritized differently than at time T3 due to changes in occupancy in HVAC zones 18 corresponding to HVAC loads 3 and HVAC load 6, which have moved to the lowest priority position after dynamic re-prioritization. If power threshold 44 is achieved, for example, in response to a signal received from demand response program 28 at controller 20, electrical loads 14 labeled HVAC load 3 and HVAC load 6 will have to be shut off in order to remain below power threshold 44.

[0026] Load shedding for HVAC loads can be achieved by the building automation system in one or more ways. For example, in some embodiments, each HVAC zone 18 has at least two schedules for HVAC load devices. These schedules can define set points for thermostats, humidistats and / or other HVAC control devices, water cooling or heating difficulty, fan speed, etc. The first schedule is for normal operation, and the second schedule is for load shedding operation. The third schedule can shut down the HVAC load or device altogether, or can operate the device at some intermediate level. Each schedule can be defined by a user (e.g., a building manager), and the load shedding schedule is selected so as to use less power than the normal schedule while still preventing the HVAC zone 18 from becoming extremely uncomfortable. In other embodiments, for example, in addition to or as an alternative to adjusting the set points of thermostats, humidistats and / or other HVAC control devices, water cooling or heating temperature, fan speed, etc., other processes can be used to shear off the HVAC load.

[0027] In some embodiments, one or more HVAC zones 18 may have a gateway 26 that associates a binary signal with two schedules. If the signal is false, the normal schedule is used, while a true signal switches the zone to a load shedding schedule. In some embodiments, the binary signal may be set by an energy management function, which may be in an external device (and thus communicate with the building automation system over a communications network) or in an internal program (in which case the signal value is set by an energy management program within the building automation system).

[0028] The controller 20 is configured and operable to execute program instructions stored in the memory 22 to manage the energy usage of the building 12, i.e., to manage the electrical loads 14. In one form, the controller 20 executes the program instructions to generate a stack of electrical loads representing a plurality of building electrical loads, e.g., similar to the corresponding Figure 2 and Figure 3, and prioritize electrical loads, for example, by degree of importance. In some embodiments, prioritization may be based on input provided through a user interface. In some embodiments, prioritization may also be performed, for example, based on a sensed temperature or ambient condition parameter history (e.g., humidity) and based on a sensed or otherwise determined or reported occupancy rate of the HVAC zone 18 (e.g., as described above). The stack extends from the bottom of the stack with the highest priority electrical load to the top of the stack with the lowest priority electrical load. In one form, the controller 20 executes program instructions to compare the prioritized electrical loads to a building power threshold and directs operation of the switching element 16 to cut off the lowest priority electrical load until the sum of the remaining electrical loads (including the HVAC loads) is equal to or less than the building power threshold, and serves the remaining electrical loads, i.e., provides power to each of the electrical loads placed below the threshold, or uses a normal set point or setting of a thermostat, humidistat, and / or other HVAC control device for the HVAC load. This servicing of electrical loads includes restoring a previously disconnected load, i.e., directing the switching element 16 to turn the load back on, or changing from a reduced HVAC set point to a normal HVAC set point for a load that was disconnected in a previous prioritization iteration but was not disconnected in the prioritization of the current iteration, e.g., due to an increase in the priority of the load since the previous iteration, e.g., where the load is an HVAC load and the occupancy of the corresponding building area or thermal zone has increased since the prioritization of the previous iteration. The controller 20 executes program instructions to dynamically repeat the prioritization of the stack, the comparison to the threshold value, and directing the switching element to disconnect and service the load in response to changes in conditions affecting the building (e.g., changes in occupancy in different HVAC zones 18, changes in time of day, changes in solar heating, etc.).

[0029] Some embodiments ensure that building occupants do not experience excessive discomfort when participating in energy management programs. For example, many demand response programs experience low participation rates because users or consumers do not want to turn off their HVAC on particularly hot or cold days. In some embodiments, prioritization assists users in identifying lower priority loads that can be shut off with minimal impact on occupant comfort. Adjusting temperature by changing set points rather than disabling HVAC also helps ensure that occupants will not experience extreme discomfort or dangerous temperature excursions, which can improve adoption rates of building energy management systems and participation rates in demand response programs.

[0030] Some embodiments represent an alternative to highly complex building energy management schemes. Some energy management solutions rely on both thermal models of the buildings being managed and computationally intensive optimization solvers. Optimization solvers require costly, powerful processing units, while building models require extensive effort in research and debugging. The expense and complexity of some building energy management systems slows adoption by building owners.

[0031] Some embodiments overcome the problem of selecting what loads to cut off by arranging them by load priority. The building energy management system will then be able to disconnect or otherwise cut off lower priority loads until the power target is achieved. This automates the system, an improvement over building management intervention. It also ensures that the target power is continuously achieved, an improvement over pre-programmed load shedding schemes. Finally, the target power is dynamic, and it is even possible to have multiple demand response power settings for different scenarios. This is an improvement over existing energy management systems.

[0032] In some embodiments, the rule-based algorithms described herein require little computing power and can be implemented by inexpensive processors. The use of measured temperature changes over time is a simpler and cheaper alternative to building thermal models because it captures all information that would otherwise be generated and used by the model (e.g., zone heat capacity, thermal resistance of walls, the impact of weather effects such as sunlight, etc.) without prior knowledge of building properties.

[0033] Embodiments of the present invention include a method for performing energy management for a building, comprising: (a) generating an energy load stack representing multiple building energy loads; (b) prioritizing the energy load stack from highest priority energy load to lowest priority energy load; (c) comparing the prioritized energy loads to a building power threshold; (d) cutting off the lowest priority energy load until the sum of the remaining energy loads is equal to or less than the building power threshold, and servicing the remaining energy loads; and (e) dynamically repeating steps (b), (c), and (d) in response to changes in circumstances affecting the building.

[0034] In one refinement, the method further includes changing the building power threshold in response to the external signal.

[0035] In one refinement, the building power threshold is varied based on a demand response signal received from the electric utility.

[0036] In another refinement, the building has a plurality of thermal zones; and at least some of the energy loads are HVAC (heating, ventilation, and / or air conditioning) loads corresponding to the plurality of thermal zones.

[0037] In yet another refinement, each thermal zone has an HVAC set point; and the HVAC load for each thermal zone is shelved by adjusting the HVAC set point.

[0038] In yet another refinement, occupied thermal zones are assigned a higher priority than unoccupied thermal zones.

[0039] In a further refinement, the method further includes determining a rate of temperature change of the plurality of thermal zones, wherein each thermal zone in the plurality of thermal zones is assigned a priority based on the rate of temperature change of each thermal zone.

[0040] In another refinement, the assigned priority increases as the temperature change increases.

[0041] Embodiments of the present invention include a building energy management system for managing energy use in a building having multiple energy loads, comprising: a plurality of switch elements corresponding to the multiple energy loads, each switch element being operable to control power flow to the corresponding energy load; a controller and an accessible memory, the controller communicating with the plurality of switch elements, wherein the controller is configured to execute program instructions stored in the memory to manage energy use in the building by performing the following actions: (a) generating an energy load stack representing multiple building energy loads; (b) prioritizing the energy load stack from the highest priority energy load to the lowest priority energy load according to a degree of importance; (c) comparing the prioritized energy loads with a building power threshold; (d) directing operation of the plurality of switch elements to cut off the lowest priority energy load until the sum of the remaining energy loads is equal to or less than the building power threshold, and serving the remaining energy loads; and (e) dynamically repeating steps (b), (c) and (d) in response to changes in circumstances affecting the building.

[0042] In one refinement, the system further includes a gateway coupling at least one of the switching elements to the controller.

[0043] In another refinement, the system further includes a network, wherein the controller communicates with the switching element via the network.

[0044] In yet another refinement, the building energy management system is operable to vary the building power threshold based on a demand response signal received from the electric utility.

[0045] In yet another refinement, the building has a plurality of thermal zones; and at least some of the energy loads are HVAC (heating, ventilation, and / or air conditioning) loads corresponding to the plurality of thermal zones.

[0046] In yet another refinement, each thermal zone has an HVAC set point; and wherein the HVAC load for each thermal zone is shelved by adjusting the HVAC set point.

[0047] In a further refinement, occupied thermal zones are assigned a higher priority than unoccupied thermal zones.

[0048] In yet another refinement, the controller is configured to execute program instructions stored in the memory to manage energy usage of the building by determining a rate of temperature change for each of the thermal zones, wherein each thermal zone is assigned a priority based on the rate of temperature change for each thermal zone.

[0049] In yet another refinement, the assigned priority increases as the rate of temperature change increases.

[0050] Embodiments of the present invention include a method for performing energy management for a building, comprising: (a) generating an energy load stack including HVAC loads corresponding to multiple HVAC (heating, ventilation and / or air conditioning) zones of the building; (b) prioritizing the energy load stack from highest priority energy loads to lowest priority energy loads; (c) comparing the prioritized energy loads to a building power threshold; (d) disconnecting each of the lowest priority HVAC loads positioned above the threshold and servicing each of the HVAC loads positioned below the threshold by adjusting an HVAC switching element set point; and (e) dynamically repeating steps (a), (b), (c) and (d) in response to changes in conditions affecting the building.

[0051] In one refinement, occupied HVAC zones are assigned a higher priority than unoccupied HVAC zones.

[0052] In another refinement, the method further includes determining a rate of change of comfort parameters for the plurality of HVAC zones, wherein each HVAC zone is assigned a priority based on the rate of change of the comfort parameter for each HVAC zone, and wherein the assigned priority increases as the rate of change of the comfort parameter increases.

[0053] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, it should be regarded as illustrative rather than restrictive in nature, and it is understood that only preferred embodiments are shown and described, and all changes and modifications made within the spirit of the present invention are expected to be protected. It should be understood that although the use of words such as preferred, preferably, preferred or more preferred used in the above description indicates that the features described in this way may be more desirable, it may not be necessary, and embodiments lacking these features can be regarded as within the scope of the present invention, that is, the scope defined by the appended claims. When reading the claims, when words such as "one", "an", "at least one" or "at least a portion" are used, it is not intended to limit the claims to only one item, unless there is a clear statement to the contrary in the claims. When the language "at least a portion" and / or "a portion" is used, the item may include a portion of the item and / or the entire item, unless there is a clear statement to the contrary.

[0054] Unless otherwise specified or limited, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and include direct and indirect mountings, connections, supports, and couplings. Additionally, "connected" and "coupled" are not limited to physical or mechanical connections or couplings.

Claims

1. A method for performing energy management for a building, comprising: (a) generating an energy load stack representing a plurality of building energy loads being powered, the plurality of building energy loads including a plurality of thermal zones corresponding to a plurality of heating, ventilation, and / or air conditioning (HVAC) loads, wherein each of the plurality of HVAC loads is operable according to a first schedule, a second schedule, or a third schedule, the first schedule being for normal operation of the HVAC load, the second schedule being for load shedding operation and using less power than the first schedule, and the third schedule being for operation to shut down the HVAC load; (b) prioritizing each building energy load in the plurality of building energy loads in the energy load stack from a highest priority energy load to a lowest priority energy load, wherein prioritizing each building energy load comprises: determining a rate of change of a parameter of each of the plurality of thermal zones, and assigning a priority to each thermal zone based on a rate of change of a parameter of each thermal zone, the assigned priority increasing as the rate of change of the parameter increases; (c) in response to a demand signal, comparing a power consumption magnitude of a plurality of building energy loads in the energy load stack to a reduced building power threshold, the reduced building power threshold being less than a normal building power threshold; (d) upon determining that the power consumption magnitude of the plurality of building energy loads in the energy load stack exceeds the reduced building power threshold, disconnecting the lowest priority energy load in the energy load stack until the power consumption magnitude of the plurality of building energy loads in the energy load stack is equal to or less than the reduced building power threshold, the disconnecting comprising adjusting the lowest priority HVAC load from operating according to a first schedule to operating according to a second schedule; (e) in response to detecting activation of a critical load while the building power threshold is at the reduced building power threshold, re-prioritizing a plurality of building energy loads in the energy load stack from a highest priority energy load to a lowest priority energy load; (f) based on reordering the priorities of the plurality of building energy loads in the energy load stack, disconnecting the lowest priority energy load from the energy load stack until the power consumption magnitude of the plurality of building energy loads in the energy load stack is equal to or less than the reduced building power threshold; and (g) dynamically repeating steps (b), (c) and (d) in response to changes in conditions affecting the building.

2. The method according to claim 1, further comprising: In response to a demand response signal, the building power threshold is changed to the reduced building power threshold.

3. The method according to claim 2, wherein: The demand response signal is received from an electric utility.

4. The method according to claim 1, wherein: Each HVAC load at each corresponding thermal zone has an HVAC set point; and wherein each HVAC load is shut off by adjusting the HVAC set point. The method of claim 1 , wherein an occupied thermal zone is assigned a higher priority than an unoccupied thermal zone.

6. The method of claim 1 , wherein determining a rate of change of a parameter of each of the plurality of thermal zones further comprises: determining a rate of change of temperature of the plurality of thermal zones, Wherein each thermal zone of the plurality of thermal zones is assigned a priority based on a rate of change of a temperature of each thermal zone.

7. The method according to claim 6, wherein: The assigned priority increases as the rate of change of temperature increases.

8. The method of claim 1 , wherein determining a rate of change of a parameter of each of the plurality of thermal zones further comprises: determining a rate of change of humidity in the plurality of thermal zones, Wherein each thermal zone of the plurality of thermal zones is assigned a priority based on a rate of change of humidity in each thermal zone.

9. The method according to claim 8, wherein: The assigned priority increases as the rate of change of humidity increases.

10. The method of claim 1, wherein determining the rate of change of a parameter of each of the plurality of thermal zones further comprises: determining a rate of change of ventilation levels for the plurality of thermal zones, Each thermal zone in the plurality of thermal zones is assigned a priority based on a rate of change of ventilation level of each thermal zone.

11. The method according to claim 10, wherein: The assigned priority increases as the rate of change of ventilation level increases.

12. A building energy management system for managing energy usage of a building, the building energy management system comprising a plurality of energy loads, the plurality of energy loads comprising a plurality of thermal zones corresponding to a plurality of heating, ventilation and / or air conditioning (HVAC) loads, the building energy management system comprising: a plurality of switch elements corresponding to the plurality of energy loads, each switch element operable to control power flow to a corresponding energy load; A controller and a memory accessible thereto, the controller being in communication with the plurality of switching elements, wherein the controller is configured to execute program instructions stored in the memory to manage energy usage of the building by performing the following actions: (a) generating an energy load stack representing the energy loads of a plurality of buildings, wherein each of the plurality of HVAC loads is operable according to a first schedule, a second schedule, or a third schedule, the first schedule being for normal operation of the HVAC load, the second schedule being for load shedding operation and using less power than the first schedule, and the third schedule operating to shut down the HVAC load; (b) prioritizing each building energy load in the plurality of building energy loads in the energy load stack from a highest priority energy load to a lowest priority energy load, wherein prioritizing each building energy load comprises: determining a rate of change of a parameter of each of the plurality of thermal zones, and assigning a priority to each thermal zone based on a rate of change of a parameter for each thermal zone, the assigned priority increasing as the rate of change of the parameter increases; (c) in response to a demand signal, comparing a power consumption magnitude of a plurality of building energy loads in the energy load stack to a reduced building power threshold, the reduced building power threshold being less than a normal building power threshold; (d) upon determining that the power consumption magnitude of the plurality of building energy loads in the energy load stack exceeds the reduced building power threshold, directing operation of the plurality of switch elements to disconnect the lowest priority energy load in the energy load stack until the power consumption magnitude of the plurality of building energy loads in the energy load stack is equal to or less than the reduced building power threshold, the disconnection comprising adjusting the lowest priority HVAC load from operating according to a first schedule to operating according to a second schedule; (e) in response to detecting activation of a critical load while the building power threshold is at the reduced building power threshold, re-prioritizing a plurality of building energy loads in the energy load stack from a highest priority energy load to a lowest priority energy load; (f) based on reordering the priorities of the plurality of building energy loads in the energy load stack, disconnecting the lowest priority energy load from the energy load stack until the power consumption magnitude of the plurality of building energy loads in the energy load stack is equal to or less than the reduced building power threshold; and (g) dynamically repeating steps (b), (c) and (d) in response to changes in conditions affecting the building.

13. The building energy management system according to claim 12, further comprising: A gateway is included that couples at least one of the switching elements to the controller.

14. The building energy management system of claim 12, further comprising: A network, wherein the controller communicates with the switching element via the network.

15. The building energy management system according to claim 12, wherein: The building energy management system is operable to change the building power threshold to a reduced building threshold based on a demand response signal received from an electric utility.

16. The building energy management system according to claim 12, wherein: Each HVAC load at each corresponding thermal zone has an HVAC set point; and wherein each HVAC load is shut off by adjusting the HVAC set point.

17. The building energy management system of claim 12, wherein occupied thermal zones are assigned a higher priority than unoccupied thermal zones.

18. The building energy management system of claim 12, wherein determining the rate of change of the parameter for each thermal zone further comprises: A rate of change of the temperature of the plurality of thermal zones is determined, and each thermal zone of the plurality of thermal zones is assigned a priority based on the rate of change of the temperature of each thermal zone.

19. The building energy management system of claim 18, wherein determining the rate of change of the parameter for each thermal zone further comprises: A rate of change of humidity of the plurality of thermal zones is determined, and each thermal zone of the plurality of thermal zones is assigned a priority based on the rate of change of humidity of each thermal zone.

20. The building energy management system of claim 19, wherein determining the rate of change of the parameter for each thermal zone further comprises: A rate of change of ventilation levels of the plurality of thermal zones is determined, and each thermal zone of the plurality of thermal zones is assigned a priority based on the rate of change of ventilation level of each thermal zone.

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