Passive skylight with two parabolic reflector segments
The present subject matter is an improved skylight to improved low sun-angle light collection and reduced high sun angle light and heat collection. A steeply sloping dome contains parabolic reflectors that redirect low elevation light into a light passage. The steeply sloping sides and the reflectors reflect high elevation angle rays away from a light passage.
1. A passive skylight comprising:
a dome to transmit light from an exterior of the dome to an interior of the dome, the dome sloping between a roof limit and a top limit;
a curb coupled below the dome, the curb defining a light passage; and
a first parabolic reflector and a second parabolic reflector positioned inside the dome, each reflector having a concave surface, each reflector positioned to direct substantially horizontal light incident on the concave surface downward through the light passage.
2. The skylight of claim 1 further comprising:
a diffuser coupled to the curb in an optical path of light reflected by the reflectors.
3. The skylight of claim 2 wherein the diffuser comprises:
a shallow truncated pyramid extending downward from the curb, and a slant from vertical of the shallow truncated pyramid is greater than a slope of the dome.
4. The skylight of claim 1 wherein the first reflector is oriented in the range of 90° to 180° relative to the second reflector.
5. The skylight of claim 1 wherein the first and second reflectors each extend between a plane at the roof limit and the top limit.
6. The skylight of claim 1 wherein the curb comprises slanted reflective internal walls.
7. The skylight of claim 1 wherein the first and second reflectors are oppositely directed relative to a horizon.
8. The skylight of claim 1 wherein the first and second reflectors abut at a lower edge of the respective reflectors and the lower edge, when installed, is oriented in a predominantly north-south direction.
9. The skylight of claim 1 wherein a height of the top limit above the roof limit is greater than fifty percent of the maximum perpendicular cross dimension between two sides of the curb.
10. The skylight of claim 1 wherein the dome comprises:
a plurality of oppositely directed side pairs that collectively define the gross geometry of the dome between the roof limit and the top limit.
11. The skylight of claim 10 wherein the first and second reflectors face a first and a second side respectively and are both coupled between a third and a fourth side of the dome, wherein the first side and second side are a first oppositely directed side pair and the third side and fourth side are a second oppositely directed side pair.
12. The skylight of claim 10 wherein the side pairs define a gross geometry of a truncated pyramid.
13. A method of providing morning and evening interior illumination and preventing heating by the midday sun, comprising:
positioning a skylight assembly over a light passage in a roof of a structure, wherein the skylight assembly is exposed to high sun elevation angle light rays during midday hours and low sun elevation angle light rays during the morning and evening hours;
allowing the low sun elevation angle light rays to pass through a steeply sloping side of a dome of the skylight assembly;
reflecting low sun elevation angle light rays with at least one of a pair of parabolic reflectors into the light passage; and
reducing the high sun elevation angle light rays incident upon skylight assembly that reach the light passage.
14. The method of claim 13 wherein reducing comprises:
reflecting the high sun elevation angle light rays incident on the dome away from the light passage.
15. The method of claim 13 further comprising:
diffusing light entering the light passage before transmission into the structure.
16. The method of claim 13 wherein positioning comprises:
installing the assembly so that members of the pair of parabolic reflectors substantially faces each of an east and a west horizon.