ROOF COVERING SYSTEM, AND ROOF COVERING AND SUPPLY MEANS FORMING PART OF THIS SYSTEM

The invention relates to a roof covering system comprising a roof covering manufactured from at least two layers of plastic foil and provided with at least one connection point, via which at least one medium can be fed between the at least two layers, as well as supply means for carrying at least one medium between the at least two layers.

A roof covering system of this type is strong and relatively inexpensive, and can be utilized for a number of possible buildings with very different applications such as for instance animal accommodation, greenhouses, sheds, sports halls, factory premises and the like. What is exceptional here is that, by selecting a suitable medium, the physical properties of the roof covering can be changed. It is for instance possible to select air as medium, which has the advantage that the thermal insulating value of the roof covering improves .

A favourable embodiment of the inventive roof covering system has the feature that the plastic foil is at least practically transparent, whereby during the day it is light in for instance the animal accommodation, greenhouses, sheds, sports halls, factory premises and the like, which can result in a considerable saving.

A further favourable embodiment of the inventive roof covering system has the feature that the at least two layers of plastic foil are connected to each other periodically. In inflated state the roof covering hereby acquires a cushion structure, which in the case of a gaseous medium results in a very good insulating value. If a liquid medium is used, the optical lens effect of the cushion structure will bring about a good diffusion of the light, this being of great importance in for instance a greenhouse because the shading effect of a support structure for the roof covering is for instance likewise diffused.

A further favourable embodiment of the inventive roof covering system has the feature that the at least two layers of plastic foil are periodically glued or welded to each other. The roof covering can then be produced relatively simply by applying for instance a glueing robot or a welding robot, so that customized work can be produced without this significantly increasing the cost price .

A further favourable embodiment of the inventive roof covering system has the feature that the supply means comprise gas supply means. The gas supply means can consist of a simple compressor for the purpose of inflating a roof covering consisting of two plastic foils and thus improving the thermal insulation, althαugh the gas supply means can for instance, also comprise a heat exchanger in which a gas is heated, or conversely cooled, before it is fed between two foils.

A further favourable embodiment of the inventive roof covering system has the feature that the supply means comprise liquid supply means. The liquid supply means can for instance consist of a simple connection to a water supply for the purpose of realizing cooling and light diffusion .

A further favourable embodiment of the inventive roof covering system has the feature that the supply means comprise a heat exchanger. Liquid can for instance be heated, or conversely cooled, in the heat exchanger before it is fed between two foils. In this manner it is for instance possible to collect and store solar heat during the day so that the stored heat can be utilized at a later time. Air is here preferably blown between two foils which form part of the roof covering, so that a good thermal insulation is obtained and the stored heat can be used optimally.

A further favourable embodiment of the inventive roof covering system has the feature that the supply means

comprise storage means. It is then possible to circulate a liquid in a closed circuit, so that substances can be added to the liquid. A liquid can for instance be used to which colouring agents or light-absorbent substances are added. It is then possible to adjust the light transmission, and thereby the light intensity under the roof covering, - so as to thus influence for instance the day and night rhythms. It is also possible to admit only that colour which is necessary to cause a certain crop to grow, whereby this crop is advantaged relative to other crops, such as weeds. An insect-repellent colour can also be chosen.

A further favourable embodiment of the inventive roof covering system has the feature that the roof covering is manufactured from at least three layers of plastic foil and provided with at least two connection points, via which at least two media can be fed between the at least three layers, as well as supply means for carrying at least two media between the at least three layers. The supply means preferably comprise gas supply means and liquid supply means, so that a good thermal insulation is guaranteed and the light transmission can moreover be regulated.

The invention also relates to roof covering and supply means as part of a roof covering system as specified in the foregoing paragraphs .

The invention will now be further elucidated with reference to the following figures, wherein:

Fig. 1 shows a possible embodiment of a roof covering system according to the invention for an open animal accommodation, shed, sports hall or factory premises;

Fig. 2 shows a possible embodiment of a roof covering system according to the invention for a greenhouse; Fig. 3A shows in schematic cross-section a pair of mutually coupled foils;

Fig. 3B shows in schematic top view a pair of coupled foils; Fig. 4A shows in schematic cross-section three mutually coupled foils; Fig. 4B shows in schematic top view three coupled foils; Fig. 5A shows in schematic cross-section a pair of mutually coupled foils with a mounting ring; Fig. 5B shows in schematic cross-section a pair of mutually coupled foils with an alternative mounting ring; Fig. 6 shows a possible embodiment of a pair of mutually coupled foils with a welded or glued seam.

Fig. 1 shows a possible embodiment of a roof covering system 1-according to the invention., ,.for ...instance for an. open animal accommodation, shed, sports hall or factory premises. The roof covering system comprises a membrane roof 2 consisting of two coupled plastic foils which are periodically welded or glued together over the whole surface. In this embodiment membrane roof 2 is supported by a number of posts 3 and tensioned using a number of guy wires 4. The roof covering system further comprises a tank 5 filled with a liquid, generally water to which for instance glycol is added in order to make the roof covering system frost-resistant, and a pump 6 which pumps the liquid between the two coupled foils via inlets 7a, 7b. Liquid heated by solar radiation leaves the space between the two coupled foils via an outlet 8 and is for instance carried through a heat exchanger 9 which cools the liquid. Preferably added to the liquid is a colouring agent which absorbs solar radiation so that it remains cool under membrane roof 2 and the sunlight is dimmed. Heat exchanger 9 can be a liquid-air heat exchanger which relinquishes the heat to the ambient air, but it can also be a liquid-liquid heat exchanger which relinquishes the heat to a heat storage, for instance a tank filled with liquid located underground. The stored heat can then for instance be used at night as additional heating, for instance using

a heating system (not further shown) such as a floor heating.

Fig. 2 shows a possible embodiment of a roof covering system 1 according to the invention for a greenhouse 10 in which vegetables, fruit or flowers can for instance be cultivated. Greenhouse 10 consists of a support frame 11 on which is mounted a membrane roof 12, consisting of three coupled plastic foils which are periodically welded or glued together over the whole surface. The roof covering system further comprises a tank 5 filled with a liquid, generally water to which glycol is for instance added so as to make the roof covering system frost-resistant, and a pump 6 which pumps the liquid between a first pair of coupled foils via an inlet 7. Liquid heated by solar radiation leaves the space between the two coupled foils via an outlet 8 and is carried for instance through a heat exchanger 9 which stores the heat in a tank 13. Preferably added to the liquid is a colouring agent which absorbs solar radiation so that greenhouse 10 remains cool and the sunlight is dimmed. At night the colouring agent can prevent a large amount of light leaving the greenhouse, thereby preventing light pollution of the horizon. The heat stored in tank 13 can be used at night as additional heating, for instance using a floor heating (not further shown) . When filled with liquid, membrane roof 12 forms a system of lenses or prisms whereby a good diffusion of incident sunlight is obtained, thereby enhancing uniform growth of the crop. Finally, roof covering system 1 comprises an air pump 14 with which air can be pumped between a second pair of coupled foils, so that membrane roof 12 for instance realizes a good thermal insulation at night and the heat generated by the floor heating is not lost.

The first pair of coupled foils can for instance also be used during the day to receive a liquid with a selected colouring agent and the second pair of coupled foils can be used to receive insulating air, while the first pair of coupled foils is used at night to receive insulating

air and the second pair of coupled foils is used to receive a highly light-dimming liquid. This prevents residues of the two liquids beginning to react.

Fig. 3A shows a schematic cross-section of a part of a membrane roof 2, consisting of two mutually coupled plastic foils 15a, 15b which are periodically welded or glued together over the whole surface such that a coupling 16 is created and a space 17 is obtained into which air or a liquid can be pressed or through which it can be carried via an inlet (not further shown) . If air is supplied via an inlet and an outlet (not further shown) is closed, membrane roof 1 is inflated, whereby a significantly improved heat insulation is obtained. If liquid is supplied via an inlet, it is possible to control the light transmission through the membrane roof subject to the clarity of the liquid. The heat absorbed by the liquid can also be discharged by draining the liquid via the outlet and carrying it through a heat exchanger. Foils 15a, 15b are for instance manufactured from PVC foil, strengthened with for instance polyamide fibres. Fig. 3B shows a schematic top view of a pair of coupled foils 15a, 15b with couplings 16 formed by for instance a welded connection or glued connection. If desired, it is also possible to utilize glued connections with more complex forms, such as for instance cross-shaped or circular, instead of spot welded or glued connections, for instance so as to improve the flow pattern or obtain a stronger connection.

Fig. 4A shows a schematic cross-section of a part of a membrane roof 12, consisting of three mutually coupled plastic foils 15a, 15b, 15c which are periodically welded or glued together over the whole surface such that a coupling 16a is created between a first pair of foils 15a, 15b and a space 17a is obtained into which air or a liquid can be pressed or through which it can be carried via an inlet (not further shown) , and that a coupling 16b is created between a second pair of foils 15b, 15c and a space 17b is obtained into which air or a liquid

can likewise be pressed or through which it can be carried via an inlet (not further shown). Foils 15a, 15b are for instance manufactured from PVC foil, reinforced with for instance polyamide fibres. Fig. 4B shows a schematic top view of three mutually coupled foils 15a, 15b, 15c with couplings 16a and 16b formed by for instance a welded connection or glued connection. Foils 15a, 15b, 15c are for instance manufactured from PVC foil, reinforced with for instance polyamide fibres .

Fig. 5A shows a schematic section of a possible embodiment of a pair of mutually coupled foils 15a, 15b provided with a per se known mounting ring 18. For arranging of mounting rings 18 the foils 15a, 15b are glued or welded to each other along a predetermined surface and an opening is made in the thus obtained Goupld-ng, ■ whereafter the mounting, ring- is arranged therein in per se known manner. Mounting rings 18 can for instance be applied for the purpose of screwing a membrane roof onto frame 11 of a greenhouse 10, as shown in Fig. 2.

Fig. 5B shows a schematic cross-section of a pair of mutually coupled foils 15a, 15b provided with a conically tapering mounting ring 19. For the purpose of arranging mounting ring 19 the foils 15a, 15b are glued or welded to each other over a predetermined surface and an opening is made in the thus obtained coupling, whereafter the mounting ring is arranged therein in per se known manner. Mounting rings 19 can for instance be applied for the purpose of mounting a membrane roof on posts 3 of a membrane roof 2, as shown in Fig. 1. The conical form of mounting ring 19 is preferably chosen here such that it has the same form as membrane roof 2 would take at that position if mounting ring 19 were omitted. In this manner foils 15a, 15b are loaded the least.

Fig. 6 shows a possible embodiment of a pair of mutually coupled foils with a welded or glued seam 20, which is embodied such that a conduit 21 is obtained which

meanders in the foil and into which an inlet pipe 22 and an outlet pipe 23 can be glued in simple manner. Welded or glued seam 20 is shown schematically here and can be considerably narrower in a practical embodiment.