CA2327648A1 - Multifunction window blinds - Google Patents
Multifunction window blinds Download PDFInfo
- Publication number
- CA2327648A1 CA2327648A1 CA002327648A CA2327648A CA2327648A1 CA 2327648 A1 CA2327648 A1 CA 2327648A1 CA 002327648 A CA002327648 A CA 002327648A CA 2327648 A CA2327648 A CA 2327648A CA 2327648 A1 CA2327648 A1 CA 2327648A1
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- Prior art keywords
- slats
- blind
- cndot
- window
- energy
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Classifications
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- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
- E06B9/00—Screening or protective devices for wall or similar openings, with or without operating or securing mechanisms; Closures of similar construction
- E06B9/24—Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blinds
- E06B9/26—Lamellar or like blinds, e.g. venetian blinds
- E06B9/38—Other details
- E06B9/386—Details of lamellae
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- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
- E06B9/00—Screening or protective devices for wall or similar openings, with or without operating or securing mechanisms; Closures of similar construction
- E06B9/24—Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blinds
- E06B9/26—Lamellar or like blinds, e.g. venetian blinds
- E06B9/28—Lamellar or like blinds, e.g. venetian blinds with horizontal lamellae, e.g. non-liftable
- E06B9/30—Lamellar or like blinds, e.g. venetian blinds with horizontal lamellae, e.g. non-liftable liftable
- E06B9/32—Operating, guiding, or securing devices therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S50/00—Arrangements for controlling solar heat collectors
- F24S50/80—Arrangements for controlling solar heat collectors for controlling collection or absorption of solar radiation
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- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
- E06B9/00—Screening or protective devices for wall or similar openings, with or without operating or securing mechanisms; Closures of similar construction
- E06B9/24—Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blinds
- E06B2009/2417—Light path control; means to control reflection
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- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
- E06B9/00—Screening or protective devices for wall or similar openings, with or without operating or securing mechanisms; Closures of similar construction
- E06B9/56—Operating, guiding or securing devices or arrangements for roll-type closures; Spring drums; Tape drums; Counterweighting arrangements therefor
- E06B9/68—Operating devices or mechanisms, e.g. with electric drive
- E06B2009/6809—Control
- E06B2009/6818—Control using sensors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B10/00—Integration of renewable energy sources in buildings
- Y02B10/20—Solar thermal
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
Landscapes
- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Sustainable Development (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Sustainable Energy (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Blinds (AREA)
Abstract
A multifunction window blind is disclosed which can be strategically used to improve the efficiency of solar energy collection by a window of a dwelling for heating purposes during winter, as well as to improve efficiency of rejection of the sun's incoming radiation for cooling purposes, during summer or in a hot climate. Heat transfer properties of the blind can be conveniently switched from energy collection mode to rejection mode, depending on the time of day or weather conditions. The same blind can be used for selectively enhancing retention or dissipation of heat during the night according to the exterior weather conditions. The disclosed structure includes a window blind with slats with different energy-absorption and energy-rejection properties of the surfaces on their opposite sides. The disclosed multifunction blinds can be used in place of conventional blinds with minimal or no modification to the existing windows.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to an energy control system generally for a window, 6 particularly a system using dual colored blinds to improve the control of the energy throughput of a window depending on heating or cooling requirements of an interior of a dwelling.
1. Field of the Invention:
The present invention relates to an energy control system generally for a window, 6 particularly a system using dual colored blinds to improve the control of the energy throughput of a window depending on heating or cooling requirements of an interior of a dwelling.
2. Background Information and the Prior Art:
11 Efficient use of energy in heating and cooling of residential and commercial buildings has been the subject of considerable interest. According to recent studies, it is believed that over 25% of the heat loss in buildings is attributable to windows. Much attention has been lavished particularly on the use of solar power transmitted through windows.
Intelligent fenestration systems for automated control of light and heat energy throughput of windows have already been 16 proposed and are in existence. However, some of the main reasons for lack of wide-spread popularity of these devices are: their complexity, cost, marginal or questionable advantage over conventional designs due to inefficient collection or rejection of solar energy, and particularly their inefficiency in simultaneously and independently controlling the desired levels of light throughput (illumination or visibility), and the heat throughput. For example, during a bright 21 sunny winter day, it may be desirable to block partially or completely the incoming light through a window to avoid too much of brightness or to have desired privacy, although it may be desirable to utilize the maximum possible amount of incoming solar energy to heat the house.
Similarly, it may be desirable to allow visibility through windows on a hot bright summer day while rejecting as much energy as possible.
A number of alternatives with a variety of features have been proposed in the prior art to develop windows or blinds to improve efficient use of solar energy, however, with a varying degree of success and complexity. For example, in US patent 3,925,945, White described a heat exchanger window having at least two panes of glass where one of the two sides of the window having heat absorbing properties, and a frame which is mounted pivotally on to a frame. The sides of the window panel can be switched from winter to summer depending on the requirements. Gillery (US patent 4,235,048) described a reversible window of a similar concept for alternately reflecting and absorbing solar energy using selectively coated glass panes.
In US patent 4,421,098, Meta proposed a window with Venetian blinds mounted inside a frame with two panes of glass to improve heat absorption as well as ventilation. Gustafson described (US patent 4,527,548) a window blind type solar collector where a heated chamber is provided within the louvers, which act as heat exchangers, in such a way that a working fluid 11 may flow through the louvers to transfer the collected heat elsewhere.
Several mechanisms with varying degree of complexity for automated control of energy transfer through window blinds have been proposed. An example of such automated systems is the one described by Patterson and Luecke in US patent 5,675,487 using photovoltaic sensors 16 and electro-mechanical devices.
The proposed alternatives in the prior art have been somewhat complex, expensive, and can not be easily adapted to existing windows. Most attempts have focused only on the heating characteristics and their operation during the day. No attention has been paid to the potential use 21 of blinds for enhancing desired heat retention or dissipation characteristics of fenestration systems during the night. Alternate use of reflective and absorptive properties of surfaces have not been effectively exploited in a practical manner. Little attention has been paid on separating light throughput from heat throughput. Orientation and the effect of the geometry of slats of the window blinds have not been used optimally.
It is therefore, an object of the present invention to add versatility to a window blind which can be used to selectively and effectively intake solar energy for illumination and heating purposes, while being able to convert most of the unwanted light energy into heat, depending on 1 the need.
Another object is to add to the same blind the switchable capability of reflecting solar energy effectively for cooling purposes such as during air-conditioning.
6 Another object is to develop a blind that can be used during the night to enhance containment of interior energy, or to improve dissipation of energy as desired.
Another object is to develop a blind that minimizes required compromise between the desired light energy throughput and heat energy throughput.
Yet another object of present invention is to make the blind simple, inexpensive and easily adaptable to existing windows which can also be automated.
These and other objects of the present invention are achieved by the preferred embodiment which is disclosed herein and comprises multifunction window blind for accomplishing numerous tasks. We have found that selectively incorporating reflective and 21 absorptive properties to the alternate sides of a window blind and by strategically selecting the orientation and geometry of the slats, it is possible to improve energy transfer properties through the window in light of the above objectives.
Fig. 1 shows the general classification of the basic modes of operation of the present 1 invention.
Fig. 2 is the cross sectional view of a fenestration system employing one configuration of the present invention operable in solar energy collection mode.
6 Fig. 3 is the cross sectional view of the same fenestration system in Fig. 2 employing one configuration of the present invention operable in solar energy rejection mode.
Fig. 4 is the cross sectional view of a fenestration system employing another configuration of the present invention operable in solar energy collection mode.
Fig. S is the cross sectional view of the same fenestration system in Fig. 4 operable in solar energy rejection mode.
Fig. 6 is the cross sectional view of the fenestration system in Fig. 2 showing the 16 functionality during its operation in a heat-dissipation and light-retention mode during the night.
Fig. 7 is the cross sectional view of the fenestration system in Fig. 6 showing the functionality during its operation in an energy-retention mode during the night.
21 Fig. 8 is the cross sectional view of the simulator used to test different configurations of the blinds.
Fig. 9 is an example of relative efficiencies of energy intake through a window having blinds with slats of different colored surfaces.
Fig. 10 is an example showing the effectiveness of the present invention operated in solar energy collection and rejection modes during a sunny winter day.
1 Fig. 11 is an example showing the effectiveness of the present invention operated in solar energy collection and rejection modes during a cloudy winter day.
Fig. 12 shows the comparison of energy-dissipation efficiency by two configurations of the blinds mounted inside a simulator of a dwelling.
Fig. 13 shows the comparison of the effect of angle of orientation of the slats, for two combination of geometries of the reflective and black surfaces.
Fig. 14 shows the convergence and divergence of solar rays depending on the geometry of 11 the reflective surface of the slats.
Fig. 15 shows the effect of the curvature of the concave-reflective surface of the slats on convergence of solar rays.
16 Fig. 16 shows two possible examples of configurations of slats for improving mechanical rigidity and effective surface area of the black surface for improved energy-collection or radiation efficiencies.
Fig. 17 shows the schematic of an example for automated operation of the multifunction 21 blinds.
DETAILED DESCRIPTION OF THE INVENTION
Transfer of heat energy can occur through three basic processes: radiation, convection and conduction. Although most of the design approaches for improving energy efficiency of fenestration systems have focused on connective or conductive properties, a significant amount of heat energy can transfer into or from a dwelling through a window via the process of radiation.
Radiative properties of an object mainly depend on its surface characteristics such as colour and texture, which applies to both heat energy as well as light energy.
It is a well known 6 phenomenon that a light coloured or a shiny surface reflects radiation more efficiently than a black, dark or rough surface. On the other hand, a black, dark, or rough surface absorbs radiation more effectively than a light coloured or a shiny surface. When a black surface absorbs light, it eventually converts the energy into heat. In the present disclosure, light coloured or shiny surfaces are commonly referred to as "reflective surfaces" whereas black, dark colored, or rough 11 surfaces are commonly referred to as "black surfaces".
The blinds described in the present invention are based on the strategic choice of differential radiative characteristics and geometry of the two surfaces of the slats. In the present disclosure, such blinds are generally referred to as "dual coloured blinds" or "DCB"s, although 16 the surfaces can be made to be different using a single colour, plurality of colors or surface textures, different shapes, or a combination thereof.
Basically, to improve energy efficiency of a dwelling, two primary alternate objectives would be to facilitate either the cooling or heating of its interior, depending on the requirement.
21 In light of the above discussed radiative properties and depending on whether the source of energy is external or internal to the dwelling, the present invention can have four basic functional modes: energy collection, rejection, retention, and dissipation, as shown in Figure 1. For example, during a sunny day in a cold winter, the source of energy (the sun) is external and the desired objective would be to collect as much solar energy as possible for heating the interior of 26 the dwelling. If it is a hot sunny summer day, the source is still external. However, it is desirable to reject as much incoming energy as possible. During a night in the winter, the interior of the dwelling becomes the source of energy and then our objective would be to retain as much heat energy as possible by minimizing the losses through the window. On the other hand, during a 1 summer night, even when the outside temperature may drop below the desired interior temperature, heat generated by the interior lighting and that dissipated by the walls which were heated during the day, may tend to raise the interior temperature above the desired level, increasing the load for an air-conditioning system. Under such circumstances the desired objective would be to let as much energy as possible dissipate to the outside through the 6 window. Most often, it may also be preferable to keep the blind closed during the night for desired privacy while allowing efficient heat dissipation through the window.
Refernng to Fig. 2 and 3, an energy control system using a dual coloured blind for a window is shown for the purpose of illustrating two basic operable configurations and not 11 limiting the present invention. As a convention, in the cross sectional figures of the blinds used in the present disclosure, a thicker line is used to represent the "black"
surface of a slat whereas a thinner line is used to represent its "reflective" surface. Fig. 2 shows the cross-sectional view of a window with one possible configuration operable in the solar energy collection mode, where the black surface is placed outwardly, for example, during a sunny winter day.
The invention is 16 not limited for use with horizontal slatted blinds and can be practiced with vertical slatted blinds to control the energy transfer through a window, a door or any other fenestration system, which are generally referred to as "windows" in the present disclosure. The window can be equipped with a single, double or mufti-glass panes.
21 Refernng to Fig. 2, radiation from the sun (1) enters through the transparent pane of the window (2) and falls on the black surfaces (3) of the slats which absorb most of the incoming radiant energy. Absorbed energy heats the air (4) near the surface and lowers its density. Warm lighter air rises along the space between the outward black surface (3) of the slats and the interior surface (5) of the window which escapes through the open spaces of the upper portion of the 26 blind into the interior of the dwelling. Cooler air (6) from the lower portion of the interior moves up through the open spaces near the bottom portion of the blind into the free space between the blind and the window. The circulation process becomes self sustaining and ensures efficient heat transfer from the black surface of the slat to ambient air and eventually to the interior. The overall effect of the circulation process is that it tends to lower the effective temperature of the surface of the slats thereby reducing radiative losses of the collected energy back to the exterior.
Induced eddy currents also prevent stagnation of hot air next to the interior wall (5) of the pane minimizing conductive heat losses. Circulation of air (7) can also occur through the open space between the adjacent slats depending on the extent to which the blind is kept open or closed.
Fig. 3 shows the same blind appeared in Fig. 2 operated in the heat rejection mode where the reflective surface (8) is oriented outward facing the sun, while the black surface (3) is now facing the interior. Solar radiation (1) enters through the window pane and falls on the reflective surface (8) of the slats which, unlike the black surface (3), reflects back most of the radiative 11 energy (9) to the exterior. As the energy is not efficiently absorbed by the slats, the surrounding air does not get heated as much as when the black surface is facing outward.
It minimizes air currents and therefore circulation of interior air, which would have tended to raise the temperature of the interior (10).
16 Fig. 4 shows another arrangement of the slats operable in the energy collection mode. In this mode the black surface (11) is concave and the reflective surface (12) is convex.
Fig. 5 shows the same blind operating in the energy rejection mode, where the reflective convex surface (12) is facing outward.
21 Two other basic modes, namely for energy retention or dissipation can be operational when the source of energy is the interior, such as the situation during the night. Fig. 6 shows a configuration that is operable in energy dissipation mode where the black surfaces of the slats are placed facing outward. The configuration in Fig. 6 is similar to what was shown in Fig. 2 except for its functionality. During a summer night, it is a commonly encountered situation 26 where the outside temperature falls below the desired interior temperature, yet the interior temperature tends to rise above the desired level as a result of the heat originating from other interior sources such as indoor lights and appliances. According to the arrangement in Fig. 6, the black surface (13) which is an efficient radiator, radiates energy (14) to the exterior through the 1 pane (15) of the window. Also it efficiently absorbs heat from the surrounding air and makes the air passage (16) between the blind and the window pane cooler. Cooler air (17) travels downward and escape through the open space ( 18) at the bottom area of the blind. Warmer air from the interior (19) enters the space between the blind and the window pane through the open space (20) at the top portion of the blind, which eventually becomes cooler due to efficient 6 absorption of its energy by the black surface of the slats. Depending on to what extent the blinds are kept open, air circulation can also occur through the spaces in between the slats (21 ). Net result is the circulation of air along the free space between the blind and the pane which enhances overall dissipation of heat from the interior to the exterior of the dwelling via the radiative surfaces of the slats. Simultaneously, inwardly facing reflective surface (22) efficiently reflects 1 l and diffuses interior light (25) emitted by the lighting sources into the interior making the interior brighter. The overall effect would be a reduction in the energy load required for air conditioning as well as for illumination of the interior, while allowing the blind to be kept closed for desired privacy. In contrary, when a conventional blind is employed, the most obvious approach for enhancing the energy dissipation through the window would be to leave the blind fully open 16 which is not as efficient and generally not the desirable choice for privacy.
Although with a different functionality, a similar configuration used in the energy rejection mode in Fig. 3 can be used to improve retention of energy during cool nights. Fig. 7 shows a configuration operable in the heat retention mode where the reflective surface (26) and 21 black surface (27) are placed facing outward and inward, respectively. Due to weak radiative characteristics of the reflective surface with respect to radiation of its own energy, dissipation of heat to the exterior via the process of radiation is minimal. Furthermore, as a result of weak absorption characteristics of the reflective surface, the energy transfer to the slats from the air passage between the blind and the window pane is also minimal which effectively reduces 26 cooling of the air passage. This minimizes eddy currents and circulation of air along the interior side of the window. In addition to minimizing radiative losses, reduced air circulation along the pane also minimizes conductive and connective heat losses through the window.
Furthermore, any light energy (28) originating from inside the dwelling is prevented from escaping through the window while it is converted to heat and radiated back (29) to the interior by the black surface.
During development of the present invention, a prototype was designed to simulate a window of an insulated dwelling and to evaluate the relative efficiency of collection, rejection, retention and dissipation of energy by blinds having slats of different surface characteristics. The 6 prototype shown in Fig. 8 consists of an enclosure (30) having a transparent window made by attaching a 1/16" clear plexiglass sheet (31) on to one side with a sealing arrangement. All other sides of the enclosure were insulated using Styrofoam (32). The probe (33) of a digital thermometer was placed inside the box near the center of the rear wall to monitor the internal temperature. A partition (34) was placed inside the box keeping sufficient space on the top (35) 11 and the bottom (36) portions of the enclosure. The partition allowed enhanced circulation of interior air (37) while preventing direct exposure of the internal thermometer probe (33) to the external radiation which ensures that the reading of the thermometer is a direct representation of the temperature of circulating air. The blind (38) to be tested was mounted at a distance of about 1 cm behind the plexiglass window (31 ).
The effectiveness of different types of blinds can be compared by maintaining a constant influx of radiation through the window of the enclosure using an external constant energy source.
If other parameters are maintained constant, the maximum temperature that the interior of the box can reach is an indicative measure of the effectiveness of a particular blind having certain 21 surface characteristics. The rate of dissipation of energy can be assumed to be proportional to the temperature difference, Ta between inside and outside. At the steady state, i.e. when the differential temperature reaches its maximum, Td(max), the rate of energy intake by the window is equal to the rate of dissipation of energy. Therefore, Td(max) can be assumed to be proportional to the energy collection efficiency of the blind that is being tested. Even though the 26 actual amount of heat is unknown, Td(max) can be used to compare different surfaces for their "relative efficiencies", if the other parameters are kept constant. Such a comparison of "relative energy absorption efficiency" for blinds with different surface characteristics is shown in Fig. 9.
Td(max) was measured by irradiating the simulated window with a 500 watt constant intensity 1 lamp illuminated at a constant distance from the window of the enclosure shown in Fig. 8. In Fig. 9, the efficiency of net energy gain for blinds with different colours have been normalized to that of a blind having white slats oriented outward. For the particular set up described above, the energy collection efficiency of the black surface can be estimated to be about 62% higher relative to the white surface. Similarly, energy collection efficiency of the reflective surface is 29%
6 lower relative to the white surface. It should be emphasized that the above numbers are given only as an example, which could be significantly improved using a properly insulated better quality window mounted on an actual dwelling having good circulation of a much larger mass of interior air. Furthermore, a better polished reflective surface than what was used in the present prototype should also perform better in reflecting energy.
Fig. 10 shows the effect of the actual solar energy influx on the temperature inside the simulator placed outside during a winter day, as a function of time. As there was no control of the natural weather conditions, two identical simulators were placed side by side with the same orientation. All the parameters were maintained as identical as possible for the two simulators 16 except the two types of blinds that were to be compared. A solar cell was placed facing the same orientation as the two simulators. The voltage of the solar cell was used to monitor the variation of the intensity of sunlight during the day. Line (39) in Fig. 10 shows the voltage of the solar cell. Line (40) shows the temperature inside the simulator with the blind having black surface facing outward. Line (41) represents the temperature of the other simulator having the 21 reflective surface facing outward. Line (42) represents the outside ambient temperature. It can be seen that when the black surface is facing outward, a differential temperature of over 40C can be reached whereas the maximum differential temperature that can be reached with the reflective surface facing outward is only about 20C.
26 Figure 11 shows the results of a similar experiment carned out during a cloudy day which demonstrates the effectiveness of the present invention for efficient collection of energy even during cloudy days.
1 The radiative properties of the blinds were investigated using a constant intensity energy source placed inside the simulator and measuring Td (max). Fig. 12 compares the values of Ta (max) measured when a blind is placed with black and reflective surfaces facing outward, respectively. For comparison purposes, duplicate measurements made in the absence of a blind are also shown. Even though the effect of the surface on dissipation of heat from the interior 6 does not appear to be as pronounced as that observed for absorption, it is clear that the configuration with the reflective surface facing outward is more efficient in retaining heat. The apparent radiative losses can be significantly masked by the other types of losses such as conductive and connective losses from the prototype used. Therefore, it should be noted that with a window having proper insulation and better performing transparent panes, where 11 connective and conductive heat losses can be expected to be significantly lower than that of the simulator used in the present study, the effectiveness of the present invention in terms of selective heat retention and dissipation would be much more pronounced.
On the other hand, when the black surface is placed facing outward, the net energy loss 16 appears to be almost same as when there is no blind. This orientational behviour of the blinds can be exploited to our advantage when radiative energy loss through the window is desirable, for example, in situations such as summer nights, or in hot climates. Then the blinds can be kept closed for privacy reasons while the heat dissipation characteristics can be maintained virtually the same as that of a window with no blinds.
Slats of conventional blinds are generally made to be curved around a longitudinal axis.
The main purpose of such a geometry is to make the slats as light and thin as possible while maintaining their mechanical rigidity. The present invention can be utilized for effectively improving energy transfer characteristics through a window irrespective of the shape of curvature 26 (eg. concave, convex or flat) of the black and reflective surfaces of the slats. However, we have found that strategic choice of concave and convex shapes for the reflective and black surfaces, respectively, can provide added flexibility and better optimal performance. Such a configuration can be exploited advantageously, for example, to obtain a high visibility or the 1 light throughput through a window with a minimal compromise of the efficiency of energy absorption as described below.
Fig. 13 shows the relative efficiency of net energy gain as a function of angle of orientation, B for the two configurations where the shape of curvature is reversed for reflective 6 and black surfaces. The definition of the angle 8 and the two configurations are shown in Fig.
14. It is clear from Fig. 13 that, with the reflective concave surface facing outward on the direction of incident radiation (i.e. 8 < 90° ), the blind shows a sharp variation of energy collection efficiency for a small change in angle. For the particular experimental set up and the orientation of the source used in the present study, the efficiency reaches a maximum at an angle 11 of orientation, 8 of around 45 degrees which gradually goes down and reaches a minimum.
Afterwards, it reaches a plateau at a level similar to the performance curve observed for the blind with the convex-reflective surface facing upward. On the other hand, the blind with the reflective-convex surface demonstrates a gradual increase in energy collection efficiency when the angle of reflective surface varied from outward to inward orientation, nearly by 180 degrees.
16 The above unique behaviour of the blind with concave-reflective slats can be exploited to gain nearly a constant and maximum energy collection efficiency for a wide range of orientations of the slats. This allows a range of visibility or the light throughput through the window with little or no compromise in terms of the efficiency of energy absorption.
21 The theoretical basis for such a behaviour of the curved blinds can be explained as shown in Fig. 14 which would be helpful in understanding the importance of the proper choice of curvature of the slats and their orientation. Referring to Fig. 14a, when the reflective concave surface (43) is facing the direction of the incident radiation (44), the surface is capable of converging most of the radiation onto the black surface (45) of the adjacent slat which absorb 26 most of the energy and transfer it to the surrounding air as heat while enhancing air circulation (46). Such convergence of the total amount of radiation on to the black surface of the adjacent slat can occur over a wide range of the angle of incidence of the solar beam as well as the angle of orientation of the slats. On the other hand, referring to Fig. 14b, if the reflective surface (47) 1 is chosen to be convex, a significant portion of radiation is reflected back to the exterior depending on the angle of inclination, B until the blind is almost completely closed with the concave-black surface facing outward. On a window of a typical dwelling, most of the solar energy reaches the blind at a downward inclination. Therefore, for a blind equipped with horizontal slats, it is preferable to mount the slats in such a way that the reflective-concave 6 surface can be oriented upwards, to allow the configuration shown in Fig.
14a. It should be noted that this orientation is the exact opposite to what is commonly used in conventional blinds of the prior art. For vertical blinds, the optimum orientation of the reflective-concave surface would depend on the horizontal direction from which sun shines on the window during the major part of the day.
The optimum curvature of the slats would depend on factors such as desired rigidity, material of construction, width of the slats and spacing in between them. The allowed maximum light throughput or the visibility through the blind also depends on the curvature of the slat as its "effective opaque thickness", which obstructs a light beam, increases with the curvature of the 16 slat. In theory, the maximum visibility, or the minimum "effective opaque thickness" of a blind is allowed when the slats are completely flat and thin which unfortunately gives the weakest rigidity. Although the "effective opaque thickness" has to be increased slightly, a curvature of the slats adds rigidity to them. In addition, it was previously shown that proper choice of the extent and the direction of curvature can make the dual coloured blinds perform significantly 21 better in terms of energy collection efficiency. For the optimum performance, an approximate relationship among the spacing between the slats, S, width, W and the radius of curvature, R can be arnved at by considering the behaviour of a parallel optical beam incident on a concave surface. It is a fair assumption that sunlight consists of parallel rays of radiation. Using the laws of physics, it can be shown that the focal length of a concave surface is approximately equal to 26 half of the radius of curvature of the reflector. Fig. 15 shows three different scenarios of the fate of the solar radiation falling on concave reflectors of three different radii of curvature. Although only the circular surfaces are considered for the purpose of present discussion, it is understood that the same concept can be applied to slats with other geometric shapes such as parabolic and 1 hyperbolic surfaces.
Fig. 15a shows the situation when the radius of curvature, R is much smaller than twice the spacing, S. The parallel solar rays (49) incident on the concave reflective surface (SO). The portion of rays reaching the surface near the exterior edge of the slat is directly reflected into the 6 interior (51 ). Another portion that reaches the middle region of the surface is reflected (52) on to the black surface (53) of the adjacent slat where most of the radiation is absorbed and converted to heat. The rest of the rays that reach the surface near the interior edge of the slat are reflected back to the exterior (54). The concave reflective surface in Fig. 15a effectively acts similar to a convex reflector which diverges the parallel incoming radiation over a wide angle of deflection.
Fig. 15b shows the behaviour of the incoming rays when R is chosen to be approximately equal to twice the spacing, S. As the focal length is approximately equal to S
( ~ '/2 R), most of the parallel rays (55) when reflected by the concave surface (56) are focused onto the black surface (57) of the adjacent slat. Under these conditions, nearly 100% of solar energy collection 16 efficiency can be achieved over a wide range of the angle of inclination of the slats, i.e. without having to close the blind completely with the black surface facing outward.
This allows high energy collection efficiency with only a little sacrifice in visibility through the blind and facilitates illumination of the interior by using diffused light entering through the window. On the other hand, when the angle of inclination of the slats, B is reduced below a certain value 21 nearly all the incoming solar radiation is reflected back by the concave surface to the exterior.
Although the rejection efficiency can be nearly 100%, it still allows certain amount of visibility and diffuse light through the window.
On the other extreme, as shown in Fig. I Sc, when R is much larger than twice the 26 spacing, S, a portion of the incoming rays (58) is reflected back to the exterior (59) whereas the other portion (60) is reflected onto the black surface (61) of the adjacent slat. This situation provides less flexibility in terms of angle of inclination for maximum energy collection.
1 The relative portions of radiation that are absorbed by the adjacent black surface, and that are reflected back to the exterior, or to the interior under the above three scenarios would also depend on the angle of inclination of the incoming radiation as well as the angle of inclination of the slats. However, by maintaining the spacing between the slats to be close to half of the radius of curvature, as shown in Fig. 1 Sb, the optimal performance can be met in terms of energy 6 absorption over a wide range of angles, as there is no need for perfect focusing of the parallel radiation on to the black surface of the adjacent slat. The width, W of the slats should be slightly greater than the spacing, S to allow sufficient overlap of slats when the blind is closed completely.
11 Another approach to increase the absorption or radiation properties of a surface is to increase the surface area. Therefore, it is beneficial to increase the surface area of the black surface of the slats. However, the contrary applies to the reflective surface which should be as smooth as possible while having the minimum possible area. Fig.l6a shows the cross sectional view of another embodiment of the slats where the black surface (62) of the slats comprises of 16 grooves to increase the effective surface area to promote energy transfer as well as to improve mechanical rigidity while maintaining a reduced mass of material. The grooves can be longitudinal or lateral or angular or a combination thereof, relative to the axis of the slat. It is understood that the grooves can be incorporated also in embodiments having curved slats.
Increasing the surface area can be exploited especially when there is a need for using a lighter 21 color other than black for the absorbing surface for decorative purposes.
Although the black surface of the embodiment shown in Fig. 16a has a large surface area, the reflective surface (63) can still have the minimal surface area which is only dictated by the width, length and the curvature of the slat.
26 Another example of possible options for improving surface area of the black surface is shown in Fig. 16b. In this embodiment the slat is pleated in such a way that the "pleats" or the "fins" increase the effective surface area of only the black surface (64) while that of the reflective surface (65) remains virtually unchanged. The pleats also can add equal or better rigidity to the 1 slats compared to conventional curved slats. The cross section of a conventional curved slat (66) having the same "effective opaque thickness", t, is shown for comparison.
Embodiments with grooves or pleats may be less suitable for compact stacking as with curved slats during folding of the blind. However, they can be used as the preferable embodiments, particularly for fenestration systems where the visibility or the passage of light is varied primarily by adjusting 6 the orientation of the slats, but not by complete folding of the blind.
As shown in Fig. 16c, in another embodiment of the present invention, slats are perforated (67, 68) in order to allow efficient circulation of air, thereby improving heat transfer from the black surface to the surrounding air, or the vice versa.
The above discussed features and versatility of the present invention can be taken to full advantage by automating the operation of the blinds for optimal adjustment of the slats and for unattended operation. A schematic diagram depicting a basic configuration of such a system is shown in Fig. 17, as an example. Refernng to Fig.l7, the desired interior temperature is set on 16 the temperature programmer, TP (69) and the desired interior brightness on the light level programmer, LLP (70) which are connected to the microprocessor (71 ). Optical sensors (72) and (73) are mounted in such a way that they respond to the light level of incoming radiation and the light passing through the blind (81 ), respectively. Optical sensor (74) which is mounted at a suitable location monitors the brightness of the interior. It is possible to keep more than one 21 sensor on either side of the blind to monitor a more representative average light level.
Temperature sensors (75) and (76) monitor the interior and exterior temperatures. Temperature sensors (77) and (78) monitor the temperature of the ambient air near the top and bottom portions of the blind. All the sensors communicate with the microprocessor (71 ).
Mechanical drive (79) which adjusts the angle of inclination of the blind is controlled by the microprocessor. If desired, 26 mechanical drive can be disengaged from electronic control and can be operated in an optional manual mode. Depending on factors such as operating climate and desired features as described in detail in the present disclosure, an algorithm is preprogrammed onto the microprocessor.
According to the response from different sensors, microprocessor can select and control the optimum orientation of the slats to best suit the preset requirements under interactive feed-back control. The automated system can be powered by a solar cell and a storage battery in such a way that the blind can be installed as a self contained and self powered system which can be operated in remote locations and in situations where normal electrical power is not available.
6 Although the present invention has been described above with respect to certain specific embodiments thereof, those skilled in the art will recognize that these embodiments were offered for the purposes of illustration rather than limitation and that the invention is not limited thereto but rather only as set forth in the appended claims.
11 Efficient use of energy in heating and cooling of residential and commercial buildings has been the subject of considerable interest. According to recent studies, it is believed that over 25% of the heat loss in buildings is attributable to windows. Much attention has been lavished particularly on the use of solar power transmitted through windows.
Intelligent fenestration systems for automated control of light and heat energy throughput of windows have already been 16 proposed and are in existence. However, some of the main reasons for lack of wide-spread popularity of these devices are: their complexity, cost, marginal or questionable advantage over conventional designs due to inefficient collection or rejection of solar energy, and particularly their inefficiency in simultaneously and independently controlling the desired levels of light throughput (illumination or visibility), and the heat throughput. For example, during a bright 21 sunny winter day, it may be desirable to block partially or completely the incoming light through a window to avoid too much of brightness or to have desired privacy, although it may be desirable to utilize the maximum possible amount of incoming solar energy to heat the house.
Similarly, it may be desirable to allow visibility through windows on a hot bright summer day while rejecting as much energy as possible.
A number of alternatives with a variety of features have been proposed in the prior art to develop windows or blinds to improve efficient use of solar energy, however, with a varying degree of success and complexity. For example, in US patent 3,925,945, White described a heat exchanger window having at least two panes of glass where one of the two sides of the window having heat absorbing properties, and a frame which is mounted pivotally on to a frame. The sides of the window panel can be switched from winter to summer depending on the requirements. Gillery (US patent 4,235,048) described a reversible window of a similar concept for alternately reflecting and absorbing solar energy using selectively coated glass panes.
In US patent 4,421,098, Meta proposed a window with Venetian blinds mounted inside a frame with two panes of glass to improve heat absorption as well as ventilation. Gustafson described (US patent 4,527,548) a window blind type solar collector where a heated chamber is provided within the louvers, which act as heat exchangers, in such a way that a working fluid 11 may flow through the louvers to transfer the collected heat elsewhere.
Several mechanisms with varying degree of complexity for automated control of energy transfer through window blinds have been proposed. An example of such automated systems is the one described by Patterson and Luecke in US patent 5,675,487 using photovoltaic sensors 16 and electro-mechanical devices.
The proposed alternatives in the prior art have been somewhat complex, expensive, and can not be easily adapted to existing windows. Most attempts have focused only on the heating characteristics and their operation during the day. No attention has been paid to the potential use 21 of blinds for enhancing desired heat retention or dissipation characteristics of fenestration systems during the night. Alternate use of reflective and absorptive properties of surfaces have not been effectively exploited in a practical manner. Little attention has been paid on separating light throughput from heat throughput. Orientation and the effect of the geometry of slats of the window blinds have not been used optimally.
It is therefore, an object of the present invention to add versatility to a window blind which can be used to selectively and effectively intake solar energy for illumination and heating purposes, while being able to convert most of the unwanted light energy into heat, depending on 1 the need.
Another object is to add to the same blind the switchable capability of reflecting solar energy effectively for cooling purposes such as during air-conditioning.
6 Another object is to develop a blind that can be used during the night to enhance containment of interior energy, or to improve dissipation of energy as desired.
Another object is to develop a blind that minimizes required compromise between the desired light energy throughput and heat energy throughput.
Yet another object of present invention is to make the blind simple, inexpensive and easily adaptable to existing windows which can also be automated.
These and other objects of the present invention are achieved by the preferred embodiment which is disclosed herein and comprises multifunction window blind for accomplishing numerous tasks. We have found that selectively incorporating reflective and 21 absorptive properties to the alternate sides of a window blind and by strategically selecting the orientation and geometry of the slats, it is possible to improve energy transfer properties through the window in light of the above objectives.
Fig. 1 shows the general classification of the basic modes of operation of the present 1 invention.
Fig. 2 is the cross sectional view of a fenestration system employing one configuration of the present invention operable in solar energy collection mode.
6 Fig. 3 is the cross sectional view of the same fenestration system in Fig. 2 employing one configuration of the present invention operable in solar energy rejection mode.
Fig. 4 is the cross sectional view of a fenestration system employing another configuration of the present invention operable in solar energy collection mode.
Fig. S is the cross sectional view of the same fenestration system in Fig. 4 operable in solar energy rejection mode.
Fig. 6 is the cross sectional view of the fenestration system in Fig. 2 showing the 16 functionality during its operation in a heat-dissipation and light-retention mode during the night.
Fig. 7 is the cross sectional view of the fenestration system in Fig. 6 showing the functionality during its operation in an energy-retention mode during the night.
21 Fig. 8 is the cross sectional view of the simulator used to test different configurations of the blinds.
Fig. 9 is an example of relative efficiencies of energy intake through a window having blinds with slats of different colored surfaces.
Fig. 10 is an example showing the effectiveness of the present invention operated in solar energy collection and rejection modes during a sunny winter day.
1 Fig. 11 is an example showing the effectiveness of the present invention operated in solar energy collection and rejection modes during a cloudy winter day.
Fig. 12 shows the comparison of energy-dissipation efficiency by two configurations of the blinds mounted inside a simulator of a dwelling.
Fig. 13 shows the comparison of the effect of angle of orientation of the slats, for two combination of geometries of the reflective and black surfaces.
Fig. 14 shows the convergence and divergence of solar rays depending on the geometry of 11 the reflective surface of the slats.
Fig. 15 shows the effect of the curvature of the concave-reflective surface of the slats on convergence of solar rays.
16 Fig. 16 shows two possible examples of configurations of slats for improving mechanical rigidity and effective surface area of the black surface for improved energy-collection or radiation efficiencies.
Fig. 17 shows the schematic of an example for automated operation of the multifunction 21 blinds.
DETAILED DESCRIPTION OF THE INVENTION
Transfer of heat energy can occur through three basic processes: radiation, convection and conduction. Although most of the design approaches for improving energy efficiency of fenestration systems have focused on connective or conductive properties, a significant amount of heat energy can transfer into or from a dwelling through a window via the process of radiation.
Radiative properties of an object mainly depend on its surface characteristics such as colour and texture, which applies to both heat energy as well as light energy.
It is a well known 6 phenomenon that a light coloured or a shiny surface reflects radiation more efficiently than a black, dark or rough surface. On the other hand, a black, dark, or rough surface absorbs radiation more effectively than a light coloured or a shiny surface. When a black surface absorbs light, it eventually converts the energy into heat. In the present disclosure, light coloured or shiny surfaces are commonly referred to as "reflective surfaces" whereas black, dark colored, or rough 11 surfaces are commonly referred to as "black surfaces".
The blinds described in the present invention are based on the strategic choice of differential radiative characteristics and geometry of the two surfaces of the slats. In the present disclosure, such blinds are generally referred to as "dual coloured blinds" or "DCB"s, although 16 the surfaces can be made to be different using a single colour, plurality of colors or surface textures, different shapes, or a combination thereof.
Basically, to improve energy efficiency of a dwelling, two primary alternate objectives would be to facilitate either the cooling or heating of its interior, depending on the requirement.
21 In light of the above discussed radiative properties and depending on whether the source of energy is external or internal to the dwelling, the present invention can have four basic functional modes: energy collection, rejection, retention, and dissipation, as shown in Figure 1. For example, during a sunny day in a cold winter, the source of energy (the sun) is external and the desired objective would be to collect as much solar energy as possible for heating the interior of 26 the dwelling. If it is a hot sunny summer day, the source is still external. However, it is desirable to reject as much incoming energy as possible. During a night in the winter, the interior of the dwelling becomes the source of energy and then our objective would be to retain as much heat energy as possible by minimizing the losses through the window. On the other hand, during a 1 summer night, even when the outside temperature may drop below the desired interior temperature, heat generated by the interior lighting and that dissipated by the walls which were heated during the day, may tend to raise the interior temperature above the desired level, increasing the load for an air-conditioning system. Under such circumstances the desired objective would be to let as much energy as possible dissipate to the outside through the 6 window. Most often, it may also be preferable to keep the blind closed during the night for desired privacy while allowing efficient heat dissipation through the window.
Refernng to Fig. 2 and 3, an energy control system using a dual coloured blind for a window is shown for the purpose of illustrating two basic operable configurations and not 11 limiting the present invention. As a convention, in the cross sectional figures of the blinds used in the present disclosure, a thicker line is used to represent the "black"
surface of a slat whereas a thinner line is used to represent its "reflective" surface. Fig. 2 shows the cross-sectional view of a window with one possible configuration operable in the solar energy collection mode, where the black surface is placed outwardly, for example, during a sunny winter day.
The invention is 16 not limited for use with horizontal slatted blinds and can be practiced with vertical slatted blinds to control the energy transfer through a window, a door or any other fenestration system, which are generally referred to as "windows" in the present disclosure. The window can be equipped with a single, double or mufti-glass panes.
21 Refernng to Fig. 2, radiation from the sun (1) enters through the transparent pane of the window (2) and falls on the black surfaces (3) of the slats which absorb most of the incoming radiant energy. Absorbed energy heats the air (4) near the surface and lowers its density. Warm lighter air rises along the space between the outward black surface (3) of the slats and the interior surface (5) of the window which escapes through the open spaces of the upper portion of the 26 blind into the interior of the dwelling. Cooler air (6) from the lower portion of the interior moves up through the open spaces near the bottom portion of the blind into the free space between the blind and the window. The circulation process becomes self sustaining and ensures efficient heat transfer from the black surface of the slat to ambient air and eventually to the interior. The overall effect of the circulation process is that it tends to lower the effective temperature of the surface of the slats thereby reducing radiative losses of the collected energy back to the exterior.
Induced eddy currents also prevent stagnation of hot air next to the interior wall (5) of the pane minimizing conductive heat losses. Circulation of air (7) can also occur through the open space between the adjacent slats depending on the extent to which the blind is kept open or closed.
Fig. 3 shows the same blind appeared in Fig. 2 operated in the heat rejection mode where the reflective surface (8) is oriented outward facing the sun, while the black surface (3) is now facing the interior. Solar radiation (1) enters through the window pane and falls on the reflective surface (8) of the slats which, unlike the black surface (3), reflects back most of the radiative 11 energy (9) to the exterior. As the energy is not efficiently absorbed by the slats, the surrounding air does not get heated as much as when the black surface is facing outward.
It minimizes air currents and therefore circulation of interior air, which would have tended to raise the temperature of the interior (10).
16 Fig. 4 shows another arrangement of the slats operable in the energy collection mode. In this mode the black surface (11) is concave and the reflective surface (12) is convex.
Fig. 5 shows the same blind operating in the energy rejection mode, where the reflective convex surface (12) is facing outward.
21 Two other basic modes, namely for energy retention or dissipation can be operational when the source of energy is the interior, such as the situation during the night. Fig. 6 shows a configuration that is operable in energy dissipation mode where the black surfaces of the slats are placed facing outward. The configuration in Fig. 6 is similar to what was shown in Fig. 2 except for its functionality. During a summer night, it is a commonly encountered situation 26 where the outside temperature falls below the desired interior temperature, yet the interior temperature tends to rise above the desired level as a result of the heat originating from other interior sources such as indoor lights and appliances. According to the arrangement in Fig. 6, the black surface (13) which is an efficient radiator, radiates energy (14) to the exterior through the 1 pane (15) of the window. Also it efficiently absorbs heat from the surrounding air and makes the air passage (16) between the blind and the window pane cooler. Cooler air (17) travels downward and escape through the open space ( 18) at the bottom area of the blind. Warmer air from the interior (19) enters the space between the blind and the window pane through the open space (20) at the top portion of the blind, which eventually becomes cooler due to efficient 6 absorption of its energy by the black surface of the slats. Depending on to what extent the blinds are kept open, air circulation can also occur through the spaces in between the slats (21 ). Net result is the circulation of air along the free space between the blind and the pane which enhances overall dissipation of heat from the interior to the exterior of the dwelling via the radiative surfaces of the slats. Simultaneously, inwardly facing reflective surface (22) efficiently reflects 1 l and diffuses interior light (25) emitted by the lighting sources into the interior making the interior brighter. The overall effect would be a reduction in the energy load required for air conditioning as well as for illumination of the interior, while allowing the blind to be kept closed for desired privacy. In contrary, when a conventional blind is employed, the most obvious approach for enhancing the energy dissipation through the window would be to leave the blind fully open 16 which is not as efficient and generally not the desirable choice for privacy.
Although with a different functionality, a similar configuration used in the energy rejection mode in Fig. 3 can be used to improve retention of energy during cool nights. Fig. 7 shows a configuration operable in the heat retention mode where the reflective surface (26) and 21 black surface (27) are placed facing outward and inward, respectively. Due to weak radiative characteristics of the reflective surface with respect to radiation of its own energy, dissipation of heat to the exterior via the process of radiation is minimal. Furthermore, as a result of weak absorption characteristics of the reflective surface, the energy transfer to the slats from the air passage between the blind and the window pane is also minimal which effectively reduces 26 cooling of the air passage. This minimizes eddy currents and circulation of air along the interior side of the window. In addition to minimizing radiative losses, reduced air circulation along the pane also minimizes conductive and connective heat losses through the window.
Furthermore, any light energy (28) originating from inside the dwelling is prevented from escaping through the window while it is converted to heat and radiated back (29) to the interior by the black surface.
During development of the present invention, a prototype was designed to simulate a window of an insulated dwelling and to evaluate the relative efficiency of collection, rejection, retention and dissipation of energy by blinds having slats of different surface characteristics. The 6 prototype shown in Fig. 8 consists of an enclosure (30) having a transparent window made by attaching a 1/16" clear plexiglass sheet (31) on to one side with a sealing arrangement. All other sides of the enclosure were insulated using Styrofoam (32). The probe (33) of a digital thermometer was placed inside the box near the center of the rear wall to monitor the internal temperature. A partition (34) was placed inside the box keeping sufficient space on the top (35) 11 and the bottom (36) portions of the enclosure. The partition allowed enhanced circulation of interior air (37) while preventing direct exposure of the internal thermometer probe (33) to the external radiation which ensures that the reading of the thermometer is a direct representation of the temperature of circulating air. The blind (38) to be tested was mounted at a distance of about 1 cm behind the plexiglass window (31 ).
The effectiveness of different types of blinds can be compared by maintaining a constant influx of radiation through the window of the enclosure using an external constant energy source.
If other parameters are maintained constant, the maximum temperature that the interior of the box can reach is an indicative measure of the effectiveness of a particular blind having certain 21 surface characteristics. The rate of dissipation of energy can be assumed to be proportional to the temperature difference, Ta between inside and outside. At the steady state, i.e. when the differential temperature reaches its maximum, Td(max), the rate of energy intake by the window is equal to the rate of dissipation of energy. Therefore, Td(max) can be assumed to be proportional to the energy collection efficiency of the blind that is being tested. Even though the 26 actual amount of heat is unknown, Td(max) can be used to compare different surfaces for their "relative efficiencies", if the other parameters are kept constant. Such a comparison of "relative energy absorption efficiency" for blinds with different surface characteristics is shown in Fig. 9.
Td(max) was measured by irradiating the simulated window with a 500 watt constant intensity 1 lamp illuminated at a constant distance from the window of the enclosure shown in Fig. 8. In Fig. 9, the efficiency of net energy gain for blinds with different colours have been normalized to that of a blind having white slats oriented outward. For the particular set up described above, the energy collection efficiency of the black surface can be estimated to be about 62% higher relative to the white surface. Similarly, energy collection efficiency of the reflective surface is 29%
6 lower relative to the white surface. It should be emphasized that the above numbers are given only as an example, which could be significantly improved using a properly insulated better quality window mounted on an actual dwelling having good circulation of a much larger mass of interior air. Furthermore, a better polished reflective surface than what was used in the present prototype should also perform better in reflecting energy.
Fig. 10 shows the effect of the actual solar energy influx on the temperature inside the simulator placed outside during a winter day, as a function of time. As there was no control of the natural weather conditions, two identical simulators were placed side by side with the same orientation. All the parameters were maintained as identical as possible for the two simulators 16 except the two types of blinds that were to be compared. A solar cell was placed facing the same orientation as the two simulators. The voltage of the solar cell was used to monitor the variation of the intensity of sunlight during the day. Line (39) in Fig. 10 shows the voltage of the solar cell. Line (40) shows the temperature inside the simulator with the blind having black surface facing outward. Line (41) represents the temperature of the other simulator having the 21 reflective surface facing outward. Line (42) represents the outside ambient temperature. It can be seen that when the black surface is facing outward, a differential temperature of over 40C can be reached whereas the maximum differential temperature that can be reached with the reflective surface facing outward is only about 20C.
26 Figure 11 shows the results of a similar experiment carned out during a cloudy day which demonstrates the effectiveness of the present invention for efficient collection of energy even during cloudy days.
1 The radiative properties of the blinds were investigated using a constant intensity energy source placed inside the simulator and measuring Td (max). Fig. 12 compares the values of Ta (max) measured when a blind is placed with black and reflective surfaces facing outward, respectively. For comparison purposes, duplicate measurements made in the absence of a blind are also shown. Even though the effect of the surface on dissipation of heat from the interior 6 does not appear to be as pronounced as that observed for absorption, it is clear that the configuration with the reflective surface facing outward is more efficient in retaining heat. The apparent radiative losses can be significantly masked by the other types of losses such as conductive and connective losses from the prototype used. Therefore, it should be noted that with a window having proper insulation and better performing transparent panes, where 11 connective and conductive heat losses can be expected to be significantly lower than that of the simulator used in the present study, the effectiveness of the present invention in terms of selective heat retention and dissipation would be much more pronounced.
On the other hand, when the black surface is placed facing outward, the net energy loss 16 appears to be almost same as when there is no blind. This orientational behviour of the blinds can be exploited to our advantage when radiative energy loss through the window is desirable, for example, in situations such as summer nights, or in hot climates. Then the blinds can be kept closed for privacy reasons while the heat dissipation characteristics can be maintained virtually the same as that of a window with no blinds.
Slats of conventional blinds are generally made to be curved around a longitudinal axis.
The main purpose of such a geometry is to make the slats as light and thin as possible while maintaining their mechanical rigidity. The present invention can be utilized for effectively improving energy transfer characteristics through a window irrespective of the shape of curvature 26 (eg. concave, convex or flat) of the black and reflective surfaces of the slats. However, we have found that strategic choice of concave and convex shapes for the reflective and black surfaces, respectively, can provide added flexibility and better optimal performance. Such a configuration can be exploited advantageously, for example, to obtain a high visibility or the 1 light throughput through a window with a minimal compromise of the efficiency of energy absorption as described below.
Fig. 13 shows the relative efficiency of net energy gain as a function of angle of orientation, B for the two configurations where the shape of curvature is reversed for reflective 6 and black surfaces. The definition of the angle 8 and the two configurations are shown in Fig.
14. It is clear from Fig. 13 that, with the reflective concave surface facing outward on the direction of incident radiation (i.e. 8 < 90° ), the blind shows a sharp variation of energy collection efficiency for a small change in angle. For the particular experimental set up and the orientation of the source used in the present study, the efficiency reaches a maximum at an angle 11 of orientation, 8 of around 45 degrees which gradually goes down and reaches a minimum.
Afterwards, it reaches a plateau at a level similar to the performance curve observed for the blind with the convex-reflective surface facing upward. On the other hand, the blind with the reflective-convex surface demonstrates a gradual increase in energy collection efficiency when the angle of reflective surface varied from outward to inward orientation, nearly by 180 degrees.
16 The above unique behaviour of the blind with concave-reflective slats can be exploited to gain nearly a constant and maximum energy collection efficiency for a wide range of orientations of the slats. This allows a range of visibility or the light throughput through the window with little or no compromise in terms of the efficiency of energy absorption.
21 The theoretical basis for such a behaviour of the curved blinds can be explained as shown in Fig. 14 which would be helpful in understanding the importance of the proper choice of curvature of the slats and their orientation. Referring to Fig. 14a, when the reflective concave surface (43) is facing the direction of the incident radiation (44), the surface is capable of converging most of the radiation onto the black surface (45) of the adjacent slat which absorb 26 most of the energy and transfer it to the surrounding air as heat while enhancing air circulation (46). Such convergence of the total amount of radiation on to the black surface of the adjacent slat can occur over a wide range of the angle of incidence of the solar beam as well as the angle of orientation of the slats. On the other hand, referring to Fig. 14b, if the reflective surface (47) 1 is chosen to be convex, a significant portion of radiation is reflected back to the exterior depending on the angle of inclination, B until the blind is almost completely closed with the concave-black surface facing outward. On a window of a typical dwelling, most of the solar energy reaches the blind at a downward inclination. Therefore, for a blind equipped with horizontal slats, it is preferable to mount the slats in such a way that the reflective-concave 6 surface can be oriented upwards, to allow the configuration shown in Fig.
14a. It should be noted that this orientation is the exact opposite to what is commonly used in conventional blinds of the prior art. For vertical blinds, the optimum orientation of the reflective-concave surface would depend on the horizontal direction from which sun shines on the window during the major part of the day.
The optimum curvature of the slats would depend on factors such as desired rigidity, material of construction, width of the slats and spacing in between them. The allowed maximum light throughput or the visibility through the blind also depends on the curvature of the slat as its "effective opaque thickness", which obstructs a light beam, increases with the curvature of the 16 slat. In theory, the maximum visibility, or the minimum "effective opaque thickness" of a blind is allowed when the slats are completely flat and thin which unfortunately gives the weakest rigidity. Although the "effective opaque thickness" has to be increased slightly, a curvature of the slats adds rigidity to them. In addition, it was previously shown that proper choice of the extent and the direction of curvature can make the dual coloured blinds perform significantly 21 better in terms of energy collection efficiency. For the optimum performance, an approximate relationship among the spacing between the slats, S, width, W and the radius of curvature, R can be arnved at by considering the behaviour of a parallel optical beam incident on a concave surface. It is a fair assumption that sunlight consists of parallel rays of radiation. Using the laws of physics, it can be shown that the focal length of a concave surface is approximately equal to 26 half of the radius of curvature of the reflector. Fig. 15 shows three different scenarios of the fate of the solar radiation falling on concave reflectors of three different radii of curvature. Although only the circular surfaces are considered for the purpose of present discussion, it is understood that the same concept can be applied to slats with other geometric shapes such as parabolic and 1 hyperbolic surfaces.
Fig. 15a shows the situation when the radius of curvature, R is much smaller than twice the spacing, S. The parallel solar rays (49) incident on the concave reflective surface (SO). The portion of rays reaching the surface near the exterior edge of the slat is directly reflected into the 6 interior (51 ). Another portion that reaches the middle region of the surface is reflected (52) on to the black surface (53) of the adjacent slat where most of the radiation is absorbed and converted to heat. The rest of the rays that reach the surface near the interior edge of the slat are reflected back to the exterior (54). The concave reflective surface in Fig. 15a effectively acts similar to a convex reflector which diverges the parallel incoming radiation over a wide angle of deflection.
Fig. 15b shows the behaviour of the incoming rays when R is chosen to be approximately equal to twice the spacing, S. As the focal length is approximately equal to S
( ~ '/2 R), most of the parallel rays (55) when reflected by the concave surface (56) are focused onto the black surface (57) of the adjacent slat. Under these conditions, nearly 100% of solar energy collection 16 efficiency can be achieved over a wide range of the angle of inclination of the slats, i.e. without having to close the blind completely with the black surface facing outward.
This allows high energy collection efficiency with only a little sacrifice in visibility through the blind and facilitates illumination of the interior by using diffused light entering through the window. On the other hand, when the angle of inclination of the slats, B is reduced below a certain value 21 nearly all the incoming solar radiation is reflected back by the concave surface to the exterior.
Although the rejection efficiency can be nearly 100%, it still allows certain amount of visibility and diffuse light through the window.
On the other extreme, as shown in Fig. I Sc, when R is much larger than twice the 26 spacing, S, a portion of the incoming rays (58) is reflected back to the exterior (59) whereas the other portion (60) is reflected onto the black surface (61) of the adjacent slat. This situation provides less flexibility in terms of angle of inclination for maximum energy collection.
1 The relative portions of radiation that are absorbed by the adjacent black surface, and that are reflected back to the exterior, or to the interior under the above three scenarios would also depend on the angle of inclination of the incoming radiation as well as the angle of inclination of the slats. However, by maintaining the spacing between the slats to be close to half of the radius of curvature, as shown in Fig. 1 Sb, the optimal performance can be met in terms of energy 6 absorption over a wide range of angles, as there is no need for perfect focusing of the parallel radiation on to the black surface of the adjacent slat. The width, W of the slats should be slightly greater than the spacing, S to allow sufficient overlap of slats when the blind is closed completely.
11 Another approach to increase the absorption or radiation properties of a surface is to increase the surface area. Therefore, it is beneficial to increase the surface area of the black surface of the slats. However, the contrary applies to the reflective surface which should be as smooth as possible while having the minimum possible area. Fig.l6a shows the cross sectional view of another embodiment of the slats where the black surface (62) of the slats comprises of 16 grooves to increase the effective surface area to promote energy transfer as well as to improve mechanical rigidity while maintaining a reduced mass of material. The grooves can be longitudinal or lateral or angular or a combination thereof, relative to the axis of the slat. It is understood that the grooves can be incorporated also in embodiments having curved slats.
Increasing the surface area can be exploited especially when there is a need for using a lighter 21 color other than black for the absorbing surface for decorative purposes.
Although the black surface of the embodiment shown in Fig. 16a has a large surface area, the reflective surface (63) can still have the minimal surface area which is only dictated by the width, length and the curvature of the slat.
26 Another example of possible options for improving surface area of the black surface is shown in Fig. 16b. In this embodiment the slat is pleated in such a way that the "pleats" or the "fins" increase the effective surface area of only the black surface (64) while that of the reflective surface (65) remains virtually unchanged. The pleats also can add equal or better rigidity to the 1 slats compared to conventional curved slats. The cross section of a conventional curved slat (66) having the same "effective opaque thickness", t, is shown for comparison.
Embodiments with grooves or pleats may be less suitable for compact stacking as with curved slats during folding of the blind. However, they can be used as the preferable embodiments, particularly for fenestration systems where the visibility or the passage of light is varied primarily by adjusting 6 the orientation of the slats, but not by complete folding of the blind.
As shown in Fig. 16c, in another embodiment of the present invention, slats are perforated (67, 68) in order to allow efficient circulation of air, thereby improving heat transfer from the black surface to the surrounding air, or the vice versa.
The above discussed features and versatility of the present invention can be taken to full advantage by automating the operation of the blinds for optimal adjustment of the slats and for unattended operation. A schematic diagram depicting a basic configuration of such a system is shown in Fig. 17, as an example. Refernng to Fig.l7, the desired interior temperature is set on 16 the temperature programmer, TP (69) and the desired interior brightness on the light level programmer, LLP (70) which are connected to the microprocessor (71 ). Optical sensors (72) and (73) are mounted in such a way that they respond to the light level of incoming radiation and the light passing through the blind (81 ), respectively. Optical sensor (74) which is mounted at a suitable location monitors the brightness of the interior. It is possible to keep more than one 21 sensor on either side of the blind to monitor a more representative average light level.
Temperature sensors (75) and (76) monitor the interior and exterior temperatures. Temperature sensors (77) and (78) monitor the temperature of the ambient air near the top and bottom portions of the blind. All the sensors communicate with the microprocessor (71 ).
Mechanical drive (79) which adjusts the angle of inclination of the blind is controlled by the microprocessor. If desired, 26 mechanical drive can be disengaged from electronic control and can be operated in an optional manual mode. Depending on factors such as operating climate and desired features as described in detail in the present disclosure, an algorithm is preprogrammed onto the microprocessor.
According to the response from different sensors, microprocessor can select and control the optimum orientation of the slats to best suit the preset requirements under interactive feed-back control. The automated system can be powered by a solar cell and a storage battery in such a way that the blind can be installed as a self contained and self powered system which can be operated in remote locations and in situations where normal electrical power is not available.
6 Although the present invention has been described above with respect to certain specific embodiments thereof, those skilled in the art will recognize that these embodiments were offered for the purposes of illustration rather than limitation and that the invention is not limited thereto but rather only as set forth in the appended claims.
Claims (22)
1. An energy control system for a window comprising:
.cndot. a blind disposed at the window of a dwelling and having plurality of slats oriented in parallel and adjustable about an angle to control the energy passing through the said blind;
.cndot. each of the said slats having two surfaces, an exterior surface facing outwardly and an interior surface facing inwardly of said window;
.cndot. one of the said surfaces being a dark coloured or light absorbing surface, referred to as the "black surface", while the other being a light coloured or a light reflective surface, referred to as the "reflective surface";
.cndot. said slats, having substantially equal spacing and equal width, wherein the width and the spacing of the slats are chosen in such a way that, when the blind is fully closed in either direction, there is a sufficient overlap of the slats for near complete blockage of light traveling through;
.cndot. means for continuously changing the angle of rotation of the slats between the two overlapping extremes allowed by the physical limitations imposed by the effective thickness, width and spacing of the slats;
.cndot. Free space above or at the top portion and below or at the bottom portion of the blind;
.cndot. free space between the slats and the pane of the window located closest to the blind, in order to allow sufficient circulation of air.
.cndot. a blind disposed at the window of a dwelling and having plurality of slats oriented in parallel and adjustable about an angle to control the energy passing through the said blind;
.cndot. each of the said slats having two surfaces, an exterior surface facing outwardly and an interior surface facing inwardly of said window;
.cndot. one of the said surfaces being a dark coloured or light absorbing surface, referred to as the "black surface", while the other being a light coloured or a light reflective surface, referred to as the "reflective surface";
.cndot. said slats, having substantially equal spacing and equal width, wherein the width and the spacing of the slats are chosen in such a way that, when the blind is fully closed in either direction, there is a sufficient overlap of the slats for near complete blockage of light traveling through;
.cndot. means for continuously changing the angle of rotation of the slats between the two overlapping extremes allowed by the physical limitations imposed by the effective thickness, width and spacing of the slats;
.cndot. Free space above or at the top portion and below or at the bottom portion of the blind;
.cndot. free space between the slats and the pane of the window located closest to the blind, in order to allow sufficient circulation of air.
2. The slats in claim 1, where their axes of rotation and longitudinal edges are substantially parallel and horizontal.
3. The slats in claim 1, where their axes of rotation and longitudinal edges are substantially parallel and vertical.
4. The two surfaces in claim 1 which are sufficiently flat.
5. The two surfaces in claim 1, where one surface is concave and the other surface is convex.
6. Said "black surface" in claim 1 which is preferably rough and black coloured, and the said reflective surface in claim 1 which is preferably shiny smooth, or mirrored.
7. Said "black surface" in claim 1 which is preferably rough and black coloured, and the said reflective surface which is of a suitable decorative colour to suit interior or exterior of the dwelling.
8. Said "reflective surface" in claim 1 which is preferably shiny, smooth, or mirrored, and the absorbing surface which is of a suitable decorative colour to suit interior or exterior of the dwelling.
9. The slats in claim 1 and 2 where:
.cndot. they are exposed to sunlight wherein the majority of light during the day is incident on a particular slat in a descending direction relative to the horizontal plane passing through the said slat;
.cndot. the said slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the lower longitudinal edge of a particular slat is positioned outward relative to the upper overlapping edge of the lower adjacent slat.
.cndot. they are exposed to sunlight wherein the majority of light during the day is incident on a particular slat in a descending direction relative to the horizontal plane passing through the said slat;
.cndot. the said slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the lower longitudinal edge of a particular slat is positioned outward relative to the upper overlapping edge of the lower adjacent slat.
10. The slats in claim 1 and 2 where:
.cndot. they are exposed to sunlight wherein the majority of light during the day is incident on a particular slat in an ascending direction relative to the horizontal plane passing through the slat;
.cndot. the slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the upper longitudinal edge of a particular slat is positioned outwardly relative to the lower overlapping edge of the upper adjacent slat.
.cndot. they are exposed to sunlight wherein the majority of light during the day is incident on a particular slat in an ascending direction relative to the horizontal plane passing through the slat;
.cndot. the slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the upper longitudinal edge of a particular slat is positioned outwardly relative to the lower overlapping edge of the upper adjacent slat.
11. The slats in claim 1 and 3 wherein:
.cndot. a particular slat has two side-ways directions, the first and the second direction, relative to the vertical plane which passes through the slat and perpendicular to the window;
.cndot. the slats are exposed to sunlight wherein the majority of light during the day is incident from the said first direction;
.cndot. the slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the overlapping edge of a particular slat which is located at the said first direction is positioned inwardly relative to the other overlapping slat.
.cndot. a particular slat has two side-ways directions, the first and the second direction, relative to the vertical plane which passes through the slat and perpendicular to the window;
.cndot. the slats are exposed to sunlight wherein the majority of light during the day is incident from the said first direction;
.cndot. the slats are arranged in such a way that, when the blind is fully closed with the reflective surface facing outward, the overlapping edge of a particular slat which is located at the said first direction is positioned inwardly relative to the other overlapping slat.
12. The slats in claim 2, 3 and 5, wherein the reflective surface is concave and the slats are positioned in such a way that their concave surface can be oriented to be facing the direction of the major portion of incident sunlight.
13. The width of the slats in claim 1 which is approximately 1.1 to 1.2 times the spacing between them.
14. Radius of the curvature of the slats in claim 5 which is approximately 2 to 3 times the spacing between the slats.
15. Said "black surface" in claim 1 which comprises means such as grooves, pleats or fins for increasing its effective surface area.
16. Said grooves, pleats or fins in claim 15 which are preferably perpendicular to the longitudinal edges of the said slats.
17. Said grooves, pleats or fins in claim 15 which are perpendicular, parallel, angular to the longitudinal edges, or a combination thereof.
18. Slats in claim 1 which are made of a metal such as aluminum, wood or a suitable polymeric material.
19. Slats in claim 1 which are made of aluminum wherein the black surface is rough or sandblasted and anodized.
20. Slats in claim 1 which are perforated.
21. Blind in claim 1 having automatic control means, comprising:
.cndot. plurality of optical sensors mounted at a suitable location of the interior of the dwelling to monitor the level of light passing through the blind;
plurality of optical sensors mounted outwardly to the blinds at a suitable location of the interior or exterior of the dwelling to monitor the level of incoming light towards the blind;
plurality of temperature sensors mounted at suitable locations in the vicinity of top and bottom portions of the blind to monitor the temperature of air being circulated along the space between the blind and the window;
a temperature programmer such as a thermostat, for setting the desired temperature inside the dwelling;
light level programmer to set the desired level of illumination inside the dwelling;
electronic control means, such as a microprocessor, communicating with the said optical sensors, temperature sensors, temperature programmer, light level programmer and electro-mechanical means;
said electro-mechanical means, responding to the signals communicated by the electronic control means to adjust the angle of inclination of the slats;
said electronic control means which controls the orientation of the slats depending on the desired optimal configuration of the blinds decided by the electronic control means according to the response of the optical and temperature sensors, settings of the temperature and light level programmers, and a set of logical instructions, or the algorithm preprogrammed on to the said electronic control means;
means for allowing optional override for manual control of the blind.
.cndot. plurality of optical sensors mounted at a suitable location of the interior of the dwelling to monitor the level of light passing through the blind;
plurality of optical sensors mounted outwardly to the blinds at a suitable location of the interior or exterior of the dwelling to monitor the level of incoming light towards the blind;
plurality of temperature sensors mounted at suitable locations in the vicinity of top and bottom portions of the blind to monitor the temperature of air being circulated along the space between the blind and the window;
a temperature programmer such as a thermostat, for setting the desired temperature inside the dwelling;
light level programmer to set the desired level of illumination inside the dwelling;
electronic control means, such as a microprocessor, communicating with the said optical sensors, temperature sensors, temperature programmer, light level programmer and electro-mechanical means;
said electro-mechanical means, responding to the signals communicated by the electronic control means to adjust the angle of inclination of the slats;
said electronic control means which controls the orientation of the slats depending on the desired optimal configuration of the blinds decided by the electronic control means according to the response of the optical and temperature sensors, settings of the temperature and light level programmers, and a set of logical instructions, or the algorithm preprogrammed on to the said electronic control means;
means for allowing optional override for manual control of the blind.
22. Automatic control means in claim 21 which is powered by a photovoltaic cell and a charge storage device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002327648A CA2327648A1 (en) | 2000-12-15 | 2000-12-15 | Multifunction window blinds |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002327648A CA2327648A1 (en) | 2000-12-15 | 2000-12-15 | Multifunction window blinds |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2327648A1 true CA2327648A1 (en) | 2002-06-15 |
Family
ID=4167837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002327648A Abandoned CA2327648A1 (en) | 2000-12-15 | 2000-12-15 | Multifunction window blinds |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2327648A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL2009390C2 (en) * | 2012-08-30 | 2014-03-03 | Beheer 141 B V | DEPARTMENT STORE. |
| FR3009013A1 (en) * | 2013-07-24 | 2015-01-30 | Somfy Sas | METHOD FOR CONTROLLING ACTUATOR FOR MOBILE EQUIPMENT |
| EP2682825A3 (en) * | 2012-07-06 | 2015-06-24 | Delta Dore | Method and device for controlling at least one device for concealing at least one opening of a room in a building |
| CN111946232A (en) * | 2020-08-06 | 2020-11-17 | 大连理工大学 | IntelliSense Passive Solar Window System |
-
2000
- 2000-12-15 CA CA002327648A patent/CA2327648A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2682825A3 (en) * | 2012-07-06 | 2015-06-24 | Delta Dore | Method and device for controlling at least one device for concealing at least one opening of a room in a building |
| NL2009390C2 (en) * | 2012-08-30 | 2014-03-03 | Beheer 141 B V | DEPARTMENT STORE. |
| EP2702864A1 (en) * | 2012-08-30 | 2014-03-05 | Beheer 141 B.V. | Greenhouse |
| FR3009013A1 (en) * | 2013-07-24 | 2015-01-30 | Somfy Sas | METHOD FOR CONTROLLING ACTUATOR FOR MOBILE EQUIPMENT |
| CN111946232A (en) * | 2020-08-06 | 2020-11-17 | 大连理工大学 | IntelliSense Passive Solar Window System |
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