WO2013153475A1

WO2013153475A1 - Distributed closed-loop daylight and artificial light control

Info

Publication number: WO2013153475A1
Application number: PCT/IB2013/052482
Authority: WO
Inventors: Dagnachew Birru
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-04-10
Filing date: 2013-03-28
Publication date: 2013-10-17

Abstract

A distributed closed-loop lighting control system (200). The system comprises at least one sensor(230) for measuring a light luminance level in the space; an indoor lighting controller (210) connected to the at least one sensor for controlling an intensity of one or more internal light sources(211) to meet a first set point for the measured light luminance level in the space; an external lighting source controller (220) for adjusting an amount of external light entering into the space to meet a second set point for the measured light luminance level in the space, wherein the external lighting source controller operates independently of the indoor lighting controller and wherein a value of the second set point is higher than a value of the first set point.

Description

DISTRIBUTED CLOSED-LOOP DAYLIGHT AND ARTIFICIAL LIGHT CONTROL

This invention relates to lighting controls, and more particularly, to a method and a system for controlling light distribution in a space including installed light sources and an external light source.

Most existing window treatments installed in residential or commercial buildings are operated manually. As a result, energy consumption cannot be efficiently reduced. Research shows that 40% of the worlds' energy is consumed in buildings: 18% in commercial buildings, and 21 % in residential buildings. In commercial buildings, 26% of the consumed power is for lighting purposes.

Maximizing the utilization of natural light (daylight) can reduce the electric energy used for lighting. With this aim, automated systems for window treatments for controlling the amount of daylight in the room have been recently developed. Such systems usually operate using open loop controls based on a form of a solar clock, the model of the building, its surroundings, and so on. Thus, an automated system for window treatments is an open-loop system with certain assumptions about the interior and exterior environment. These assumptions are often not necessarily correct or updated when surrounding conditions are changed.

Thus, these systems cannot efficiently regulate the daylight in the room. Further, a design of such an automated system to achieve optimal results is complex and costly. For example, there is a need to populate a database that would include, for each building, the required lighting conditions, the expected lighting conditions, the current surrounding shading conditions, and so on. To populate such a database, a study is performed using external photo sensors. However, the database, and hence the automated system cannot be optimized for each space, resulting in sub-optimal occupant comfort and energy savings. Practical tests of a commercially available automated system show that identical blinds in adjacent rooms behave differently, and furthermore, that blinds allowed direct sun to reach inside (glare) during a clear sky, but did not fully open during an overcast sky.

Another drawback of existing automated systems for window treatments is that daylight regulation is not performed in conjunction with interior lighting conditions. For example, on a sunny day interior lights can be dimmed, thus increasing energy savings. Alternatively, during overcast sky conditions, luminance levels of indoor lights should be increased.

An improved solution is a closed-loop window treatment control system that adjusts the blind height and the slats' angles based on interior lighting conditions.

However, such a system cannot be installed in an area where there is also a closed- loop electric light control. The existence of two independent closed-loop systems controlling indoor electric lights and window treatments significantly downgrades the overall performance of the combined system.

For example, when a certain required luminance level is independently provided to two closed-loop control systems controlling interior lighting and blinds in a room, usually, the electric lights' loop converges faster to supply the needed luminance level, thus the blinds remain mostly closed. As a result, power savings are not maximized and further, the occupant may not be satisfied because the blinds are shut.

In the related art, an integrated controller that controls both the window

treatments and electric lights is also disclosed. Such a controller is a newly designed and manufactured system that combines the functionality of both of the closed-loop systems mentioned above. However, this requires closed-loop systems with centralized operation or with integrated controllers.

Therefore, it would be advantageous to provide a closed-loop system for daylight and indoor light control that overcomes the deficiencies noted above.

Certain embodiments disclosed herein include a distributed closed-loop lighting control system. The system comprises at least one sensor for measuring a light luminance level in a space; an indoor lighting controller connected to the at least one sensor for controlling an intensity of one or more internal light sources to meet a first set-point for the measured light luminance level in the space; an external lighting source controller for adjusting an amount of external light entering into the space to meet a second set-point for the measured light luminance level in the space, wherein the external lighting source controller operates independently of the indoor lighting controller and wherein a value of the second set-point is higher than a value of the first set-point. Certain embodiments disclosed herein also include a distributed closed-loop lighting control system. The system comprises at least one sensor for measuring a light luminance level in a space; an indoor lighting controller connected to the at least one sensor for controlling an intensity of one or more internal light sources to meet a first set-point for the measured light luminance level in the space; and an external lighting source controller connected to the at least one sensor for adjusting an amount of external light entering into the space to meet a second set-point for the measured light luminance level in the space, wherein the external lighting source controller operates independently of the indoor lighting controller and wherein a value of the second set- point is higher than a value of the first set-point.

The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

Figure 1 is a schematic diagram of a distributed closed-loop control system according to one embodiment.

Figure 2 is a schematic diagram of a distributed closed-loop control system according to another embodiment.

Figure 3 is a flowchart describing a process for distributed closed-loop control of indoor and external light sources according to one embodiment.

Figure 4 is a flowchart describing a process for adjusting the amount of external light entering a space according to an embodiment.

It is important to note that the embodiments disclosed are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts through several views.

A distributed closed-loop control system for efficiently controlling the amount of light from indoor sources and daylight (external lighting) in a space is disclosed according to certain embodiments of the invention. The system is based on a closed- loop window treatment controller and a closed-loop indoor lighting controller that operate interdentally, but exchange information between each other. This information includes at least the measured luminance level at the interior space. The distributed closed-loop system allows meeting a setpoint defined by a user while providing optimal performance. In accordance with an embodiment, the optimal performance is achieved when the power savings and exposure to daylight are maximized.

Fig. 1 shows a non-limiting schematic diagram of the distributed closed-loop control system 100 according to one embodiment. The system 100 includes an indoor lighting controller 1 10 and an external lighting source controller 120. The controller 1 10 controls the intensity of the internal light sources (e.g., electric lights) 1 1 1 using a closed-loop mechanism. The controller 120 controls the window treatments 121 to adjust the amount of external light entering into the space also a using a closed-loop mechanism. For example, the controller 120 can change the slats' angle and height of motorized binds installed in a window. The external light may be daylight or a light illuminated from any other external source.

The system 100 also includes one or more sensors 130 that measure the light luminance level (designated as s(k)) in the space. The one or more sensors 130 may be distributed in different areas within the space (e.g., a room). The light in the space may result from an external light source (daylight) coming through window treatments 121 and the internal light sources 1 1 1 . The light luminance level, s(k), may be a vector; each element of the vector is the measured level at a certain area. In one embodiment, the functionality of the indoor lighting controller 1 10 can be integrated in the one or more sensors 130.

According to an embodiment of the invention, the measured light luminance level, s(k), is provided to both controllers 1 10 and 120, such that the adjustment of the internal and external light sources is based on the same measured value. The value s(k) is communicated by means of an electric signal which may also be transferred over a cable or a wireless medium.

The indoor lighting controller 1 10 computes the difference between the measured luminance level s(k) and the required luminance level, set-point 101 , selected by a user for the internal light sources 1 1 1 . In a similar fashion, the external lighting source controller 120 computes the difference between the measured luminance level s(k) and the required luminance level, set-point 102, for the external light source. According to one embodiment, the setpoint 102 is always greater than the setpoint 101 by a delta value. The delta value is greater than any hysteresis in the indoor lighting controller 1 10. For example, the setpoint 101 may be 500 lux, while the setpoint 102 may be 600 lux.

The setpoint 101 may be selected using an interface 140. In one embodiment, the interface 140 sets that setpoint 102 to be greater than setpoint 101 by adding a delta value. In another embodiment, the user may select the setpoint 102 as well.

The interface 140 may be a computer interface, for example, a tablet computer, a

PDA, a PC, a remote control, and the like. In an exemplary embodiment, the computer interface provides a graphical user interface (GUI) through which the user can select his/her lighting preferences in the space, such as more daylight than indoor light, warm lighting versus bright lighting, and so on. The GUI selects the values for setpoints 101 and 102 accordingly. In other exemplary embodiments, the interface 140 may be any mechanical means, e.g., a wall side switch.

By setting the setpoint 102 to a higher luminance level than the setpoint 101 of the indoor lighting controller 1 10, the space would be lit mostly using the external light source. Specifically, the controller 1 10 will converge to the setpoint 101 quicker than the controller 120. However, once the controller 1 10 stops adjusting the intensity levels of the electric lights 1 1 1 , the external lighting source controller 120 continues its operation to meet the higher setpoint 102. Thus, the controller 120 attempts to provide more daylight by opening the slat angles or increasing the blind height of the window treatments 121 . As a result, the indoor lighting controller 1 10 lowers the luminance level of the electric lights 1 1 1 , as more light is detected by sensors 130. Thus, electrical lights 1 1 1 are dimmed, relative to their initial levels, resulting in energy savings. This process continues until the controller 120 meets setpoint 102.

In one embodiment, the system 100 includes a glare sensor 150 that operates as an open-loop system. The sensor 150 detects if glare exists, for example, from an external light source, and if so, the slats' angles and/or the blind height of the window treatments 121 are adjusted to mitigate the glare. The slat angles and/or the blind height of the window treatments 121 are constraints to the controller 120.

Fig. 2 illustrates another embodiment of a distributed closed-loop control system 200. The system 200 includes an indoor lighting controller 210, an external lighting source controller 220, and one or more sensors 230. In one embodiment, the system 200 includes a glare control sensor 250 to mitigate glare. In an embodiment, the functionality of the indoor lighting controller 210 can be integrated in the one or more sensors 230.

The controller 210 controls the intensity of the internal light sources (e.g., electric lights) 21 1 using a closed-loop mechanism. The controller 220 controls the window treatments 221 to adjust the amount of external light entering into the space, by also using a closed-loop mechanism. The one or more sensors 230 measure the light luminance level (designated as s(k)) in the space. The one or more sensors 230 may be distributed in different areas within the space (e.g., a room).

According to this embodiment, there is a connection 205 between the indoor lighting controller 210 and the external lighting source controller 220, which may be a wired or wireless connection. On the connection 205, the measured light luminance level, s(k) and a modified setpoint 202, are sent from the controller 210 to controller 220. To this end, the controller 210 receives a setpoint 201 selected for the electric lights 21 1 and generates the setpoint 202 by including a delta value. As mentioned above, the delta value should be greater than any hysteresis in the indoor lighting controller 210. The setpoint 201 is selected through an interface 240 that may be a computer interface or a mechanical interface.

The controllers 210 and 220 independently adjust the lights 21 1 and window treatments 221 to meet the setpoints 201 and 202 respectively. This is performed using the process described in depth above and also with reference to Fig. 3.

Fig. 3 shows an exemplary and non-limiting flowchart 300 describing a process for distributed closed-loop control of interior and external light sources according to an embodiment described herein. The process can be performed by any of the systems 100 and 200 described above. At S310, a first setpoint (SP1 ) selected for the indoor lights, and a second setpoint (SP2) selected for the external light, are input. According to one embodiment, the luminance level defined in the second setpoint is higher than the first setpoint. Both setpoints may be entered by a user. Alternatively, the first setpoint is set by the user and the second setpoint is set by the interface (e.g., an interface 140) and/or the indoor lighting controller (e.g., controller 210).

At S320, the luminance level of light from the light sources is measured by sensors at one or more measuring areas within the space. The measured luminance level, s(k), is provided as an input to both an indoor lighting controller and an external lighting source controller.

At S330, it is checked if an absolute (Abs) value of a difference between the measured luminance level, s(k), and the second setpoint, SP2, is greater than a predefined threshold, of. If so, execution continues to S335; otherwise, execution returns to S320. The threshold, d, is a hysteresis value set to avoid oscillation and may be defined by the user or be a configurable value. At S335, the external lighting source controller adjusts the blinds' height and/or slats' angles to meet the second setpoint. In one embodiment, this is performed using an iterative process described with reference to Fig. 4.

Independently and in parallel to the execution of S330 and S335, at S340, it is checked if an absolute value (Abs) of a difference between the measured luminance level, s(k), and the first setpoint is higher than the predefined threshold, d. If so, execution continues with S345; otherwise, execution returns to S320. At S340, the indoor lighting controller adjusts the intensities of the indoor lights to meet the first setpoint. This includes dimming and un-dimming the intensities of indoor lights until the first setpoint is met. One of ordinary skill will realize that there are multiple techniques that can be employed by the indoor lighting controller for this purpose.

At S350, it is checked if the operation of the controllers should continue, and if so execution returns to S320, after waiting a predefined time interval; otherwise, execution ends. The predefined waiting time interval may be set by the user.

It should be noted that the process 300 may be periodically repeated. The process may also be triggered when the measured luminance level is changed below or above a certain predefined threshold. It should also be noted that when the second set- point cannot be met, for example, at sunset, at night, or when glare exists, the process 300 will be performed only to meet the first setpoint set for the indoor lights. In such a case, the external lighting controller is constrained by the predefined setpoints determined by the user or the glare sensor.

Fig. 4 shows an exemplary and non-limiting flowchart S330 describing a process for adjusting the amount of external light entering a space according to an embodiment disclosed herein. The process can be performed by an external lighting source controller (e.g., controller 120 or 220 described above) that controls motorized window blinds installed in a window or windows.

At S410, it is checked if glare exists based on an input provided by a glare sensor (e.g., sensor 150 or 250). If so, at S420, the blinds' heights and/or slats' angles are adjusted until the glare sensor indicates that the glare is below a threshold level. It should be noted that S410 is optional and performed in systems that include an open loop glare control system. Furthermore, in an embodiment an input from the glare sensor may cause control to return to S410 regardless of the state of the process.

If S410 results with a 'No' answer, execution continues with S425, where the slats' angles of the window treatments are adjusted to their maximum open angle. The maximum open angle is defined, for example, by the manufacture of the window treatments. Then, at S430, it is checked if there is more light than desired in the space. That is, if the measured luminance level, s(k), is higher than a value of the second setpoint. If so, at S440 the blinds' slats are closed at a predefined angle. This angle may be the smallest angle that the blinds' slats can be changed in their closed position. In an embodiment, S440 may also include adjusting the position of the window treatments to enable less light to enter through the window. For example, the position of the window treatments can be adjusted by lowering the height of the window treatments (blinds or shades) covering the window at a predefined height or shifting the window treatments covering the window to one side to cover more area of the window.

If S430 results with a 'No' answer, execution continues with S450 where it is checked if the there is less light than desired in the space, i.e., if the measured luminance level, s(k), is lower than a value of the second setpoint. In addition, it is checked if the slats' angle is smaller than an angle that can cause glare conditions. If both checks result with an 'Yes' answer, execution proceeds to S460, where the blinds' slats are opened at a predefined angle. This angle may be the smallest angle to which the blinds' slats can be changed in their open position. In an embodiment, S460 may also include adjusting the position of the window treatments to enable more light to enter through the window. For example, the position of the window treatments can be adjusted by raising the height of the window treatments (blinds or shades) covering the window at a predefined height or shifting the window treatments covering the window to one side to cover less area of the window.

At S470 it is checked if the measured luminance level, s(k), is equal to the second setpoint, and if so, execution ends; otherwise, execution returns to S410. It should be noted that the process 400 may be periodically repeated. The process 400 may also be triggered when the measured luminance level is changed below or above a certain predefined threshold or based on an input provided by the glare sensor.

The various embodiments disclosed herein can be implemented as hardware, firmware, software or any combination thereof. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit, a non-transitory computer readable medium, or a non-transitory machine-readable storage medium that can be in a form of a digital circuit, an analogy circuit, a magnetic medium, or combination thereof. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units ("CPUs"), a memory, and input/output interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU, whether or not such computer or processor is explicitly shown. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit.

While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with references to the appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention. Furthermore, the foregoing describes the invention in terms of embodiments foreseen by the inventor for which an enabling description was available, notwithstanding that insubstantial modifications of the invention, not presently foreseen, may nonetheless represent equivalents thereto.

Claims

CLAIMS What is claimed is:

1. A distributed closed-loop lighting control system (200), comprises:

at least one sensor (230) for measuring a light luminance level in a space;

an indoor lighting controller (210) connected to the at least one sensor for controlling an intensity of one or more internal light sources (21 1 ) to meet a first set- point for the measured light luminance level in the space;

an external lighting source controller (220) for adjusting an amount of external light entering into the space to meet a second set-point for the measured light luminance level in the space, wherein the external lighting source controller (220) operates independently of the indoor lighting controller (210) and wherein a value of the second set-point is higher than a value of the first set-point.

2. The system of claim 1 , further comprises:

a glare sensor (250) connected to the external lighting source controller (220) for detecting glare, the glare sensor provides an input to the external lighting source controller (220) based on the detection of glare.

3. The system of claim 2, wherein the external lighting source controller (220) controls at least motorized window treatments (221 ) installed in one or more windows.

4. The system of claim 3, wherein the external lighting source controller (220) is configured to:

open the blinds' slats to a maximum open angle (S425);

check if the measured luminance level is higher or lower than the value of the second set-point (S430, S450);

adjust a position of the window treatments to enable less external light to enter if the measured luminance level is higher than the value of the second set-point (S440); and adjust a position of the window treatments to enable more external light to enter if the measured luminance level is lower than the value of the second set-point (S460).

5. The system of claim 1 , further includes:

an interface (240) for setting at least the first set-point, wherein the interface is connected at least to the internal lighting source controller (210).

6. The system of claim 5, wherein the indoor lighting controller (210) sets the value of the second set-point based on the value of the first set-point, wherein the value of the second set-point is higher than the value of the first set-point by a delta value that is greater than a hysteresis in the indoor lighting controller (210).

7. The system of claim 6, wherein the indoor lighting controller (210) is connected to the external lighting source controller (220) through a connection (205) on which the second set-point and the measured light luminance level are provided to the external lighting source controller (220), wherein the connection may be any one of a wired connection and a wireless connection.

8. The system of claim 7, wherein the functionality of the indoor lighting controller (210) is integrated with the at least one sensor (230).

9. The system of claim 1 , wherein the system converges to enable lighting of the space weighted for using the external light source, wherein the external light source is sunlight.

10. A distributed closed-loop lighting control system (100), comprising:

at least one sensor (130) for measuring a light luminance level in a space;

an indoor lighting controller (1 10) connected to the at least one sensor (130) for controlling an intensity of one or more internal light sources (1 1 1 ) to meet a first set- point for the measured light luminance level in the space; and an external lighting source controller (120) connected to the at least one sensor (130) for adjusting an amount of external light entering into the space to meet a second set-point for the measured light luminance level in the space, wherein the external lighting source controller (120) operates independently of the indoor lighting controller (1 10) and wherein a value of the second set-point is higher than a value of the first set- point.

1 1 . The system of claim 10, further comprises:

a glare sensor (150) connected to the external lighting source controller (120) for detecting glare, the glare sensor further provides an input to the external lighting source controller (120) based on an the detection of glare (S410).

12. The system of claim 10, further includes:

an interface (140) for setting the first set-point and second set-point, wherein the interface is connected at least to the internal lighting source controller (1 10).

13. A method (300) of a distributed closed-loop lighting control, comprising

receiving a measurement of a light luminance level in a space (S320);

checking if a first absolute value of a difference between a measured luminance level and an input first set-point is greater than a predefined threshold, wherein the predefined threshold is a hysteresis value pre-set to avoid oscillation (S340);

adjusting an intensity of one or more internal light sources to meet the input first set-point for the measured light luminance level in the space, if the first absolute value is higher than the predefined threshold (S345);

independently of the adjustment of the intensity of the one or more light sources: checking if a second absolute value of a difference between a measured luminance level and an input second set-point is greater than a predefined threshold

(S330); and

adjusting an amount of external light entering into the space to meet the input second set-point for the measured light luminance level in the space if the second absolute value is higher than the predefined threshold, wherein the second set-point is higher than the first set-point.

14. The method of claim 13, wherein adjusting the amount of external light entering into the space to meet the input second set point further comprises controlling motorized window treatments (121 , 221 ) installed in one or more windows by:

opening the blinds' slats to a maximum open angle (S425);

checking if the measured luminance level is higher or lower than the input second set-point (S430, S450);

adjusting a position of the window treatments to enable less external light to enter if the measured luminance level is higher than a value of the second set-point (S440); and

adjusting a position of the window treatments to enable more external light to enter if the measured luminance level is lower than the value of the second set-point (S460).

15. The method of claim 14, further comprising:

setting at least one of the blinds' heights and slats' angles based on existence of glare (S410).