Daylight collectors with diffuse and direct light collection
09816675 ยท 2017-11-14
Assignee
Inventors
Cpc classification
E04D13/032
FIXED CONSTRUCTIONS
E04D13/033
FIXED CONSTRUCTIONS
F21S11/007
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21S11/002
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
E04D13/031
FIXED CONSTRUCTIONS
E04D2013/0345
FIXED CONSTRUCTIONS
G02B19/0028
PHYSICS
E04D13/0305
FIXED CONSTRUCTIONS
International classification
F21S11/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
Lighting devices and methods for providing daylight to the interior of a structure are disclosed. Some embodiments disclosed herein provide a daylighting device including a tube having a sidewall with a reflective interior surface, a light collecting structure, and a light reflector positioned to reflect daylight into the light collector. In some embodiments, the light collector is associated with one or more light-turning and/or light reflecting structures configured to increase the amount of light captured by the daylighting device. Optical elements may allow for the absorption and/or selective transmission of infrared light away from an interior of the daylighting device.
Claims
1. A skylight comprising: a skylight cover; a prismatic element configured to refract at least a portion of light that passes through the skylight cover, wherein the prismatic element comprises a non-prismatic surface and a prismatic surface, wherein the prismatic surface is opposite the non-prismatic surface, and wherein the non-prismatic surface is positioned between the prismatic surface and the skylight cover, wherein the prismatic surface comprises at least one prism having a riser surface and a draft surface, wherein a riser angle of the riser surface is from 35 degrees to 43 degrees or from 47 degrees to 85 degrees relative to a surface normal to the non-prismatic surface; and an element positioning assembly configured to: position the skylight cover over an opening in a roof of a building; dispose the prismatic element relative to a plane of the roof such that an angle formed at an intersection of a second plane containing the prismatic element and the plane of the roof is from 0 to 40 degrees, and orient the prismatic element so that the riser surface faces the sun and directs daylight into the opening in the roof.
2. The skylight of claim 1, wherein the draft surface has a draft angle, wherein the riser angle is different from the draft angle.
3. The skylight of claim 2, wherein the riser angle is between 45 degrees and 55 degrees.
4. The skylight of claim 1, wherein the prismatic element comprises a prismatic film having at least one surface positioned parallel to the skylight cover.
5. The skylight of claim 1, wherein the prismatic element comprises a plurality of prismatic grooves.
6. The skylight of claim 5, wherein at least a portion of the plurality of prismatic grooves are formed in at least one of a radial pattern, a linear pattern, or a curve-linear pattern.
7. The skylight of claim 1, wherein the prismatic element is positioned up to 40 degrees from horizontal.
8. The skylight of claim 7, wherein the prismatic element is positioned substantially parallel to the plane of the roof.
9. The skylight of claim 1, wherein the skylight cover is angled relative to the plane of the roof, the skylight cover having a pole side and an equatorial side, the equatorial side being positioned closer to the equator and the pole side being opposite the equatorial side, wherein the pole side of the skylight cover is offset from the roof, and the equatorial side is positioned closer to the roof than the pole side.
10. The skylight of claim 1, wherein the skylight cover is clear, and wherein the skylight cover is substantially flat, angled, or at least partially dome-shaped.
11. The skylight of claim 1, wherein the prismatic element is integrated with the skylight cover.
12. A skylight assembly comprising: a skylight cover; a prismatic element configured to refract at least a portion of light that passes through the skylight cover, wherein the prismatic element comprises a non-prismatic surface and a prismatic surface, wherein the prismatic surface is opposite the non-prismatic surface, and wherein the non-prismatic surface is positioned between the prismatic surface and the skylight cover; and an element positioning assembly configured to position the skylight assembly over an opening in a roof of a building; dispose the prismatic element relative to a plane of the roof such that an angle formed at an intersection of a second plane containing the prismatic element and the plane of the roof is from 0 to 40 degrees, and orient the prismatic element so that the riser surface faces the sun and directs daylight into the opening in the roof.
13. The skylight assembly of claim 12, wherein the positioning assembly includes at least one of: an adhesive that bonds the prismatic element to the skylight cover; a frame that holds the prismatic element within 6 inches of the skylight cover; a spacer configured to be positioned between the prismatic element and the skylight cover; a tab or slot for attachment to the prismatic element; or an adhesive that bonds the prismatic element to a portion of the skylight assembly near the skylight cover.
14. The skylight assembly of claim 12, wherein angling the prismatic element forms a raised side of the prismatic element along at least one edge of the prismatic element, wherein the raised side is a side other than the side of the prismatic element closest to the equator.
15. The skylight assembly of claim 12, wherein the prismatic element is aligned with the angle of the skylight cover.
16. The skylight assembly of claim 12, wherein the position of the prismatic element less than or equal to six inches from the plane of the roof.
17. A method of installation of a skylight assembly, the method comprising: providing a skylight assembly, the assembly comprising a skylight cover; and a prismatic element configured to refract at least a portion of light that passes through the skylight cover, wherein the prismatic element comprises a planar surface and a prismatic surface, wherein the prismatic surface is opposite the planar surface, and wherein the planar surface is positioned between the prismatic surface and the skylight cover, wherein the prismatic surface comprises at least one prism having a riser surface and a draft surface; positioning the skylight assembly over an opening in a roof of a building; orienting the skylight so that the riser surface faces the sun and directs daylight into the opening in the roof when the skylight is installed as part of a skylight installation; and positioning the prismatic element so that no portion of the prismatic element is above six inches of the plane of the roof.
18. The method of claim 17 further comprising angling the prismatic element up to 40 degrees relative to the plane of the roof.
19. The method of claim 17 further comprising securing the prismatic element within the skylight assembly.
20. The method of claim 19, wherein securing the prismatic element further comprises at least one of: bonding the prismatic element to the skylight cover using an adhesive; attaching the prismatic element to a frame that holds the prismatic element within 6 inches of the skylight cover; positioning a spacer between the prismatic element and the skylight cover; attaching the prismatic element a tab or slot within the skylight assembly; or bonding the prismatic element to a portion of the skylight assembly near the skylight cover using an adhesive.
21. A skylight assembly comprising: a skylight cover; a prismatic element configured to refract at least a portion of light that passes through the skylight cover, wherein the prismatic element comprises a non-prismatic surface and a prismatic surface, wherein the prismatic surface is opposite the non-prismatic surface, and wherein the non-prismatic surface is positioned between the prismatic surface and the skylight cover; and an element positioning assembly configured to position the skylight assembly over an opening in a roof of a building; position the prismatic element so that no portion of the prismatic element is greater than or equal to about six inches above a plane of the roof, and orient the prismatic element so that the riser surface faces the sun and directs daylight into the opening in the roof.
22. The skylight of claim 21, wherein the prismatic element is positioned below the plane of the roof.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Various embodiments are depicted in the accompanying drawings for illustrative purposes, and should in no way be interpreted as limiting the scope of the inventions. In addition, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. Any feature or structure can be removed or omitted. Throughout the drawings, reference numbers can be reused to indicate correspondence between reference elements.
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DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
(34) Although certain embodiments and examples are disclosed herein, inventive subject matter extends beyond the examples in the specifically disclosed embodiments to other alternative embodiments and/or uses, and to modifications and equivalents thereof. Thus, the scope of the claims appended hereto is not limited by any of the particular embodiments described below. For example, in any method or process disclosed herein, the acts or operations of the method or process can be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations can be described as multiple discrete operations in a manner or order that can be helpful in understanding certain embodiments; however, the order of description should not be construed to imply that these operations are order-dependent. Additionally, the structures, systems, and/or devices described herein can be embodied as integrated components or as separate components. For purposes of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments can be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as can be taught or suggested herein.
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(36) As used herein, the terms substantially vertical and vertical are used in their broad and ordinary sense and include, for example, surfaces that are generally perpendicular to the ground, surfaces that are generally perpendicular to a horizontal plane, and/or surfaces that deviate by less than about 10 from a plane perpendicular to the ground and/or a horizontal plane. Such surfaces can be planar, curved, or irregularly shaped while still being substantially vertical so long as an elongate dimension of a surface is generally vertical. The terms substantially horizontal and horizontal are used in their broad and ordinary sense and include, for example, surfaces that are generally parallel to the ground, surfaces that are generally parallel to the roof of a building, and/or surfaces that deviate by less than or equal to about 10 from a plane parallel to the ground and/or a roof. Such surfaces can be planar, curved, or irregularly shaped while still being substantially horizontal so long as an elongate dimension of a surface is generally horizontal.
(37) The light collector permits exterior light, such as natural light, to enter the interior of the reflective tube 120. The light collector 110 can have one or more components. For example, the light collector 110 can include a transparent dome, a prismatic dome, other prismatic elements, one or more light turning structures or elements, a durable cover, one or more reflective surfaces (e.g., positioned inside or outside of a portion of the collector 110), other optical elements, other components, or a combination of components. At least some components of the light collector can be configured to be positioned on the roof 102 of the building or in another suitable area outside the building. The light collector 110 can include a transparent cover installed on the roof 102 of the building or in another suitable location. The transparent cover can be cylindrically shaped, dome-shaped, or can include any other suitable shape or combination of shapes, and can be configured to capture sunlight during certain periods of the day. In certain embodiments, the cover keeps environmental moisture and other material from entering the tube. The cover can allow exterior light, such as daylight, to enter the system.
(38) In the example embodiments disclosed, the measure h.sub.c represents a height of a substantially vertical sidewall portion of the light collector 110. In certain embodiments, the sidewall portion presents a substantially vertical daylight-collection surface through which daylight may enter the daylighting device 100. The measure w.sub.c represents a width of a portion of the collector, such as the width of the base or top portions of the collector 110. In certain embodiments, the width of the collector is substantially uniform over its height h.sub.c. The width w.sub.c of the collector at its base can be greater than the width of the tube 120 at a point near the collector base. In some embodiments, a daylight device is configured such that a width of the tube into which daylight is directed, at least in a region disposed in proximity to the collector base, is less than the height h.sub.c of the collector. The width of the tube w.sub.t may represent a width of a target area to which the light collector 110 is configured to direct daylight entering the collector. The term target area is used herein according to its broad and ordinary meaning and can be used to refer to an area through which a daylight collector is configured to direct daylight in order for the daylight to enter an internally-reflective tube between a roof structure and interior room of a building.
(39) The relationship between the height of the collector and the width of the tube or width of the target area of the collector can be characterized using a ratio between the quantities that will be referred to herein as the aspect ratio. In general, the aspect ratio refers to the ratio between the height of the collector and the width of the tube with which the collector is configured to be used. For example, in some embodiments, the height h.sub.c of the collector, as compared to the width w.sub.t of the tube/target area 120, or width w.sub.c of the collector 110, can have an aspect ratio of approximately 0.5 to 1, 0.75 to 1, 0.8 to 1, 0.9 to 1, 1 to 1, 1.2 to 1, greater than or equal to any of the foregoing aspect ratios, less than or equal to 2.75 to 1, or within a range bounded by any two of the foregoing aspect ratios. In certain embodiments, the aspect ratio is in the range of 1.2-1.5 to 1, 1.0-1.75 to 1, 0.75-2.0 to 1, or 0.5-2.75. The term collector is used herein according to its broad and ordinary meaning and includes, for example, a cover, window, or other component or collection of components, configured to direct daylight into an opening of a building. A collector can include optical elements that refract and/or reflect daylight such that the luminous flux of natural light entering a building is greater than if an opening in the building included a fenestration apparatus without optical elements.
(40) In some embodiments, the cover includes a light collection system configured to enhance or increase the daylight entering the tube 120. The collector 110 can include one or more optical elements, either integrated or non-integrated with respect to the cover, configured to turn light entering one or more portions of the collector 110 generally in the direction of the tube 120, or opening in the building. The light collector 110 can include a top cover. For example, the top cover can be clear and/or include prisms for refracting daylight toward the collector base aperture. The prisms can be fabricated into the cover material or can be formed in a separate prismatic element placed beneath or above a clear dome. As used herein, prismatic element is used in its broad and ordinary sense and includes, for example, prismatic films, molded prismatic assemblies, extruded prismatic materials, another prismatic material, or a combination of materials.
(41) The daylighting device 100 can be configured such that light enters the collector 110 and proceeds through the tube 120, which can be internally reflective, thereby allowing light to propagate through the tube to a targeted area of the building. An auxiliary lighting system (not shown) can be installed in the daylighting device 100 to provide light from the tube to the targeted area when daylight is not available in sufficient quantity to provide a desired level of interior lighting.
(42) The collimator 130 can be configured such that light that would otherwise enter the diffuser at undesirable angles is turned to a more desirable angle. For example, the collimator 130 can ensure that light passing through the daylighting device will exit the daylighting device at an exit angle of less than or equal to about 45 degrees from vertical, or at a substantially vertical orientation, when the diffuser 140 is in a horizontal arrangement. In some embodiments, the collimator 130 may ensure that light passing through the daylighting device will exit the daylighting device at an exit angle of less than or equal to about 45 degrees from a longitudinal axis of the daylighting device or a portion of the daylighting device. In certain embodiments, the collimator 130 is configured to reduce or prevent light from exiting the daylighting device 100 at an angle of between about 45 degrees and about 60 degrees from vertical. In this manner, the collimator 130 may reduce or eliminate glare and visibility issues that light exiting a lighting fixture between those angles can cause.
(43) The daylighting device 100 includes a light-diffusing structure, or diffuser 140. The diffuser 140 spreads light from the tube into the room or area in which it is situated. The diffuser 140 can be configured to distribute or disperse the light generally throughout a room or area inside the building. Various diffuser designs are possible.
(44) When the daylighting device 100 is installed, the tube 120 can be physically connected to, or disposed in proximity to, the light-aligning structure, or collimator 130, which is configured to turn light propagating through the daylighting device such that, when light exits the daylighting device 100 and/or enters a diffuser 140, the light has increased alignment characteristics, as compared to a device without a collimator. In some embodiments, a substantial portion of light propagating through the daylighting device 100 may propagate within the daylighting device at relatively low angles of elevation from a horizontal plane of reference. Such angles of propagation may, in some situations, cause the light to have undesirable properties when it exits the daylighting device. For example, the optical efficiency of a diffuser substantially positioned within a horizontal plane can be substantially reduced when light is incident on the diffuser at low angles of elevation from the horizontal plane. As another example, light that is incident on a diffuser at low angles of elevation can result in light exiting the daylighting device at an exit angle of greater than or equal to about 45 degrees from vertical. Light exiting a daylighting device at such angles can create glare and visibility issues in the area or room being illuminated.
(45) Though the embodiment depicted in
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(47) The light collector 210 can be mounted on a roof 202 of the building and may facilitate the transmission of natural light into a tube 220. In certain embodiments, the collector 210 is disposed on a pitched roof. In order to compensate for the pitch in the roof, the collector 210 can be mounted to the roof 202 using a flashing 204. The flashing can include a flange 204a that is attached to the roof 202, and a curb 204b that rises upwardly from the flange 204a and is angled as appropriate for the cant of the roof 202 to engage and hold the collector 210 in a generally vertically upright orientation. Other orientations are also possible. In certain embodiments, at least a portion of the roof 202 is substantially flat.
(48) The light collector 210 has a height h.sub.c and is disposed adjacent to a tube opening having a width, or diameter, w.sub.t. The tube opening may provide a target area into which the light collector 210 is configured to direct daylight. As used herein, the height h.sub.c may refer to the height of a substantially vertical sidewall portion of the collector 210, or may refer to the height of the collector 210 including the height of a cover portion disposed above the vertical portion. In certain embodiments, the substantially vertical sidewall portion may provide a vertical daylight-collection surface for daylight incident on certain portions of the collector 210. In certain embodiments, the height h.sub.c is approximately 20-26 inches. In other embodiments, the height h.sub.c can be approximately 35-45 inches. In addition, the width w.sub.t of the tube opening can be between 15-30 inches. For example, in an embodiment, the height h.sub.c of the collector 210 is approximately 42 inches and the width w.sub.t of the tube opening is approximately 25 inches. The collector 210 may have a width w.sub.c slightly greater than the width w.sub.t of the tube opening such that when the light collector is disposed above the tube opening, a lip of the collector 210 extends beyond the width of the tube opening. For example, the collector 210 may have a 1-inch lip around a circumference or perimeter of the tube opening, such that the width w.sub.c of the collector 210 is approximately 2 inches greater than the width of the tube opening W.sub.t. The height h.sub.c of the collector 210 and the width w.sub.t of the tube opening can be configured to obtain a desirable aspect ratio that provides satisfactory performance characteristics. In certain embodiments, the aspect ratio of height h.sub.c to width w.sub.t is approximately 1.7:1. In some embodiments, the aspect ratio is greater than or equal to about 0.5:1 and/or less than or equal to about 2.75:1. Such aspect ratios, in connection with daylighting device features described herein, may provide improved daylight capturing characteristics.
(49) The tube 220 can be connected to the flashing 204 and can extend from about a level of the roof 202 through a ceiling level 209 of the interior room 207. The tube 220 can direct light L.sub.D2 that enters the tube 220 downwardly to a light diffuser 240, which disperses the light in the room 207. The interior surface of the tube 220 can be reflective. In some embodiments, the tube 220 has at least a section with substantially parallel sidewalls (e.g., a generally cylindrical inside surface). Many other tube shapes and configurations are possible. The tube 220 can be made of metal, fiber, plastic, other rigid materials, an alloy, another appropriate material, or a combination of materials. For example, the body of the tube 220 can be constructed from type 1150 alloy aluminum. The shape, position, configuration, and materials of the tube 220 can be selected to increase or maximize the portion of daylight L.sub.D1, L.sub.D2 or other types of light entering the tube 220 that propagates into the room 207.
(50) The tube 220 can terminate at, or be functionally coupled to, a light diffuser 240. The light diffuser 240 can include one or more devices that spread out or scatter light in a suitable manner across a larger area than would result without the diffuser 240 or a similar device. In some embodiments, the diffuser 240 permits most or substantially all visible light traveling down the tube 220 to propagate into the room 207. The diffuser can include one or more lenses, ground glass, holographic diffusers, other diffusive materials, or a combination of materials. The diffuser 240 can be connected to the tube 220, or other component of the daylighting device 200, using any suitable connection technique. In some embodiments, the diffuser 240 is located in the same general plane as a ceiling level 209 of the building, generally parallel to the plane of the ceiling level 209, or near the plane of the ceiling level 209. In certain embodiments, the building 205 has an open ceiling, exposing structure associated with the roof 202. For example, certain high-bay buildings may have open-ceiling configurations, exposing structural I-beams and/or the like. In an open ceiling configuration, the diffuser 240 can be disposed adjacent to a ceiling-level plane 209, rather than a physical ceiling structure.
(51) In certain embodiments, the diameter of the diffuser 240 is substantially equal to the diameter of the tube 220, slightly greater than the diameter of the tube 220, slightly less than the diameter of the tube 220, or substantially greater than the diameter of the tube 220. The diffuser 240 can distribute light incident on it toward a lower surface below the diffuser (e.g., the floor 208) and, in some room configurations, toward an upper surface of the room 207. In some embodiments, a diffuser 240 provides substantial amounts of both direct diffusion and indirect diffusion. In some embodiments, the diffuser 240 reduces the light intensity in one or more regions of the room interior 207.
(52) One or more daylighting devices configured according to the embodiment described with respect to
(53) The daylighting device 200 can be configured to sustain significant physical stress without substantial structural damage. For example, in certain embodiments, the daylighting device 200 is configured to withstand a drop test, wherein a bag of sand having particular weight/size characteristics is dropped onto the top of the device from a minimum height. To pass such test, the device can be required to withstand the fall test without allowing the bag to fall through the opening in the building. In some embodiments, a daylighting system is configured to meet standards and/or regulations promulgated by standards organizations and/or government agencies that are designed to improve the safety of rooftop environments containing daylighting fixtures. For example, certain embodiments are configured to meet the Federal Occupational Safety and Health Administration (OSHA) regulations, which provide, for example, that skylight screens shall be of such construction and mounting that they are capable of withstanding a load of at least 200 pounds applied perpendicularly to a surface. Daylighting devices can be constructed to meet regulatory standards. In certain embodiments, one or more portions of the flashing 204, and/or collector 210 can be constructed and/or mounted such that the collector 210 is not damaged to the extent that an opening or aperture providing an ingress into the building interior 207 is created therein, when a 267-lb. sand bag, having an approximately 5.5 bull nose, is dropped generally perpendicularly to a plane of the roof and/or to a top surface of the collector 210 from a height of about 36 above the roof onto the center of the top portion of the daylight collector.
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(55) In the embodiment depicted in
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(57) In certain embodiments, the daylighting device 400 includes a thermal insulation subsystem, or portion 406, that substantially inhibits thermal communication between the interior 407 of a structure and the outside environment. The thermal insulation subsystem can have any suitable configuration, such as, for example, one of the configurations disclosed in U.S. Patent Application Publication No. 2011/0289869, entitled Thermally Insulating Fenestration Devices and Methods, the entire contents of which are incorporated by reference and made a part of this specification.
(58) The tubular daylighting device can include a thermal break in any materials or components of the daylight device that have high thermal conductivity. For example, a spacer or gap in the sidewall of the tube can be positioned near a thermal insulating portion and the thermal insulating portion and thermal break can be configured to form a substantially continuous layer between the building interior and the exterior environment. In certain embodiments, the insulating portion and thermal break are disposed in the same plane as other building insulation material, such as fiberglass or the like.
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(60) The daylighting device 500 includes a light collector 510 having a height h.sub.c. As used herein, the height h.sub.c may refer to the height of a substantially vertical sidewall portion of the collector 510. For example, the substantially vertical sidewall portion may provide a vertical daylight-collection surface for daylight incident on certain portions of the collector 510. The light collector 510 can be disposed about, or adjacent to, the tube 520, which extends through an opening 529 in a building. The opening 529 has a width w.sub.o; the tube 520 has a width w.sub.t. The opening of the tube or the opening 529 of the building may provide a target area into which light can be directed by the light collector 510 or otherwise received into the daylighting system 500. In certain embodiments, the height h.sub.c of the light collector 510 is greater than the width w.sub.o of the opening 529, and/or width w.sub.t of the tube/target area. For example, the daylighting installation 500 can include, a light collector 510 configured such that the height of the light collector h.sub.c is approximately 1.2 to 2.5 times greater than the width w.sub.t. That is, the height of the light collector h.sub.c has an aspect ratio of approximately 0.5-2.75, 1.1-2.1, or 1.2:1 to 2.1:1 with respect to the width w.sub.o of the opening 529. In certain embodiments, the aspect ratio is greater than 2.5:1. In certain embodiments, the width w.sub.t of the tube 520 is approximately 21 inches, and the width w.sub.o of the opening 529 is greater than, or approximately equal to, the width w.sub.t of the tube 520. In certain embodiments, the light collector 510 has a width w.sub.c of approximately 23 inches, a height h.sub.c of approximately 36 inches, and a collimator 530 terminating in a base having a width of approximately 31 inches.
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(62) The light collector 610 illustrated in
(63) Light turning features of the light collector 610 can include prismatic patterns formed on a surface of the collector 610. Such a pattern can be, for example, molded into the inside and/or outside surface of the collector 610. The pattern can be formed by any suitable method, such as by using a casting, or injection molding technique. In certain embodiments, a prismatic element, or other prismatic structure, is adhered to, connected to, or otherwise associated with the collector 610. In certain embodiments, the prisms can be established by horizontal grooves that are defined by opposed faces that may have a flat or curved cross-sectional shape. Furthermore, as disclosed further below, grooves can vary in depth and pitch and/or in other respects. Examples of prismatic structures are illustrated in
(64) The top portion 612 of the collector 610 can be associated with light turning characteristics. For example, as shown, light L.sub.DT entering the collector 610 through top portion 612 can be turned in a direction towards the tube opening 618, or opening in a building, such that a resulting solar altitude of the light L.sub.DT has a solar altitude of .sub.3. In certain embodiments including optical turning elements associated with both a top portion 612 and a sidewall portion 614, the resultant solar altitude .sub.3 of the top portion 612 is greater than the resultant solar altitude .sub.2 of the sidewall portion 614. That is, light L.sub.DT striking the top portion 612 can be turned to a greater degree that light L.sub.DS striking the side portion 614. In certain embodiments, the top portion 612 does not include a prismatic structure or light-turning characteristics. In certain embodiments, the sidewall portion 612 does not include a prismatic structure or light-turning characteristics. For example, the top portion can include a clear acrylic surface that is substantially optically transparent. In certain embodiments, the top portion is at least partially optically opaque, or reflective. Such qualities can be desirable in order to reduce the amount of light transferred through the collector 610 into the tube 620 at various points during the day, such as during the middle of the day when sunlight levels are relatively intense.
(65) The tube 620 can be a separate component of the daylighting device 600 than the light collector 610. For example, the tube can be an internally reflective channel of rigid construction, such as having a construction of aluminum and/or other material that is disposed adjacent to, or connected to, the light collector 610. In certain embodiments, the tube 620 and the collector 610 are integrated such that the two components substantially combined into a single structure.
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(67) The top portion 712 can include any suitable shape. For example,
(68) Though generally illustrated herein as having a cylindrical, or oval-shaped cross-section in certain embodiments, a light collector in accordance with the present disclosure may have any suitable cross-sectional shape. Furthermore, the cross-sectional shape of a light collector may vary at different points along a vertical axis of the light collector.
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(70) In certain embodiments, the prismatic element is molded into a thin polymer sheet that can be placed inside a protective transparent collector structure. The sheet can be molded to include various prismatic patterns. Various embodiments of prismatic patterns are illustrated in
(71) In certain embodiments, the side portion 1014 is cylindrically shaped, providing a 360-degree sunlight capture zone. The effective light capture area of the side portion 1014 can be an area of a cylinder in direct exposure to rays of sunlight, as well as a portion of the top cover 1012 that is directly exposed to the sunlight. In certain embodiments, in the presence of unobstructed, substantially collimated light, the effective capture area of the side portion 1014 can be approximately 90 degrees of the 360 degree circumference of the side portion 1014, or approximately 25% of the total surface area of the side portion 1014.
(72) In certain embodiments, the prismatic element 1015a, with either outwardly-facing or inwardly-facing prisms, extends along the inside of at least a portion 1017 of the side portion 1014 of the collector 1010. In certain embodiments, sunlight may refract down into the tube if the sunlight is within approximately +/45 degrees incident angle to the surface of the side portion 1014 of the collector. The side portion 1014 can be hollow, and may extend from the top portion 1012 down, terminating in an open lower end 1018, through which light can pass.
(73) In certain embodiments, the light collector 1010 can be configured such that optical elements associated with the side portion 1014 capture sunlight having elevations ranging from 20-40, while optical elements associated with the top portion 1012 capture incident light at solar elevations greater than approximately 45. By capturing sunlight incident at a wide range of solar altitudes, the optical elements of the light collector 1010 can substantially enhance the light collection performance of the daylighting device 1000 over a wide range of latitudes and seasons.
(74) As shown in
(75) In certain embodiments, the prismatic elements 1015a and/or 1015b can include prisms configured to refract light. The prismatic elements 1015a and/or 1015b can have a prismatic surface including a plurality of prisms and a non-prismatic (e.g. planar surface) opposite the prismatic surface. The plurality of prisms can include prism grooves on the prismatic surface of the prismatic element. In certain embodiments, the grooves can be linear when the prismatic element 1015a is in a flat configuration and, thus, form circles when the prismatic element 1015a is formed into a cylindrical configuration.
(76) The outer surface of the prismatic element can be positioned against, or proximate to, an inner surface of the sidewall portion of the collector. The prism grooves can be outwardly facing, as shown in
(77) The top portion 1012 can be made integrally with the side portion 1014 and may extend from an open base 1018 to a closed top portion 1012, forming a continuous wall. Alternatively, the top portion 1012 can be an at least partially separate physical component from the side portion 1014. In the depicted embodiment, the top portion 1012 is substantially flat, and can be associated with one or more optical components, such as a prismatic element 1015b. However, as discussed above, the top portion 1012, or any other portion of the light collector 1010, can be shaped in any suitable manner. For example, the top portion 1012 can be angled such as illustrated in
(78) In certain embodiments, the top portion 1012 is at least partially constructed of transparent acrylic. In certain embodiments, the top portion 1012 can be formed with prismatic elements, which can be prism lines that are etched in, molded in, or otherwise integrated with or attached to the top portion 1012. In certain embodiments, the prism elements increase light throughput by capturing light originating outside the collector 1010 and turning it downward through the open base portion 1018, and into a tube assembly. Prismatic elements 1015b associated with the top portion 1012 may differ from the prismatic elements 1015a associated with the side portion 1014. For example, the prismatic element 1015b can include prismatic grooves having opposing faces that lie at angles of approximately 70 and 30, respectively, with respect to a vertical plane. In some embodiments, the angles can be approximately 45 and 18. Prisms including faces that lie at other angles are also contemplated with respect to embodiments of top, side, and/or other portions of light collecting assemblies disclosed herein.
(79)
(80) The prismatic surface of the prismatic element 1015b can be positioned against, or proximate, an inner surface of the top portion 1012. In some embodiments, the prismatic element 1015b can be molded into the top portion 1012. The non-prismatic surface of the prismatic element 1015b can be upwardly or outwardly facing towards the direction of incoming light. The prism grooves of the prismatic surface of the prismatic element 1015b can be downwardly or inwardly facing toward the interior of the light collector. The outwardly facing non-prismatic surface of the prismatic element 1015b can provide a first refraction of light and the prismatic surface of the prismatic element 1015b can provide a second refraction of light toward the aperture 1018.
(81)
(82)
(83)
(84) The reflector 1080 can be a flat or curved reflective panel associated with the light collector 1010 that reflects at least a portion of sunlight, which would otherwise exit the light collector 1010, toward the collector base aperture 1018. The light reflector 1080 can be disposed within, adjacent to, or in integration with, a light collecting assembly. The reflector can be made of material having high luminous reflectance. For example, the luminous reflectance of the reflector 1080 can be greater than or equal to about 0.9, greater than or equal to about 0.95, greater than or equal to about 0.98, or greater than or equal to about 0.99, when measured with respect to CIE Illuminant D.sub.65. The reflector 1080 can be curved, such as illustrated in
(85) The reflector 1080 can be sloped inward by a defined slope angle .sub.slope. Sloping the reflector 1080 relative to a vertical orientation can advantageously increase the effective solar altitude by up to about twice the slope angle. For example, light incident at an angle on the vertical reflector can be reflected at the same angle . Light incident at an angle on a reflector sloped by an angle .sub.slope can be reflected by an amount +2 .sub.slope. Thus, a sloped reflector can advantageously increase the effect solar altitude angle, such as, for example by twice the slope angle. Additional embodiments of reflectors that can be incorporated in the light collecting assembly are described herein.
(86) The daylighting device 1000 can be configured as a skylight that provides illumination to the interior of a part of a building (e.g., a room of a building, lobby of a building, etc.) through an opening (e.g., a vertical opening) in the roof of the building or the attic area of the building. An example of a skylight includes a tubular daylighting device comprising a tubular light conduit and a diffusing element. Embodiments of a tubular daylighting device are described in U.S. Publication No. 2013/0083554 which is incorporated by reference herein in its entirety for all that it disclosed. Other examples of a skylight can include: a fixed skylight comprising a light transmitting element fixedly positioned in a frame disposed on a top or a side of the building; a skylight comprising a light transmitting element that is hingedly attached to a frame and is configured to be opened to allow ventilation; or a retractable skylight in which the light transmitting element can be retracted off a frame so that the interior of the building can be illuminated with ambient light and be ventilated. The light transmitting element of the skylight can include a light collector (e.g., light collector 1010) and one or more prismatic elements (e.g., 1015a, 1015b, 1015b). The light transmitting element of the skylight can have a planar geometry or a three-dimensional geometry. For example, the light transmitting element of the skylight can be dome shaped. The light transmitting element can have a rectangular shape, circular shape, oval shape, square shape, or any other regular/irregular shape as may be dictated by architectural requirements or constraints.
(87) With reference now to
(88) The skylight 1100 can include a skylight cover 1102 and a prismatic element, such as the prismatic element 1015b shown in
(89) The prismatic element 1015b can have a non-prismatic surface that is configured to receive light transmitted through the skylight cover 1102 and a prismatic surface comprising a plurality of prisms or grooves configured to refract the received light. The non-prismatic surface can be planar (e.g., as illustrated in
(90) The skylight 1100 can be configured so that it can be positioned on various locations on the roof, such as, for example, a north, south, east, or west facing roof. The positioning of the non-prismatic surface of the prismatic element 1015b to face the direction of incoming light can provide an angle of refraction that increases the range of solar altitudes at which radiation can be captured and turned towards the daylighting aperture at the base of the light collector.
(91) In some embodiments, a thermally insulating section is disposed between the skylight 1100 and a thermally-controlled portion of the building that receives illumination via the skylight 1100. For example, the thermally insulating section can be disposed at the level of building insulation. Examples of thermally insulating sections are disclosed in U.S. Pat. No. 8,601,757, the entire contents of which are incorporated by reference herein and made a part of this specification.
(92) With reference to
(93) The skylight 1100 can be positioned in a frame that is attached to an opening in a roof or in an attic area of a building. The frame can include ridges, shelves and/or grooves configured to receive the skylight cover 1100 and/or the prismatic element 1015b. The skylight 1100 can be immovably positioned in the frame or movably positioned in the frame such that it can be at least partially opened. As discussed herein, the skylight 1100 can include a tubular light conduit that allows propagation of light transmitted through the prismatic element 1015b towards an aperture of the skylight. The tubular light conduit can include various optical elements (e.g., reflectors, redirectors, diffusing elements, etc.) that are configured to condition light transmitted through the prismatic element 1015b prior to being emitted through the aperture. In various embodiments, the skylight 1100 can include a diffuser positioned to provide diffused light to the interior of the room. The diffuser may positioned near or adjacent an aperture of the skylight within the building.
(94) Various embodiments of the skylight 1100 can include a positioning assembly that is configured to position the skylight cover 1102 over an opening in a roof of the building. The positioning assembly can be further configured to position the prismatic element 1015b at a desired orientation with respect to the plane of the roof to increase light collection efficiency by the skylight 1100.
(95)
(96) In certain embodiments, prisms 1156a include two surfacesa draft surface 1146a and a riser surface 1148a. In the embodiment of
(97)
(98) Each of the prisms 1156b can include two surfacesa riser surface 1146b, and a draft surface 1148b. In the embodiment of
(99) In the embodiment illustrated in
(100) The prism angles .sub.1 and .sub.2 can be equal, or may vary, depending on the configuration of the prismatic element 1115b. Furthermore, adjacent prisms 1156b, or groups of prisms, may have varying prism angles. Such varying prism angles may promote mixing of light propagating through a light collector. In certain embodiments the prismatic element 1115b includes prisms having uniform prism angles. In certain embodiments, the prism angles .sub.1 and .sub.2 have angles of approximately 70 and 30, respectively. In certain embodiments .sub.1 can have angles between 60 and 90, between 60 and 80, between 65 and 75, between 67 and 73, or another acceptable range. In certain embodiments .sub.2 can be between 20 and 40, between 25 and 35, between 27 and 33, or another acceptable range. In some embodiments, the performance of the efficiency of light collection by the light collector 1010 and/or the skylight 1100 can be improved when the prism angle .sub.1, also referred to as the riser angle, is between 30 and 85, between 35 and 75, between 40 and 70, between 45 and 65, or between 50 and 60. For example, in various embodiments, the prism angle .sub.1 can have a value between about 35 degrees and about 43 degrees. As another example, the prism angle .sub.1 can have a value between about 47 degrees and about 85 degrees. In some embodiments, the prism angle .sub.1 can be approximately equal to 50.
(101) With further reference to
(102) With specific reference to
(103) Table A-1 below illustrates the adjusted solar elevation .sub.3 of sunlight incident at various solar elevations .sub.1 on a horizontal acrylic prismatic element with various prism angles .sub.1, also referred to as the riser angle. The adjusted solar elevation .sub.3 refers to the angle of daylight after refraction by the prismatic element 1015b when the prismatic element associated with the top cover of the daylight collector is positioned with the non-prismatic surface facing outward (i.e., the non-prismatic surface is disposed between the prismatic surface and the sky) as illustrated in
(104) When selecting the solar elevation .sub.1 in Table A-1 the slope of the roof (also referred to as roof pitch) and any incline of a prismatic element from a plane of the roof can be accounted for as follows. If the prismatic element is parallel to the ground, the solar elevation .sub.1 selected can be the actual solar elevation. When using Table A-1 for determining the adjusted solar elevation after refraction by a prismatic element not parallel to the ground, an effective solar elevation can be used for the solar elevation .sub.1. For example, when the prismatic element is in a plane parallel to the roof, the effective solar elevation can be obtained by adding the equator-facing roof pitch component to the actual solar elevation if the prismatic element is parallel to a roof section angled towards the equator. The effective solar elevation can be obtained by subtracting the polar-facing roof pitch component from the actual solar elevation if the prismatic element is parallel to a roof section angled away from the equator. The effective solar elevation can be further adjusted if the prismatic element 1015b is inclined from the plane of the roof. For example, if the prismatic element is inclined from the roof pitch towards the equator side of the roof (as shown in
(105) In some embodiments, a light collector having a prismatic element with a prism riser angle .sub.1 between 35 degrees and 85 degrees can allow for a higher aspect ratio of a daylight collector, improved light collection at lower solar altitudes, increased light collection, and/or improved illumination performance.
(106) TABLE-US-00001 TABLE A-1 Adjusted Solar Elevation (.sub.3) Riser Angle Solar Elevation (.sub.1) (.sub.1) 20 30 40 50 60 70 80 90 100 110 120 35 63.2 68.5 75.8 85.1 97.5 40 60.4 65.4 72.3 80.8 91.2 105.1 45 57.7 62.7 69.2 77.3 86.8 98.2 113.6 50 55.2 60.1 66.5 74.2 83.2 93.5 105.7 123.3 55 52.8 57.6 64.0 71.5 80.1 89.8 100.7 113.7 134.5 60 50.3 55.2 61.5 68.9 77.4 86.6 96.8 108.2 121.9 65 47.7 52.7 59.1 66.5 74.8 83.8 93.5 104.1 115.7 130.1 70 45.0 50.0 56.5 64.0 72.3 81.0 90.6 100.6 111.3 123.2 137.9 75 41.9 47.2 53.9 61.5 69.9 78.7 88.0 97.7 107.8 118.5 130.2 80 38.3 44.0 51.0 58.9 67.4 76.3 85.5 95.0 104.7 114.8 125.2
(107) Table A-2 below illustrates the angle of the solar elevation of sunlight incident .sub.1 on a horizontal acrylic prismatic element with prism angles .sub.1 and .sub.2 of 70 and 30, respectively, and the adjusted solar elevation .sub.3 after refraction by the prismatic element 1015b when the prismatic element associated with the top cover of the daylight collector is positioned with the non-prismatic surface facing outward as illustrated in
(108) TABLE-US-00002 TABLE A-2 Horizontal Prismatic Element Adjusted Solar Elevation (.sub.1) Adjusted Solar Elevation (.sub.3) Efficiency (%) 20.0 41.0 85.0% 30.0 46.6 90.0% 40.0 53.7 95.0% 50.0 61.8 98.0% 60.0 70.8 93.0% 70.0 80.2 88.0% 80.0 90.1 83.0% 90.0 100.8 77.0%
(109) Table B below illustrates an the angle of the solar elevation of sunlight incident .sub.1 on horizontal and vertical polycarbonate prismatic elements and the adjusted solar elevation .sub.3 after refraction by the horizontal prismatic element 1015b when the prismatic element is positioned with the non-prismatic surface facing outward as illustrated in
(110) TABLE-US-00003 TABLE B Horizontal Prismatic Vertical Prismatic Element Adjusted Element Adjusted Solar Elevation (.sub.1) Solar Elevation (.sub.3) Solar Elevation (.sub.3) 20.0 44 33 30.0 49 45 40.0 56 58 50.0 64 80 60.0 73 TIR @ 52 (.sub.1) 70.0 82 TIR
(111) Table C illustrates the angle of the solar elevation of the light incident .sub.1 on a prismatic hemispherical dome made of acrylic, the adjusted solar elevation .sub.3 after the refraction of the prismatic dome when the prismatic element is positioned with the non-prismatic surface facing the direction of incoming light and the prismatic surface facing inward.
(112) TABLE-US-00004 TABLE C Acrylic Hemispherical Prismatic Dome Adjusted Solar Elevation (.sub.1) Adjusted Solar Elevation (.sub.3) Efficiency (%) 20.0 36.0 85.0% 30.0 40.0 85.0% 40.0 51.0 86.0% 50.0 56.0 85.0% 60.0 61.0 62.0% 70.0 54.0 46.0% 80.0 50.0 40.0% 90.0 45.0 35.0%
(113) The prismatic element 1015b uses the non-prismatic side of the lens to provide large incident angles at low solar elevations in order to produce large refraction angles. The riser angle .sub.1 is configured to help to minimize optical losses and maintain a downward trajectory of light due to shallow negative incident angles at low solar elevations and small positive incident angles at higher solar elevations. The draft angle .sub.2 is configured to minimize the blockage of light in the downward direction throughout all solar elevations. The resultant total light turning performance is increased over a wide range of solar elevations.
(114) The efficiencies of the prismatic element 1015b configured as illustrated in
(115) Table D provides example configurations for a number of possible embodiments of daylight collectors. The configurations provided in Table D correspond to the performance data shown in
(116) TABLE-US-00005 TABLE D Collector Vertical Lens Height h.sub.c Height Top Cover Collector Type (inches) (inches) Reflector Configuration Low Profile (LP) 6.5 3 None Flat Medium Profile (MP) 8.5 None Yes Flat High Profile (HP) 13.0 4.5 Yes Flat Medium Profile (MP) 8.5 None Yes 20 Slope High Profile (HP) 13.0 4.5 Yes 20 Slope
(117) The configurations and values provided in Table D are illustrative of various possible daylight collector configurations, and do not limit the scope of the disclosure in any way. Furthermore, although certain configurations are provided in the table, the respective collector configurations and dimensions need not conform in any way to such values, and can be configured to be any suitable combinations of configurations and dimensions.
(118) In the tested configurations, each collector is substantially cylindrical with a width w.sub.c of 10 inches. The table provides a collector height h.sub.c. The vertical lens height refers to the height of a vertical prismatic element disposed within the light collector, such as illustrated in
(119) With additional reference to
(120) In certain embodiments, the top portion 1012 can be configured to reduce the effective capture area of the light collector 1010 at solar altitudes higher than a certain value to prevent over illumination and/or heating during midday hours (such as, for example, between 10 am and 3 pm, between 11 am and 2 pm, or during a time when the solar altitude is greater than or equal to 50 degrees or greater than or equal to 60 degrees). In certain embodiments, at least a portion of the top portion 1012 can be configured to reflect some or all of the light striking such portion at solar altitudes above a certain angle. For example, at least some of the top portion 1012 can be configured to reflect at least a portion of overhead sunlight in order to reduce light and/or heat during midday hours. Embodiments of the light collector 1010 with a prismatic element 1015b positioned to receive daylight transmitted through the top portion 1012 can be beneficial in sunny and high solar altitude conditions. A prismatic element 1015b in the top portion 1012 can direct a substantial portion, most, or substantially all daylight incident on the top portion 1012 towards a reflector, such as, for example, the reflector 1980 shown in
(121) In certain embodiments, the top portion 1012 of the light collector 1010 can be constructed at least partially from clear acrylic, transparent plastic, another suitable material, or a combination of materials. Embodiments of the light collector 1010 with a clear top portion can be beneficial in diffuse daylight conditions due to relatively high transmission of overhead sunlight. The prismatic elements can be constructed from an optically transparent material having a high index of refraction such as acrylic, polycarbonate, another suitable material, or a combination of suitable materials.
(122) The walls of the side portion 1014 can be substantially vertical, or may have any desirable inward or outward slope. In certain embodiments, the walls of side portion 1014 are sloped to allow for nesting of multiple such components to allow for tighter packaging.
(123) In certain embodiments, the side portion 1014 provides a substantially vertical daylight-collection surface for sunlight collection, which may provide higher aspect ratios for light collection. Prismatic elements can be integrated with at least a portion of the wall of the side portion 1014. In alternative to, or in addition to, prisms integrated in the side portion 1014, the above-described prismatic element can be used to refract light downward. The non-prismatic back side 1149a of the prismatic element 1115a, shown in
(124) Referring to
(125)
(126) An embodiment of the skylight 1100a is positioned at Position C, and a comparative example of the skylight 1100b is positioned at Position D. In the illustrated embodiment, the roof can have a roof pitch (corresponding to the slope of the roof) of about 20 degrees. If the solar elevation angle is 40 degrees, a ray 1106i of sunlight can be incident on the skylight 1100a at an effective solar elevation of 20 degrees with respect to a plane of the non-prismatic surface of the prismatic element 1015b as a result of the roof pitch being 20 degrees and the skylight 1100a being positioned on the pole side of the roof. The angle of incidence of ray 1106i with respect to a surface normal to the non-prismatic surface of the prismatic element 1015b at the region of incidence is 70 degrees. If the riser surface of the prismatic element 1015b is inclined at a riser angle .sub.1 of about 55 degrees, then from Table A-1 it is noted that incident sunlight is refracted by the prismatic element 1015b through the prismatic surface at an adjusted solar elevation angle of 52.8 degrees with respect to the plane of the non-prismatic surface of the prismatic element 1015b. Thus, the adjusted solar elevation with respect to a horizontal plane parallel to the ground is the actual solar elevation (40 degrees) plus the adjusted solar elevation angle with respect to the non-prismatic surface of the prismatic element of light refracted by the prismatic element (52.8 degrees, from Table A-1) minus the effective solar elevation angle adjusted for the slope of the roof and/or any inclination of the prismatic element 1015b away from the plane of the roof (20 degrees). Accordingly, for the embodiment illustrated in
(127) Because of the increased angle light, the number of reflections undergone by the ray of light 1106r that enters the conduit 1103a is lesser than the number of reflection undergone by the ray of light 1108r that enters the conduit 1103b. For example, for the embodiment illustrated in
(128)
(129) The light collector can include one or more portions or segments, such as segment 1214c, that are not associated with prismatic structures. For example, a segment, such as segment 1214c, disposed relatively near to the base 1218 may require relatively less turning of light, or no turning of light to achieve desirable levels of light collection. Therefore, as shown, light L3 entering the bottom segment 1214c may enter the tube 1220 substantially without being refracted toward the tube by the light collector 1210.
(130) Although the light collector illustrates three segments, a light collector in accordance with certain embodiments disclosed herein may contain any number of segments or regions. Furthermore, different segments can be associated with optical elements having varying characteristics, or can be uniform through one or more segments.
(131) As shown in
(132)
(133) The prismatic grooves can be defined by opposing prism faces. The grooves may have a flat or curved cross-sectional shape. The prism faces can vary in depth, pitch, angles, shapes, and/or widths, depending on height and/or position The prismatic grooves can circumscribe the entire circumference of the collector, and can be substantially uniform throughout the height or circumference, or perimeter, of a portion of the collector. prisms/grooves vary with respect to one or more parameters at different heights or points along the circumference of the collector. In certain embodiments, the various prism elements included in the light collector 1010 can have different prism angles, depending on what portion of the collector 1010 they are associated with. The prism angles can vary along the length of the prismatic grooves. As illustrated in
(134) In certain embodiments, the prism elements in the light collector 1010 have uniform prism angles throughout the collector 1010. In certain embodiments, prisms within a single region of the collector 1010 have varying prism angles. For example, it can be desirable for adjacent prisms, or adjacent groups of prisms, to include different prism angles in order to mix the light that propagates through a portion of the light collector 1010. For example, if substantially collimated light enters a prismatic portion of a light collecting assembly that includes prisms with equal prism angles, light entering the tube can be concentrated in certain regions. Such light concentration may cause undesirable hot spots in the destination area. By varying the prism angles, the effect of such hot spots can be reduced.
(135) In certain embodiments, a flat or curved reflective panel is associated with a light collector that reflects at least a portion of sunlight that would otherwise exit the light collector through a portion generally opposite to a region of the light collector through which daylight is received.
(136) As is shown in
(137) The use of a curved reflector 1480 may allow for sunlight capture from a greater range of circumferential angles about the light collector. This increase in angular reflection of sunlight may provide a number of benefits, such as increased light mixing. For example, in embodiments in which sunlight enter a tube opening from a wide range of circumferential angles, the distribution of light exiting the tube can be more uniform and may reduce the presence of hot spots on a diffuser at the base of the tube. Such light mixing can prevent collimated light from reaching the diffuser prisms in such a way as to cause rainbows to appear in the building interior.
(138) With respect to certain embodiments in which light is directed into a central feeder tube, and dispersed into multiple branch tubes, light mixing can be important in promoting the dispersion of sunlight into the various branch tubes. In certain embodiments, branch tubes each receive approximately equal amounts of light from the central feeder tube.
(139) The collection and redirection of sunlight using a light reflector, such as the curved reflector 1480, may substantially increase the performance of a conventional tubular daylighting device. A number of parameters may contribute to increased performance of certain embodiments of sunlight-collection systems. For example, the sunlight collection area of a light collector may affect the performance of such a system. In certain embodiments, the height and width of the collector in relation to the diameter of a tube opening into which light is directed can be determined by the refractive turning power of optical elements (e.g., integrated prisms, prismatic element or lens film, etc.) within, or associated with, the light collector. This aspect ratio of collector height to tube opening width, or diameter, may depend on the solar altitude range that is desired to capture and refract into the tube. This range can be from approximately 20 to 70 degrees for most locations in the United States. For example, using lower-end solar altitude of approximately 20 degrees as the design point for refracting light into the tube from the optical elements associated with a light collector having vertical side walls, the collector height can be designed to an approximate range of 1.2 to 2.5 times the tube diameter. These values may vary based on material index of refraction and prism angles, among other things. As an example, a system can include a collector height of approximately 35-45 inches and a tube diameter of approximately 20-25 inches. The diameter of the collector can be approximately equal to the diameter of the tube opening, or can be larger or smaller than the diameter of the tube. The actual effective front light-capture area of the collector is associated with the direct non-reflected sun, which, in certain embodiments, can be limited to an exposure angle of approximately 90 degrees due to the off axis curvature limitation of the optics in the collector prisms.
(140)
(141)
(142) The reflector 1580 is disposed along an inside or outside surface of the light collector 1510, such as along a surface that is positioned substantially opposite to a direction at which light L.sub.S may enter the light collector 1510 at one or more points during the day. For example, the reflector 1580 may generally face in a southern direction in an embodiment located at a point in the northern hemisphere. As shown, daylight L.sub.S may enter the light collector 1510 and strike a point on the reflector 1580. The reflector may reflect at least a portion of the daylight in the visible spectrum towards the tube opening 1528. If not for the reflector, a substantial portions of the light L.sub.R may instead propagate out of the tube or be absorbed by materials associated with the light collector 1510. Therefore, inclusion of a reflector 1580 in a daylighting system 1500 may increase the amount of light transmitted through the light collector 1510 into the tube 1520.
(143) In certain embodiments, the reflector 1580 has one portion or more than one portion that is sloped at an angle with respect to vertical (not shown). The location of sloped portion can comprise a fraction of the overall height of the reflector 1580, preferably in a region near the top cover portion of the collector 1510. In some embodiments, the sloped portion angles inwardly from vertical. For example, an upper end of the sloped portion can be closer to a centroid of the top cover portion than a lower end of the sloped portion. In some embodiments, the angle of the slope of the sloped portion can be between 1 and 10 from vertical. In some embodiments, the upper end of the sloped portion is adjacent to the top cover portion of the collector 1510. In certain embodiments, the lower end of the sloped portion is at a position that is spaced between one-fifth and on-half of the height of the collector from the top cover portion. For example, the sloped portion can extend a portion of the reflector from the top of the reflector to up to 50% of the height of the collector. In some embodiments, the sloped portion is not greater than of the height of the collector. In some embodiments, the angle of the sloped portion varies along the height of the sloped portion. For example, the angle of the slope at the top of the collector may be greater that the angle of the slope at the bottom of the sloped portion. In some embodiments, the sloped portion may have two or more portions with each portion having a different angle. In a non-limiting example embodiment, the collector height is 20 inches, the sloping portion of the reflector extends 6 inches from the top and is sloped inward at 5 degrees from vertical.
(144)
(145) The dashed line in
(146) In certain embodiments, the reflector 1680 is configured to transmit wavelengths other than infrared. For example, the reflector 1680 can partially reflect and partially transmit visible light. As another example, the reflector 1680 can reflect most or substantially all visible light while transmitting and/or absorbing at least a portion of ultraviolet light.
(147)
(148) The transparent portion 1711 and the reflector assembly 1780 can be connected at a seam 1730 to form a combined structure, such as an enclosed cylinder or other shape. The structures can be combined in any suitable manner. For example, the structures can be adhered together through the use of an adhesive substance, or by welding or other technique. In certain embodiments, the structures 1711, 1780 are connected using one or more physical connection structures, such as clips, slots, staples, and the like. For example, as shown in
(149)
(150) In certain embodiments, an outside surface 1881 of at least a portion of the light collector 1810 is coated or covered with a layer of material having a relatively high thermal emissivity factor, serving to aid in the transfer of thermal energy away from the light collector 1810. The emissivity factor is related to the ratio of absorbed thermal energy to reflected and/or transmitted thermal energy. In certain embodiments, the outside surface 1881 is in thermal communication with a material having an emissivity factor of greater than about 0.9. Furthermore, high-emissivity material(s) used in connection with a light collector such as that depicted in
(151)
(152) Although three segments are shown, a light collector can include any suitable number of segments or portions. In certain embodiments, different segments can be associated with different optical refraction, transmission and/or reflection characteristics. For example, in some embodiments, at least a portion of the top segment 1914a is associated with a prismatic element 1915, or other optical element or elements. As shown in
(153) In the depicted embodiment, the middle segment 1914b is also associated with light turning structure 1915, such as prismatic element. A prismatic element 1915 can extend along approximately 50%, or 180, of the perimeter of the light collector 1910, as shown, and can generally face a direction from which daylight enters the collector 1910. The prismatic element 1915 can be a unitary structure that can extend from segment 1914a to 1914b, or can be separate sheets or films. The prismatic element 1915 can include prisms having similar or different light-turning characteristics. In certain embodiments, the segment of the prismatic element 1915 positioned in segment 1914a is configured to turn daylight to a greater degree than the segment of the prismatic element 1915 positioned in segment 1914b.
(154) Collector segment 1914c can be associated with light-turning prismatic structure, or may not, depending on collector 1910 characteristics. For example, as shown, the segment 1914c may allow for daylight to pass into the collector 1910 without substantially altering an angle of the daylight with respect to a horizontal plane. Therefore, the segment 1915c may present a substantially clear acrylic material without additional optical elements to daylight entering therein.
(155) In addition to, or in place of, a light turning structure 1915, one or more portions or segments of the light collector 1910 can be associated with a reflector assembly 1980. In the embodiment shown in
(156) Reflective characteristics of the reflector 1980 may vary in different portions or segments of the reflector. Furthermore, while
(157) The reflector 1980 can be constructed from a material system that has high luminous reflectance and high transmittance of infrared light. The finish of the reflector 1980 can be specular or have any desired level of specularity. Wavelength-selective light reflectance can be achieved using any suitable materials. Examples of wavelength-selective material systems include dielectric coatings and/or multi-layer films that use small differences in refractive index between many layers of the film to achieve desired optical properties. Multi-layer films can include coextruded stacks of two or more polymers having different refractive indices.
(158) After infrared light is transmitted through a wavelength-selective reflector 1980, the infrared light can transmit through an infrared transmissive material, such as, for example, acrylic or PET. In some embodiments, the sidewall of the collector 1910 is made from an infrared transmissive material. In some embodiments, the infrared light is absorbed after transmitting through a wavelength-selective reflector 1980. In such embodiments, the infrared light can be absorbed by an infrared absorbing paint or adhesive positioned to receive the infrared light after it transmits through the reflector 1980. In some embodiments, the infrared paint or adhesive is adhered to a metal substrate. The metal substrate can form a portion of the sidewall of the collector that is not transparent (e.g., a portion of the sidewall configured to face away from direct sunlight). The metal substrate can be heated by the paint or adhesive when it absorbs infrared light, and the infrared light can then be reemitted in a direction generally away from the daylighting aperture 1918 and the tube 1920.
(159) In some embodiments, an exterior surface of the portion of the sidewall of the collector 1910 that absorbs infrared light has high emissivity. High emissivity can be obtained by applying a high emissivity material, such as paint, to the surface, or by performing another type of surface treatment, such as anodization. At least some anodized metals exhibit high emissivity, and such metals can form at least a portion of the exterior surface of the light collector 1910. A high emissivity surface can also be provided on the outside surface of the tube 1920, which can permit the tube 1920 to readily reemit infrared radiation absorbed by the tube 1920 out of the daylighting device 1900.
(160) In certain embodiments, the daylighting device 1900 is configured to reject heat during summer months, when the solar altitude is higher, and to direct heat into the building being illuminated by the daylighting device during winter months, when the solar altitude is lower.
(161) A daylighting device incorporating a light collector in accordance with the embodiments described above can be configured to maintain an illumination level within a range of about +/20% of a given value throughout a period of interest, such as the hours from around 9:00 am to 3:00 pm. Furthermore, such a device may provide around 20,000 lumens of light, or more, at a given time, depending on, among other things, external daylight conditions.
(162)
(163) The light collector 2010 can include a substantially clear dome-shaped cover portion 2012. The cover portion 2012 can be configured to capture daylight having a solar altitude of approximately 30-90. The combination of vertical sidewall and dome-shaped cover portions may provide improved performance during both clear and cloudy weather conditions.
(164) In general, with respect to a light collector embodiments in accordance with
(165) Design considerations in manufacturing daylight collectors in accordance with one or more embodiments disclosed herein may take into consideration various cost-related and/or other factors. For example, different materials that can be selected for incorporation in a daylight collector can be available at different prices. Furthermore, different materials may have different physical properties contributing to the performance and/or ease of manufacturing of various components of the collector. Therefore, certain information about the physical dimensions of a light collector can be useful in making design or other decisions. Table E provides example physical specifications for a number of possible embodiments of daylight collectors. The dimensions provided in Table E correspond to the areas and dimensions called out in
(166) TABLE-US-00006 TABLE E Scaled-Up Low Scaled-Up Collector High Aspect High Aspect Aspect Low Aspect Type Ratio Ratio Ratio Ratio Collector 23 27.3 23 27.3 Diameter (W.sub.c) Tube 21 25.3 21 25.3 Diameter (W.sub.t) A 23.6 28.2 10.4 12.5 B 18.0 21.1 18.0 21.1 C 41.6 49.3 28.4 33.6 Cover 2.88 ft.sup.2 4.09 ft.sup.2 2.88 ft.sup.2 4.09 ft.sup.2 (2012) Surface Area Front 5.9 ft.sup.2 8.40 ft.sup.2 2.6 ft.sup.2 3.7 ft.sup.2 Prismatic Portion (2015a) Area Front 23/6 36.1 28.2 42.8 10.4 36.1 12.5 42.8 Prismatic Portion (2015a) Size Back Portion 10.4 ft.sup.2 14.7 ft.sup.2 7.2 ft.sup.2 10.0 ft.sup.2 (2080) Area Back Portion 41.6 36.1 49.3 42.8 28.4 36.1 33.6 42.8 (2080) Size
(167) The values provided in Table E are approximations of various possible daylight collector dimensions, and are not limiting on the scope of the disclosure in any way. Furthermore, although certain values are provided in the table, the respective collector dimensions need not conform in any way to such values, and can be configured to be any suitable dimensions. As shown in the table, construction of a daylight collector may demand more than 8 ft.sup.2 of prismatic material, as well as more than 14 ft.sup.2 of reflective back portion material. Therefore, costs associated at least with such materials/areas may represent a significant factor in daylight collector design.
(168) In certain embodiments, a light collector in accordance with one or more embodiments described herein can be configured such that fabrication and/or installation of the collector are simplified. For example, the side portion of a light collector 2014 can be formed from a substantially flat or curved sheet that can be formed into a generally cylindrical shape, as shown by the top view of
(169)
(170)
(171) At least some of the embodiments disclosed herein may provide one or more advantages over existing lighting systems. For example, certain embodiments effectively allow increased daylight capture through the use of a light collector incorporating one or more prismatic elements and/or reflective elements. As another example, some embodiments provide techniques for directing light to a building interior using a light collector having a height greater than the width of an opening in the building, or of a base aperture of the collector, through which light is transmitted. The height of the collector may provide an increased target light capture area. Certain embodiments may provide additional benefits, including reducing the incident angle at the diffuser of light propagating through the daylighting device, which can result in the diffuser operating with higher optical efficiency.
(172) Discussion of the various embodiments disclosed herein has generally followed the embodiments illustrated in the figures. However, it is contemplated that the particular features, structures, or characteristics of any embodiments discussed herein can be combined in any suitable manner in one or more separate embodiments not expressly illustrated or described. It is understood that the fixtures disclosed herein can be used in at least some systems and/or other lighting installations besides daylighting systems.
(173) It should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Moreover, any components, features, or steps illustrated and/or described in a particular embodiment herein can be applied to or used with any other embodiment(s). Thus, it is intended that the scope of the inventions herein disclosed should not be limited by the particular embodiments described above, but should be determined only by a fair reading of the claims that follow.