SYSTEM AND METHOD OF PREDICTIVE OCCUPANCY ROOM CONDITIONING
A HVAC controls system for zone controls that is comprised of one or more Wall Sensor Units (WSU) and zero or more Damper/Register Units (DRUs). The invention is a low networked cost solution for residential and light commercial that is easy to install in new and existing building. The WSUs detect, log and use occupancy data to predict where in a building HVAC conditioning is needed and to save energy where it is not needed. The DRU use shape memory alloy wires to control the opening and closing of a damper plate with very little power allowing batter operation.
Latest MOUNTAINLOGIC, INC. Patents:
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. patent application Ser. No. 12/284,795, filed Sep. 25, 2008, now pending, which application claims the benefit of U.S. Provisional Application No. 60/997,426, filed on Oct. 4, 2007, which application is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
The technical field of this invention relates to zoned residential Heating Ventilation and Air Conditioning (HVAC) and lighting controls that employ embedded systems and wireless communications. HVAC systems use a large proportion of a building's energy usage and need to be optimized for both environmental and economic reasons.
There is a long history of invention and research associated with HVAC technology. Programmable Thermostats: Programmable setback thermostats that can be set by the occupant for set point, reset point and schedule have been available on the market for a number of years [EnergyStar]. In spite of favorable engineering analysis for prospective energy savings, field studies show that real-world field performance is no better than manual thermostats [Sachs] [Shiller] [Cross and Judd]. These studies have been suggested a number of causes including, dead band gap, difficulty of programming, and comfort issues, with the most likely cause being user overriding the energy saving features.
Residential and Light Commercial Zoning: Modern forced air zone control and VAV (Variable Air Volume) extends back decades. The most extensive use to date has been for commercial and industrial applications. There is substantial ongoing research, including that at the CEC as shown in “Advanced Variable Air Volume System Design Guide”[CEC] and Natural Resources. Canada's CANMET Energy Technology Centre (CETC) is currently involved in an ongoing residential zoned research project[CANMET Natural Resources Canada] with the company Ecologix [Ecologix Heating Technologies, Inc]. Home Comfort Zone teaches a basic version of zoned HVAC control[Alles]. Zone HVAC controls and systems are also taught in the patents of [Alles] [Girmado] [Parker] [Jackson] and [Nelson]. These systems, have several failures: 1) they are expensive to install, 2) are even more expensive to retrofit and 3) they make use of a barometric bypass damper that recycles conditioned overpressure air back into the return system causing reduced performance of the central HVAC plant.
Automated diagnostics, performance monitoring and continuous commissioning: The importance of initial commissioning and ongoing monitoring has long been established in buildings[ASHRAE][Bushby][SoCal-Edison]. According to Brambley, “Performance monitoring, automated fault detection and diagnosis, commissioning, optimal control and the use of development environments, design tools and trainers are complementary, and in some respects synergistic technologies that have strong potential to realize significant energy savings and other performance improvements in commercial buildings, including existing buildings. There is a significant body of previous R&D relating to these technologies that indicates their potential, both generically and for specific approaches and methods. In a significant number of cases, there is the opportunity to establish R&D programs and projects that leverage this existing work in order to move relatively quickly to tools that can be deployed in the marketplace.”
Actuated register/damper design: Actuated dampers and registers are very common in commercial and industrial HVAC installations and are occasionally seen in residential use. There are ongoing efforts to advance dampers such as pneumatic bladders [Alles], the technology offered by Zone Comfort as a retrofit option and the ratcheted Nitinol Shape Memory Alloy (SMA) based devices described by [Patel, et al].
Wired Network Technology: Wired electrical communication has been used for decades in residential HVAC controls. The most common use is the simple closure of a 24 VAC circuit to signal a central HVAC plant to turn on. Serial data links, Power Line Communication (PLC) and true networks are common in commercial HVAC application, but have seen limited use in residential HVAC. An example of a serial protocol is RS-232C. Examples of a of a wired network used in HVAC are BACNET and GANNET.
Wireless Technology: IEEE 802.15.4/ZigBee[IEEE][ZigBee Alliance] was essentially designed for sensor, command and control application such as residential HVAC. Other wireless technologies such as Z-Wave and Bluetooth are also in the marketplace.
Occupancy Sensors: Industrial and commercial HVAC systems have long used occupancy sensors and some limited use has been seen in residential settings [Seymour] [Simmions] [Keating] [Disser] [Bilger] [Gutta] [Gua] [Mozer].
Occupancy Prediction: While scheduled occupancy has been wide spread for both residential and commercial use (see programmable thermostats above), sensor based predictive occupancy has not seen commercial success. Mozer teaches a concept of a Neurothermostat in his prototype “Adaptive Control of Home Environment,” system that includes HVAC, domestic hot water and lighting control. The Neurothermstat makes use of a PC based neural network and X10 sensors and controls. Mozer reports that the X10 communication protocol adds too much latency for his application. The Mozer design uses standard neuro-network train with energy use and occupancy error as feed back values.
BRIEF SUMMARY OF THE INVENTION
Modern life has patterns centered around work and play. The system takes advantage of these realities in the home and predicts where energy is needed for maximum comfort and efficiency. Using integrated sensors, the embodiment learns the rhythms of the homeowners, what time they wake on a workday, what time they use the kitchen or what time they go to bed; and heats or cools individual rooms before they enter to the desired temperature. By learning how a family uses a home, the system greatly reduces the energy used in areas that are vacant, resulting in maximum comfort and efficiency. When a room is entered unexpectedly, the system rapidly brings the room to the desired temperature as the system focuses resources on real use. A combination of home zone controls, sensors and advanced learning software provide homeowners with a highly cost effective means of increasing comfort and reducing greenhouse emissions.
The system is intended to be very low cost in mass production and is designed for optional installation by the homeowner. The potential energy savings from advanced residential predictive HVAC zone controls is substantial. A first order analysis suggests that a savings of about 50% of HVAC energy usage versus a fixed manual thermostat can be expected, depending on resident usage patterns and climate. If, for example, just 10% of California homes were to implement a system that was able to achieve just a 10% air conditioning electricity savings, California could see a reduction of 111.54 mega Watts of peak demand as demonstrated by [Cal Energy Peak Loads]
Existing programmable EnergyStar thermostats' failure to perform [EnergyStar] in the field as well as anticipated is largely due to their complex user interface. The proposed system does not require complex user programming, but simply learns when a resident occupies a room and with a simple up/down button their preferred temperature setting. By having the room properly conditioned (heated or cooled) before a resident enters a room the system delivers a much higher acceptance of temperature setback than EnergyStar systems have been able to achieve. The proposed system includes wireless duct register/damper units (DRUs) that control airflow into a room and wireless wall sensor units (WSU) that measure room temperature and occupancy. Each existing HVAC register is replaced with the new design and a wall sensor unit is placed in each room. In retrofits the existing HVAC thermostat is replaced with a special version of the wall sensor that can also control the central heat pump or furnace. Once installed the system will record the occupancy of each room and the preferred temperature. The system then reviews occupancy data and predicts if a room will be occupied and conditions the room appropriately. If an occupant unexpectedly enters a room the occupancy sensors detect entrance and focus the HVAC system onto that room to quickly condition it.
The system has great potential to integrate into other long term energy efficiency efforts beyond immediate energy savings. This smart residential HVAC system can easily be integrated with fresh air economizers such as the one demonstrated in the California Department of Energy's PIER Night Breeze project and indeed extended by opportunistically over cooling expected unoccupied rooms when cool outside air is available. The system also easily integrates future opportunities, includeing smart grid interfaces for on-demand load shedding, dynamic cost response changes to set points and time of day load shifting.
Advantages of the invention include a low manufacturing cost, a low installation cost, very high energy use efficiency, high user acceptance, high comfort level and a low error rate.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
DETAILED DESCRIPTION OF THE DRAWINGS
Referring in particular to
DETAILED DESCRIPTION OF THE INVENTION
In the following description, for purposes of explanation and non-limitation, specific details are set forth, such as particular nodes, functional entities, techniques, protocols, standards, etc. in order to provide an understanding of the described technology. It will be apparent to one skilled in the art that other embodiments may be practiced apart from the specific details disclosed below. In other instances, detailed descriptions of well-known methods, devices, techniques, etc. are omitted so as not to obscure the description with unnecessary detail. Individual function blocks are shown in the figures. Those skilled in the art will appreciate that the functions of those blocks may be implemented using individual hardware circuits, using software programs and data in conjunction with a suitably programmed microprocessor or general purpose computer, using applications specific integrated circuitry (ASIC), and/or using one or more digital signal processors (DSPs). Generally speaking, the systems, methods, and techniques described herein may be implemented in digital electronic circuitry, computer hardware, firmware, software, or in combinations of these elements. Apparatus embodying these techniques may include appropriate input and output devices, a computer processor, and a computer program product tangibly embodied in a machinereadable storage device for execution by a programmable processor. A process embodying these techniques may be performed by a programmable processor executing a program or script of instructions to perform desired functions by operating on input data and generating appropriate output. The techniques may be implemented in one or more computer programs or scripts that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of volatile and non-volatile memory, including by way of example semiconductor memory devices, such as Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and Compact Disc Read-Only Memory (CD-ROM). Any of the foregoing may be supplemented by, or incorporated in, specially-designed ASICs (application-specific integrated circuits). The computer program instructions or scripts may also be provided as data signals embodied in a carrier wave or other propagation medium via a communication link (e.g., a modem or wired or wireless network connection).
This invention provides highly efficient, low cost and easy to install zoned HVAC controls for residential use. The system includes Wall Sensor Units (WSU) that superficially appear to be programmable thermostats, but include temperature/humidity, occupancy sensors, advanced software, processor, FLASH memory for recording occupancy information and a ZigBee wireless network capability. The system also includes ZigBee based wireless battery operated Damper/Register Units (DRUs) that are actuated by Shape Memory Alloy (SMA) wires. The preferred embodiment for the DRU includes two SMAs that when commanded each actuate a pusher that in turn each each presses on a push tab on the damper plate, and a single shared return spring. Also included in the system are additional components including ZigBee wireless outside air enthalpy sensors, ZigBee wireless duct pressure/flow sensors and HVAC plant controller where needed by the installation. Each of the components have an embedded MCU and ZigBee support. The system is intended to support zoned control and as each building the system is installed into is likely to be different the number and configuration of each installation will be different. Residential HVAC zones typical are based on a room that has a door that closes. There are some places where rooms are connected without doors that close such as is often found between kitchens and living rooms in open plan homes. In these cases where the air between rooms communicates well they may be treated as one zone. There are special cases in very large or unique rooms where the temperate difference between different places in the room can become uncomfortable, such as a long narrow room with large window only at one end, can be broken into more than one zone if there are HVAC supplies at each end that can be individually controlled. In each of these zones a WSU is placed on the wall and at least one DRU is placed at the exit of the HVAC source duct into the zone. If there is more that one HVAC outlet in a zone then each HVAC outlet has its own DRU. An exception to this is the case of a home, such as a studio, that is functionally a single zone then DRUs are not needed. The WSU in a zone controls each DRU in a zone via wireless ZigBee communication. Most communication between the WSU and DRU is from the WSU to the DRU ordering the DRU to open or close. The DRU will communicate back to the WSU open/close state confirmation, temperature, low battery and fault data. The DRUs act as a ZigBee End Device (ZED). Most WSU's function as ZigBee Router (ZR), but one WSU will act as a ZigBee coordinator (ZC) unless a HVAC central controller is present in which case the HVAC central controller acts as the ZC.
The WSU redundant occupancy sensors are able determine if the room is occupied. Redundant senors are used because often one time of sensor will not be able to determine if a human is present. For example, PIR sensors can only detect humans when they move and microphones can only detect their presence when they make noise. Conversely, occupancy sensor often have false positives. By combining the inputs from multiple sensor and filtering, a much more accurate picture of occupancy can be obtained. Each WSU records the occupancy of its zone in its FLASH memory in 15 minute increments with a rolling record for 4 years. The occupancy record is used to predict future occupancy. The occupancy record is examined using a Decaying Occupancy Temporal (DOT) Algorithm by looking at periodic occupancy records with decaying impact from older records. Occupancy is recorded as 1 if occupied and 0 in unoccupied. For example if looking at the past four days then eight times the occupancy value the same time one day before the target record is added with four times the occupancy value from two days before plus two times the value of occupancy record from three days before plus the occupancy value from four days before. This algorithm can be used over different time intervals such as past n 15 minutes, past n hours, past n days, past n months, past n years or time-logical intervals such as past n week days, past n weekend days, same day of month past n months. These various occupancy interval measurements are weighted and summed and compared against a user configurable economy/comfort threshold. The weighing values for the various occupancy interval measurements are determined by a genetic algorithm running in the background that uses the uses the weighing values as the genetic representation and performance with recent occupancy history as a fitness function to select the weighting values. Each WSU also keeps a record of set points, reset points and ventilation rates in FLASH in 15 minute increments based on a one week calendar that can be altered by the occupants.
If the occupancy sensors or thermal sensors in a WSU are triggered a request is sent to the ZC. Every 15 minutes the ZC sends a command to the WSUs to execute the occupancy prediction algorithm and returns any conditioning results to the ZC. If there is a conditioning request pending the ZC opens a sufficient number of DRUs to keep the pressure of the ducts low enough to maintain a high enough air flow for heat transfer, HVAC central plant safety and to prevent damage to the duct system. The DRUs to open is determined by current HVAC needs and by near future HVAC needs by the ZC querying the WSUs that will run their respective prediction algorithms for current and near future occupancy as well as distance from current set/setback point. From these values, the ZC opens the next most likely DRUs to open until enough are opened to provide adequate air flow in the duct network and to also provide minimum building ventilation. The WSU contain a full set of algorithms for setback, pre-cooling, fresh air economizers, load shedding, economic/comfort trade-offs and time of day meters optimization. The ZC also contains a full set of algorithms for controlling all standard HVAC plant types as well as relays for signaling the central HVAC plant.
The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
1. A heating, ventilation, and air conditioning (HVAC) control system, comprising:
- at least one HVAC automated damper/register unit (DRU), each HVAC automated DRU having a functional unit configured to be directed to a first position to permit air flow through the HVAC damper/register unit and further directed to a second position to restrict air flow through the HVAC damper/register unit, a DRU processor unit configured to direct the functional unit, and a DRU network communications circuit;
- at least one wall sensor unit (WSU), each WSU having an occupancy sensor, an environmental sensor, a WSU processor unit configured to receive data from the occupancy sensor and the environmental sensor, and a WSU network communications circuit;
- a system coordinator, the system coordinator having a system coordinator processor unit and a system coordinator network communications circuit configured to bi-directionally communicate with the at least one HVAC automated DRU and the at least one WSU via the respective network communications circuits; and
- a memory coupled to the system coordinator and arranged to store instructions executable by the system coordinator processor unit, the instructions configured to perform an occupancy logging algorithm and an occupancy prediction algorithm, the occupancy prediction algorithm configured to receive input from the at least one WSU and send control commands to the at least one HVAC automated DRU.
2. The HVAC control system of claim 1 wherein the system coordinator is integrated into a first WSU, the system coordinator processor unit is the WSU processor unit of the first WSU, and the system coordinator network communications circuit is the WSU network communications circuit of the first WSU.
3. The HVAC control system of claim 1 wherein the occupancy sensor includes at least one of a motion sensor, an acoustic sensor, and a light sensor.
4. The HVAC control system of claim 1 wherein the environmental sensor includes at least one of a temperature sensor, a humidity sensor, and a pressure sensor.
5. The HVAC control system of claim 1, further comprising:
- a network computing device module, the network computing device module having:
- a display interface configured to communicate HVAC control system status information;
- a user input interface configured to receive manually entered HVAC control system command information; and
- an electronic signal interface configured to bidirectionally pass electronic HVAC control system control information.
6. The HVAC control system of claim 5 wherein the network computing device module further has a smart-grid interface configured to pass information to a smart grid.
7. The HVAC control system of claim 1 wherein the DRU network communications circuit, the WSU network communications circuit, and the system coordinator network communications circuit are configured according to a ZigBee architecture.
8. The HVAC control system of claim 1 wherein the occupancy prediction algorithm is arranged to predict periodic events based on the periodic occupancy records logged by the system coordinator, each predicted periodic event representing the occupancy status of a room during a certain time.
9. The HVAC control system of claim 8 wherein the occupancy prediction algorithm includes a decaying occupancy temporal (DOT) algorithm configured to analyze periodic occupancy records logged by the system coordinator and assign decaying impact from older occupancy records.
10. The HVAC control system of claim 8 wherein the occupancy prediction algorithm is configured to send a first control command to the at least one HVAC automated DRU based on a predicted periodic event.
11. A computer readable storage device having thereon a plurality of computer instructions, the computer instructions arranged to direct a system coordinator processing unit to perform acts in a heating, ventilation, and air conditioning (HVAC) system, the acts comprising:
- initializing a plurality of occupancy data structures, at least one occupancy data structure for each room of a plurality of rooms, each occupancy data structure of a corresponding selected room configured to store information representing the occupancy status of the selected room during a plurality of time windows;
- periodically accessing the occupancy data structures at an index representative of an access period and logging in each occupancy data structure a first status when the corresponding selected room is determined to be occupied and logging in each occupancy data structure a second status when the corresponding selected room is determined to be unoccupied, wherein each access period corresponds to one of the plurality of time windows;
- retrieving occupancy status information from the plurality of occupancy data structures;
- predicting if an occupancy status of a first room will change in a future time window; and
- directing an HVAC automated damper/register unit to change position based on a predicted occupancy status change of the first room.
12. The computer readable storage device of claim 11 wherein each time window represents N minutes, N an integer between 1 and 60, and wherein each occupancy data structure includes entries for M time windows, M. an integer between 24 and 52560000.
13. The computer readable storage device of claim 11, having computer instructions arranged to direct the system coordinator processing unit to perform acts further comprising:
- receiving occupancy status information from a plurality of wall sensor units, the wall sensor units mounted in a plurality of rooms.
14. The computer readable storage device of claim 11, having computer instructions arranged to direct the system coordinator processing unit to perform acts further comprising:
- receiving occupancy status information from a manually operated user interface.
15. The computer readable storage device of claim 11, having computer instructions arranged to direct the system coordinator processing unit to perform acts further comprising:
- performing a decaying occupancy temporal (DOT) algorithm configured to analyze occupancy status information stored in the plurality of occupancy data structures and assign decaying impact from older occupancy records.
16. A system comprising a system controller to control a heating, ventilation, and air conditioning (HVAC) system, the system controller including:
- an input interface;
- an output interface;
- a network communications circuit;
- a processor unit coupled to the input interface, the output interface, and the network communications circuit; and
- a memory coupled to the processor unit, the memory arranged to direct the processor unit to: store, over a first period of time, occupancy data detected by a plurality of wall sensor units; store, over a second period of time, position information related to positions of a plurality of functional units, each functional unit associated with one of a plurality of HVAC automated damper/register units (DRU's); store, over a third period of time, selected temperature data received via the input interface; predict a periodic event based on the occupancy data, position information, and selected temperature data, the predicted periodic event representative of predicted temperature conditions of a selected room during a future fourth time period; and generate a command arranged to direct the functional unit of at least one HVAC automated DRU.
17. The system of claim 16 wherein the network communications circuit is configured to receive the occupancy data from the plurality of wall sensor units.
18. The system of claim 16 wherein the system controller is embedded in a first wall sensor unit.
19. The system of claim 16 wherein the system controller is embedded in an HVAC furnace control module.
20. The system of claim 16 wherein the predicted periodic event is related to a pattern of usage of a plurality of rooms.
International Classification: G05D 23/00 (20060101);