Daylighting panel

Abstract

A daylighting panel for integration into a building or larger vehicle comprises a translucent facade element (800) containing a glass sheet 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 equipped with a luminaire (807), characterised in that the inner walls including the rear end are covered by a reflecting layer (808).

Claims

1. Daylight illumination system comprising a light transport tube (801) for horizontal integration into a building or vehicle, the light transport tube having a front end and a rear end, wherein the rear end is sealed, the inner walls including the rear end are equipped with a reflecting layer (808), and a side wall contains one or more openings each of which is sealed with a luminaire (807), characterized in that the reflecting layer (808) provides a reflectivity, averaged over all angles of incidence, polarizations and wavelengths from the visible range, of 96.5% or more, and the open front end is suitable for attaching to the inner side of a flat transparent facade element (800) of the building or wall element of the vehicle while in a horizontal position, or the front end is sealed to a transparent front plate (800) configured for integration into the building's faade or vehicle wall without protruding outwardly from the building's faade or vehicle wall and wherein the flat transparent faade element or wall element or front plate is oriented essentially parallel to the faade or wall.

2. Daylight illumination system of claim 1 wherein the light transport tube (801) is for horizontal integration into a building, wherein the open front end is suitable for attaching to the inner side of a flat and transparent facade element (800) of the building, or the front end is sealed to a transparent front plate (800) suitable for integration into the building's facade.

3. Daylight illumination system according to claim 2, wherein the transparent 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 of claim 3, wherein the total thickness is from the range 15-250 mm.

5. Daylight illumination system of claim 1, wherein the front end and the one or more openings sealed with a luminaire (807) in the light transport tube (801) are arranged in a way that the cross-sectional area of the front end suitable for sealing, or sealed, to the front plate (800), and the cross-sectional area of the one or more openings sealed with a luminaire (807), form about a right angle.

6. Daylight illumination system of claim 1, wherein the reflecting layer (808) provides a reflectivity, averaged over all angles of incidence, polarizations and wavelengths from the visible range, of 97% or more.

7. Daylight illumination system of claim 6, wherein the reflectivity is 97.5% or more.

8. Daylight illumination system of claim 7, wherein the reflectivity is 98% or more.

9. Daylight illumination system of claim 1, wherein the light guiding inner walls of the light transport tube (801) are covered by a reflective silver or aluminum layer or a reflective multilayer polymer film providing at least 95% directed reflection and less than 5% diffuse reflection.

10. Daylight illumination system according to claim 1, wherein the reflecting layer used in the present light transport tube provides reflectivity with low color shift characterized by a Fidelity Index Rf of 90 or more, and a Gamut Index Rg from the range 95 to 105 in accordance with IES TM-30-15.

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

12. Daylight illumination system according to claim 11, wherein the light transport tube (801) has a rectangular cross section, and a height of about 30 cm and a width of about 90 cm.

13. 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 that a daylight illumination system according to claim 1 is integrated into an envelope of the building or vehicle wall; providing a reflecting film providing a reflectivity, averaged over all angles of incidence, polarizations and wavelengths from the visible range, of 96.5% or more, for lining the inner walls of light transport tube (801) having a length of 5 to 20 meter, which light transport tube is suitable for horizontal integration into a building or vehicle and wherein the cross section of the light transport tube has a height from the range 8 to 50 cm; has a width from the range 20 to 300 cm; and the length of the light transport channel tube is from the range 500 to 2000 cm.

14. The method of claim 13, wherein the reflectivity is 97% or more, and the length is 6 to 12 meter.

15. The use of claim 14, wherein the reflectivity is 97.5% or more.

16. Daylight illumination system of claim 11, wherein the height is from the range 10 to 35 cm, the width is from the range 30 to 120 cm, and the length is from the range 600 to 1200 cm.

17. Daylight illumination system according to claim 1, wherein the cross section of the light transport tube (801) is rectangular or circular or triangular or pentagonal or hexagonal.

18. Daylight illumination system of claim 17, wherein the light transport tube (801) has a rear end which is slanted downwards.

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

20. Daylight illumination system of claim 19, wherein the light source is a LED light source.

21. Building or vehicle comprising a daylight illumination system according to claim 1, characterized in that an envelope of the building's with its facade comprises the attached light transport tube (801) integrated as a facade element, or the vehicle's outer wall comprises a translucent or transparent wall element, to which the present light transport channel's front end is attached in about horizontal positioning and its rear end reaches towards the vehicle's interior.

22. 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 that a daylight illumination system according to claim 1 is integrated into an envelope of the building or vehicle wall introducing daylight into the interior of the building or vehicle in 5 to 20 meter distance from a window.

23. The method of claim 22, wherein the distance is 6 to 12 meter.

24. 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 that a daylight illumination system according to claim 1 is integrated into the building envelope or vehicle wall, with its light transport channel aligned about horizontally away from the building's facade or outside wall of the vehicle without protruding outwardly from the building's faade or vehicle wall and wherein the flat transparent faade element or wall element or front plate is oriented essentially parallel to the faade or wall.

Description

DESCRIPTION OF EMBODIMENTS SHOWN IN FIGURES

(1) FIG. 1a schematically shows the present daylight illumination system for integration into the building with a transparent front surface (hw) according to the present invention. The light transport channel (rectangular light tube) of length l, width w and height h (in the example: h=0.3 m, w=0.9 m, l=11 m) is sealed from inside to the facade element having a width of at least w and a height of at least h. The faade element may be a window with standard double or triple glazing.

(2) FIG. 1b gives a schematic side view of a mirrored light transport channel 801, 808 of length l and rectangular cross section of height h with transparent front plate 800, whose rear end comprises a mirror inclined by 45, thus guiding incoming light towards the luminaire opening 807.

(3) FIG. 2 schematically shows the side view of the present daylight illumination system comprising a rectangular light tube of height h with its light entry side 801 (left side of the figure) attached to the transparent front plate 800, rear side 811 (right side of the figure) containing a luminaire 807, reflective layer 808 (dashed line) covering the light tube's inner walls and rear end; possible light paths 812 are indicated by dotted lines (reflection on rear end 813 omitted).

(4) FIG. 3 schematically shows a front view of the facade element 700, 705 comprising two at least partially transparent sections with 2 light channels 701, 702 attached to the interior there. Typically, the height (703, 704, A, B) of the faade element is larger than the channel height, in this example specified as 0.3 m. Further specific dimensions of an individual exemplary embodiment of the assembly are shown in FIG. 3.

(5) FIG. 4 shows a section of a building with a daylight illumination system according to the present invention. The daylight illumination system comprises a front plate (as a facade element) 800 and a light transport channel (light tube) 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 front plate 800 towards the desired section 809 of the building (e.g. a separate room). In FIG. 4, 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. 4 also comprises a window 802, several walls 806, frame 803 and the floor 804.

(6) FIG. 5 shows the cross section (side view) of the prototype light channels of example 3 lined with high reflective film (not shown in the figure); 800 denotes the insulating glass unit of the faade (front side; 4 mm glass sheet, 12 mm air gap, 4 mm glass sheet); 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 cm83 cm and the one towards the middle of the channel sized 30 cm80 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.

ABBREVIATIONS USED IN THE SPECIFICATION OR CLAIMS

(7) PMMA the acrylic polymer Polymethylmethacrylate PET the polyester Polyethyleneterephthalate PVB the polymer Polyvinylbutyral LED light emitting diode

EXAMPLE 1

Model Channel

(8) A rectangular model light channel in scale 1:10 with clear glass as front plate and open rear end is of height 3 cm, width 9 cm and length 110 cm. This model system has the same optical properties, including light flux at rear end, as the same system upscaled to a height of 30 cm, width of 90 cm and length of 11 m, or such system (as shown in FIG. 1b) equipped with a 45 mirror in rear end directing light towards the opening/luminaire inserted rectangularly to the front plate into the bottom of the light channel. The following materials are used as reflecting layer 808 covering the channel's inner walls including the rear end (where applicable): MIRO-SILVER 27 (M27; manufactured by Alanod, Ennepetal, Germany) comprises a silver layer bonded to an aluminum base material and covered by reflection enhancing oxide layers (manufacturer's data: diffuseness <6%; reflectivity 98% or more). Commercial multilayer reflecting film (3M; manufactured by 3M). 3M Specular Film DF2000MA (DF2000MA; manufactured by 3M) comprises a metal-free multilayer polymer film (manufacturer's data: reflectivity >99% and reflected color/shift CIE u, v less or equal 0.002 [ASTM E1164/E108]).

(9) Light source is artificial sunlight (LED lighting system) as described by Darula Stanislav et al., Applied Mechanics and Materials 861, 469 (2017).

(10) For comparison purposes, light flux is calculated assuming specular reflection at inner walls with reflectivity 97% over all incidence angles in the same light channel.

(11) The light flux is determined at the rear end of the model channel; results are compiled in Table 1.

(12) TABLE-US-00001 TABLE 1 Light flux (in % of incoming light) at channel end, depending on incidence angle Calculated M27 3M DF2000MA Sun angle (comparison) % % % % 70 4.8 11 35 47 50 26.3 32 53 68 35 45.9 46 70 72 30 52.8 54 68 79 20 65.9 63 76 82

(13) Light transport in the channel is surprisingly efficient even at high sun angles.

EXAMPLE 2

Average Light Flux (Office Hours) at Varying Latitudes

(14) Average light flux at the rear end (l=11 m) of a south facing horizontal light channel of h=0.3 m and w=0.9 m as shown in FIG. 1b, 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://enerqyplus.net/weather).

(15) For the simulation, a raytracing tool (LightTools 8.5, Synopsis' Optical Solutions Group, Pasadena, US) is used to characterize the system, assuming a reflectivity of 97% over all incidence angles. 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.

(16) Table 2 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).

(17) TABLE-US-00002 TABLE 2 Average light flux (lm) and minimum light flux (lm) after 11 m transport length Frankfurt Madrid Abu Dhabi Average 4300 5900 6000 Minimum 3450 5050 4850

EXAMPLE 3

Full Scale Prototype

(18) In order to further validate the simulation results of example 2, 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 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 openings of each tube into the first room is sized 3080 cm, starting at 8 m from the faade, and in the second office 2983 cm and located at 11.1 m from the faade, 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 29cm (see FIG. 5). 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, faade side, are fitted with a simple plexiglass and then with a double glazing (4-12-4). Field measurements are performed in Austria with faade facing south. Photos of the 1st room taken at fixed times on Sep. 21, 2017, are evaluated to quantify the light intensity on the workplace; results are shown in Table 3.

(19) TABLE-US-00003 TABLE 3 Illuminance on the office desk in the front room derived from the illuminance; measurement performed on Sep. 21, 2017. Time of day 10:00 11:00 12:00 13:00 14:00 Illuminance (lux) 313 766 1045 832 785