US-12624854-B1 - HVAC systems with start time optimization

Abstract

A heating, ventilating, or air conditioning (HVAC) system that operates equipment to affect a physical property of an environment. The HVAC system obtains schedules including two time periods during which a criterion for the physical property of a environment is to be satisfied (for example, occupied time periods) and a third time period occurring between the two time periods during which the criterion need not be satisfied (for example, unoccupied time periods). The HVAC system performs one prediction of the physical property forward from the end of the middle time period and one prediction backward from the last of the three time periods to determine a transition period during the second time period within which to operate the equipment by finding an intersection of the predictions. The HVAC system controls the equipment during the transition time period to satisfy the criterion at the beginning of the last time period.

Inventors

• Michael J. Risbeck
• Camille M. Aucoin
• Benjamin J. Sveum
• Christopher R. Amundson
• Matthew J. Asmus

Assignees

• TYCO FIRE & SECURITY GMBH

Dates

Publication Date

20260512

Application Date

20250103

Claims (20)

1. 1 . A heating, ventilating, or air conditioning (HVAC) system that operates HVAC equipment to affect at least one physical property of an environment of a building zone, the HVAC system comprising: one or more memory devices having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to perform operations comprising: obtaining a schedule for the environment comprising at least (i) a first time period and a third time period during which a criterion for the at least one physical property of the environment is to be satisfied and (ii) a second time period occurring between the first time period and the third time period and during which the criterion for the at least one physical property of the environment need not be satisfied; determining a transition time during the second time period at which to start pre-conditioning the environment based on an intersection of (i) a first timeseries comprising predicted values of the physical property when the HVAC equipment are operated in a first control mode during the second time period and satisfying the criterion at a beginning of the third time period, wherein the first timeseries is initialized at the beginning of the third time period and determined by backward simulation using a thermal model of the building zone and (ii) a second timeseries comprising predicted values of the physical property when the HVAC equipment are operated in a second control mode during the second time period and satisfying the criterion at an end of the first time period, the intersection defining a temperature-time point at which the predicted values of the physical property in the first timeseries and the second timeseries are equal; and operating the HVAC equipment in the first control mode during a terminal portion of the second time period beginning at the transition time.
2. 2 . The HVAC system of claim 1 , wherein the first control mode comprises controlling the at least one physical property towards a value of a setpoint and the second control mode comprises at least one of: the equipment being off; the equipment not controlling the at least one physical property towards the value of the setpoint; or the equipment not affecting the at least one physical property of the environment.
3. 3 . The HVAC system of claim 1 , wherein the at least one physical property comprises at least one of a temperature, a humidity, or a carbon dioxide level and the environment is a space of a building.
4. 4 . The HVAC system of claim 3 , wherein a form of a first model used to generate the predicted values of the first timeseries or a form of a second model is used to generate the predicted values of the second timeseries chosen based on physical characteristics of the space, wherein the first model is the thermal model of the building zone and predicts the values of the physical property in the first timeseries based on predicted amounts of heat transfer between the building zone and the HVAC equipment when operated in the first control mode.
5. 5 . The HVAC system of claim 4 , further comprising determining parameters of the first model or the second model using at least one of: historical behavior of the environment; a configuration of the equipment; or a manufacturer specification of the equipment.
6. 6 . The HVAC system of claim 5 , the operations further comprising predicting a variable or condition of the building indicative of occupancy and using the prediction of the variable or condition of the building to determine times at which the environment is predicted to be occupied.
7. 7 . The HVAC system of claim 6 , wherein the variable or condition of the building indicative of occupancy is a load for the HVAC equipment.
8. 8 . The HVAC system of claim 1 , wherein the environment was or is predicted to be occupied during the first time period and the third time period and the environment is predicted to be unoccupied during the second time period.
9. 9 . The HVAC system of claim 1 , wherein the criterion is satisfied when the at least one physical property is within a range comprising a target value of the at least one physical property.
10. 10 . The HVAC system of claim 1 , wherein determining the transition time during the second time period based on the first timeseries and the second timeseries comprises determining a time at which the first timeseries and the second timeseries coincide.
11. 11 . A method for controlling HVAC equipment to affect at least one physical property of an environment of a building zone, the method comprising: obtaining a schedule for the environment comprising at least (i) a first time period and a third time period during which a criterion for the at least one physical property of the environment is to be satisfied and (ii) a second time period occurring between the first time period and the third time period and during which the criterion for the at least one physical property of the environment need not be satisfied; determining a transition time during the second time period at which to start pre-conditioning the environment based on an intersection of (i) a first timeseries comprising predicted values of the physical property when the HVAC equipment are operated in a first control mode during the second time period and satisfying the criterion at a beginning of the third time period, wherein the first timeseries is initialized at the beginning of the third time period and determined by backward simulation using a thermal model of the building zone and (ii) a second timeseries comprising predicted values of the physical property when the HVAC equipment are operated in a second control mode during the second time period and satisfying the criterion at an end of the first time period, the intersection defining a temperature-time point at which the predicted values of the physical property in the first timeseries and the second timeseries are equal; and operating the HVAC equipment in the first control mode during a terminal portion of the second time period beginning at the transition time.
12. 12 . The method of claim 11 , wherein the first control mode comprises controlling the at least one physical property towards a value of a setpoint and the second control mode comprises at least one of: the equipment being off; the equipment not controlling the at least one physical property towards the value of the setpoint; or the equipment not affecting the at least one physical property of the environment.
13. 13 . The method of claim 11 , further comprising predicting a load for the HVAC equipment, using the prediction of the load or condition of a building to determine times at which the environment is predicted to be occupied, and determining the third time period based on the times at which the environment is predicted to be occupied.
14. 14 . The method of claim 11 , wherein the criterion is satisfied when the at least one physical property is within a range comprising a target value of the at least one physical property.
15. 15 . The method of claim 11 , wherein determining the transition time during the second time period based on the first timeseries and the second timeseries comprises determining a time at which the first timeseries and the second timeseries coincide.
16. 16 . One or more non-transitory computer-readable media having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to perform operations comprising: obtaining a schedule for an environment of a building zone comprising at least (i) a first time period and a third time period during which a criterion for at least one physical property of the environment is to be satisfied and (ii) a second time period occurring between the first time period and the third time period and during which the criterion for the at least one physical property of the environment need not be satisfied; determining a transition time during the second time period at which to start pre-conditioning the environment based on an intersection of (i) a first timeseries comprising predicted values of the physical property when HVAC equipment are operated in a first control mode during the second time period and satisfying the criterion at a beginning of the third time period, wherein the first timeseries is initialized at the beginning of the third time period and determined by backward simulation using a thermal model of the building zone and (ii) a second timeseries comprising predicted values of the physical property when the HVAC equipment are operated in a second control mode during the second time period and satisfying the criterion at an end of the first time period, the intersection defining a temperature-time point at which the predicted values of the physical property in the first timeseries and the second timeseries are equal; and operating the HVAC equipment in the first control mode during a terminal portion of the second time period beginning at the transition time.
17. 17 . The one or more non-transitory computer-readable media of claim 16 , wherein the first control mode comprises controlling the at least one physical property towards a value of a setpoint and the second control mode comprises at least one of: the equipment being off; the equipment not controlling the at least one physical property towards the value of the setpoint; or the equipment not affecting the at least one physical property of the environment.
18. 18 . The one or more non-transitory computer-readable media of claim 16 , wherein the at least one physical property comprises at least one of a temperature, a humidity, or a carbon dioxide level and the environment is a space of a building.
19. 19 . The one or more non-transitory computer-readable media of claim 18 , wherein a form of a first model used to generate the predicted values of the first timeseries or a form of a second model is used to generate the predicted values of the second timeseries chosen based on physical characteristics of the space, wherein the first model is the thermal model of the building zone and predicts the values of the physical property in the first timeseries based on predicted amounts of heat transfer between the building zone and the HVAC equipment when operated in the first control mode.
20. 20 . The one or more non-transitory computer-readable media of claim 19 , further comprising determining parameters of the first model or the second model using at least one of: historical behavior of the environment; a configuration of the equipment; or a manufacturer specification of the equipment.

Description

BACKGROUND The present disclosure relates generally to controlling HVAC equipment. HVAC equipment is used to condition a space to be comfortable, healthy, and safe for occupants of an environment by using energy (e.g., electrical power or fuel). Reducing the energy consumption of HVAC equipment reduces the cost of energy incurred by building owners and reduces greenhouse gas emissions caused by operating the HVAC equipment. However, it can be challenging to determine a control strategy for HVAC equipment that reduces energy consumption while ensuring that the space is conditioned to acceptable limits for building occupants. The systems and methods described herein address this challenge and reduce the energy consumption and greenhouse gas emissions caused by operating HVAC equipment. SUMMARY At least one embodiment relates to a heating, ventilating, or air conditioning (HVAC) system that operates HVAC equipment to affect at least one physical property of an environment. The HVAC system includes one or more memory devices having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to perform operations. The operations include obtaining a schedule for the environment. The schedule includes at least (i) a first time period and a third time period during which a criterion for the at least one physical property of the environment is to be satisfied and (ii) a second time period occurring between the first time period and the third time period and during which the criterion for the at least one physical property of the environment need not be satisfied. The operations also include predicting, using a first model, a first timeseries of the at least one physical property of the environment during the second time period, the first timeseries satisfying the criterion at a beginning of the third time period, wherein the first model describes behavior of the at least one physical property of the environment when the HVAC equipment is conditioning the environment in a first control mode. The operations also include predicting, using a second model, a second timeseries of the at least one physical property of the environment during the second time period, the second timeseries satisfying the criterion at an end of the first time period, wherein the second model describes the behavior of the at least one physical property of the environment when the HVAC equipment is in a second control mode. The operations also include determining, based on the first timeseries and the second timeseries, a transition time during the second time period at which to transition from operating the HVAC equipment in the second control mode to operating the HVAC equipment in the first control mode to cause the criterion to be satisfied at the beginning of the third time period. The operations also include operating the HVAC equipment in the first control mode during a terminal portion of the second time period beginning at the transition time. In some embodiments, the first control mode includes controlling the at least one physical property towards a setpoint and the second control mode includes at least one of the equipment being off or the equipment not controlling the at least one physical property towards the setpoint. In some embodiments, the at least one physical property includes at least one of a temperature, a humidity, or a carbon dioxide level and the environment is a space of a building. In some embodiments, a form of the first model or the second model is chosen based on physical characteristics of the space. In some embodiments, the environment was or is predicted to be occupied during the first time period and the third time period and the environment is predicted to be unoccupied during the third time period. In some embodiments, the operations also include predicting a variable or condition of the building indicative of occupancy and using the prediction of the variable or condition of the building to determine times at which the environment is predicted to be occupied. In some embodiments, the variable or condition of the building indicative of occupancy is a load for the HVAC equipment. In some embodiments, the criterion is satisfied when the at least one physical property is within a range including a target value of the at least one physical property. In some embodiments, determining the transition time during the second time period based on the first timeseries and the second timeseries includes determining a time at which the first timeseries and the second timeseries coincide. In some embodiments, the operations also include determining parameters of the first model or the second model using at least one of using historical behavior of the environment, using a configuration of the building automation system, using a manufacturer specification of the equipment. Another embodiment relates to a method for controlling HVAC equipment to affect at least one physical prope