WO2000077337A2

WO2000077337A2 - System for controlling light entrance into an inner space of a building

Info

Publication number: WO2000077337A2
Application number: PCT/IB2000/000938
Authority: WO
Inventors: Franciscus Alphonsus Maria Taeymans
Original assignee: Etap Nv
Current assignee: Etap Nv
Priority date: 1999-06-04
Filing date: 2000-06-05
Publication date: 2000-12-21
Anticipated expiration: 2001-12-04
Also published as: DE60007780D1; ATE257900T1; AU5837000A; EP1255908A2; WO2000077337A3; NL1012238C2; AU5837100A; DE60007780T2; WO2001002687A3; EP1255908B1; WO2001002687A2

Abstract

A system for controlling light entrance into an inner space of a building, comprising a Venetian blind type sun protection device arranged along a pane of a window of the inner space, the top surfaces of the slats thereof being so designed that daylight incident on the top surface is reflected back in a plane through the longitudinal axis of the slat and the direction of incidence. According to the invention, there is provided a reflective surface extending on a window side along a part of the ceiling of the inner space, for reflecting daylight reflected back by the top surface of the slats and having reflected from the inside of the pane, deeper, with respect to the window side, into the inner space. The invention also relates to a method for controlling light entrance into an inner space of a building.

Description

Title: System for controlling light entrance into an inner space of a building.

This invention relates to a system for controlling light entrance into an inner space of a building, comprising a window arranged in a wall of the inner space, the window including a pane through which day Hght can enter into the inner space, and a Venetian blind-type sun protection device arranged along an inside of the pane bounding the inner space, comprising a number of spaced apart slats having a top surface and a bottom surface as well as longitudinal axes substantially located in an upright plane and extending substantially horizontally and parallel to each other, the top surface of each slat being of reflective design, such that daylight incident on the top surface is reflected back in a plane through the longitudinal axis of the slat and the direction of incidence, regardless of the angular position of the top surface with respect to the pane, and of which slats the angular position of the top surface with respect to the pane is adjustable by adjusting means, such that by adjusting the angular position the entrance into the inner space of daylight transmitted by the pane can be controlled. Such a system is known from DE 197 00 11 and is used in order for solar radiation entering via the window to be reflected back as much as possible by mirror surfaces provided on the slats.

In the known system, the slats, at their top surface, consist of mirror facets extending in the longitudinal direction, with adjacent mirror faces of adjacent mirror facets including an angle of about 90° and having a stepped configuration viewed in cross section of the slat. Through proper adjustment of the angle of the slats, it can be accomplished that daylight incident on the top surface is reflected back in a plane through the longitudinal axis of the mirror facet in the direction of incidence. Only in the case of right-angled incidence of the sunlight on the slats will the reflected light be unable to cause any nuisance to the surroundings. In the known system for controlling light entrance, if the weather is clear, the daylight entrance is damped by means of the sun protection device until light entrance is optimal for a part of the inner space near the window. However, at location& of the inner space further removed from the window, that is, in a direction transverse to the window, deeper into the inner space, the daylight entrance is thereby damped unduly, so that additional lighting is needed. For this additional lighting, typically, use is made of artificial light, which is less natural for a person staying in the inner space, entails considerable cost, and affects the environment. The object of the invention is to provide a system for controlling light entrance into an inner space of a building of the type mentioned in the preamble, in which, while maintaining the advantages mentioned, the use of artificial light can be reduced to a considerable extent

To that end, the system for controlling light entrance is characterized, according to the invention, in that it further comprises a reflective surface extending on a window side along a part of the ceiling of the inner space, for reflecting daylight reflected back by the top surface of the slats and having reflected from the inner side of the pane, deeper, with respect to the window side, into the inner space. By the use of the reflective surface, the component of the daylight reflected back in the plane of incidence by the top surface of the slats and having reflected from the inner side of the pane can be utilized to (additionally) light a part of the inner space located at a greater distance from the window. It is precisely the light falling directly onto the top surfaces of the slats, the so-called upper hemispheric light, that has a relatively high intensity, so that it can relatively strongly illuminate the parts located deeper into the inner space. It is noted that a predictable reflection from the window is possible only with a sun protection device of which the top surface of the slats reflects incident light back in a plane through the longitudinal axis of the slat and the direction of incidence. Preferably, to prevent any nuisance by reflection, sunlight is then reflected back in the direction of the source, that is, the sun.

It is further noted that the reflective surface can also be used to reflect the light reflected via the ground, via the pane and the spaces between the slats, directly incident onto the ceiling, the so-called lower hemispheric light, deeper into the utility space. In an advantageous embodiment, at least a part of the reflective surface has an inclined or curved configuration with respect to the ceiling for the focused reflection of the daylight to a predetermined part of the inner space. What can thus be achieved is that, for instance, a workplace can be additionally lighted.

Preferably, the reflective surface extends at least over the width of the window. When several windows next to each other are included in the wall, the reflective surface can advantageously extend along the entire window side of the space, that is, the wall of the space in which windows are provided. The distance over which the reflective surface extends from the window side in depth direction into the room depends inter alia on the height of the window and is preferably between about 900 mm and about 1500 mm.

In an advantageous embodiment, the reflective surface comprises one or more reflective channels having their centerlines extend substantially parallel to the slats. What is thus achieved is that, for different angles of incidence, the daylight can be reflected to substantially the same area. In this way, the location to which the light is directed depends to a lesser extent on the position of the sun. Preferably, the channel is provided with a cross section of such shape that the Hght exits the channel at an angle of less than about 60° with respect to a plane extending perpendicularly to the ceiHng along the longitudinal axis of the channel. What is thus achieved is that the light can be comfortably perceived by a person present in the inner space. What can be achieved by making the channel pivotable about its centerHne, such that, by pivoting, an edge of the channel located on the window side can be positioned further from the ceiHng than an edge located deeper into the inner space, is that even light incident at a very steep angle, for instance in summer, can be perceived in the above-mentioned comfortable manner. This is of importance in particular for a first channel arranged most proximally to the window, of a series of parallel channels successively located deeper into the inner space.

The reflective surface is advantageously designed as mirror surface, for instance a plastic evaporated onto a carrier, or a plastic provided with a microstructure of a suitable refractive index and reflective direction. Thus, a relatively strong and controlled reflection can be reaHzed, which is favorable to the efficiency of the system.

In a further advantageous embodiment, the reflective surface is built up from a number of modules. These modules can be adapted, as regards their dimensions, to modules of a system ceiling, such that they can be included as a module in a system ceiling. What is thus achieved is that the system can be readily used in an inner space already laid out.

In another advantageous embodiment, the system for controlling Hght entrance further comprises an artificial Hghting for artificially Hghting the inner space and a control system for supplementarily metering artificial Hght depending on the amount of dayHght entering the space. What is thus achieved is that in each case as Httle artificial Hght as possible is suppHed to the space, while yet a desired minimum Hght intensity can be maintained. Preferably, the control system is so designed that in different places of the inner space, the amount of supplemental artificial Hght can be etered independently.

Advantageously, at least a part of the artificial lighting can be integrated with the reflective surface, so that at least a part of the artificial Hght is reflected deeper into the space via the reflective surface. What is thus achieved is that the Hght directed deeper into the space comes roughly from the same direction, regardless of whether it is dayHght, artificial Hght or a mixture thereof. This is advantageous in particular in rapidly changing weather conditions. In yet another embodiment of the system for controlling light entrance, the sun protection device comprises at least one group of slats whose angular position can be adjusted independently of the angular position of the other slats. What is thus achieved is that one part of the sun protection device that is formed by the group of slats can be set, for instance, for optimum solar screening, while another part can be set for optimum ceiHng reflection. The angular position of the slats within the group is then preferably the same, but it may also vary.

A group of slats comprises a number of adjacent slats, preferably at least two slats. Preferably, the sun protection device comprises a separately adjustable upper group of slats extending nearer the ceiHng, and a separately adjustable lower group of slats extending closer to the floor of the inner space. In this way, the Hght intensity of a part of the inner space located nearer the window can be adjusted independently of the intensity of the inwardly directed dayHght to be reflected.

It will be clear that the slats of the lower or bottom group can be separately controlled on the basis of Hght intensity measured at different positions, for instance adjustment of the angular position of the upper group on the basis of measurement of the intensity of the dayHght entering via the reflective surface, and adjustment of the angular position of the lower group on the basis of measurement of the intensity of daylight entering through the lower group.

In a suitable manner, further, the adjusting means can be computer-controlled means which are adapted to automatically control the adjustment angle of each of the slats based on a function of the time and/or of the measured Hght intensity.

The angle adjusting means of a group can be mechanically coupled or can be electronically coupled by means of a control. In an advantageous embodiment, a number of slats are provided with a less strongly reflective top surface, preferably a group of successive slats extending proximal to the floor. Such a group of slats can form a viewing zone for persons sitting and/or standing near the sun protection device. Such a viewing zone provides the advantage that the chance of blinding by a virtual Hght source located adjacent the floor as a result of reflection from the inside surface of the pane can be reduced. It is noted that a less strongly reflective surface in this context is understood to include a surface substantiaUy free of reflection. Such a viewing zone can coincide with a lower group of slats and can, for instance, have a length of 0.5 meters.

The system for controlling Hght entrance according to the invention enables a relatively strong daylight entrance in a non-disturbing manner. The Hght is transmitted in a selective and metered manner. This proceeds inter aHa as follows. A large portion of the lower hemispheric Hght of relatively low luminance, coming from the ground outside, is transmitted directly. This is diffuse Hght, which, via the solar protection device, ends up in particular on the reflective surface provided on the ceiling of the utility space screened by the sun protection device, adjacent the window in front of which the sun protection device is placed. The reflective surface then extends on the side of the sun protection device remote from the window.

A part of the upper hemispheric sunlight reflected by the slats in the direction of incidence wiU reflect from the window glass and pass between the slats in the direction of the reflective surface. The higher the sun is in the sky, the steeper the direction of the reflected radiation and the closer to the window the reflective surface is illuminated.

Diffuse light coming from the blue sky or from a cloudy sky is reflected in a similar manner to the sunHght. Such Hght ends up at approximately the same place as the transmitted ground Hght.

In a suitable embodiment of the sun protection device according to the invention, the top surface of the slats is of retroreflective design through a layer or coating appHed thereto, which contains transparent glass or plastic beads. Such retroreflective material is, for instance, the material ScotchHte High Intensity Grade carried by the firm 3M.

In another suitable embodiment of the sun protection device, the top surface of the slats is of retroreflective design through a layer or coating appHed thereto which contains total-reflection prisms. Such retroreflective material is, for instance, the material ScotchHte Diamond Grade VIP carried by the firm 3M.

Preferably, in the above embodiments of the sun protection device, the layer or coating is in the form of a self-adhesive film or self-adhesive tape.

In yet another embodiment of the sun protection device, the slats, at the top surface thereof, are retroreflective in that they consist, at that surface, of horizontally extending mirror facets. In such a construction, light falling on the top surface that is incident at an angle from virtually the horizontal to virtually the vertical, is reflected back for a large part in a plane through the longitudinal axis of the mirror facet and the direction of incidence.

Further advantageous embodiments of the invention are described in the subclaims.

The invention also relates to a sun protection device and a method for controUing Hght entrance into an inner space of a building. The invention wiU be further elucidated on the basis of an exemplary embodiment which is represented in a drawing. In the drawing:

Fig. 1 shows a schematic side elevation of an inner space of the building in which the system is-arranged; Fig. 2 is a schematic perspective view of a sun protection device with two groups of slats whose angular position can be set independently; and

Figs. 3A-3D show a cross section of a reflective channel on which light falls in different positions. The figures are only schematic representations of preferred embodiments for clarifying the invention. In the figures, equal or corresponding parts are designated by the same reference numerals.

Fig. 1 represents a sun protection device 1 of the Venetian blind type in cross section. The sun protection device 1 comprises a number of elongate slats 2. The longitudinal axes L of the spaced apart slats 2 extend substantiaUy level, that is, in the drawing, in horizontal direction, are paraUel to each other and are located in a plane substantially upright, that is, vertical in the drawing.

The sun protection device 1 is arranged near a pane 3 of a window, not shown, in a wall of the inner space B in a building. DayHght from the free space V outside the building falls onto the upper side (window side) of the slats 2. At least on the upper side 2A, the slats 2 are retroreflective in that they are provided with retroreflective material at the top side. This material can be provided on the slats 2 as a layer. Preferably, such a layer is in the form of a self-adhesive film or a self-adhesive band or tape.

Retroreflective material is material that does not only reflect incident light back in the plane of incidence, but also in the direction of incidence, that is, reflects the Hght for the most part back to the Hght source. Such material can be a material based on transparent glass or plastic beads, for instance as marketed by 3M under the name of ScotchHte High Intensity Grade. Such material can also be a material based on total- reflection prisms, for instance as marketed by 3M under the name of ScotchHte Diamond Grade VIP. Such genuine retroreflective material, when appHed to the top surface 2A of-the slats 2, has the advantage that the surroundings are not hindered by reflected light from, for instance, the sun, since the sunHght is reflected back exclusively in the direction of the sun.

Also when the slats 2 are partly opened, a large part of the incident light from the upper hemisphere (sun, blue sky or luminous clouds) is reflected in the plane of the direction of incidence or in the direction of incidence itself.

The system further comprises a reflective surface 10 extending on the window side along a part of the ceiHng 7 of the inner space B, for reflecting dayHght 9 reflected back by the top surface 2A of the slats 2 and having reflected from the inner side of the pane 3, deeper, with respect to the window side, into the inner space B. The reflective surface 10 is designed as a number of mirrors whose mirror surface incHnes with respect to the ceiling 7 and whose centerHnes extend substantiaUy paraUel to the slats.

The system further comprises an artificial light K and a control system R for the metered supply of artificial Hght, depending on an amount of light measured by means of a sensor S at a workplace W2 located deeper into the space.

By means of adjusting means I' shown in Fig. 1, the angular position α of the top surface 2A of the slats 2 from a lower group BE can be adjusted, while independently thereof the angular position of the slats from the upper group BO can be set with adjusting means I".

The angular position α of the top surface 2A of the slats 2 with respect to the pane 3 is preferably adjustable between 0° (horizontal) and 90° (vertical). The adjusting means I' can control, for instance, the light transmission of the slats from the lower groups BE depending on the Hght intensity measured by means of a sensor S^* at a workplace Wl located near the pane. Similarly, the adjusting means I" can control the angular position of the slats from the upper group BO on the basis of the Hght intensity on the reflective surface 10 as measured by means of a sensor S".

The system according to the invention offers the possibility of a relatively strong daylight admission in a non-disturbing manner. The light is admitted in a selective and metered manner. This proceeds in different ways, as follows.

A large part of the low -luminance lower hemispheric Hght coming from the ground 4 of the space outside the space to be screened is transmitted directly by the sun protection device 1, in that it can pass between the slats 2, as indicated by arrows 5 and 6 enclosing an angle γ. The brightness of ground or lawn can actually be more than 5,000 cdVm². The transmitted Hght is diffuse Hght ending up substantiaUy on the reflective surface 10 in the vicinity of the window 3.

Direct solar radiation is reflected by the top surface 2A of the slats 2 in the direction of the sun, as indicated by the double-headed arrow 8. A part of the reflected Hght will in turn be reflected from the pane 3 in the direction of the reflective surface 10 fitted on the ceiHng 7. This is indicated by the arrow 9. This directed component of the direct solar radiation reflected from the pane glass towards the ceiling can account for 5 to 8% of the total solar radiation. The higher the sun is in the sky, the steeper the angle at which this directed component enters the space to be screened and the closer to the pane 3 the ceiling 7 is thereby illuminated. To that end, the reflective surface 10 on the ceiling comprises a number of obHque mirrors. The light travels as a homogenous parallel beam and thus causes a homogeneous luminance on the reflective surface 10 of the ceiling 7 over the entire irradiated surface. By means of the reflective surface 10 a metered amount of the "directed sunlight" is sent to a workplace W2 located deeper into the space to be screened, or to a waU which it is desired to illuminate additionaUy.

Diffuse Hght coming from the blue or cloudy sky (having a luminance of sometimes more than 10,000cd/m²) is reflected, for every smaU area of the sky, in the same way as sunHght, albeit that, obviously, a smaller amount of light is involved. For a small part, this diffuse light, after reflection from the top surface 2A of the slats 2, is Hkewise reflected by the pane 3 and, after passing between the slats 2, reaches approximately the same position on the ceiHng as the "transmitted ground Hght". Investigation has revealed that if the sky is cloudy, this "reflected sky Hght" still amounts to about 50% of the "transmitted ground Hght". It may therefore be acceptable in some cases to use the system according to the invention on the northern or western side of a building as weU, for instance there where the luminance of the sky is too high for proper use of displays.

By setting the angular position of the top surface 2A of the slats 2 of the sun protection device, the Hght intensity at the workplace Wl can be controUed to a desired level. DayHght 8 incident via the top surface 2A of the slats is reflected via the inner side of the pane 3 as indicated by arrow 9 to the reflective surface 10, independently of the position of the slats. This Hght is subsequently reflected by means of the reflective surface 10 to the workplace W2, so that the daylight can penetrate there to a greater extent. If necessary, additional artificial Hght from the artificial Hghting K can be added with the control system R. By integrating the artificial lighting with the reflective surface, as is indicated with the artificial Hghting K', the Hght directed deeper into space, to the workplace W2, can in each case come roughly from the same direction, regardless of whether dayHght, artificial Hght or a mixture thereof is involved.

Advantageously, by means of the slats provided in the lower group, the dayHght admission to the workplace Wl can be optimized, while independently thereof by means of the slats from the upper group BO, daylight admission to the workplace W2 can be optimized.

Fig. 2 is a schematic perspective view of the sun protection device of the Venetian bHnd type in the operating condition. The sun protection device comprises a number of spaced apart slats 2 whose longitudinal axes L are located substantially in an upright plane and extend substantiaHy level and paraUel to each other. The top surface 2A is of retroreflective design, such that dayHght incident on the top surface 2A is reflected back in the direction of incidence, regardless of the angular position α of the top surface 2A about the longitudinal axis L. The angular position α of the top surface 2A with respect to the longitudinal axis L is adjustable by means of adjusting means I. The adjusting means I' from a lower group BE are coupled, so that the angular position α of these slats can be adjusted independently with respect to the angular position of the other slats. In the same way, the adjusting means I" of the slats from the upper group BO are coupled, so that of these slats 2 too, the angular position α with respect to the other slats can be set independently. The coupHng of the adjusting means is effected mechanically. The sun protection device can be raised and lowered by means of hoisting cords H. Figs. 3A-3D show a cross section of a reflective channel G on which

Hght falls in different positions of incidence. Fig. A shows a beam of sunHght 9 which has been reflected by the top surface 2A of the slats via the inside surface of the panes 3, which beam enters at an angle of 45° with respect to the normal to the ceiling. In Figs. B, C, and D, this angle of incidence is 30°, 15° and 0°, respectively. From the figures it appears that given this increasingly steeper angle of incidence, the light is in each case reflected substantially to the same area. The light exits at an angle of less than 67° with respect to the median plane of the channel when the Hght falls perpendicularly. Given an angle of incidence of 15°, the angle of exit is less than 60°. To that end, the cross section of the channel G is provided with a curved central part with flat sidewalls extending obliquely outwards with respect thereto. This makes the cross section of the channel substantially U-shaped. The channel is manufactured from sheet material, for instance metal or plastic, having on the inside thereof a reflective surface.

It is noted that the invention is not limited to the exemplary embodiments described here, but that many variants are possible. Such variants wiU be clear to those skilled in the art and are understood to fall within the scope of the invention as set forth in the foUowing claims.

Claims

1. A system for controlHng Hght entrance into an inner space of a building, comprising a window arranged in a waU of the inner space, the window including a pane through which dayHght can enter into the inner space, and a Venetian blind type sun protection device arranged along an inner side of the pane bounding the inner space, comprising a number of spaced apart slats having a top surface and a bottom surface as weU as longitudinal axes substantiaHy located in an upright plane and extending substantiaHy horizontally and parallel to each other, the top surface of each slat being of reflective design, such that dayHght incident on the top surface is reflected back in a plane through the longitudinal axis of the slat and the direction of incidence, regardless of the angular position of the top surface with respect to the pane, and of which slats the angular position of the top surface with respect to the pane is adjustable by adjusting means, such that by adjusting the angular position the entrance into the inner space of dayHght transmitted by the pane can be controUed, further comprising a reflective surface extending on a window side along a part of the ceiling of the inner space, for reflecting dayHght reflected by the top surface of the slats and having reflected from the inner side of the pane, deeper, with respect to the window side, into the inner space.

2. A system according to claim 1, wherein at least a part of the reflective surface has an incHned or curved configuration with respect to the ceiling for the directed reflection of the dayHght to a predetermined part of the inner space.

3. A system according to claim 1 or 2, wherein the reflective surface comprises one or more reflective channels having their centerHnes extending substantiaHy parallel to the slats.

4. A system according to any one of the preceding claims, wherein at least a part of the reflective surface is designed as a mirror surface.

5. A system according to any one of the preceding claims, wherein the reflective surface can be incorporated as a module into a system ceiling.

6. A system according to any one of the preceding claims, further comprising an artificial lighting for artificially lighting the inner space, and a control system for supplementarily metering artificial Hght depending on the amount of dayHght entering into the space.

7. A system according to claim 6, wherein at least a part of the artificial Hghting is integrated with the reflective surface, so that at least a part of the artificial Hght can be reflected via the reflective surface deeper into the space.

8. A system according to any one of the preceding claims, wherein the sun protection device comprises at least one group of slats whose angular position can be adjusted independently of the angular position of the other slats.

9. A system according to claim 8, wherein the sun protection device comprises a separately adjustable upper group of slats extending proximal to the ceiHng of the inner space, and a separately adjustable lower group of slats extending proximal to the floor of the inner space.

10. A system according to any one of the preceding claims, wherein a number of slats is provided with a less strongly reflective top surface.

11. A method for controlling light entrance into an inner space of a building, wherein by means of slats of a sun protection device, dayHght is reflected back in a plane through the longitudinal axis of the slat and the direction of incidence of the dayHght, to an inner side of a pane bounding the inner space, and wherein the daylight reflected back is at least partly reflected by the inner side of the pane and is directed deeper into the inner space via a reflective surface extending on a window side along a part of the ceiHng of the inner space.

12. A method according to claim 11, wherein the Hght entrance is controlled by adjusting the angular position of at least one group of slats of the sun protection device independently of the other slats.

13. A method according to claim 11 or 12, wherein the angular position of at least two group of slats is set, while the angular position of the groups is dependent on a Hght intensity measured at different locations.

14. A sun protection device of the Venetian bHnd type, comprising a number of spaced apart slats whose longitudinal axes in an operating condition are located substantially in an upright plane and extend substantially horizontaUy and paraUel to each other, and of which the top surface is of reflective design, such that daylight incident on the top surface can be reflected back in a plane through the longitudinal axis of the slat and the angle of incidence, regardless of the angular position of the top surface, and of which slats the angular position of the top surface is adjustable by means of adjusting means, while the angular position of at least one group of slats can be adjusted independently of the angular position of the other slats.

15. A sun protection device according to claim 14, wherein the top surface of a number of slats is made of less strongly reflective design.