EP2481876A1 - Top-lighting device for protecting an area against solar radiation - Google Patents

Abstract

The method involves arranging a truncated cone screen (3) such that the screen forms an equatorial opening on a side of Earth's equator and a polar opening on a side of Earth's pole close to an installation site i.e. horizontal roof (1) with lighted area (2), where the screen is continuous between the openings. Shape, orientation and position of the screen are selected such that one quarter of the area is lighted by the direct radiation of solar midday sun at summer solstice and the quarter of the lighted area is lighted by the radiation of solar midday sun at winter solstice. Independent claims are also included for the following: (1) a device for solar protection of lighted area on an installation site from direct radiation of sun (2) a top lighting device placed in an opening of a roof likely to be exposed to direct radiation of sun.

Description

The invention relates to a method for protecting an area that can be exposed to the direct radiation of the sun, in particular from a roof area or a window, against direct solar radiation in summer, and a device for protection obtained by implementing said method. It extends to a zenith lighting device comprising such a protective device.

The protection of such a zone, in particular of a roof zone, in particular of an area delimited by a frame equipped for example with a glazing unit (for example a skylight), against the direct radiations of the Sun makes it possible to limit the warming the air in the room under the roof. Indeed, obscure the direct radiation of the Sun avoids the greenhouse effect due to the presence of glazing mounted in the roof frame.

However, if we often want to avoid such direct lighting on a roof glazing in summer, in winter this direct radiation can be sought both for the light it provides and for the natural warming it provides, including by effect Greenhouse. The same problem arises with other areas likely to be exposed to solar radiation (opening on the roof, skylights, opening of buildings, ...).

Many known devices are mobile and time-and-season orientable to protect an area from the sun's rays in the summer while allowing the sun to hit that area in the winter. However these known devices are energy consumers and they are complex and fragile because of their moving parts. They also have the disadvantage of being expensive to manufacture and maintain.

Other known fixed devices allow to hide a window on the roof of the sun's rays, but either obscure the direct rays of the Sun both in summer and winter, or they do not allow sufficient natural lighting of the room under the sun. the roof when they obscure the sun's rays in summer. These Known devices prevent the penetration of light through the frame of the roof window in any season.

The invention therefore aims at providing a method of protecting an area, such as a roof area, which can be exposed to the direct radiation of the sun, making it possible to protect said area from direct sunlight in the summer and allowing said area to receive direct radiation from the Sun in winter.

The invention also aims at providing a method of protecting such a roofing zone enabling said zone to receive a significant amount of indirect light in summer, although it is obscured by the direct radiation of the Sun in this season.

The invention aims to provide such a simple protection method and easy to implement.

The invention is particularly aimed at a method of economic protection.

The invention also aims at providing a device for protecting such a zone which has the same advantages.

It aims in particular a protection device which requires only a minimum maintenance corresponding to the current cleaning.

The invention also relates to a zenith lighting device comprising such a protection device whose installation is simple and does not require adjustments.

• un écran est disposé au-dessus de la zone éclairée de façon à l'occulter d'au moins une partie des rayons directement issus du Soleil à midi solaire au solstice d'été,
• l'écran est monté fixe par rapport au site d'installation,
  caractérisé en ce que :
• l'écran est disposé de sorte qu'il forme, avec la zone éclairée, une première ouverture, dite ouverture équatoriale, du côté de l'équateur terrestre, et une deuxième ouverture, dite ouverture polaire, du côté du pôle terrestre le plus proche du site d'installation, l'ouverture polaire étant plus haute que l'ouverture équatoriale par rapport à la zone éclairée,
• l'écran est continu entre l'ouverture équatoriale et l'ouverture polaire,
• la forme, l'orientation et la position de l'écran sont choisies pour que:
  • o moins d'un quart de la zone éclairée soit éclairé par des rayons directs du Soleil à midi solaire au solstice d'été,
  • o au moins un quart de la zone éclairée soit éclairé par des rayons directs du Soleil à midi solaire au solstice d'hiver.

To do this, the invention relates to a method of solar protection of an area, said illuminated area, on an installation site likely to be exposed to direct radiation from the Sun, wherein:

• a screen is placed above the lighted area so as to obscure at least a portion of the rays directly from the Sun at solar noon at the summer solstice,
• the screen is fixed mounted relative to the installation site,
  characterized in that
• the screen is arranged so that it forms, with the illuminated area, a first opening, called the equatorial opening, on the side of the terrestrial equator, and a second opening, called the polar opening, on the side of the nearest terrestrial pole the installation site, the polar opening being higher than the equatorial opening with respect to the illuminated area,
• the screen is continuous between the equatorial opening and the polar opening,
• the shape, orientation and position of the screen are chosen so that:
  • o less than a quarter of the illuminated area is lit by direct sunlight at solar noon on the summer solstice,
  • o at least a quarter of the illuminated area is lit by direct sunlight at solar noon at the winter solstice.

Throughout the text, we denote by equatorial any element situated on the Earth's equator side with respect to the other elements. For example, for an installation site in the Northern Hemisphere, the equatorial edge of the screen is the edge on the south side of the screen.

Likewise, "polar" means any element located on the side of the terrestrial pole closest to the installation site. For example, in the Northern Hemisphere, the polar edge of a screen is the edge on the north side of the screen.

In addition, throughout the text, the term "solar noon" designates the hour of noon according to the solar time, sometimes also called "true midi". This is the culmination point of the Sun in the Earth's sky on a given day, seen from a given land installation site. It is also the point at which the hour angle of the sun is zero at the site of installation considered.

An installation site according to the invention is fixed in the terrestrial reference, that is to say that its latitude, longitude and azimuthal orientation are fixed. Thus an installation site according to the invention may in particular be a building roof or a floor.

In particular, a lit area is an immovable surface capable of being exposed to the direct radiation of the sun and being heated by this one. Said illuminated area is in particular located substantially under a protective screen disposed according to a method according to the invention. We want to protect this lit area (and / or a volume of air below) any warming due to the radiation of the Sun in summer, and we wish instead to promote its warming by the radiation of the Sun in winter.

An illuminated zone according to the invention extends to all types of surfaces, and in particular comprises surfaces heated by the effect of solar radiation and glazed surfaces allowing at least some components of the sun's light to pass through. For example, an illuminated area according to the invention located on the roof is particularly likely to allow greenhouse heating of a volume of air located under the roof.

In a method according to the invention, the screen is fixedly mounted relative to the installation site and therefore it is fixed relative to the illuminated area. It is a method of obtaining a simple and economical device, without any mobile mechanical part as soon as it is installed and as long as it performs its functions.

In a method according to the invention, we take full advantage of the variation of the position of the Sun in the Earth's sky according to the time but also and especially according to the seasons so that the direct illumination of the illuminated zone varies according to time and seasons.

In such a method, the screen is disposed above the illuminated area, that is to say it is placed substantially above the illuminated area in a direction orthogonal to a plane tangent to said illuminated area . In particular, for a horizontal illuminated area, the screen is generally vertically above the illuminated area. On the other hand, the orthogonal projection of the screen does not generally have the same shape as the illuminated area.

In addition, the screen is arranged at a distance from the illuminated area, that is to say, it is generally disjoint from the latter. Each screen disposed according to the invention is above an illuminated area.

In addition, the edges of the screen, that is to say the outer perimeters delimiting the surface of the screen, are not necessarily located at the vertical edges of the illuminated area. In particular, the screen may be shifted north or south relative to the screen. For example, in areas between a pole and the nearest tropic of this pole one can choose to shift the equatorial edge of the screen towards the equator with respect to the vertical equatorial edge of the illuminated area. That is to say between the North Pole and the Tropic of Cancer for example, the southern edge of the screen is advantageously shifted towards the South with respect to the southern edge of the illuminated area.

In fact, in this part of the terrestrial globe, the rays coming from the Sun, at solar noon at the summer solstice in particular, have a non-zero angle with respect to the vertical (provided they are not just in the tropics) .

Thus, if it is desired to protect the entire illuminated area from the direct rays of the Sun, the screen must be arranged slightly offset from the equatorial edge of the illuminated area. The screen is further offset in that the installation site is far from the tropic towards the nearest pole. Similarly, the screen is all the more offset in that it is arranged high relative to the illuminated area.

The screen is arranged so that it forms, with the illuminated area in particular and with the installation site in general, an equatorial opening formed by the equatorial edge of the screen and a curve of the illuminated surface, or the installation site. Said curve is formed of the points closest to each point of the equatorial edge of the screen. Similarly, the polar edge of the screen forms with the illuminated area and / or the installation site a polar opening.

The polar opening is on average higher compared to the illuminated area and / or the installation site than the equatorial opening. So the polar aperture is larger than the equatorial aperture (especially if the east-west clutter of the equatorial edge of the screen is similar to the east-west clutter of the polar edge of the screen).

Thus, for example, for a light area and a substantially flat installation site, and for a substantially flat screen, the screen is advantageously installed inclined in a north-south direction relative to the plane of the installation site.

The equatorial edge of the screen is usually installed lower than its polar edge. Thus, for example, in the northern hemisphere, a screen is disposed upper edge north, and lower edge south. The lower edge of the screen is thus located on the south side in the northern hemisphere and on the north side in the southern hemisphere.

This arrangement of the screen makes it possible, in summer, to protect the lighted area from the direct rays of the Sun while allowing a diffuse or reflected (and therefore non-direct) light to illuminate the illuminated area. This diffuse or reflected light penetrates through the polar opening. In particular, if the installation site is a roof, and the illuminated area a window, this arrangement of the screen provides a significant natural lighting of a room under the illuminated area, while avoiding heating by greenhouse effect in summer.

The shape, the azimuthal direction and the position of the screen are chosen in such a way that at least three-quarters of the illuminated area are obscured from the direct rays of the Sun at solar noon at the summer solstice and that at least a quarter of the illuminated area is illuminated by direct rays of the Sun passing through the equatorial opening at solar noon at the winter solstice.

In addition, a screen according to the invention is advantageously chosen continuously between its equatorial edge and its polar edge. There is therefore only one screen, in one piece, between the equatorial edge and the polar edge.

Thus, the shape of the screen is chosen, in combination with its orientation and its final disposition above the illuminated area, on the one hand so that its equatorial edge is at least partly at a distance from the surface of the screen. the illuminated area and that of the installation site. Through the equatorial opening thus formed, direct rays of the Sun can pass and air can circulate.

• aucun rayon direct du Soleil ne passe par l'ouverture équatoriale à midi solaire au solstice d'été,
• la zone éclairée soit entièrement éclairée par des rayons directs du Soleil passant par l'ouverture équatoriale à midi solaire au solstice d'hiver.

More particularly, the shape, the azimuthal direction and the position of the screen may, for example, be chosen such that:

• no direct ray of the Sun passes through the equatorial opening at solar noon at the summer solstice,
• the illuminated zone is entirely illuminated by direct rays of the Sun passing through the equatorial opening at solar noon at the winter solstice.

The invention thus makes it possible to minimize the greenhouse effect through an illuminated zone formed of a translucent or transparent glazed surface in summer, and to maximize the greenhouse effect by such a zone illuminated in winter.

For example, with an absolutely opaque and undrilled screen, one can choose the shape, the azimuthal direction and the position of the screen so that no direct ray of the Sun impacts the illuminated area at solar noon at the summer solstice.

For example, the shape and layout of a screen can be chosen so that the projection of its solar midday shadow to the summer solstice covers at least the illuminated area, especially so that the outline of the shadow of the screen corresponds perfectly to the contour of the lit area at solar noon at the summer solstice.

In a method according to the invention, the shape, the azimuthal direction and the position of the screen can be chosen so that at the summer solstice no direct ray of the Sun impacts the illuminated area and whatever the time between sunrise and sunset.

By means of a method according to the invention, the illuminated area impacted by direct sun rays at solar noon increases between the summer solstice and the winter solstice and decreases between the winter solstice and the solstice of the sun. summer.

avec :

• α l'angle entre la zone éclairée et les rayons du Soleil à midi solaire au solstice d'hiver,
• L la dimension de la zone éclairée selon la direction nord-sud au point considéré, et
• 1/4 ≤ p ≤ 1 la proportion de la zone éclairée à éclairer à midi solaire au solstice d'hiver par des rayons directs du Soleil.

Advantageously and according to the invention, in certain particularly simple embodiments, the shape, the orientation and the position of the screen are chosen so that the edge of the screen delimiting the equatorial opening, called the equatorial edge, is located at all points at a minimum height h from the illuminated area, such that: $$\mathrm{h}\ge \mathrm{p}\mathrm{.}\mathrm{The}\mathrm{.}\tan \left(\mathrm{\alpha }\right)$$

with:

• at the angle between the illuminated zone and the solar rays at solar noon at the winter solstice,
• L the size of the area illuminated in the north-south direction at the point in question, and
• 1/4 ≤ p ≤ 1 the proportion of the illuminated area to be illuminated at solar noon at the winter solstice by direct rays of the Sun.

Also, in an advantageous embodiment of a method according to the invention, the screen is arranged so as to obscure the illuminated area of any direct ray of the Sun at solar noon at the summer solstice.

In another particularly advantageous embodiment of a method according to the invention, the amount of light passing through the screen in any season is adjusted by choosing a screen having holes allowing the passage of direct rays of the sun.

Thus, although the greenhouse effect is strongly limited in summer by shading performed on almost the entire lit area, a few holes in the screen provide more natural lighting. The choice of such a screen is particularly advantageous when the illuminated area is a light penetration surface in a room under the roof, such as a window for example.

The number of holes, their dimensions, their shapes, their embodiments and their arrangements on the screen are parameters that can be chosen according to different criteria such as, for example: the amount of light that must pass through the screen, the aesthetics of the screen, etc.

Alternatively, in a particular embodiment of the invention, a non-pierced but partially translucent screen may be chosen.

In addition, advantageously and according to the invention, the shape, the direction and the position of the screen are chosen so that the majority - in particular all - of the illuminated area is illuminated by direct rays of the Sun passing through the equatorial opening at solar noon at the winter solstice.

In the particular case where all of the illuminated area is illuminated at this time, p = 1. This configuration maximizes thermal recovery in winter.

An illuminated zone according to the invention can be of any type, and can be found on any type of installation site. In particular, it can be an area of a roof or a floor.

Advantageously and according to the invention, the installation site is a roof and in that the illuminated area is an opening in the roof, said opening being closed by a cover member in a waterproof material and at least translucent.

At least one translucent material according to the invention is translucent or transparent to at least a portion of the solar radiation. For example, such a material may be selected from glass, polycarbonates, and the like.

Such a covering element is advantageously a covering window, such as a porthole, a punctual skylight, a skylight (for example vault type), a fixed frame, a skylight frame with a snuffbox, a ventilation frame or smoke extraction, a Velux®, etc.

Also, advantageously and according to the invention, the cover element is mounted on a frame itself mounted on the periphery of the opening formed in the roof, the direct rays of the Sun on the cover element for heating a the volume of air below the roof, particularly below the illuminated surface and under the roofing element.

Advantageously, the respective mountings of the cover member on the frame, and the frame on the periphery of the opening may be made sealingly, at least watertight.

Thus, the waterproofness of the roof is achieved while permitting the penetration of light in an underlying room. In addition, a greenhouse effect is possible when the lighted glass area is hit by direct sunlight.

Also, in order to ensure complete waterproofness of the roof, advantageously and according to the invention, the cover element can be mounted in a sealed manner around the illuminated area, the direct rays of the Sun on the illuminated area for heating a volume of air below the roof, particularly below the illuminated area and under the cover element.

Thus, at least in the closed state, the illuminated zone is not a source of air exchange between a volume of air (a room) located under the roof and the outside so as to minimize heat losses. .

However, there is nothing to preclude the provision of an illuminated area, in particular an opening on the roof which, by its nature and its assembly, allows a watertightness and a relative permeability to the air, for ventilation purposes. example.

In an advantageous embodiment of the invention, the screen is chosen from a material that is opaque to solar radiation.

In addition, advantageously and according to the invention, the screen being outside and disjoint from the installation site (at least by its equatorial and polar edges) allows the creation of a convective air flow under the screen.

Especially in summer, when the screen is heated by solar radiation, the air under the screen and close to it warms up and rises to the polar edge of the screen which is higher than the equatorial edge of the latter. An aspiration is created at the bottom of the screen, near its equatorial edge. A convection movement is then established between the screen and the illuminated area, generally substantially in a north-south direction, in particular from the equatorial edge to the polar edge. This airflow helps to refresh the illuminated area.

In addition, the screen mounted according to the method of the invention being disjoined from the illuminated area and located outside, its heating does not lead to heating, for example a room under a roof.

Finally, a method according to the invention can be implemented on existing installation sites, for example on existing roof windows. Such a method makes it possible to add a solar protection a posteriori, and from the outside.

The protection method according to the invention makes it possible to obtain a device for protecting an illuminated area against the direct radiation of the sun in summer.

The invention extends in particular to a protection device directly obtained by a protection method according to the invention.

The invention also relates to such a protection device obtained by combining all or part of the characteristics mentioned above or below, especially in relation to the protection method according to the invention.

In particular, such a device comprises at least one screen and means for fixing this screen above said illuminated area according to a method according to the invention.

• disposé au-dessus de la zone éclairée de façon à l'occulter d'au moins une partie des rayons directement issus du Soleil à midi solaire au solstice d'été,
• monté fixe par rapport au site d'installation,
  caractérisé en ce que l'écran :
• forme, avec la zone éclairée, une première ouverture, dite ouverture équatoriale, du côté de l'équateur terrestre, et une deuxième ouverture, dite ouverture polaire, du côté du pôle terrestre le plus proche du site d'installation, l'ouverture polaire étant plus haute que l'ouverture équatoriale par rapport à la zone éclairée,
• est continu entre l'ouverture équatoriale et l'ouverture polaire,
• présente une forme, une orientation et une position telles que :
  • moins d'un quart de la zone éclairée est éclairé par des rayons directs du Soleil à midi solaire au solstice d'été,
  • au moins un quart de la zone éclairée est éclairé par des rayons directs du Soleil à midi solaire au solstice d'hiver.

Advantageously and according to the invention, such a device is a device for protecting an area, called the illuminated area, on an installation site likely to be exposed to direct radiation from the sun, said protection device comprising a screen:

• disposed above the lighted area so as to obscure at least a portion of the rays directly from the Sun at solar noon at the summer solstice,
• fixed mounted relative to the installation site,
  characterized in that the screen:
• forms, with the illuminated zone, a first opening, called equatorial opening, on the side of the terrestrial equator, and a second opening, called polar opening, on the side of the terrestrial pole closest to the installation site, the polar opening being higher than the equatorial opening with respect to the illuminated area,
• is continuous between the equatorial opening and the polar opening,
• has a shape, an orientation and a position such that:
  • less than a quarter of the illuminated area is illuminated by direct sunlight at solar noon at the summer solstice,
  • at least a quarter of the illuminated area is lit by direct sunlight at solar noon at the winter solstice.

A device according to the invention is simple and economical because it has no moving part in operation, and in particular no motorization.

• un châssis apte à être monté sur le pourtour de l'ouverture,
• un élément de couverture en un matériau étanche et au moins translucide, dont les bords sont adaptés pour être montés sur le châssis,
• au moins un dispositif de protection comportant un écran :
  • disposé au-dessus de la zone éclairée de façon à l'occulter d'au moins une partie des rayons directement issus du Soleil à midi solaire au solstice d'été,
  • monté fixe par rapport au site d'installation,
  caractérisé en ce que l'écran :
• forme, avec la zone éclairée, une première ouverture, dite ouverture équatoriale, du côté de l'équateur terrestre, et une deuxième ouverture, dite ouverture polaire, du côté du pôle terrestre le plus proche du site d'installation, l'ouverture polaire étant plus haute que l'ouverture équatoriale par rapport à la zone éclairée,
• est continu entre l'ouverture équatoriale et l'ouverture polaire,
• présente une forme, une orientation et une position telles que :
  • moins d'un quart de la zone éclairée est éclairé par des rayons directs du Soleil à midi solaire au solstice d'été,
  • au moins un quart de la zone éclairée est éclairé par des rayons directs du Soleil à midi solaire au solstice d'hiver.

The invention also extends to a zenith lighting device intended to be disposed in an opening in a roof that can be exposed to the direct radiation of the Sun, the opening delimiting an area, said illuminated area, and said device zenith lighting system comprising:

• a frame adapted to be mounted on the periphery of the opening,
• a cover element made of a waterproof and at least translucent material, the edges of which are adapted to be mounted on the chassis,
• at least one protective device comprising a screen:
  • disposed above the lighted area so as to obscure at least a portion of the rays directly from the Sun at solar noon at the summer solstice,
  • fixed mounted relative to the installation site,
  characterized in that the screen:
• forms, with the illuminated zone, a first opening, called equatorial opening, on the side of the terrestrial equator, and a second opening, called polar opening, on the side of the terrestrial pole closest to the installation site, the polar opening being higher than the equatorial opening with respect to the illuminated area,
• is continuous between the equatorial opening and the polar opening,
• has a shape, an orientation and a position such that:
  • less than a quarter of the illuminated area is illuminated by direct sunlight at solar noon at the summer solstice,
  • at least a quarter of the illuminated area is lit by direct sunlight at solar noon at the winter solstice.

Such a zenith lighting device may be prefabricated in the factory according to a prefabrication note according to a manufacturing method relating to the final installation site of said zenith lighting device. In particular, such a zenith lighting device can be manufactured in a different latitude from that installation site, provided you know the latitude of the installation site. The mounting of a device according to the invention is then simplified, since the entire window and the screen (s) of protection can be delivered and installed in a block or kit.

The invention also relates to a zenith lighting device characterized in combination by all or some of the features mentioned above or below in particular in connection with the protection method according to the invention.

A protection device or a zenith lighting device obtained by a method according to the invention makes it possible in particular to obtain an effective protection against the greenhouse effect of a roof glazing in summer, while obtaining a heating effect by important greenhouse in winter.

Such devices also allow to maintain significant natural lighting throughout the year thanks to its large north-facing opening in the northern hemisphere, or south in the southern hemisphere. This lighting can advantageously be improved, without substantially increasing the greenhouse effect in summer, thanks to (or) screen (s) pierced (s) of holes or slightly translucent (s).

• la figure 1 est une vue schématique en perspective d'un dispositif d'éclairage zénithal conforme à l'invention, supposé monté dans l'hémisphère Nord,
• la figure 2 est une vue schématique en coupe par un plan vertical contenant l'axe nord-sud du dispositif d'éclairage zénithal conforme à la figure 1,
• la figure 3 est une vue schématique en perspective de dispositifs conformes à l'invention montés sur une toiture plane, et installés dans l'hémisphère Nord,
• la figure 4 est une vue schématique latérale depuis le sud du dispositif conforme à la figure 3,
• la figure 5 est une vue schématique en coupe transversale par un plan vertical comprenant l'axe nord-sud, désigné par A sur la figure 4 du dispositif, conforme aux figures 3 et 4,
• la figure 6 est une vue schématique en perspective de deux dispositifs de forme conforme à l'invention, supposés montés dans l'hémisphère Nord,
• la figure 7 est une vue schématique latérale depuis l'ouest des dispositifs de la figure 6.

Other objects, features and advantages of the invention will appear on reading the following non-limiting description which refers to the appended figures in which:

• the figure 1 is a schematic perspective view of a zenith lighting device according to the invention, assumed to be mounted in the northern hemisphere,
• the figure 2 is a schematic sectional view through a vertical plane containing the north-south axis of the zenith lighting device conforming to the figure 1 ,
• the figure 3 is a schematic perspective view of devices according to the invention mounted on a flat roof, and installed in the northern hemisphere,
• the figure 4 is a schematic side view from the south of the device according to the figure 3 ,
• the figure 5 is a schematic cross-sectional view through a vertical plane including the north-south axis, designated A on the figure 4 of the device, in accordance figures 3 and 4 ,
• the figure 6 is a schematic perspective view of two shaped devices according to the invention, assumed to be mounted in the northern hemisphere,
• the figure 7 is a schematic side view from the west of the devices of the figure 6 .

The vertical plane along the north-south axis at the installation site according to one of the Figures 1 to 7 is also called the meridian of sidereal time in astronomy, or the "local meridian" is the plane (or disk) containing the North Celestial Pole, the South Celestial Pole, and the zenith of the installation site. It is noted A on the figure 4 . Solar noon is reached when the sun crosses this plane.

In all Figures 1 to 7 the zenithal protection and lighting devices according to the invention are shown installed in the northern terrestrial hemisphere. In addition, the letters N and S respectively designate the north and south directions, E designates the east direction, and W the west direction.

In general, an installation site according to the invention, and in particular a roof, is advantageously inclined less than 90 degrees from the horizontal - that is to say that the installation site n is not vertical. The installation site is notably advantageously inclined less than 45 degrees relative to the horizontal, and is particularly substantially horizontal, that is to say that it forms an angle less than 20 degrees with the horizontal . Nothing, however, prevents the implementation of a method according to the invention for an inclined installation site, including an inclined roof, for example 20 degrees.

In all the figures, the installation site is assumed to be a horizontal roof 1, that is to say that it forms a plane orthogonal to the local zenith-nadir axis, it is the plane of the roof. The invention however applies both to other areas to protect and other configurations.

The zenith lighting device shown in figure 1 , has a frustoconical screen 3 mounted fixed above an illuminated area 2 covered by a glazing 4. The glazing is framed by a frame 6 itself mounted on a roof 1 in which an opening has been arranged to be able to arrange said frame 6.

Nothing prevents, in a zenith lighting device according to the invention that the frame 6 is in two parts: a part attached to the roof 1, and a second part movable relative to the first part, to be able to open the glazing 4, so as to form an opening.

The screen is attached to the frame, to a curb, or to the roof by means 5 fixing. Thus arches 5 can be used on which the screen 3 is bolted. The hoops themselves are bolted to the frame 6 in the embodiment shown.

The screen 3 is inclined in the north-south direction. Thus it has an upper edge 31 higher with respect to the plane of the roof 1 than its opposite edge: the lower edge 32.

The zenith lighting device being shown installed in the northern hemisphere, the upper edge 31 of the screen is oriented towards the north: it is the polar border 31. The lower edge 32 is oriented towards the south: it is the equatorial edge 32. The equatorial edge 32 defines with its projection orthogonal to the plane of the roof, an opening, called the equatorial opening.

It is through this equatorial opening, between the equatorial edge 32 and the roof 1, that the sun's rays at solar noon at the winter solstice can pass to impact the illuminated surface 2, and in particular the glazing 4.

Similarly, the upper edge 31 defines with its projection orthogonal to the plane of the roof, an opening, called the polar opening, larger than the equatorial opening. The polar opening is particularly on average and in each north-south section higher than the equatorial opening.

The screen 3 is made of a material opaque to sunlight. That is why, in summer, the majority of the lighting of a room under the illuminated zone 2 comes from diffuse or reflected solar light penetrating through the polar opening. Also in order to obtain a more intense natural lighting through the glazing 4 without significantly increasing the greenhouse effect, small holes have been drilled in the screen 3.

Other means make it possible to improve the natural lighting through the glazing, for example the lower surface of the screen may be covered with a reflective material so as to transmit a maximum of diffuse or reflected light received by the opening polar towards the illuminated surface 2.

The height of the equatorial edge 32 can be defined as described below.

By considering a point x of a curvilinear abscissa of the equatorial edge of the illuminated zone, the illuminated zone has a width L (x) in the north-south direction, in this abscissa.

In the case of an illuminated area, such as a generally planar roof portion, defining a plane, so that for all x at solar noon at the winter solstice, a proportion p of L (x) is impacted by direct rays of the Sun, the lower (equatorial) edge of the screen must be arranged at a minimum height h (x) defined by the relation (R1): $$\mathrm{h}\left(\mathrm{x}\right)\mathrm{\ge }\mathrm{p}\mathrm{.}\mathrm{The}\left(\mathrm{x}\right)\mathrm{.}\tan \left(\mathrm{\alpha }\right)$$

dans laquelle :

• l est la latitude du site terrestre considéré, exprimée en degrés,
• δ est l'inclinaison de l'axe de rotation de la Terre autour d'elle-même par rapport à une droite orthogonale au plan de l'écliptique, soit environ +23°,
• θ est l'inclinaison de la toiture selon la direction nord-sud par rapport à l'horizontale locale, exprimée en degrés positivement lorsque le bord nord de la zone est plus élevé que le bord sud de la zone, et négativement dans le cas inverse.

In this relation, α represents the angle of the Sun's rays relative to the said zone 1 plane at solar noon at the winter solstice at the latitude of the installation site. α is therefore determined, in degrees, by the relation (R2): $$\mathrm{\alpha }\mathrm{=}\mathrm{90}\mathrm{°}\mathrm{-}\mathrm{l}\mathrm{-}\mathrm{\delta }\mathrm{+}\mathrm{\theta }$$

in which :

• l is the latitude of the terrestrial site considered, expressed in degrees,
• δ is the inclination of the axis of rotation of the Earth around itself with respect to a line orthogonal to the plane of the ecliptic, approximately + 23 °,
• θ is the slope of the roof in the north-south direction relative to the local horizontal, expressed in positive degrees when the northern edge of the zone is higher than the southern edge of the zone, and negatively in the opposite case .

In particular, in the embodiments shown in Figures 1 to 7 the illuminated area being flat and horizontal, θ is zero. It should be noted that θ is not necessarily always determined in the case of complex roofs or illuminated areas located at the ridge of a roof. It is then more correct to use the angle that the illuminated area makes with the local horizontal for θ.

The coefficient p can be chosen as a function of the proportion of illuminated zone 2 which it is desired to be illuminated by direct rays of the Sun at solar noon at the winter solstice.

The relationship (R1) simply expresses the height at which the lower edge of a screen is installed relative to the illuminated area. However, there is nothing to prevent lighting, for example a quarter (p = 1/4), from the lit area at solar noon to the winter solstice, without illuminating a quarter of L (x) for any x. We can thus predict that some portions of the illuminated area are illuminated at more than a quarter by the direct radiation of the Sun, and others of less than a quarter. This is particularly the case when the equatorial edge of the screen does not have the same shape as the equatorial edge of the illuminated area.

Similarly, the relationship (R1) is a simplified relationship that does not take into account the installation of the screen to obscure the area lit by the direct rays of the Sun in summer. Indeed, to protect the entirety of the lit area at midday solar at the summer solstice, the equatorial edge of the screen must be all the more offset towards the equator with respect to the vertical of the southern edge of the zone. illuminated, that the installation site of the protective device or the overhead lighting device from a method according to the invention is close to a terrestrial pole.

d'où la relation (R4) : $$\mathrm{\beta }\mathrm{=}\mathrm{\alpha }\mathrm{+}\mathrm{2}\mathrm{\delta }$$

Indeed, at solar noon at the summer solstice, the rays of the Sun arrive on the roof with an angle β determined by the relation (R3): $$\mathrm{\beta }\mathrm{=}\mathrm{90}\mathrm{°}\mathrm{-}\mathrm{l}\mathrm{+}\mathrm{\delta }\mathrm{+}\mathrm{\theta }$$

hence the relation (R4): $$\mathrm{\beta }\mathrm{=}\mathrm{\alpha }\mathrm{+}\mathrm{2}\mathrm{\delta }$$

Thus, to obtain a complete coverage of the illuminated zone up to its equatorial edge in summer, and a direct lighting of a proportion p of the lighted area in winter, an embodiment of the method according to the invention is to arrange the lower edge of the screen at a height h (x) for any point x of the curvilinear abscissa of the equatorial edge of the illuminated area according to the relation (R5): $$\mathrm{h}\left(\mathrm{x}\right)\mathrm{\ge }\mathrm{p}\mathrm{.}\mathrm{The}\left(\mathrm{x}\right)\mathrm{\cdot }\frac{\tan \left(\mathrm{\alpha }\right)\mathrm{.}\tan \left(\mathrm{\alpha }\mathrm{+}\mathrm{90}\mathrm{-}\mathrm{\beta }\right)}{\tan \left(\mathrm{\alpha }\right)\mathrm{+}\tan \left(\mathrm{90}\mathrm{-}\mathrm{\beta }\right)}$$

On the sectional view of such a zenith lighting device shown in FIG. figure 2 the solar rays at solar noon at the summer solstice and at solar noon at the winter solstice were represented.

The sun's rays at solar noon at the summer solstice arrive at an angle β with respect to the plane of the roof. The sun's rays at solar noon at the winter solstice arrive at an angle α with respect to the plane of the roof. The angle β is related to the angle α by the relation (R4).

The height of the equatorial edge 32 with respect to the plane of the roof 1 can be determined thanks to the relation (R5) as a function of the proportion p of illuminated zone 2 which it is desired to receive direct rays from the Sun at solar noon at winter solstice.

Thus, for example, for a zenith lighting device according to the invention having an illuminated zone 2 of constant width of 1 meter in the north-south direction, said zenith lighting device being intended to be installed on a roof in Toulouse (31000, France) latitude of about l = 44 °, the angle α is about α = 23 °, and the angle β is about β = 69 °. To be able to illuminate exactly 50% (p = 0.5 and case of equality in the relation (R5)) of the illuminated zone 2 at solar noon at the winter solstice, the equatorial edge 32 of the screen 3 must therefore be arranged in average at a height of about h ₅₀ = 25 cm.

In addition, the equatorial edge 32 of the screen must be arranged offset towards the equator, with respect to the equatorial edge of the illuminated surface 2, by a distance d determined by the relation (R6): $$\mathrm{d}\mathrm{=}\mathrm{h}\mathrm{/}\tan \left(\mathrm{\beta }\right)$$

In the preceding example, the equatorial edge 32 of the screen should therefore be shifted towards the south by approximately d = 10 cm with respect to the vertical of the equatorial edge of the illuminated surface 2.

Several protection devices according to the invention are shown in the assembled state on the figures 3 and 4 . Each device comprises a profiled screen 3 whose profile has a monotonous curvature in a section through the plane of the local meridian, and means 5 for fixing this screen above an illuminated surface 2. Each screen is fixed to the frame 6, to a curb, or to the roof 1 by means 5 fixing. Thus arches 5 can be used on which each screen 3 is bolted. The hoops themselves are bolted to the frame 6 in the embodiment shown.

Each screen is arranged above a corresponding illuminated area.

The illuminated areas of the roof are covered by a transparent cover 4 mounted on a frame 6. The transparent cover 4 is framed by the frame 6 itself mounted on the roof 1 in which an opening has been provided to be able to arrange said frame 6 .

In this embodiment, the screens 3 are made of a material opaque to the sun's rays and are pierced. Thus the cover 4 is entirely obscured by the direct radiation of the Sun at solar noon at the summer solstice with the exception of the sun's rays that can pass through each screen through the holes.

Indeed, the figure 5 teaches a device in accordance with figures 3 and 4 , sectional view through the A plane (from the West). Sun rays at solar noon at the summer solstice arrive at an angle β with respect to the roof. The polar edge 31 and the equatorial edge 32 are therefore shifted towards the south with respect to the respective polar and equatorial edges of the cover 4, to protect the latter from incident sun rays with an angle β.

The polar edge 31 of each screen is disposed higher relative to the plane of the roof than their equatorial edge 32. So that each screen is generally inclined in the north-south direction.

It should be noted that any form of screen can be used as soon as its lowest point obscures the illuminated zone 2 of incident rays with an angle β, without obscuring it from incident rays with an angle α passers by the equatorial opening between the equatorial edge 32 of a screen and the roof 1.

Thus, the straight lines tangential to the polar edge 31 and the equatorial edge 32, of angle β, must be intersecting with the roof 1, but not with the illuminated zone 2. Similarly, the line tangent to the equatorial edge 32, of angle α, must intersect with the illuminated zone 2 and therefore with the cover 4.

The height and the shift towards the south of the equatorial edge 32 of each screen can for example be chosen according to the relations (R5) and (R6).

To the Figures 6 and 7 a long opening in a horizontal flat roof is shown covered by a roof element 4 of north-south main direction vault type. The cover element 4 is a glazing unit, mounted on a frame 6, itself mounted on the periphery of the opening made in the roof 1.

The Figures 6 and 7 show an embodiment in which a series of two screens 3 - each above an illuminated area - is arranged in the north-south direction. The north-south distance between the screens can be adapted according to the desired lighting in winter and summer.

In particular, the distance between two successive screens can be chosen so that no direct ray of the sun can reach one or other of the illuminated areas passing between the two screens at the summer solstice.

In particular, in Figures 6 and 7 only the equatorial screen (south side) is selected and installed according to a method according to the invention. It allows in particular the penetration of direct rays of the sun in winter, especially at solar noon at the winter solstice (with an angle α), while protecting the lit area in summer, especially at solar noon at the summer solstice (with an angle β)

The two screens of Figures 6 and 7 can not be considered as parts of the same screen according to the invention. Indeed, a screen according to the invention is continuous between its equatorial edge and its polar edge, and it allows the direct illumination of at least a quarter of the illuminated area above which it is mounted, so that only the equatorial screen is in accordance with the invention.

The invention can be the subject of many other embodiments not shown.

In particular, the dimensions, the shape, the orientation and the arrangement of a screen 3 according to the invention can be modified to obtain a direct illumination by sun rays more or less important in summer and / or winter. Similarly, these parameters are adjusted for each latitude of the globe to which the device according to the invention obtained by a method according to the invention, or the zenith lighting device according to the invention, is intended to be installed.

In addition, the equatorial edge 32 of each screen is not necessarily at the same distance h from the plane of the roof over its entire length (in the east-west direction), as shown in FIG. figure 4 . This height can, as shown in figure 1 , vary along the length of the screen.

If the screen is chosen pierced with holes, the holes can be of all types, of all shapes, and distributed in various patterns. These holes do not prevent the screen from being continuous between its equatorial edge and its polar edge.

Moreover, a curb can sometimes enhance a cover element 4 relative to the roof. The screen of a device according to the invention can advantageously be attached to this curb, to the frame of the cover element, or directly to the roof itself.

Claims (10)

A method of solar protection of an area, said area (2) lit, at an installation site likely to be exposed to direct radiation from the Sun, wherein: - a screen (3) is disposed above the area (2) illuminated so as to hide at least a portion of the rays directly from the Sun at solar noon at summer solstice, the screen (3) is fixedly mounted relative to the installation site,
characterized in that - The screen (3) is arranged so that it forms, with the illuminated area, a first opening, called the equatorial opening, on the side of the Earth's equator, and a second opening, called the polar opening, on the side of the pole. closest to the installation site, the polar opening being higher than the equatorial opening with respect to the illuminated zone (2), the screen (3) is continuous between the equatorial opening and the polar opening, the shape, orientation and position of the screen (3) are chosen so that: o less than a quarter of the lit area (2) is lit by direct sunlight at solar noon at the summer solstice, o at least a quarter of the lit area (2) is lit by direct sunlight at solar noon at the winter solstice. Method according to claim 1, characterized in that the shape, orientation and position of the screen (3) are chosen so that the edge of the screen delimiting the equatorial opening, said equatorial edge (32), is is at all points at a minimum height h with respect to the illuminated zone (2), such that: $$\mathrm{h}\mathrm{\ge }\mathrm{p}\mathrm{.}\mathrm{The}\mathrm{.}\tan \left(\mathrm{\alpha }\right)$$

with: • at the angle between the illuminated zone (2) and the sun's rays at solar noon at the winter solstice, • the size of the zone (2) illuminated along the north-south direction at the point in question, and • 1/4 ≤ p ≤ 1 the proportion of the illuminated zone (2) to be illuminated at solar noon at the winter solstice by direct rays of the Sun. Method according to one of claims 1 or 2, characterized in that the screen (3) is arranged to obscure the area (2) lit by any direct ray of the Sun at solar noon at the summer solstice. Method according to one of claims 1 or 2, characterized in that the amount of light passing through the screen in any season is adjusted by choosing a screen (3) having holes allowing the passage of direct rays of the Sun. Method according to one of claims 1 to 4, characterized in that the shape, orientation and position of the screen (3) are chosen so that the majority of the illuminated area (2) is illuminated by radii direct sun through the equatorial opening at solar noon at the winter solstice. Method according to one of claims 1 to 5, characterized in that the installation site is a roof (1) and in that the area (2) illuminated is an opening in the roof (1), said opening being closed by a cover element (4) made of a waterproof and at least translucent material. Method according to claim 6, characterized in that the cover element (4) is mounted on a frame (6) itself mounted on the periphery of the opening in the roof, the direct rays of the Sun on the covering element (4) for heating a volume of air under the roof (1), in particular below the illuminated surface and under the roofing element. Method according to one of claims 1 to 7, characterized in that the screen (3) is selected from a material opaque to solar radiation. Device for protecting an area, called illuminated zone (2), at an installation site liable to be exposed to direct radiation from the Sun, said protection device comprising a screen (3): disposed above the zone (2) illuminated so as to obscure at least a portion of the rays directly from the sun at solar noon at the summer solstice, - fixed mounted relative to the installation site,
characterized in that the screen (3): - form, with the zone (2) illuminated, a first opening, called equatorial opening, on the side of the terrestrial equator, and a second opening, called the polar opening, on the side of the earth pole closest to the installation site, the polar opening being higher than the equatorial opening with respect to the illuminated zone (2), - is continuous between the equatorial opening and the polar opening, - has a shape, orientation and position such that: • less than a quarter of the lit area (2) is lit by direct sunlight at solar noon at the summer solstice, • at least a quarter of the illuminated area (2) is lit by direct sunlight at solar noon at the winter solstice. A zenith lighting device intended to be arranged in an opening in a roof (1) capable of being exposed to direct radiation from the Sun, the opening delimiting an area, called illuminated zone (2), and said lighting device zenith comprising: a frame (6) able to be mounted on the periphery of the opening, - a cover element (4) made of a waterproof and at least translucent material, the edges of which are adapted to be mounted on the chassis, at least one protective device comprising a screen (3): Disposed above the zone (2) illuminated so as to obscure at least a portion of the rays directly from the sun at solar noon at the summer solstice, • fixed mounted to the installation site, characterized in that the screen (3): - form, with the illuminated zone, a first opening, called equatorial opening, on the side of the terrestrial equator, and a second opening, called polar opening, on the side of the terrestrial pole closest to the installation site, the opening pole being higher than the equatorial opening with respect to the illuminated zone (2), - is continuous between the equatorial opening and the polar opening, - has a shape, orientation and position such that: • less than a quarter of the lit area (2) is lit by direct sunlight at solar noon at the summer solstice, • at least a quarter of the illuminated area (2) is lit by direct sunlight at solar noon at the winter solstice.

Images