GB2107769A

GB2107769A - Light transmitting panel

Info

Publication number: GB2107769A
Application number: GB08129830A
Authority: GB
Inventors: Alan Pounder
Original assignee: BROOKS G R P ACCRINGTON LIMITE
Current assignee: BROOKS G R P ACCRINGTON LIMITE
Priority date: 1981-10-02
Filing date: 1981-10-02
Publication date: 1983-05-05
Also published as: GB2107769B

Abstract

A light transmitting panel for use as a roof light 1 comprises two layers 3, 4 of translucent glass reinforced plastics material, with sheets of plastics bubble sheeting 5 provided in the cavity between said layers to improve thermal insulation. Other light transmitting filling media are envisaged, as alternatives to the plastics bubble sheeting 5.

Description

SPECIFICATION Light transmitting building members This invention relates to light transmitting building members, and is particularly aithough not exclusively concerned with roof lights.

Roof lights are widely used in the roofs of large buildings such as factories, where they may comprise sheets of translucent material inserted at intervals in a roof which is composed of sheets of other material (such as steel or asbestos). Over recent years, much attention has been directed to improving heat insulation in buildings, and sheet material for such roofs may comprise a relatively thick layer of insulating material (such as, for example, polyurethane foam) sandwiched between two relatively thin layers of load bearing material (such as, for example, steel). Such sheet material can provide quite effective insulation, but the insulation is not so readily available where roof lights are to be provided.Therefore, conflicting requirements arise in that it is evidently desirable to provide as much natural light in a building as possible, by way of roof lights, to minimize the costs of artificial lighting. On the other hand, if thermal insulation afforded by roof lights is poor, it is desirable to provide as few roofing lights as possible.

Attempts to solve this problem have been made by providing roof lights which comprise a plurality of spaced skins, with cavities therebetween. It has been found that the insulating properties of such roof lights can be considerably enhanced.

However, such insulating properties still tend to be considerably less than those afforded by the composite sheet materials mentioned above. Also, where more than two spaced skins are provided in a roof light, the light transmission factor of the roof light may be reduced to an unacceptable level.

Preferred embodiments of the present invention aim to provide roof lights which may be improved in the foregoing respects.

More generally, according to a first aspect of the present invention, there is provided a light transmitting building member comprising two spaced layers of light transmitting material defining a cavity therebetween, and a light transmitting filling medium contained in said cavity.

Advantageously, said layers may be of glass reinforced plastics material. However, any other suitable light transmitting material may be used.

Preferably, the filling medium comprises at least one sheet of plastics bubble sheeting. By "plastics bubble sheeting" is meant a sheet of transparent or translucent plastics material formed with bubbles of air or gas therein. Such sheeting has been introduced recently for use in the packaging industry. ?e plastics material of the sheeting is preferabiy ultraviolet resistant.

Preferably, the building member is a roof light.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a perspective view of a roof light; and Figure 2 illustrates a sheet of plastics bubble sheeting, on an enlarged scale.

The roof light 1 illustrated in Figure 1 comprises two layers 2 and 3 of translucent glass reinforced plastics material, which define therebetween a cavity 4. Such a design of roof light is available at the present time, and has been used quite successfully in providing natural light through a roof, whilst affording improved thermal insulation, due to the provision of the air gap 4. However, the insulation of such a roof light is not as good as the insulation provided by presently available opaque composite sheet material of which roofs may be constructed. Thus, for example, condensation may form under such a roof light in use, and often, an occupant of the building may be misied into thinking that the roof light is leaking, because of the condensation.

To improve the roof light 1, we fill the cavity 4 with three sheets of the plastics bubble sheeting 5 shown in Figure 2. The sheeting 5 is of a type readily available at the present day for packaging purposes, and comprises two very thin flexible plastics films which are sandwiched together with prominent bubbles 6 of air therebetween. The plastics films may have a very high light transmission coefficient, and the three sheets of sheeting 5 together do not significantly reduce the light transmission factor of the roof light 1 when positioned in the cavity 4. However, in use, it will be appreciated that air is trapped in the cavity 4 between the sheets 5 and the layers 2 and 3, and, of course, air is also trapped in the bubbles 6 themselves. Thus, the heat insulating properties of the roof light 1 incorporating the sheets 5 is considerably enhanced.

It may be appreciated that roof lights incorporating the sheets 5 may be produced in a very simple and economical manner. Firstly, the layers 2 and 3 are manufactured from G.R.P. in a conventional manner. The three sheets 5 (or more or less as desired) are then glued into position in one of the layers 2 and 3. It will be appreciated that the sheets 5 may be readily deformed (and compressed to some extent) to the shape of the cavity 4. The layers 2 and 3 are then glued or bonded together.

Different filling media may be employed as alternatives to the sheets 5 of plastics bubble sheeting. There may be used any suitable filling medium which both transmits light and serves to restrict the circulation of air in the cavity 4. For example, there may be used chopped or crumpled cellophane or other clear material Chips or other particles of translucent or transparent plastics material may be used. Plastics material produced as individual bubbles may also be used.

It is to be appreciated that the illustrated roof light 1, when provided with the sheets 5 of plastics bubble sheeting, affords another feature which can be particularly important in factory environments. The sheets 5 thoroughly diffuse the light passing through the roof light, so that under strong natural light conditions, the roof light does not tend to throw a vary bright and well defined window of light into an area which may be lit in a relatively subdued fashion. The use of the sheets 5 may then facilitate the use of very clear plastics skins (such as 2 and 3) of a roof light, which skins have not been acceptable in certain applications previously, because of their inability to diffuse light.

It will be appreciated that building members such as the roof light 1 may be used as wall lights or in any other suitable fashion.

Claims

1. A light transmitting building member comprising two spaced layers of light transmitting material defining a cavity therebetween, and a light transmitting filling medium contained in said cavity.

2. A building member according to Claim 1, wherein said layers are of glass reinforced plastics material.

3. A building member according to Claim 1 or 2, wherein the filling medium comprises at least one sheet of plastics bubble sheeting.

4. A building member according to Claim 3, wherein the plastics material of the sheeting is ultraviolet resistant.

5. A building member according to any preceding claim, being a roof light.

6. A light transmitting building member substantially as hereinbefore described with reference to the accompanying drawing.