Daylighting illumination system

Abstract

A daylight illumination system for integration into a building or larger vehicle comprises a translucent facade element (800) containing a glass sheet and a light redirection element (302 or 708), and a light transport channel (801) for guiding light about horizontally into an interior of the building, the light transport channel comprising one opening attached to the interior side of said facade element and at least one opening towards the interior of the building, characterised in that the light redirection element (302 or 708) is formed as a structured polymer film or sheet attached to a glass sheet of the facade element (800) and is configured for changing the direction of incident light into the about horizontal light transport channel.

Claims

1. Daylight illumination system for integration into a building or a vehicle, the daylight illumination system comprising a translucent façade element (800) or wall element containing a glass sheet and a light redirection element (302 or 708), and a light transport channel (801) for guiding light about horizontally into an interior of the building or vehicle, the light transport channel comprising one opening attached to the interior side of said facade element or wall element and at least one opening towards the interior of the building or vehicle, characterised in that the light redirection element (302 or 708) is formed as a structured polymer film or sheet attached to a glass sheet of the facade element (800) or wall element and is configured for changing the direction of incident light into the about horizontal light transport channel, and the light transport channel containing an air or gas filling being sealed against the ambient atmosphere.

2. Daylight illumination system of claim 1 for integration into a building, the daylight illumination system comprising a translucent facade element (800) containing a glass sheet and a light redirection element (302 or 708), and a light transport channel (801) for guiding light about horizontally into an interior of the building, the light transport channel comprising one opening attached to the interior side of said facade element and at least one opening towards the interior of the building, characterised in that the light redirection element (302 or 708) is formed as a structured polymer film or sheet attached to a glass sheet of the facade element (800) and is configured for changing the direction of incident light into the about horizontal light transport channel.

3. Daylight illumination system according to claim 2, wherein the translucent facade element (800) comprises an insulating glazing unit containing at least 2 parallel glass sheets and at least one polymer film, wherein the total thickness of the facade element (800) is from the range 10 to 1000 mm.

4. Daylight illumination system according to claim 2, wherein the translucent facade element (800) comprises at least 2 parallel glass sheets, and the light redirection element (302) is attached to the interior surface of the glass sheet suitable for forming a section of the outer surface of the building envelope.

5. Daylight illumination system according to claim 2, wherein the translucent facade element (800) comprises a light collector (100, 200, 700, 800), the light collector comprising at least one waveguide layer (301), at least one light collection and redirection element (302) which is configured for coupling sun light (303) into the waveguide layer, and at least one outcoupling element (304) configured for outcoupling light from the waveguide layer into a light transport channel (801) of the daylight illumination system.

6. Daylight illumination system of claim 1, wherein the light transport channel comprises at least one opening towards the interior of the building or vehicle equipped with a light distribution element (807) allowing the guided light to leave the channel into the interior of the building or vehicle.

7. Daylight illumination system of claim 1, wherein the openings of the light transport channel for light entry and for a light distribution element (807) are arranged about rectangularly to each other, the light channel preferably being suitable for mounting with the opening for light entry, and attached facade element (800) or wall element with light redirection element (302), about vertically, and the opening for light distribution element (807) about horizontally.

8. Daylight illumination system of claim 1, wherein the light guiding inner walls of the light transport channel (801) are covered by a reflective layer.

9. Daylight illumination system according to claim 1, wherein the cross section of the light transport channel (801) has a height from the range 8 to 50; has a width from the range 20 to 300 cm and the length of the light transport channel (801) is from the range 500 to 2000 cm.

10. Daylight illumination system according to claim 1, wherein the light redirection element (302 or 708) is embodied as a plurality of grating couplers and/or holograms and/or mirrors and/or micromirrors and/or reflective micro structures.

11. Daylight illumination system according to claim 1, wherein the light redirection element (302 or 708) comprises a metal and/or a material of low refractive index such as air, each embedded in a polymer film.

12. Daylight illumination system according to claim 1 further comprising an artificial light source.

13. Daylight illumination system according to claim 1 comprising a light transport channel, whose cross section narrows down by a factor 1.2 to 5 over a distance of up to 2 m from its front opening.

14. Daylight illumination system according to claim 1 comprising glass sheet, light redirection element and light transport channel essentially as depicted in FIG. 1, 8, 11 or 13.

15. Building or vehicle comprising a daylight illumination system according to claim 1, and an envelope with a facade or outside wall in which the light redirection element is integrated in a translucent facade element or wall element or window.

16. Method for improving the light quality in a building or vehicle by increasing the amount of daylight brought into the building or vehicle, characterized in mounting a daylight illumination system according to claim 1 to the building or vehicle to integrate the system into the building envelope or vehicle wall, with the light transport channel of the system aligned about horizontally away from the building's façade or outside wall of the vehicle.

17. Daylight illumination system of claim 1 wherein the light transport channel has an inside surface which has a mirrored lining to reflect the light, and the mirror lining being interrupted by luminaire sections whereby the light may leave the light transport channel in the sections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows a daylight illumination system for integration into the building with a closed front surface according to the 1.sup.st embodiment of the present invention.

(2) FIG. 2 schematically shows a daylight illumination system for integration into the building with a facade element according to the 1.sup.st or 2.sup.nd embodiment of the present invention, indicating the distinction between the center area or the area of the channel attachment section (cross section h×w) and the non-active area or light collection area (cross section h′×w′) and according to the 2 exemplary embodiments of the present invention.

(3) FIG. 3 schematically shows a cross-section through a light collector with a light transport channel according to an exemplary embodiment of the present invention.

(4) FIG. 4 schematically show a cross-section through a light collector with a light transport channel according to an exemplary embodiment of the present invention.

(5) FIG. 5 schematically shows a cross-section through a light collector with outcoupling elements on the surface of a backplane according to an exemplary embodiment of the present invention.

(6) FIG. 6 schematically shows a cross-section through a light collector with a bent waveguide layer to direct light towards the interior of a building according to an exemplary embodiment of the present invention.

(7) FIG. 7a schematically shows a front view of the light collector according to an exemplary embodiment of the present invention.

(8) FIG. 7b schematically shows a first cross-section through the light collector of FIG. 7a.

(9) FIG. 7c schematically shows a second cross-section through the light collector of FIG. 7a.

(10) FIG. 8 shows a building with daylight illumination system according to an embodiment of the present invention.

(11) FIG. 9 schematically shows a cross-section of an exemplary four layer light collector with all light guide plates of identical size.

(12) FIG. 10 schematically shows a cross-section of an exemplary light collector with a light collection and redirection element with a V-groove prism structure.

(13) FIG. 11 schematically shows a cross section of an exemplary facade element comprising two glass sheets (705, 710) and an air gap 706 in between, where a polymer film 708 comprising the light redirecting element is attached to one of the glass sheets.

(14) FIG. 12 shows a process for preparing a redirecting polymer film.

(15) FIG. 13 shows an example for the front part of the present general embodiment 1 with section 24 giving a magnification of section 23 within section 22, which section 22 gives an enlarged view of the front plate section 21.

(16) FIGS. 14a and 14b shows 2 photographs of offices illuminated with the present in accordance with the present invention (prototype, embodiment 1).

(17) FIG. 15 shows the construction of the prototype light channel.

(18) In principle, identical parts can be provided with the same reference symbols in the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

(19) FIG. 1 schematically shows an example for a daylight illumination system and for integration into the building (see FIG. 800) with a closed front surface according to the 1.sup.st embodiment of the present invention. The facade element comprising a section of width w and height h (i.e. roughly the cross section of the channel) contains at least one light redirection element which is configured for coupling sunlight into light transport channel of length l.

(20) FIG. 2 schematically shows a daylight illumination system comprising a facade element according to the 1.sup.st or 2.sup.nd embodiment of the present invention: The element of width w′ and height h′ contains an at least partially transparent channel attachment section of width w and height h, which in this embodiment is a central section. According to the 1.sup.st embodiment of the present invention, the façade element is of width w′ and height h′, contains a light redirecting element in its central section of width w and height h, and does not contain a light collector. According to the 2.sup.nd embodiment of the invention, the central section is surrounded by a collector section or light collection area (w′×h′−w×h), in which the waveguide layer extends and where light is collected by the waveguide layer. This light collector further comprises at least one outcoupling element configured for coupling light from the waveguide layer into the light transport channel (see also reference sign 801 in FIG. 8) of the daylight illumination system. This allows that the light collector to gather light from an area that is larger than the cross-section area of the light transport channel, which will become even more apparent from the explanations of FIG. 3. The system collects light in a different manner compared to the prior art and also guides the collected light in a different manner towards the light transport channel.

(21) As can be gathered from FIGS. 1 and 2, the present daylight illumination system does not comprise any moving parts for sun tracking and has flat dimensions. The system is not based on fiber optics and, as a prefabricated element, the system can be integrated smoothly into the glass facade and the building envelope to be exposed to daylight.

(22) The light transport channel extends from and is connected to the channel attachment section/central section of the facade element (in FIG. 2 indicated with the center cross section of width w and height h).

(23) FIG. 3 shows a cross-section through a light collector 300 according to the second embodiment of the invention with an at least partially transparent central section through which light can directly enter the light transport channel 305 according to an exemplary embodiment of the present invention. This collector is similar to the light collector shown in FIG. 2. The light collector 300 is embodied as our pre-fabricated facade element. The light collector 300 comprises a waveguide layer 301, a light collection and redirection element 302 which is configured for coupling sun light 303 into the waveguide layer 301. Further, an outcoupling element 304 configured for outcoupling light from the waveguide layer into a light transport channel 305 which can be part of the daylight illumination system. The waveguide layer 301 can be embodied in several different ways as has been explained in detail hereinbefore. Solid and/or liquid light guides may be used. In a preferred embodiment the waveguide layer 301 is embodied as a light guide plate which is part of the sandwich construction of the light collector 300. Out coupling element 304 is embodied as a mirror coupling light out of the waveguide layer 301 towards the interior of the building and thus into the light transport channel 305. The light which is transported in the waveguide layer by Total Internal Reflection (TIR) is shown with reference sign 307 and the light which is coupled out of the collector is shown with reference sign 309. The outer edges of the waveguide layer 300 comprise an attached mirror 306 configured for redirecting light travelling within the waveguide layer towards the edges back towards at least one center or the channel attachment section 308 of the light collector. Due to the use of the waveguide layer which is embodied as a waveguide plate or a waveguide panel within a facade element and also due to the light collection by TIR in the solid waveguide layer, the light collector is configured for collecting light from an area that is larger than the cross-section area of the light transport channel. The light that is collected in a large light collection area (see FIG. 2) is guided by the light collector to a comparatively smaller light transport channel. Thus, when comparing the present invention with systems which only collect light in an area that is defined by the cross-section of the light transport channel, this leads to an increase of the amount of light that is guided into the building. The daylight illumination system of the present invention thus provides for a higher light collection efficiency as compared to know system.

(24) FIG. 4 schematically show a cross-section through a light collector 400 according to the second embodiment of the invention with a closed front surface (i.e. where no light can directly enter the light transport channel, in other words all the light is redirected and transported through the waveguide layer), similar to the light collector shown in FIG. 2, and a light transport channel 405 according to an exemplary embodiment of the present invention. The light 407 couple into the light collector is transported towards the mirrors 404 which reflect the light towards the light transport channel 409. The light 409 which is coupled out can thus travel in the mirror-lined duct 405 via Total Internal Reflection (TIR) into the building. The light collection and redirection element 402 is also located in this embodiment at the back panel or backplane of the laminated sandwich structure of light collector 400. Light collector 400 also comprises mirrors 406 to redirect the light towards the outcoupling elements 404. As can be seen from FIG. 4, the waveguide layer 401 is also located in the centre 408 of light collector 400 such that also in this central area the daylight 403 can be coupled into the system, transported to the outcoupling elements and can be coupled into the light transport channel 405.

(25) FIG. 5 schematically shows a cross-section through a light collector 500 according to the second embodiment of the invention with outcoupling elements on the surface of a layer directed towards the interior of the building according to an exemplary embodiment of the present invention. FIG. 5 further shows that the outcoupling element of the light collector is embodied as light extraction elements 503 that are located at a surface adjacent to the waveguide layer 501. It is also schematically shown that the light collection and redirection element 502 is located at the same depth of the light collector as the outcoupling element 503. The light extraction elements are used in this embodiment instead of the mirrors 404 in FIG. 4. However, also a combination of these elements is possible. The light extraction elements may e.g. be applied as part of a micro-optical foil to the surface of the waveguide layer, for example in at least parts of the at least one center of the light collector or the channel attachment section.

(26) FIG. 6 schematically shows a cross-section through a light collector 600 according to the second embodiment of the invention with a bent waveguide layer 601 to direct light 604 towards the interior of a building according to an exemplary embodiment of the present invention. The bent section is shown with reference sign 603. Light collection and redirection element 602 is also shown. Additional elements may preferably be applied to the end of the waveguide layer directed towards the interior of the building. These additional elements may for instance be, but are not limited to, a refractive index gradient layer to bridge the difference in refractive index between the waveguide layer and air, a cone or wedge type element, or a combination of a cone or wedge type element with a refractive index gradient layer or may be formed by a transparent refractive index matched micro (TRIMM) particles in a transparent polymer material. The collector shown here can be combined with a front and/or back panel. This is also the case for collectors 500, 400 and 300 disclosed hereinbefore.

(27) FIG. 7a schematically shows a front view of the facade element with two at least partially transparent central sections. Facade element 700 comprises two sections 701, 702 which are channel attachment sections since a light transportation channel is attached to the interior there. In general, the light collection area defines the area where the light collector is capable of collecting light and redirecting it into the light transport channel. Furthermore, specific dimensions of an individual exemplary embodiment of the light collector are shown in FIG. 7a.

(28) FIG. 7b schematically shows a first cross-section through the facade element 700 of FIG. 7a along line A or line B in accordance with the first embodiment of the invention (see reference signs 703 and 704 in FIG. 7a), or along line A in case of a facade element comprising waveguide layer and outcoupling element according to the second embodiment of the invention, see reference sign 703 in FIG. 7a. The specific embodiment of the facade element 700, which also functions as a light collector, comprises a cover glass 705 (for example 3 mm thickness), a PMMA or PVB layer 706 (for example 3 cm thickness), an optional high refractive index layer or gradient refractive index layer 707 (for example 0.07 mm thickness), a prism film with mirror coating 708 (for example 0.07 mm) as a light collection and/or redirection element, a PET or PVB substrate film 709 (for example 0.2 mm thickness) and a back glass or insulation 710 (for example 3 mm thickness). In case of the 1.sup.st embodiment of the invention, layer 706 may be replaced by an air gap as typical for thermal insulation glazings. In a preferred variant of the 1.sup.st embodiment of the invention, the mounting is reversed, with glass sheet 710 forming the exterior side of the facade element and glass sheet 705 forming the side if the facade element, where the light transport channel is attached.

(29) Similar to FIG. 7b, FIG. 7c schematically show a second cross-section through the light collector 700 of FIG. 7a for the second embodiment of the invention, along line B, see reference sign 704 in FIG. 7a. In addition to the elements shown and explained in the context of FIG. 7b, the back glass 711 (for example 3 to 3.35 mm thickness) and the redirecting mirror 712 as out coupling element are shown in FIG. 7c.

(30) It must be noted that the structure of the light collector shown and explained in the context of FIGS. 7a to 7c is not bound to the exemplary dimensions shown in FIG. 7a, but can also be applied to other lengths, widths etc. Thus, the layered structure of this embodiments is to be seen and is disclosed herewith as being independent from the numeral dimensions shown in FIG. 7a. The same holds true for the building and the daylight illumination of following FIG. 8.

(31) FIG. 8 shows a section of a building with a daylight illumination system according to an embodiment of the present invention. The daylight illumination system comprises a facade element or light collector 800 and a light transport channel 801. The light transport channel is for guiding light from an outside of the building to an interior of the building. The light transport channel 801 comprises walls which provides for internal reflection to guide the light from the light collector 800 towards the desired room 809 of the building. In FIG. 8 the light transport channel is embodied as a mirrored horizontal light tube 805. Also a light distribution element 807 in form of the daylight luminaire is shown. The building of FIG. 8 also comprises a window 802, several walls 806, frame 803 and the floor 804.

(32) FIG. 9 schematically shows a cross-section through the light collection area of a light collector according to the second embodiment of the present invention. Light collector 900 consists of a plurality 905 of waveguide layers 901, the light collection and redirection element 906 that redirects the incident daylight consists of a plurality of stripes or patches attached to each of the plurality of waveguide layers, the stripes or patches displaced towards each other in a way that combined they cover the whole area or the entire width of the light collection area. Between the plurality of waveguide layers air gaps 902 are provided. At the edges or lateral ends of the light collector 900, distance holders 903 are provided between the individual waveguide layers. Furthermore, reflectors 904 are provided at the edges or lateral ends of the light collector 900. In an embodiment, the width 907 of the light collection and redirection element 906 may be 3 cm for a thickness of waveguide layer 901 of 1 cm. FIG. 9 only shows a part of the light collector 900 and only shows the light collection area in which the light is coupled into the waveguide layer. The light will be guided further to the left where the section or area is located in which the outcoupling element is located.

(33) FIG. 10 schematically shows a cross-section of a part of an exemplary light collector 1000 with a light collection and redirection element 1006 as of the second embodiment of present invention embodied as a micro-optical film with a V-groove prism structure. An adhesive layer 1002 (e.g. 25 micrometer, n=1.6) is used below the waveguide layer 1001 (e.g. 1 cm of PMMA, n=1.5) and below the adhesive layer 1002 a high refractive index layer (e.g. 50 micrometer, n=1.7) is used. The prism layer 1004 (e.g. 25 micrometre Acrylate coated with an Aluminium mirror of e.g. 50 nanometer) is located on top of the substrate (e.g. PET, 100 micrometre). In other words, between the light collection and redirection element 1006 and the waveguide layer 1001, a gradient refractive index layer with two layers is used. There is one layer of n=1.7, the high refractive index layer, and one layer of n=1.6, i.e., the adhesive.

(34) FIG. 11 shows a schematic cross section of an exemplary facade element as it may be part of the 1.sup.st embodiment of present invention comprising two glass sheets (705, 710) and an air gap 706 in between, where a polymer film (typically a PVB film) 708 comprising the light redirecting element is attached on the interior side of one of the glass sheets. In a preferred variant of this assembly, glass sheet 710 carrying redirecting film 708 is on the exterior side of the building, light 711 enters the building through sheet 710, gets redirected by film 708, and enters the light transport channel (not shown in this FIG. 11), which is attached to glass sheet 705.

(35) FIG. 12 shows a process for preparing a redirecting polymer film: Using a suitable microstructuring tool (A), a UV curable coating on a suitable polymer film is structured and cured (step B). The structured layer thus obtained is subjected to metal vapour under an oblique angle (C). Subsequently, another resin layer is coated, which covers the metallic microplanes and fills the gaps between the structures to provide a smooth polymer surface (step D).

(36) FIG. 13 shows an example with typical dimensions for the front part of the present light channel with double glass front plate of height h comprising a redirecting film (general embodiment 1). Section 24 shows a part of the exterior glass sheet covered by the present light directing film of 0.2 mm thickness; section 24 showing an enlarged part from section 22, which depicts a fraction of the double glass unit's cross section, again indicating the positioning of the present light redirecting film (thickness of exterior glass sheet with redirecting film in this example: 4 mm). Section 22 itself represents the enlarged view of section 21 (front plate).

(37) FIGS. 14a and 14b show 2 photographs of offices illuminated by the 2 parallel prototype light channels of example 2 (luminaires beginning at 8 m distance in FIG. 14b, and at 11.1 m distance from the façade in FIG. 14a).

(38) FIG. 15 shows the cross section (side view) of the prototype light channels of example 2; 800 denotes the insulating glass unit of the façade (4 mm glass sheet, 12 mm air gap, 4 mm glass sheet) containing the redirecting film; 801 denotes the volume of the light channel; 807 denotes the 2 openings (Luminaires, side view showing their short side) the one at the channel end sized 29 cm×83 cm and the one towards the middle of the channel sized 30 cm×80 cm; 815 denote the rounded reflector at the end of the tube (radius 29 cm) and the reflective sheet over the middle luminaire; 821 indicates the straight tube length of 11.1 m; 822 indicates the distance between the 2 luminaire openings of 2.8 m.

(39) The invention thus may be further represented by the following embodiments:

(40) 1. A daylight illumination system for integration into a building, the daylight illumination system comprising a translucent facade element (800) containing a glass sheet and a light redirection element (302 or 708), and a light transport channel (801) for guiding light about horizontally into an interior of the building, the light transport channel comprising one opening attached to the interior side of said facade element and at least one opening towards the interior of the building, characterised in that

(41) the light redirection element (302 or 708) is formed as a structured polymer film or sheet attached to a glass sheet of the facade element (800) and is configured for changing the direction of incident light into the about horizontal light transport channel.

(42) 2. Daylight illumination system of embodiment 1, wherein the light transport channel comprises at least one opening towards the interior of the building equipped with a light distribution element (807) allowing the guided light to leave the channel into the interior of the building, the light transport channel preferably containing an air or gas filling being sealed against the ambient atmosphere.

(43) 3. Daylight illumination system of embodiment 1 or 2, wherein the openings of the light transport channel for light entry and for a light distribution element (807) are arranged about rectangularly to each other, the light channel preferably being suitable for mounting with the opening for light entry, and attached facade element (800) with light redirection element (302), about vertically, and the opening for light distribution element (807) about horizontally.

(44) 4. Daylight illumination system of embodiment 1, 2 or 3, wherein the light guiding inner walls of the light transport channel (801) are covered by a reflective layer, preferably a reflective silver or aluminum layer or a reflective multilayer polymer film, most preferably providing at least 95% directed reflection and less than 5% diffuse reflection.

(45) 5. Daylight illumination system according to any of embodiments 1 to 4, wherein the translucent facade element (800) comprises an insulating glazing unit containing at least 2 parallel glass sheets and at least one polymer film, wherein the total thickness of the facade element (800) preferably is from the range 10 to 1000 mm, especially 15 to 50 mm.

(46) 6. Daylight illumination system according to any of embodiments 1 to 5, wherein the translucent facade element (800) comprises at least 2 parallel glass sheets, and the light redirection element (302) is attached to the interior surface of the glass sheet suitable for forming a section of the outer surface of the building envelope.

(47) 7. Daylight illumination system according to any of embodiments 1 to 6, wherein the cross section of the light transport channel (801) has a height from the range 8 to 50, especially about 10 to 35 cm; has a width from the range 20 to 300 cm, especially about 30 to 120 cm; and the length of the light transport channel (801) is from the range 500 to 2000 cm, especially about 600 to 1200 cm.

(48) 8. Daylight illumination system according to any of embodiments 1 to 7, wherein the translucent facade element (800) comprises a light collector (100, 200, 700, 800), the light collector comprising

(49) at least one waveguide layer (301),

(50) at least one light collection and redirection element (302) which is configured for coupling sun light (303) into the waveguide layer, and

(51) at least one outcoupling element (304) configured for outcoupling light from the waveguide layer into a light transport channel (801) of the daylight illumination system.

(52) 9. Daylight illumination system according to any of the above embodiments, wherein the light redirection element (302 or 708) is embodied as a plurality of grating couplers and/or holograms and/or mirrors and/or micromirrors and/or reflective microstructures.

(53) 10. A building comprising

(54) a daylight illumination system according to any of embodiments 1 to 9, and an envelope with a facade in which the light collector is integrated as facade element.

(55) 11. The use of a daylight illumination system according to any of embodiments 1 to 9 for introducing daylight into the interior of a building in 5 to 20, especially 6 to 12, meter distance from a window.

(56) 12. A method for improving the light quality in a building by increasing the amount of daylight brought into the building, characterized in that a daylight illumination system according to any of embodiments 1 to 9 is integrated into the building envelope, with its light transport channel aligned about horizontally away from the building's facade.

(57) 13. A light collector (100, 200, 700, 800) for use in a daylight illumination system (800), especially as described in the above embodiments 1 to 9, and for integration into a building, the light collector comprising

(58) at least one waveguide layer (301),

(59) at least one light collection and redirection element (302) which is configured for coupling sun light (303) into the waveguide layer, and

(60) at least one outcoupling element (304) configured for outcoupling light from the waveguide layer into a light transport channel (801) of the daylight illumination system.

(61) 14. A light collector according to embodiment 13, wherein the light collector is constructed in the form of a prefabricated facade element, and wherein the waveguide layer is a light guide plate.

(62) 15. A light collector according to embodiment 13 or 14, which is a static collector and has flat dimensions.

(63) 16. A light collector according to any of embodiments 13 to 15, wherein the light collection and redirection element (302) is embodied as a plurality of grating couplers and/or holograms and/or mirrors and/or micromirrors and/or reflective microstructures.

(64) 17. A light collector according to any of embodiments 13 to 16, wherein the light collector comprises a plurality of stacked waveguide layers (900).

(65) 18. A light collector according to any of the embodiments 13 to 17, wherein edges of the waveguide layer comprise an attached mirror (306, 406, 904) configured for redirecting light travelling within the waveguide layer towards the edges back towards at least one center or a channel attachment section (308) of the light collector.

(66) 19. A Light collector according to any of the embodiments 13 to 18, wherein the outcoupling element (304) is chosen from the group comprising flat mirror containing elements, parabolic mirror containing elements, elements containing optical light extraction structures at the surface such as e.g. prisms, pyramids, cones, or any combination thereof, or wherein the outcoupling element is provided by a bent waveguide layer (603) to redirect the light by total internal reflection within the waveguide layer.

(67) 20. A light collector according to any of the embodiments 13 to 19, wherein the light collector comprises a transparent front panel and a transparent back panel, and wherein the front and back panel are embodied as a glass panel, or a plastic panel such as a polymethylmethacrylate panel, a polyacrylate panel, a polycarbonate panel, or any combination thereof.

(68) 21. A light collector according to any of the embodiments 13 to 20, wherein the light collector comprises at least one coating or film laminated to it to control its reflection and transmission properties.

(69) 22. A light collector according to any of the embodiments 13 to 21, wherein the light collector comprises a cover glass, a PMMA layer as waveguide layer, high refractive index layer or a gradient refractive index layer, a prism film with mirror coating, a PET substrate and a back glass.

(70) 23. A daylight illumination system for integration into a building, the daylight illumination system comprising a light collector (800) according to any of the embodiments 13 to 22, a light transport channel (801) for guiding light from an outside of the building to an interior of the building,

(71) wherein the outcoupling element (304) of the light collector is configured for directing light from the waveguide into the light transport channel,

(72) wherein the light transport channel (801) comprises walls providing total reflection of the light, and wherein the light transport channel comprises at least one light distribution element (807) at which the guided light is allowed to leave the channel into the interior of the building.

(73) 24. A daylight illumination system according to embodiment 23, wherein the light collector is configured for collecting light from an area that is larger than the cross-section area of the light transport channel.

(74) 25. A daylight illumination system according to any of the embodiments 23 to 24, wherein the waveguide layer is a solid light guide, and wherein the light transport channel is a mirror-lined duct.

(75) 26. A building comprising a daylight illumination system according to any of embodiments 23 to 25, and an envelope with a facade in which the light collector is integrated as facade element.

(76) Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from the study of the drawings, the disclosure, and the appended claims. In the claims the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfil the functions of several items or steps recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

(77) Any reference signs in the claims should not be construed as limiting the scope of the claims.

Abbreviations Used in the Specification or Claims

(78) PMMA the acrylic polymer Polymethylmethacrylate

(79) PET the polyester Polyethyleneterephthalate

(80) PVB the polymer Polyvinylbutyral

(81) LED light emitting diode

Example 1: Average Light Flux (Office Hours) at Varying Latitudes

(82) Average light flux at the rear end (l=11 m) of south facing horizontal light channels, each of h=0.3 m and w=0.9 m, during standard office hours between 8 am and 5 pm is calculated for sky conditions found in Frankfurt a.M. (35% sunshine hours), Madrid and Abu Dhabi (based on public climate data: https://energyplus.net/weather) and light channel designs as described below.

(83) Channel 1 comprises a front element comprising a light redirecting film (FIG. 1, 1st embodiment of the invention; film prepared as described in the example of WO 20141024146, FIGS. 5a-5h, but omitting second components described therein. The encapsulated mirrors are curved and have a width of 250 micrometer and repeat with a periodicity of 100 micrometer. The curvature is progressive as to better redirect light horizontally, the mirrors are modeled with a reflectance of 95%. The total film thickness is 300 micrometer. The film is laminated to the inner face of the outer glazing (4 mm) of a double glazing unit (4-12-4) covering the full surface of the vertical opening of the light tube facing the exterior.

(84) Channel 2 comprises a front element comprising a light redirecting film and a collector. The redirecting film is similar to the one used in channel 1 with an extra adaptation of the mirror curvature in the bottom part and no mirrors in the upper 14 cm. The collector parts replace the inner glass pane of the double glazing. The area above and below the tube opening the collector is composed of a thick transparent plate which is curved and where the horizontal part ends with a wedge. The vertical part is 9 cm high, 3 cm thick, structured on its back side and the structures are coated with a reflective material. The structures are prismatic structures with the facets facing the tube opening tilted at 41° from the vertical and the other facets at 19° from the vertical. The wedge angle is 26°. The horizontal facet of the wedge is coated with a reflective material to outcouple light only on the tube side. The front element has a total height h=0.48 m (FIG. 2, 2nd embodiment of the invention)

(85) Channel 3 comprises a front element identical to the one described in channel 1 with further adaptation of the mirror curvatures. This element is composed of a light redirecting film laminated to the inner face of the outer glass pane in a double glazing. The total height of the front element is 0.6 m, double the height of the final tube height after 11 m (0.3 m). Therefor the tube height changes within the first meters. The tube height is reduced to it final height on 1.41 m, the slanted face of the tube is flat and forms an angle of 12° with the horizontal.

(86) Channel 4 is similar to channel 1 but the material used to encapsulate the mirrors is different from the one used for the structures and the curvature has been optimized to reach a more horizontal redirection of light. The difference in refractive index in this embodiment is subtle (0.02) but it increases the redirecting performance by some percent.

(87) Channel 5 is like channel 1 but the light redirecting element is based on refractive properties of materials and does not contain a metallic reflector. To achieve light redirection, this system uses total internal reflection and therefore the change in refractive index. The system is composed of three different materials. The structure layer on the right has a standard refractive index of (n=1.5), it is then coated with a low refractive index material (n=1.4) and finally encapsulated with a third material (n=1.4).

(88) Channel 6 is like channel 1 but the redirecting foil is replaced by a commercial product (3M Daylight Redirecting Film). Such a foil uses the refractive index difference between air and the structured polymer foil. The changing curvature increases the angular rang for which light is redirected in the right direction. Based on the profile of this commercial products, the optical properties are simulated.

(89) Channel 7 is like channel 1 but the redirecting foil is replaced by a foil as described in Patent US 20020159154 A1 FIG. 2. Such a foil uses the refractive index difference between air and the polymer foil. The interfaces to the encapsulated air act like mirrors and reflect light deep into the light duct. For the application in light ducts, the design was optimized to maximize light flux at the end of the duct. The air gaps are 100 micrometer wide, 3 micrometer thick, 45 micrometer spaced and tilted by 10° to flatten the angle at which light from the sky is redirected into the tube.

(90) For the purpose of comparison, light flux of another channel is calculated, which covers a glass front plate without any light redirecting element (reference).

(91) For the simulation, a raytracing tool (LightTools 8.5, Synopsis' Optical Solutions Group, Pasadena, US) is used to characterize the system, in all cases assuming a reflectivity of 97% over all incidence angles for the light tube. The system transmittance is characterized for each incoming angle of the hemisphere with a resolution of 1° in elevation and 2° in azimuth. The transmittance is calculated between the front end of the duct and the rear end of the duct. This transmittance vector is then multiplied by the available luminance and solid angle for each direction at each time step. The sky luminance for each direction and over the whole year is computed based on the Perez model using the direct and diffuse irradiance from the hourly climatic data. Both the luminance for the sky and the ground (albedo of 30%) are considered. Hereby, the hourly light flux at the end of the system is computed.

(92) Table 1 compiles results (in lumen) for the average light flux during office hours (Average) and for the minimum light flux during 50% of office hours (Minimum, i.e. during 50% of working hours, the light flux at the end of the duct will be equal to or higher than the given value) after 11 m transport length. The values are computed for the result obtainable using two identical light tubes. The average light flux is computed during said workhours. The minimum light flux is the minimum value reached when considering the best half of occupied hours. This value can be used to derive the minimum desk illuminance reached during 50% of occupied hours.

(93) TABLE-US-00001 TABLE 1 Average light flux (lm) and minimum light flux (lm) after 11 m transport length by 2 light tubes Channel Frankfurt Madrid Abu Dhabi Reference Average 4300 5900 6000 Reference Minimum 3450 5050 4850 Channel 1 Average 5350 7650 7850 Channel 1 Minimum 3750 6450 5650 Channel 2 Average 5450 7800 8100 Channel 2 Minimum 3800 6550 5700 Channel 3 Average 7550 10300 11500 Channel 3 Minimum 4650 6950 5850 Channel 4 Average 5700 7950 8300 Channel 4 Minimum 3900 6500 5650 Channel 5 Average 4878 6836 7674 Channel 5 Minimum 3516 5976 5518 Channel 6 Average 5100 7450 7900 Channel 6 Minimum 3400 6000 5250 Channel 7 Average 5490 7724 9632 Channel 7 Minimum 3848 6594 5728

(94) The above results are validated by measurements with 1:10 reduced scale prototypes of each channel.

(95) The daylighting system of the invention provides a surprisingly high light intensity.

Example 2: Full Scale Prototype

(96) In order to further validate the simulation results of example 1, a 1:1 prototype is built. The prototype consists of two offices and two light tubes. Both offices are windowless and illuminated by one opening in each tube, they are 2.8 m wide and 3 m long with a ceiling at 2.6 m. The rooms (see FIGS. 14a and 14b) are painted white and furnished with a table and chairs. The tubes both have a rectangular cross section with interior dimension of 29 cm height and 87 cm width. The tubes are both 11.39 m long in total and placed in parallel with some space between them. One is fitted with a 3M DF200MA reflective foil and one with a Alanod Miro Silver DL reflective metal foil. All four openings in the bottom surface of the 2 tubes providing light to the rooms are offset by 14.5 cm with respect to the ceiling. The 14.5 cm distance between the room ceiling and the tube opening in each case is fitted with a reflective foil. The opening of each tube into the first room (FIG. 14b) is 30×80 cm, starting at 8 m from the façade, and in the second office (FIG. 14a) 29×83 cm and located at 11.1 m from the façade, at the very end of the tube (short length of the opening in direction of the tube length). The tube is ending with a quarter circle shaped reflector above the opening at the end of the tube, with a radius of 29 cm (see FIG. 15). Above the first opening, a reflective sheet is placed with an angle of 29° from the horizontal and a length of 27.8 cm to capture light from the tube and redirect it. The vertical openings on the front, façade side, are fitted with a simple plexiglass and then with a double glazing (4-12-4) integrating the 3M Daylight Redirecting Film redirecting foil. Field measurements are performed in Austria with façade facing south. Photos of the 1.sup.st room taken at fixed times on Sep. 26, 2017, are evaluated to quantify the light intensity on the workplace; results are shown in Table 2.

(97) TABLE-US-00002 TABLE 2 Illuminance on the office desk in the front room, illuminaires 8 m from façade, derived from the illuminance. Measurement performed on Sep. 26, 2017 with the 3M Daylight Redirecting Film light redirecting foil at the façade. Time of day 10:00 11:00 12:00 13:00 14:00 Illuminance 343 902 1139 614 892 (lux)

(98) Illuminance values up to 1700 lux are detected at other times in the same office with a lux meter placed on the desk.