Abstract:
An air duct cover provides a sensor platform that contains a rich set of sensors. In addition, the air duct cover may include an energy harvesting capability, thereby increasing efficiency in an HVAC system and sustaining the sensors on the sensor platform. The air duct cover may also integrate a smoke detection device. As power is provided by the air duct cover, maintenance requirements for the smoke detection device are substantially eliminated. The air duct cover may also serve as an air quality control device, with dust, smoke, and carbon monoxide (CO) sensors that allow it to detect the amount of dust flowing through and to serve as a smoke detector.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an integrated, self-sustaining, sensor-based energy optimization system. More particularly, the present invention relates to an energy optimization system based on detecting environmental and usage conditions at specific locations of a building. 
         [0003]    2. Description of the Related Art 
         [0004]    Heating, ventilation, and air condition (HVAC) systems in commercial buildings typically have zone-level resolutions. A zone is often a relatively large section of a building containing many rooms. For example, control of air conditioning may be provided at a section level—i.e., the air conditioning system provides the user the ability to monitor and control air flows and temperature to a section of a building at a time, and not for a smaller area, such as a single room. In fact, in most residential units with centralized air conditioning, the entire unit is maintained as a single zone. Even though such an HVAC system is easy to install and maintain, the system is considerably inefficient because many portions of a section of a building may be unoccupied at any given time. However, because of the zone-level control resolution, these unoccupied areas are heated or cooled. 
         [0005]    Smoke detectors are required in all commercial and residential buildings. Existing smoke detectors are either battery-operated or require back-up batteries, which have to be maintained. The maintenance task is carried out sufficiently often that the cost of the maintenance is not insignificant. 
       SUMMARY 
       [0006]    According to one embodiment of the present invention, an air duct cover provides a sensor platform that includes a rich set of sensors. In addition, the air duct cover may include an energy harvesting capability, thereby increasing efficiency in an HVAC system and providing power to support the sensors on the sensor platform. The air duct cover may also integrate a smoke detection device. As power is provided by the air duct cover, maintenance requirements for the smoke detection device are substantially eliminated. 
         [0007]    In one embodiment of the present invention, the air duct cover may serve as an air quality control device, with dust, smoke, and carbon monoxide (CO) sensors that allow it to detect the amount of dust and particulates flowing through and to serve as a smoke detector. 
         [0008]    In one embodiment, the air duct cover includes fans that act as windmills (i.e., fans that drive an electricity generator) to harvest power from the pressurized air flow in the air duct. The harvested power charges an on-board battery which provides power to the sensors, and for data processing and wireless data transmission. 
         [0009]    According to one embodiment, the air duct cover increases local control capability, such as providing room-specific temperature control, thereby avoiding the drawbacks of building section-level control in the prior art. The sensor platform on the air duct cover detects current occupancy and current temperature in its immediate vicinity (e.g., a room in a commercial or residential building). In addition, the louvers or shutters on the air duct cover may be mechanized by a motor, so as to allow them to open or close a vent to different extents automatically, based on the detected temperature and occupancy. In one embodiment, the air duct cover is a part of a control system with an intelligent algorithm that can predict likely times of occupancy and accordingly prepare the room to the comfort of the occupants when they enter the room. 
         [0010]    A significant advantage of the present invention is its “backward compatibility” with existing centralized facility management system, but enhances the control resolution from “section level” to “room level,” thus significantly improves over existing zone-based systems. 
         [0011]    The present invention is better understood upon consideration of the present invention in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows system  100 , which includes controller  101  and smart air duct cover  102 , according to one embodiment of the present invention. 
           [0013]      FIG. 2  is a block diagram  200  showing one set of control operations in local microprocessor  107  of air duct cover  102  and in controller  101 , in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    The inventor of the present invention observes that the living, dining and family rooms in a residence are unlikely to be occupied between certain hours at night, while bedrooms are likely occupied during those hours. However, in existing prior art systems, temperature is often set for the whole residence, so that even unoccupied areas are heated or cooled. Worse still, the thermostat in many residences is provided in a controller which is located in an area that is likely to be unoccupied during those times (e.g., the living room), and as the unoccupied areas usually are significantly different in floor area than the occupied areas (e.g., the bedrooms), the occupied rooms are over-heated or over-cooled. Because the whole residence is treated as a single zone, and because the sensors are often inappropriately placed, such an existing prior art system is not only inefficient, but also incapable of maintaining a comfortable temperature across the house, as to create discomfort in the occupants. Recently, Nest Corporation (https://nest.com/) provide a controller that learns user behavior. However, even such a controller provides only whole-house heating or cooling control, and does not provide room-level resolution for heating or cooling control. 
         [0015]    Accordingly, the present invention provides a controller that tracks the temperature and occupancy of each room and closes the vent automatically when the room reaches the preset desired temperature. The controller also detects an unoccupied room using a passive infra-red (PIR) sensor and automatically controls the room to, for example, +/−5° C. of the preset temperature. Sensors, which are provided in substantially all rooms, communicate to the controller to allow shutting off centralized A/C or heating for a given zone if all the occupied rooms within the zone attain preset temperature thresholds. 
         [0016]    According to one embodiment of the present invention, an air duct cover includes sensors that allow a controller or a facility management system to implement an energy conservation program. In one embodiment, the air duct cover provides temperature and occupancy sensors, so as to achieve room-level temperature control in a centralized HVAC system and to thereby conserve energy use. The air duct cover may also include mechanized, motor-driven louvers for controlling air flow into the room, which may be used as one mechanism for temperature control. With an occupancy detector, the air duct cover provides also room-level lighting control. The air duct cover of the present invention may be used in both commercial and residential buildings. 
         [0017]      FIG. 1  shows system  100 , which includes controller  101  and smart air duct cover  102 , according to one embodiment of the present invention. In one embodiment system  100  may be a stand-alone system used in a single residence or an office suite. Alternatively, system  100  may be integrated into a facility management system, such as that described in co-pending patent application (“Smart Facility Management Application”) by the same inventor, entitled “Smart Facility Management Platform,” filed on the same day as the present application. The disclosure of the Smart Facility Management Application is hereby incorporated herein by reference in its entirety. 
         [0018]    As shown in  FIG. 1 , smart air duct cover  102  communicates with controller  101  over wireless communication using a suitable communication protocol, such as MQTT. Control of the local operations of smart air duct cover  102  is provided by microcontroller or processor  107 , which is powered by a rechargeable battery. Smart air duct cover  102  provides a sensor platform to support many different type of sensors, e.g., temperature and humidity sensors  103 , smoke and gas sensors (e.g., a carbon monoxide (CO) sensor)  104 , occupancy sensor  105  (e.g., a passive IR sensor), and dust sensor  106 . Smart air duct cover  102  also provides mechanized louvers driven by motor  109  to open and close the vent under local control or control by controller  101 . As the air flow in the air duct is usually slightly pressurized by a centralized pumping mechanism, smart air duct cover  102  also provides one or more fans  108 , which harvest energy from the air flow inside the air duct. The harvested energy charges the rechargeable battery to power sensors  103 - 106 , motor  109  and microprocessor  107 . As described below, as smart air duct cover  101  senses the local environment and provides local air conditioning or heating actuators, controller  101  may be located in any suitable location in the building, or even remotely. 
         [0019]    Dust sensor  106  detects the amount of dust passing through smart air duct cover  102 , thereby providing an estimate indicative of the air quality in the building. For example, one implementation of dust sensor  106  detects PM2.5 and PM10 particulate matters, so that it is suitable to serve in a warning system for alerting allergy or asthma patients. An increase in dust detected in dust sensor  106  can also indicate an air filter that is due for maintenance. The local controller (e.g., microprocessor  107 ) or controller  101  may provide an alert to the facility maintenance company or to the home-owner to indicate the need for an air filter replacement. One example of a suitable dust sensor for implementing dust sensor  106  is the GP2Y1010AU sensor available from Sharp Corporation, Japan. 
         [0020]    As mentioned above, temperature and humidity sensor  103  and PIR sensor  105  provide readings that may be used for energy optimization in commercial and residential buildings. Suitable temperature and humidity sensors for implementing temperature and humidity sensor  103  include, for example, the AM2303 sensor form Aosong (Guangzhou) Electronics Co., Ltd., Guanzhou, China. Suitable PIR sensors for implementing occupancy sensor  105  include, for example, a wide angle PIR sensor (28032) from Parallax, Inc., Rocklin, Calif. 
         [0021]    Smoke and gas sensors  105  may be provided by a combined gas sensor that can detect liquid petroleum gas (LPG), CO and methane, such as a gas sensor board (27983) available also from Parallax, Inc., Rocklin, Calif. Dust sensor  106  may also serve as a smoke detector by detecting an increase in particulate matters typically found in smoke. 
         [0022]    The inventor discovered that a prototype implementation of air duct cover  102 , which is installed in an air duct and which uses modified computer cooling fans, generated a voltage of 2.5 volts and delivered a 20 mA current, while the air conditioning or the heater is operating. A standard size air duct cover may accommodate two or more 3-inch (diameter) fans in the smallest ducts. The inventor surmises that a series connection of the output voltages of these fans would provide 5 volts of output voltage and a current of 20 mA, or 100 mW of power. As common vents may accommodate up to four such fans, which may be connected as two parallel series-connected pairs, such a configuration would provide 5-volt output voltage and a 40 mA current capability, for a 200 mW power harvested. Such a power output is sufficient to fully charge a 1200-mWh NiCd AA battery in six hours. Larger vents in commercial buildings and airports will potentially allow harvesting more power. 
         [0023]      FIG. 2  is a block diagram  200  showing one set of control operations in local microprocessor  107  of air duct cover  102  and in controller  101 , in accordance with one embodiment of the present invention. As shown in  FIG. 2 , steps  201 - 205  may be carried out in microprocessor  107 . According to readings from occupancy sensor  105 , microprocessor  107  determines at step  202  whether or not the room at which air duct cover  102  is installed is occupied. If not, the temperature threshold for the room is adjusted suitably by up to +/− five (5) degrees in the direction of reduced energy usage. If the room is determined to be occupied, no adjustment to the temperature threshold is made. When temperature and humidity sensor  103  indicates at step  204  that the temperature threshold is reached, microprocessor  107  actuates motor  109  at step  205  to close the vent, such as to shut off further heating or cooling of the room due to the air flow through air duct cover  102 . 
         [0024]    At steps  206 - 209 , which may be carried out in controller  101  simultaneously with steps  201 - 205  in microprocessor  107 , controller  101  determines whether or not heating or air conditioning operations in the zone in which air duct cover  102  is part of should be shut off. At step  206 , controller  101  computes a suitable metric. For example, as shown in step  206 , a metric zoneOFFb is calculated. In this embodiment, zoneOFF is the difference between the total of all current temperatures in all rooms in the zones (after temperature threshold adjustments of step  203 , everywhere) and the total of all differences in all rooms in the zone between their respective temperature thresholds and their respective temperatures. Controller  101  then determines at step  207  whether or not the calculated zoneOFF metric is greater than zero. If so, the air conditioning or heating for the zone is switched off at step  209 . Otherwise, at step  208 , the air conditioning or heating is switched on (or left on). 
         [0025]    The above detailed description is provided to illustrate the specific embodiments of the present invention and is not intended to be limiting. Numerous variations and modifications of the present invention are possible. The present invention is set forth by the accompanying claims.