Patent Description:
Due to the mounting global energy crisis, there is a continued focus on improving building design and engineering to reduce energy consumption and enable 'smart' energy use. Such 'smart' buildings may incorporate a number of dynamic systems that can react to changing environmental conditions in order to minimize overall energy use while maintaining user comfort. Examples include, but are not limited to: variable transmittance electrochromic windows, automated window shades, photovoltaic energy generation and storage systems, heat pump systems, attic fan systems, and sophisticated HVAC systems. For example, an intelligent building energy management system might register that it is a hot, bright, sunny day, and trigger electrochromic windows into a low transmittance state, or lower automated window shades, in order to reduce solar heat gain in the building and minimize building cooling loads. Alternatively, the energy management system might register that the temperature outside has fallen below the internal building temperature, and activate a heat pump or attic fan system to utilize the temperature differential to provide low-energy use building cooling. As another example, a building control system might sense a bright sunny day, but with low building energy use needs, and thus direct captured photovoltaic energy into an energy-storage system or feed it directly into the grid, rather than into local-use applications.

In order for a building energy management system to intelligently respond to changing building conditions, a network of sensors may be required to provide the necessary data for the control system to react to. To provide all of the data needed to fully run such a smart building, a variety of sensors might be required, including but not limited to: temperature sensors, light intensity sensors, and wind (e.g., direction, intensity) sensors. While such sensors are readily available, the shear number of sensors that may be required to ensure a complete building map, combined with the dynamic building controls, can create a large and complicated building energy management system. Any way to combine or reduce the overall number of smart building elements (e.g., sensors or controls) could significantly reduce the overall complexity and cost of the system.

<CIT> describes a conventional residential environmental navigation system. <CIT> describes a solar-powered wireless communication module with daylight intensity measurement. <CIT> describes a method and apparatus for determining measurement values characterizing a solar radiation intensity at a location of a PV generator. <CIT> describes an air conditioning control system. <CIT> describes a photovoltaic device for measuring irradiance and temperature. <CIT> describes providing a dimmer capable of eliminating waste of electric power generated by a solar battery and increasing an amount of power generation by the solar battery sufficiently.

The present invention provides a method of utilizing a photovoltaic device as a sensor for building energy management and a system for managing energy in a building as defined in the appended claims.

In this way, the exemplary embodiments can combine power and sensor data generation into a single unit, thereby reducing the number, complexity, and cost of individual components, which simplifies the overall intelligent building energy management system as compared to conventional building energy management systems.

Prior to describing the exemplary embodiments in greater detail, and to provide a better understanding of the invention, this disclosure will first describe some of the problems with conventional building energy management systems.

As explained above, due to the mounting global energy crisis, there is a continued focus on improving building design and engineering to reduce energy consumption and enable 'smart' energy use. In order for a building energy management system to intelligently respond to changing building conditions, a network of sensors may be required to provide the necessary data for the control system to react to. To provide all of the data needed to fully run such a smart building, a variety of sensors might be required, including but not limited to: temperature sensors, light intensity sensors, and wind (e.g., direction, intensity) sensors. While such sensors are readily available, the shear number of sensors that may be required to ensure a complete building map, combined with the dynamic building controls, can create a large and complicated building energy management system. Any way to combine or reduce the overall number of smart building elements (e.g., sensors or controls) could significantly reduce the overall complexity and cost of the system.

Photovoltaic (PV) modules are increasingly being attached onto or integrated into buildings in order to provide a clean, renewable source of energy to offset building energy needs. The output of a photovoltaic device (e.g., array, module or cell) consists of a certain voltage and current, whose product determines the overall power output of the device. The specific voltage and current output from a device, relative to benchmark values obtained under specific conditions (i.e. ideal AM1. <NUM> G1-sun solar irradiation), can be used to provide information about current light intensity and temperature conditions. For example, both the voltage and current produced by a PV device depend on the incident illumination, but the dependence is different for each parameter. In contrast, the current is relatively insensitive to the temperature, but the voltage produced is proportional to the temperature. By mapping the response of a specific PV device over a variety of illumination and temperature conditions, the output parameters of the device can be used as light intensity and ambient temperature data input into an intelligent building energy management system, in addition to providing power. Such mapping could be readily incorporated into a PV device manufacturer's quality assurance testing routine. Since most PV arrays incorporate a large number of modules over relatively large areas, such systems could replace the need for a large number of independent sensors. A small number of auxiliary conventional (non-PV) sensors could be utilized as a backup and/or dynamic calibration of the PV device sensor data. Additionally, small-area PV devices, likely individual cells or modules, could be used to provide additional sensor data in areas that conventional module or arrays may not be desirable, be it for aesthetic, financial or energy reasons, such as low illumination intensity locations. Such small-area PV sensors could still provide some marginal power to help offset the energy needs of the building energy management system, such as powering a wireless transmitter for sending the sensor data to the management system.

While conventional roof-top PV arrays may make sense in some situations, providing a convenient source of PV device-based sensor data for an intelligent building energy management system, in other situations (e.g. limited roof-top area) such arrays may not make financial or energy-use sense. In these situations, building-integrated photovoltaic (BIPV) devices may provide an alternative opportunity to provide energy management sensor data along with (optional) power. One of the most attractive forms of building-integrated photovoltaic devices is a semitransparent PV device integrated into a building window. A number of solar technologies have been explored for these applications, including but not limited to: conventional crystalline silicon and inorganic thin-film technologies (e.g. cadmium telluride, or copper-indium-galliuni-selenide [CIGS]), which are made semitransparent via laser ablation of portions of the active area; and amorphous silicon and organic photovoltaic (OPV) technologies, which are made semitransparent via utilization of dual transparent contacts and low-bandgap absorber materials. While all of these technologies could be used to provide BIPV device-based sensor data for intelligent building energy management systems, OPV-based BIPV presents a number of attractive features for both power and sensor data applications.

OPV devices are uniquely suited for BIPV applications due to their ability to have high visible light transmission (VLT), up to <NUM>%, tunable absorption profiles, and their potentially low-cost, large-area production capabilities. The unique ability to tune the absorption profile of the absorbed materials in OPV devices has enormous benefits for semitransparent window BIPV applications. This allows the color, VLT, and spectral response of the OPV device to be altered for different applications, markets, and visual effects. This increases the flexibility and usability of the technology, and gives more options to designers and end-users. As with all solar technologies, cost is a maj or concern. The ability to produce OPV devices via low-temperature and atmospheric pressure high-throughput solution coating techniques enables potentially very low-cost manufacturing, which is critical to ensuring large-scale adoption of the technology. The use of this technology for power generation is the subject of several filings under the trade name SolarWindow™. This technology can also be harnessed for sensor data applications, as well, with or without power generation. The same properties that make OPV devices attractive for power-generating BIPV applications make them attractive for BIPV smart-building sensor applications; namely their high VLT, tunable color, and potentially low-cost production.

The present invention recognizes that conventional building sensors for use in intelligent building energy management systems add additional cost, complexity, and design restrictions on already complex systems. The shear number of building sensors required to adequately cover a building may result in excessively complex and expensive building energy management systems. By utilizing core smart-building PV components, such as roof-top power-generating PV arrays, low-power independent PV devices, power-generating BIPV units, or low-power BIPV devices as building sensors, the number of individual components and thus the overall complexity and cost of smart-building systems might be reduced.

These problems and others are addressed by the present invention, wherein a first aspect provides a method of utilizing a photovoltaic device as a sensor for a building energy management, the method comprising the steps of: providing the photovoltaic device for both generating power and providing information about current building conditions, the current building conditions including light intensity and ambient temperature, wherein the photovoltaic device includes a semitransparent window unit; determining the information about current building conditions by comparing a voltage output parameter and a current output parameter from the photovoltaic device to predetermined values obtained under specific benchmark conditions; using, by an energy management system, the information about the current building conditions as input parameters for determining optimal settings for one or more heating, cooling, and dynamic energy-saving building elements including at least an electrochromic window element; and determining, by the energy management system based on the information about the current building conditions, whether the electrochromic window element should be in a high visible light transmission state or a low visible light transmission state.

A further aspect provides a system for managing energy in a building, the system comprising:
a photovoltaic device; an energy management system, in communication with the photovoltaic device wherein the photovoltaic device is configured for generating power and providing information about current building conditions, wherein the photovoltaic device includes a semitransparent window unit, wherein the energy management system is configured to compare a voltage output parameter and a current output parameter received from the photovoltaic device to predetermined values obtained under specific benchmark conditions to determine information about the current building conditions including light intensity and ambient temperature; and one or more heating, cooling, and dynamic energy-saving building elements, including at least an electrochromic window element, wherein the energy management system is configured to determine optimal settings for the one or more heating, cooling, and dynamic energy-saving building elements, including the electrochromic window element, based on the information about the current building conditions, and determine, based on the information about the current building conditions, whether the electrochromic window element should be in a high visible light transmission state or a low visible light transmission state.

An example, not forming part of the claimed invention can provide a conventional roof-top PV array, made of any of a number of PV technologies, including but not limited to: crystalline silicon, thin-film inorganic technologies such as cadmium telluride, CIGS, or amorphous silicon, or OPV, wherein the PV array is tied into the intelligent building energy management system in such a way that in addition to providing power to the building, either to an energy storage system, a local microgrid, or the larger grid infrastructure, the output parameters of the array, either as a whole or from the individual modules or cells, is used as sensor data to provide information on the current building conditions, including but not limited to light intensity and ambient temperature. The parameters output from the array, modules, and/or cells, such as the voltage and current are necessarily already tracked, and so obtaining this information has no additional costs. This data can then be converted to useful building condition sensor information through comparison with benchmark values obtained under specific conditions, in the form of a calibration map that was performed as part of the array, module, and/or cell manufacturing quality assurance testing, or during system design and installation. A small number of auxiliary conventional building sensors could be used to further supplement and/or calibrate the PV sensor data. In such a way, an existing smart-building component, in this case a power-generating PV array, module, and/or cell, could also serve to provide useful building sensor information, contributing two elements of the intelligent building energy management system from a single component, decreasing system complexity and cost. Due to the generally large areas covered by conventional PV arrays, such combined PV-sensor systems could provide extensive information about building conditions, reducing the number of independent sensor elements required considerably.

A further example, not forming part of the claimed invention comprises a comparably small-area conventional PV device, either a module or cell, made of any of a number of PV technologies, including but not limited to: crystalline silicon, thin-film inorganic technologies such as cadmium telluride, CIGS, or amorphous silicon, or OPV, wherein the device output parameters are used to provide building condition sensor information as described previously. In this case, the small-area PV device may be used in a location in which it is not desirable to put a large PV array, be it due to aesthetic, financial, or energy-payback reasons. The small-area PV device can provide the desired sensor information, while still providing modest power output that can be used to offset building energy needs, or can be used to power independent low-energy need systems, such as for wireless transmission of the sensor data to the intelligent building energy management system. In such an implementation, if power output from the sensor drops below that sufficient to allow wireless sensor data transmission, that could be interpreted by the energy management system as, for example, a below-threshold light intensity.

A further example, not forming part of the claimed invention comprises a BIPV device, such as a semitransparent window unit, composed of any of a number of PV technologies, including but not limited to: crystalline silicon or thin-film inorganic technologies such as cadmium telluride, CIGS, or amorphous silicon, wherein the BIPV device is tied into the intelligent building energy management system in such a way that in addition to providing power to the building, either to an energy storage system, a local microgrid, or the larger grid infrastructure, the output parameters of the device are used as sensor data to provide information on the current building conditions, including but not limited to light intensity and ambient temperature. The output parameters can be calibrated into useful sensor information through comparison with a calibration map as described previously. In the case of a semitransparent window unit, such building sensor information is very beneficial, as windows are a major source of building energy loss, and thus are a key component of any intelligent building energy management system. The sensor data from such BIPV window units can be used to provide information on how to operate building HVAC or whether or not to actuate such energy-saving components as electrochromic window or dynamic window shade elements.

A further example, not forming part of the claimed invention comprises an OPV-based BIPV device, such as a semitransparent window unit, and particularly a SolarWindow™, wherein the BIPV device is tied into the intelligent building energy management system in such a way that in addition to providing power to the building, either to an energy storage system, a local microgrid, or the larger grid infrastructure, the output parameters of the device are used as sensor data to provide information on the current building conditions, including but not limited to light intensity and ambient temperature. The output parameters can be calibrated into useful sensor information through comparison with a calibration map as described previously. As described above, such building sensor information is very beneficial for semitransparent window BIPV applications, such as SolarWindow™, as windows are a major source of building energy loss, and thus are a key component of any smart-building energy management system. The sensor data from such BIPV window units can be used to provide information on how to operate building HVAC or whether or not to actuate such energy-saving components such as electrochromic window or dynamic window shade elements. In the case of OPV-based BIPV devices, and particularly SolarWindow™, the combined power generation and sensor data window units have additional benefits due to their attractive aesthetics, namely their high VLT and tunable color. In contrast, conventional sensors would be highly visible, non-transparent elements when placed on a window, and BIPV units based on other PV technologies sensors have much poorer aesthetics, in that they generally have low VLT and fixed, undesirable visual colors/appearances.

A further example, not forming part of the claimed invention comprises a comparably small-area BIPV device, such as a semitransparent window unit, either a module or cell, made of any of a number of PV technologies, including but not limited to: crystalline silicon, thin-film inorganic technologies such as cadmium telluride, CIGS, or amorphous silicon, or OPV, wherein the device output parameters are used to provide building condition sensor information as described previously. In this case, the small-area BIPV device may be used in a location in which it is not desirable to put a large BIPV device, be it due to aesthetic, financial or energy-payback reasons. The small-area BIPV device can provide the desired sensor information, while still providing modest power output that can be used to offset building energy needs, or can be used to power independent low-energy need systems, such as for wireless transmission of the sensor data to the central building management system. In this exemplary implementation, if power output from the sensor drops below a predetermined power output that is sufficient to allow wireless sensor data transmission, then the intelligent building energy management system can interpret this information as, for example, a below-threshold light intensity.

Other features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description and drawings.

These and other aspects and features of embodiments of the present invention will be better understood after a reading of the following detailed description, together with the attached drawings, wherein:.

The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.

Referring now to the drawings, a conventional intelligent building energy management system with discrete power generation, sensor data generation, and controllable building elements, as shown in <FIG>, will be described in contrast to exemplary embodiments of PV devices that combine power and sensor data generation into a single unit, in order to simplify overall intelligent building energy management system, as illustrated in examples shown in <FIG>.

As explained above, <FIG> is a schematic view illustrating a conventional intelligent building energy management system with discrete power generation, sensor data generation, and controllable building elements. In this exemplary conventional intelligent building energy management system, power from two roof-mounted PV arrays <NUM> is fed through their respective power conditioners (inverters) <NUM> into the building control unit <NUM>, which utilizes additional data from two separate roof-mounted sensors <NUM> to determine whether or not to activate two attic fans (or heat pumps) <NUM>.

With reference to <FIG>, examples of PV devices will now be described. The examples of PV devices can be configured to combine power and sensor data generation into a single unit, thereby simplifying the overall intelligent building energy management system as compared to conventional building energy management systems, such as the conventional example described in <FIG>.

<FIG> is an example of an intelligent building energy management system, not in accordance with the claimed invention, wherein the PV arrays provide both power and sensor data to the energy management system. In this example, two roof-mounted PV arrays <NUM> , which may be comprised of one or more of any of a number of PV technologies, including but not limited to: crystalline silicon, thin-film inorganic technologies such as cadmium telluride, CIGS, or amorphous silicon, or OPV, or combinations of one or more types of PV technologies, send their power to their respective power conditioners (inverters) <NUM>. The example illustrates two roof-mounted PV arrays <NUM>. However, one or more roof-mounted PV arrays <NUM> may be provided. Next, the power conditioners <NUM> convert the power from the PV arrays <NUM> into an appropriate format for whatever the current use for the power is; e.g. no conditioning or voltage conversion for direct current (DC) applications such as charging batteries for energy storage or DC-powered micro-grid applications, or inverters for producing alternating current (AC) for contributing to the larger grid infrastructure. The output parameters of voltage and current describe the power produced by the PV arrays <NUM>, and these parameters determine what the appropriate use for the power is. As such, these parameters may be monitored and used, and in some cases are always monitored and used, as input parameters into the intelligent building energy management system <NUM> , which controls the power output (solid line). By comparing these output parameters to benchmark values obtained under specific conditions (i.e. ideal AM1. <NUM> <NUM>-sun solar irradiation), they can be used to provide information about current light intensity and/or temperature conditions, along with other information. Thus, the output parameters can be passed along to the energy management system <NUM> as sensor data (dashed line), and the control unit can use a calibration map to convert that data into useful information about building conditions, such as light intensity and ambient temperature. The energy management system <NUM> can then use that data to determine whether or not to activate one or more attic fans (or heat pumps), such as the two attic fans (or heat pumps) <NUM> illustrated in <FIG>. In this way, the exemplary embodiments of PV devices <NUM> can be configured to combine power and sensor data generation into a single unit, thereby simplifying the overall intelligent building energy management system as compared to conventional building energy management systems, such as the conventional example described in <FIG>. The foregoing example describes a highly simplified building control system to illustrate the inventive features of the present invention. In operation, a building control system may include many more PV power and sensor generating units, additional sensor units, and additional controllable building elements.

<FIG> is an example of of an intelligent building energy management system, not in accordance with the claimed invention, wherein a roof-mounted PV array provides both power and sensor data to the energy management system. In this example, a small-area PV device also can provide sensor data and sufficient power to allow wireless transmission of the sensor data. The roof-mounted PV array <NUM> sends power to its power conditioner (inverter) <NUM> , which provides both power (solid line) and sensor data (dashed line) to the energy management system <NUM>. The roof-mounted small-area PV sensor device <NUM> provides power directly to a wireless transmitter <NUM> , which sends the sensor data derived from the PV sensor device output parameters to a wireless receiver <NUM> , which then passes the sensor information to the energy management system <NUM>. The energy management system can use the sensor data from either or both of the PV array <NUM> and the PV sensor device <NUM> to determine whether or not to turn on the attic fans (or heat pumps) <NUM>. In this way, this exemplary embodiment of a roof-mounted PV array <NUM> can provide both power and sensor data to an energy management system <NUM> , and additionally or alternatively, a small-area PV device <NUM> can provide sensor data and sufficient power to allow wireless transmission of the sensor data, thereby simplifying the overall intelligent building energy management system as compared to conventional building energy management systems, such as the conventional example described in <FIG>.

<FIG> is a schematic view of an example of an intelligent building energy management system, in accordance with the claimed invention wherein a BIPV device (<NUM>), in the form of, for example, a semitransparent window unit such as SolarWindow™ described above, provides both power and sensor data to the energy management system. The semitransparent window BIPV device <NUM> sends power to its power conditioner (inverter) <NUM> , which passes both power (solid line) and sensor data (dashed line) derived from its output parameters to the energy management system <NUM> , which determines whether an electrochromic window element <NUM> should be in its high VLT or low VLT state. In this way, this example can provide a BIPV device <NUM> that provides both power and sensor data to an energy management system <NUM> , thereby simplifying the overall intelligent building energy management system as compared to conventional building energy management systems, such as the conventional example described in <FIG>.

<FIG> is a schematic view of an example of an intelligent building energy management system wherein a BIPV device, not in accordance with the claimed invention, for example a semitransparent BIPV device, provides sensor data to the energy management system. As shown in <FIG>, a semitransparent BIPV device <NUM> provides power directly to a wireless transmitter <NUM> , which sends the sensor data derived from the PV sensor device output parameters to a wireless receiver <NUM> , which then passes the sensor information to the energy management system <NUM>. The energy management system <NUM> then determines whether a dynamic window shade element <NUM> should be raised or lowered. In this way, this exemplary embodiment can provide a BIPV device <NUM> that provides both power and sensor data to an energy management system <NUM> , thereby simplifying the overall intelligent building energy management system as compared to conventional building energy management systems, such as the conventional example described in <FIG>.

The photovoltaic device can be a conventional roof-top photovoltaic array based upon one or more of the following photovoltaic technologies: crystalline silicon, cadmium telluride, copper-indium-gallium-selenide, copper-zinc-tin-sulfide, amorphous silicon, or organic pliotovolaties, and both the power output and sensor output can be used by the building energy management system.

The photovoltaic device can be a small-area roof-top photovoltaic module or cell, and the power output of the device can be used to power a wireless transmitter for sending the sensor data output to the building energy management system.

The photovoltaic device can be a semitransparent building-integrated photovoltaic module or cell based upon one of the following photovoltaic technologies: crystalline silicon, cadmium telluride, copper-indium-gallium-selenide, copper-zinc-tin-sulfide, or amorphous silicon, and both the power output and sensor output can be used by the building energy management system.

The photovoltaic device can be a semitransparent building-integrated photovoltaic module or cell based upon one of the following photovoltaic technologies: crystalline silicon, cadmium telluride, copper-indium-gallium-selenide, copper-zinc-tin-sulfide, or amorphous silicon, and the power output can be used to power a wireless transmitter to send the sensor output data to the building energy management system.

The photovoltaic device can be a semitransparent building-integrated photovoltaic module or cell based upon organic photovoltaic technology, and both the power output and sensor output can be used by the building energy management system.

Claim 1:
A method of utilizing a photovoltaic device (<NUM>) as a sensor for a building energy management, the method comprising the steps of:
providing the photovoltaic device (<NUM>) for both providing power to the building and using output parameters of the photovoltaic device (<NUM>) as sensor data to provide information about current building conditions, the current building conditions including light intensity and ambient temperature, wherein the photovoltaic device (<NUM>) includes a semitransparent window unit;
determining the information about current building conditions including light intensity and ambient temperature by comparing a voltage output parameter and a current output parameter from the photovoltaic device (<NUM>) to predetermined values obtained under specific benchmark conditions;
using, by an energy management system (<NUM>), the information about the current building conditions as input parameters for determining optimal settings for one or more heating, cooling, and dynamic energy-saving building elements including at least an electrochromic window element (<NUM>); and
determining, by the energy management system (<NUM>) based on the information about the current building conditions, whether the electrochromic window element (<NUM>) should be in a high visible light transmission (VLT) state or a low visible light transmission (VLT) state.