GB2165277A - A canopy for limiting the passage of solar rays - Google Patents

Abstract

A canopy for shielding an area from direct sun rays in which the canopy is constructed so that it provides a plurality of light paths for light entering the enclosed area. As these light paths are orientated differently to one another only a small proportion of direct sunlight enters the covered area without reflection and thus the effect of heating by the sun is reduced. Due to the fact that indirect light or "skylight" emanates from all parts of the sky, the amount of "skylight" entering the enclosed area is sufficient for illumination purposes. It is stated that the canopy may be constructed of "earthenware or ceramic pots" or reinforced concrete.

Description

SPECIFICATION Solar shield/canopy The present invention relates to a solar shield or roof canopy intended to provide adequate interior light while reducing the proportion of direct sunlight in the total light flux which it passes.

In accordance with the present invention there is provided a solar shield which is so constructed and arranged as to differentially attenute direct sunlight as compared with skylight by having a multiplicity of different parts of its surface arranged to transmit light from differing parts of the sky.

In daylight the rays of light incident on any given area comprise "sunlight" i.e. rays directly from the sun and "skylight" i.e. rays which have been scattered and/or reflected in the atmosphere. The invention is based on an appreciation of the fact that although light comes from all over the sky, the source of radiant energy (i.e. the sun) which provides the heating effect is highly localised and directional.

In a preferred embodiment of this invention, the device achieves the differential attenuation by means of light baffles and can be arranged such that a multiplicity of different parts of its surface will transmit light from differing parts of the sky.

The invention further provides an element for constructing, in association with a muliplicity of like elements a light shield according to the invention, the element being of cellular construction, the walls of the cells constituting the light baffles and the shape of the element being such as to form a domed structure when the element is assembled into side-byside relation with the surrounding like elements.

The present invention will be further described by way of example with reference to the accompanying drawing, in which the sole figure is a cross-sectional view of a dome structure embodying the present invention.

The Figure shows a dome-shaped canopy or shield 1 which may be fixed to a building or the ground by fixing means 5 and is made from a plurality of tapering hollow cells 2 in which each cell is firmly attached to the ones surrounding it. As shown the cells have an outer aperture 4 and an inner aperture 3 which allow the light rays to pass through the canopy. In this embodiment all the cells are identical in structure. However, it is easy to envisage a construction where the cells are not all identical, the canopy being made from cells of different cross-sectional diameters, or indeed of differing cross-sectional shapes. It is also conceivable that instead of the canopy being dome shaped, it could simply be an arch covering the area to be protected.

An example of one possible way to construct the canopy shown would be to use earthenware or ceramic pots as the cells, cemented or fixed together in any suitable way.

Any other suitable constructional material may, of course, be used.

The purpose of having such a cellular structure for the canopy in this embodiment of the invention is so that the walls of the cells act as light baffles which define a number of light paths through which the light rays have to pass if they are to enter the enclosed area.

Each cell is effectively "aimed" at a different point in the sky. As seen in the figure only the rays of direct sunlight that are substantially parallel to the central axis of the cells will pass directly through the canopy. All other rays not hitting the canopy at the correct angle will be incident on the walls 6 of the cells and be reflected; scattered or absorbed.

Thus using such a dome shaped construction gives protection for the enclosed area, regardless of which position the sun is in the sky and as such a large surface is open to the rays of indirect light the covered area is kept well illuminated.

In embodiments where it is preferred that the canopy absorb as much of the incident energy as possible the cell walls can be made as light-absorbing as possible i.e. matt black.

This will substantially reduce the amount of reflection of the rays from the walls into the enclosed area.

In practice this invention could be used for shielding various equipment or containers in which it is advantageous to have the area well illuminated but where it is necessary to keep the temperature as low as conveniently possible.

The canopy itself or a roof below it (such as 7 in the Figure) may protect the area under and lit by it from the weather. The inner or outer ends of the cells may be closed, in the latter case, with a suitable drain-away arrangement for any water which collects.

In the particular structure shown the dome is self-supporting, the walls of the cells being of a rigid nature. This allows the cells to be completely open to the environment, facilitating the free flow of air through the canopy. A construction of this nature would be very useful in covering equipment such as refrigeration condensers where free air flow is an essential requirement.

In other embodiments of the invention that are possible the canopy may be bounded by a transparent membrane or shaped glass plate.

A canopy in this form would be more useful in situations where the external and internal environment were to be kept separate.

In another structure, the canopy, instead of relying on simple radiation and convection to lose the heat absorbed by the incident solar energy, may have cell walls with internal spaces to define a liquid flow path. Pumping liquid through these intersticies provides not only a good heat exchanging mechanism to cool the canopy but may also harness the absorbed solar energy instead of releasing it to the atmosphere. In this particular form of construction it may be possible to make the cellular walls from a pliable material and use the pressure of the fluid in the hollows of the walls to impart the necessary rigidity to the canopy.

In the above and other embodiments of the invention, the cells may be so arranged that direct sunlight which passes through the canopy (by virtue of the cell being "aimed" at the area of the sky currently occupied by the sun) always falls on the same point or at least within the same localised area. This may be useful if the building on which the canopy is provided is arranged so that this "focused" sunlight can be used for interior lighting purposes.

Thus it can be seen that a device constructed in the manner described above will serve both the purposes of restricting the amount of direct sun light falling on an area to be protected and keep the area well illuminated.

Numerous other applications of the present invention will be apparent. It can be applied to a sun canopy for use as a sun shade for parked cars; for example a roof canopy embodying the present invention may be erected in a manner so as to be supported by a central column or other supporting structure and be open at the periphery of the canopy so that cars can be driven in and parked out of the direct heat from the sun. In this or other similar applications of the invention the canopy can be dome shaped so as, with the central column, to be rather similar in shape to a mushroom or so as to be in the form of a Dutch barn. The invention is equally applicable to various other circumstances where good lighting without the sun's heat is desirable such as covered walkways, piazas and so forth.

A canopy according to the invention can be made of reinforced concrete or any other suitable material.

It will be appreciated that the particular embodiments described are only used for purposes of example, there being many other ways in which to put the invention into practice.

Claims (15)

1. A solar shield which is so constructed and arranged as to differentially attenute direct sunlight as compared with skylight by having a multiplicity of different parts of its surface arranged to transmit light from differing parts of the sky.

2. A shield according to claim 1 wherein the differential attenuation is achieved by means of light baffles.

3. A shield according to claim 1 or 2 wherein the light baffles are so arranged such that they provide a multiplicity of light paths therebetween to transmit light from respective ones of said differing parts of the sky.

4. A device according to claim 3 wherein the shield is constructed from a layer of adjoined cells, said light baffles being the walls of said cells and said light paths being channels defined by said walls.

5. A shield according to claim 4 wherein the cross sectional shape of the cells is circular.

6. A shield according to claim 4 wherein the cross sectional shape of the cells is other than circular.

7. A shield according to claim 4 wherein at least some of the cells differ in cross sectional shape or size.

8. A shield according to any one of claims 4 to 7 wherein the walls of the cells are rigid.

9. A shield according to any one of claims 2 to 8 wherein the light baffles are provided with internal conduits for passage of fluid.

10. A shield according to any one of the preceding claims wherein the shield is provided with a transparent membrane or other transparent layer.

11. A shield according to any one of the preceding claims wherein the shield is dome shaped.

12. A shield according to any one of the preceding claims and which is so arranged that sunlight passing through it falls on a localised area beneath the shield.

13. A shield substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

14. An element for constructing, in association with a multiplicity of the elements, a light shield according to any one of the preceding claims, the element being of cellular construction, the walls of the cells constituting the light baffles and the shape of the element being such as to form a domed structure when the element is assembled into side-byside relation with the surrounding like elements.

15. An element according to claim 14 and substantially as hereinbefore described.