High aspect ratio daylight collectors
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.
1. An at least partially transparent light-collecting device configured to direct daylight through a collector base aperture and into an interior of a building when the light-collecting device is installed on a roof of the building, the device comprising:
a top cover portion;
a substantially vertical sidewall portion configured to support the top cover portion above an upper end of the substantially vertical sidewall portion and to define a collector base aperture at a lower end of the substantially vertical sidewall portion, wherein the substantially vertical sidewall portion has a height that extends between the top cover portion and the collector base aperture, and wherein the height of the substantially vertical portion is greater than a width of the collector base aperture;
a prismatic element configured to refract a portion of light that passes through the substantially vertical sidewall portion; and
a reflector configured to turn at least a portion of the refracted light towards the collector base aperture, wherein the reflector has a luminous reflectance greater than or equal to about 0.95 when measured with respect to CIE Illuminant D 65 ;
wherein the light-collecting device is configured to be positioned over an opening in a roof of a building and is configured to direct daylight into the opening in the roof when the light-collecting device is installed as part of a daylighting device installation.
2. The device of claim 1 , wherein the reflector is associated with the substantially vertical portion.
3. The device of claim 1 , wherein the collector base aperture is substantially circular in shape, and the width is equal to a diameter of the collector base aperture.
4. The device of claim 1 , wherein an aspect ratio of the height of the vertical portion to the width of the collector base aperture is greater than 1.2 to 1.
5. The device of claim 4 , wherein the aspect ratio is greater than 1.5 to 1.
6. The device of claim 4 , wherein the aspect ratio is greater than 2 to 1.
7. The device of claim 1 , wherein the top cover portion is clear, and wherein the top cover portion is substantially flat or at least partially dome-shaped.
8. The device of claim 1 , wherein the top cover portion includes a second prismatic element configured to refract daylight passing through the top cover portion.
9. The device of claim 8 , wherein the second prismatic element comprises a prismatic film with prisms having a riser angle and a draft angle, and wherein the riser angle is different from the draft angle.
10. The device of claim 1 , wherein the vertical portion comprises a plurality of vertically-arranged segments, including at least an upper segment and a lower segment.
11. The device of claim 10 , wherein the upper segment is associated with first optical elements having first light-turning characteristics and the lower segment is clear.
12. The device of claim 10 , wherein the upper and lower segments are each approximately 5 to 30 inches in height.
13. The device of claim 10 , wherein the upper and lower segments are each greater than or equal to about 10 inches in height.
14. The device of claim 1 , wherein the height of the vertical portion is between approximately 35 and 45 inches.
15. The device of claim 1 , wherein the height of the vertical portion is between approximately 18 and 35 inches.
16. The device of claim 1 , wherein the width of the collector base aperture is between approximately 20 and 30 inches.
17. The device of claim 1 , wherein the width of the collector base aperture is between approximately 8 and 16 inches.
18. The device of claim 1 , wherein the vertical portion is constructed out of a single planar sheet formed in the shape of an ellipse, wherein two ends of the sheet are joined to form a singular vertical seam.
19. The device of claim 1 , wherein the vertical portion comprises a plurality of curved sheets that are configured to be joined together to form an ellipse.
20. The device of claim 1 , wherein the vertical portion comprises one or more sheets that are configured to be joined together to form an angular portion, a curved portion, or a combination of at least one angular portion and at least one curved portion.
21. A method of illuminating an interior of a building, the method comprising:
receiving daylight on a substantially vertical surface;
turning the daylight towards an aperture lying in a substantially horizontal plane using a prismatic film disposed within a light-collecting device; and
reflecting the daylight towards the aperture using a reflector;
wherein the substantially vertical surface has a height greater than a width of the aperture.