WO2008069658A1

WO2008069658A1 - Roof construction for a cultivation space

Info

Publication number: WO2008069658A1
Application number: PCT/NL2007/050619
Authority: WO
Inventors: Patricia Anette Martine Offermans
Original assignee: Van Diemen B.V.
Priority date: 2006-12-04
Filing date: 2007-12-04
Publication date: 2008-06-12

Abstract

Roof structure (4) for a cultivation space (1). A supporting structure (5, 6) having gutters and attachment profiles is present. The roof (4) comprises film cushions composed of elongate webs of film material (9, 10) which are attached to one another at the attachment profiles (110). The structure is designed such that any water is drained away by the attachment profile (110) and, more particularly, the top side thereof being covered with the cushion film. The attachment and the attachment profile (110) comprise a retaining strip (108) and a further retaining strip (109).

Description

ROOF CONSTRUCTION FOR A CULTIVATION SPACE

The present invention relates to a roof for a cultivation space according to the preamble of claim 1.

Numerous structures have been proposed in the prior art for insulating cultivation spaces, such as greenhouses, In the case of one known structure, the cultivation space is provided with a pointed roof structure, the panels of which are of a double-walled design. These may be produced by means of two light-transmitting hard polycarbonate panels which are spaced apart.

Certain applications require further insulation of the cultivation space with respect to the environment. In addition, there is an increasing tendency to construct cultivation spaces which are sealed with respect to the environment.

This wilt become more important as different methods of cultivation are being adopted. As an example, the control of dispensing moisture to the crop by spraying water together with any further substances which have been incorporated therein in the respective cultivation space may be mentioned. In this case, the moisture has to be controlled in such a manner that no condensation forms on the leaves, while at the same time ensuring that the moisture content is so high that moisture can be absorbed via the roots through condensation on the soil. With such a system, it is important that there are no cold spots, as these will immediately lead to condensation due to the high moisture content, with all the undesired consequences this entails, such as the formation of droplets.

EP 1,637,031 discloses an inclined roof comprising film webs which have been shaped to form a cushion. The construction thereof is complicated and no details are given with regard to fitting of the webs and/or sealing. In order to seal film cushions with respect to a further structural element, structures are known in which a stiffener is provided in a fixed position at the end of a cushion during production and this stiffener is fitted in a profile. Such a structure can be achieved in a very simple manner, but demands a very high degree of dimensional accuracy. In addition, with a structure of this type, it is no longer possible to transport the cushion in a space-saving manner to the site where it is to be used. Numerous other structures have been proposed in the prior art which are not very satisfactory either.

EP 0,277,073 discloses an attachment means for a single film layer, comprising a retaining profile about which the film web is folded and which is fitted in a cavity in which a further retaining profile interacting therewith is provided. EP 1,350,906 discloses a structure with a film roof which is based on a single film web which is folded around a retaining profile.

None of these prior-art structures are easy to install and all of them suffer from problems of water leakage.

It is an object of the present invention to provide a roof for a cultivation space, the properties of which roof have been improved further.

This object is achieved by the roof described above and having the characteristics of claim 1.

According to the invention, the double-walled insulating roof covering is formed by two film webs which are spaced apart and are shaped into cushions by the fact they are closer together at their ends than in the center of the covering part formed by the cushion film. Such cushions can be produced in a very simple manner and have been found to offer sufficient resistance to external weather conditions while also ensuring that the cultivation space is completely sealed, provided that a suitable film material is selected.

Folding the sheets of film material over the attachment strip prevents the risk of rain penetrating to the inside. This is particularly important when using a roof with film cushion where the film cushion is arranged substantially horizontally. The film webs can be attached in the cavity in any conceivable manner. However, according to an advantageous embodiment of the invention, the film webs are attached by realising said cavity in said profile in such a manner that when said retaining strip and the layers of film material applied thereto are fitted in said cavity and a force is applied to said film material, said retaining strip is forced out of said cavity, in which a further retaining strip which is to be fitted in said cavity is present, said cavity and said further retaining strip being embodied such that when a force is exerted on said film material, said further retaining strip inhibits movement of said retaining strip.

According to this preferred embodiment, a separate locking of the retaining strip is provided by means of a further retaining strip. In this case, the locking is such that when a force is applied to the retaining strip the further retaining strip is gradually forced further into position. Therein the structure is embodied such that the retaining strip cannot be removed from the cavity of the attachment profile without first removing the further retaining strip. If the cushion, that is to say the retaining strip, is not subjected to load, the further retaining strip can be fitted and removed relatively easily. Once the further retaining strip has been taken out, the retaining strip can be removed in a simple manner or will move by its own accord out of the cavity of the attachment profile.

The retaining strip may be integrally formed with the film cushion. However, according to an advantageous embodiment of the invention, it is a separate component as a result of which the retaining strip as well as the further retaining strip can be supplied to the attachment site separately. In this case, both layers of film material are fitted on one side of said retaining strip and lying on top of one another. The material may preferably be supplied on the building site on rolls and the same applies to the material of the film cushion which can be supplied in the form of rolls. This makes it possible to cover great lengths in a very quick and effective manner. Consideration may in this case be given to shopping streets, cultivation spaces such as greenhouses and the like. These may be several tens to several hundreds of meters long and the present invention makes it possible to provide a sheathing, such as a roof covering, over such great lengths in a quick and effective manner.

According to a particular embodiment of the invention, both layers of film material from which the cushion is constructed are fixedly clamped by the retaining strip. According to a particular embodiment, these can additionally also be engaged by the further retaining strip.

Both the stiffener or bead and the retaining strip may be standard profiles. Preferably, the outer periphery is smooth, that is to say, it does not have any protruding ribs, recesses or the like. The above-described clamping action can be achieved by the interaction between the stiffeners, beads or retaining strip and the attachment profile without there thus being any need to use screws or the like. More particularly, such stiffeners are or such a retaining profile is circular in shape, so that standard profiles are sufficient. Such a construction is less affected by variations in the thickness of the film to be used.

The attachment profile preferably comprises two adjacent cavities, one for the retaining profile and one for the further retaining profile and these cavities are preferably arranged in a staggered manner with respect to one another. The inlet to these cavities is preferably arranged and embodied in such a manner that it drains water away in the position of use, so that there is no risk of any damage through water ingress upon exposure to the environment.

Preferably, a roof which is designed in this way is a flat, substantially horizontal roof from which the covering sections which are formed by the cushions protrude in a slightly convex manner.

According to a particular embodiment of the invention, the film is preferably light- transmitting. In this case, it is possible to take measures so that only certain ranges of the light spectrum can pass through or be changed. In addition, it is possible to provide a screening structure in order to prevent external light from entering a cultivation space, for example on summery days. Such a screen can be fitted both externally and internally. When fitted internally, a screen is provided between the film webs and may, for example, comprise a number of slats which are arranged on one of the film webs and which, through being tilted, optionally (partially) prevent light from passing through. According to a further advantageous embodiment of the invention, a particularly insulating gas is provided between the film webs. In addition, it is possible to provide a constant pressure between the film webs. As a result thereof, a complete sealing with respect to the environment is ensured.

According to a particular embodiment of the invention, the film webs are brought closer to one another near the spot where they are attached to the supporting structure and attached to one another in a sealing manner. A stiffener or bead structure may be provided for this purpose. The supporting structure may comprise a combination of longitudinal and cross beams which together form a grid structure. This pressing structure does not have to extend on all sides of the cushion. It is possible to construct a series of cushions from two webs.

In order to provide insulation, the supporting structure has to be insulated in some way with respect to either the environment or the cultivation space. According to a particular embodiment of the invention, the supporting structure is provided with an insulating layer and a further profile is provided on this insulating layer. The film webs which form the cushions are preferably attached to said profile, so that a structure is provided which is completely free from thermal bridges.

If a high insulating value of the cultivation space is desired and, in addition, a damp- proof structure is required, the structure with side walls may, in an advantageous embodiment of the invention, be designed in the form of panels of plastic material which are arranged at a distance from one another.

According to a further embodiment of the invention, the temperature of the floor of the cultivation space is lower than that of the remainder of the cultivation space so that water vapor will condense in a controlled manner.

The film cushion may consist of a number of webs of material which are attached to one another. A material which is particularly satisfactory is an ETFE film. The invention also relates to a film cushion comprising a number of webs of film material which have been attached to one another to form a closed loop.

In addition, the invention relates to a method for providing a sheathing in a supporting structure, which supporting structure is provided with an attachment profile embodied to accommodate a retaining profile and a further retaining profile therein, to provide a roll of cushion material comprising two webs of film material lying on top of one another and to provide a separate roll of retaining strip material and further retaining strip material, respectively, which retaining strip material is fitted in a cavity of said attachment profile and is fixed in said cavity of said attachment profile by said retaining strip material and further retaining strip material, respectively.

The cushion may be filled with air or another gas in any way which is known in the prior art. A permanent connection to a source of gas or air may be present.

The present invention makes it possible to compensate for dimensional inaccuracies on the building site as the first retaining profile can be positioned in an arbitrary position with respect to the webs of film material. In addition, a roll of film material which serves as a cushion can be wound up in a very compact and tight manner. In addition, contamination can largely be excluded with this structure, in particular at the location of the retaining profile and the further retaining profile. With the present invention, no kits or other sealing means are required. In addition, there is no need to use screws or the like.

The invention will be described in more detail below with reference to the exemplary embodiments illustrated in the drawing, in which:

Fig. 1 diagrammatically shows a perspective and partially cut-away view of a cultivation space according to the invention,

Figs.2a-c show a detail of the roof structure according to the present invention; Fig. 3 diagrammatically shows a variant of the invention provided with the cushion film according to the invention;

Fig. 4 shows the composition of a cushion from various webs; Figs. 5a-e show a detail of the structure illustrated in Fig. 3 with the various steps for attaching the cushion to an attachment profile; and Figs. 6a-d shows the fitting of a roof sheathing to a building structure.

In fig. 1, a cultivation space is denoted overall by reference numeral 1 and is preferably designed to grow crops therein.

The growing or cultivation space consists of a number of walls 2, the ends of which are delimited by posts 3. Although not illustrated in any more detail, the walls preferably consist of plastic panels which are a small distance apart. In this case, the plastic is light-transmitting and provides a high degree of insulation. The post is either made from a plastic material or from a heat-conducting material. In the latter case, measures are taken to prevent the formation of a thermal bridge between the post and the environment or the post and the interior of the growing space.

Reference numeral 4 denotes the roof of the growing space which consists of a number of longitudinal beams 5 and cross beams 6 which intersect. Inside the grid delimited by the latter, cushions 7 are in each case fitted.

As can be seen in fig. 2, each cushion 7 consists of two webs of film material 9 and 10 which are spaced apart and between which air is introduced at a slight excess pressure.

To this end, fig. 1 shows a compressor 19 which produces an excess pressure in each of the cushions 7 via a line 20 and a distribution system which is not illustrated in any more detail.

As can be seen in fig. 2, each beam 6 (as well as each beam 5) is provided with a layer of insulating material 16. On the latter, a profile 8 is fitted in turn and this profile 8 is provided with the attachment means containing the end 11 of the cushion 7. The end 11 of the cushion 7 is provided with a bead or core 15 in order to facilitate the attachment thereof. Fig. 2 also indicates how an attachment clip 12 may be provided on beam 6, if desired, which ensures the attachment of two adjacent air cushions 7. In the case of the illustrated structure with the attachment clip 12, the webs 9 and 10 are not interrupted and they are only pressed together locally so that sealing in that location is not an issue.

Fig. 2 also shows a slat structure 18 which is situated on the bottom web 10. It can be tilted in a manner which is not illustrated in any more detail such that light is prevented from passing through the light-transmitting film material of webs 9 and 10, as a result of which the interior of the cultivation space 1 is screened off with respect to the environment

As can be seen in fig. 1, a spraying installation 13 is provided, having outlets 14 for dispensing atomized water vapor. The floor 17 of the cultivation space 1 has a lower temperature than the remainder of the cultivation space so that any water vapor may condensate there. Incidentally, all walls, including the roof of the cultivation space according to the present invention, are embodied in such a manner that there is no condensation of water vapor there. As a result thereof, it is possible to introduce water vapor into a growing space at a relatively high humidity, such as, for example 85% or more, without condensation forming in undesirable locations. As a result, the crops can continuously or discontinuously be supplied with moisture in a very simple manner which significantly stimulates growth.

Fig. 3 illustrates a building structure, such as a greenhouse, comprising a number of posts 102 and beams 103 which also serve as gutters. Cushions 104 according to the present invention are in each case provided between adjacent parallel beams. These provide a roof covering/roof sheathing which is simple to fit and insulates very well.

Figs. 5a-e show details of how cushion 104 is attached to beam 103. As can be seen in fig. 5, each beam is provided with an attachment profile 110. This may be integral with the latter, but it is also possible to attach this to the beam 103 in any conceivable manner. Profile 110 comprises an internal cavity having an inlet 113. The internal cavity comprises a first cavity 111 and a second cavity 112. These are arranged slightly offset with respect to one another. In addition, retaining strips or beads are provided. Reference numeral 108 denotes a first bead and reference numeral 109 a second bead.

The cushion comprises two sheets of film material 105, 106 which are situated on top of one another at the end 107. If desired, a welded joint or the like may be present.

Starting from the situation in fig. 5a, part 107 is laid on the attachment profile 110 in such a manner that a sufficient length thereof protrudes to be introduced in the first cavity 111. At the same time as the sheets 105, 106 lying on top of one another are introduced, the first stiffener 108 is inserted which pushes the sheets 105, 106 lying on top of one another against the top of the attachment profile 110 (fig. 5c). However, if in this situation a force were to be exerted on the sheets 105, 106 in a direction away from the attachment profile 110, this would result in a downwards movement of the first bead 108 and result in the clamps of the sheets 105, 106 becoming detached with respect to the attachment profile 110. In order to prevent this, a second bead or stiffener 109 is provided in the second cavity 112 after the first bead or stiffener 108 has been inserted. This is shown diagrammatically in figs. 4d and e.

The structure according to the present invention in which the top side 01 of the attachment profile is covered by the film webs does not result in problems with ingress of water. Water will run to the gutter which is situated next to the attachment profile without the attachment profile being subjected to water or other weather conditions.

According to a further variant of the invention, it is possible to position one or both sheets in front of the second bead, i.e. to clamp it between the second bead 109 and the attachment profile 110. This method of attaching is simpler.

In fig. 5e, the second bead 109 is in such a stable position that, when the downwardly acting force of the first bead 108 exerts a tensile force on the sheets 105, 106 so as to move them out of the attachment profile 110, the second bead 109 is pushed further into position in the cavity 112 without the first bead 108 being able to move downwards to a substantial degree. As a result thereof, the seal between the first bead 108, the sheets 105, 106 and the attachment profile 110 is still ensured or even improved, as the clamping force acting on this seal increases. It will be understood that if there is no clamping force, it is relatively easy to remove the second bead 109 again and thus take the other parts of the structure apart. It will also be understood that it is possible to design the first bead as an integral part of the cushion 104. However, this means that the film material forming the cushion cannot be wound up in a compact manner.

Fig. 4 shows a cross section of a cushion which is embodied as a loop comprising several webs 115 which are in each case welded together at 116. The loop is denoted overall by reference numeral 114. Obviously, it is possible to use a greater or smaller number of welds.

Finally, fig. 6 shows an application of the present invention which substantially corresponds to that which is shown in fig. 1. Fig. 6a provides providing two sheets 105, 106 rolled up to form a roll 117 without stiffener. Fig. 6b shows how this double web is rolled out. Fig. 6c shows how a roll 118 of first stiffener material and a roll 119 of second stiffener material are provided. The beams 103 are provided with attachment profiles 110 and, subsequently, the first stiffener 108 and second stiffener 109 are fitted in the manner which is described above. A line 120 (fig. 6d) is provided, by means of which air or another gas can be supplied to the space between the film webs and, by inflating the latter, a film cushion is created having very good insulating values and other desirable properties. By way of example, a pressure for inflation of approximately 300 mbar is mentioned. It will be understood that it is also possible to use a different pressure.

It will be understood that the sheets 105, 106 may be treated in any desired way in order to obtain certain optical or thermal insulating properties.

By means of the present invention, it is possible to move large amounts of roof- sheathing material in a very compact manner and to install such material in a particularly quick way. The sheets only have to be approximately cut to size at the production site, and further finishing may be carried out at the building site. Removal can also be carried out in a quick manner. Such a roof sheathing has a particularly low weight, as a result of which the requirements for the other parts of the structure can also be lowered, resulting in a less expensive way of building.

It will be understood that the cultivation space 1 according to the present invention may be provided with further structures which are customary in the prior art. Thus, it is possible to provide lighting on the beams 5, 6. In addition, measures may be taken in order in order to be able to grow the respective crops (not shown) in such a manner that they can be moved, for example by means of rolling containers or growing systems suspended from the beams 5 and 6 or another structure.

Upon reading the above description, those skilled in the art will immediately be able to think of further variants which lie within the scope of the present invention.

Claims

1. Roof (4) for a cultivation space (1) comprising a supporting structure (5, 6) and a double-walled covering (7) attached thereto, wherein said double-walled covering (7) comprises two film webs (9, 10) which are spaced apart and shaped to form a cushion, in which an attachment profile (110) is provided for said film webs, provided with a cavity (111, 112) having a lateral inlet (113) for fixing said film webs therein, characterized in that said film webs (9, 10), starting from said inlet (113), are lying against one another and folded over the top part (01) of said attachment profile and delimit the cushion volume from said top part (01) in a direction extending away from each other.

2. Roof as claimed according to in claim 1, wherein a gutter (103) is provided, adjacent to said attachment profile, on the side of the inlet.

3. Roof according to claim 1 or 2, wherein the attachment for said film webs comprises a retaining strip (108, 109) which can be received into said cavity, wherein both layers of film material are fitted on one side of said retaining strip (108) and lying on top of one another, said cavity in said profile being embodied in such a manner that when said retaining strip (108) and the layers of film material applied thereto are fitted in said cavity and a force is applied to said film material, said retaining strip is forced out of said cavity (111), wherein a further retaining strip (109) which is to be fitted in said cavity is present, said cavity and said further retaining strip being embodied such that when a force is exerted on said film material, said further retaining strip (109) blocks movement of said retaining strip (108).

4. Roof according to claim 3, wherein both layers (5, 6) of the film material are fitted between said further retaining strip and said boundary of said cavity.

5. Roof according to one of the preceding claims, wherein said profile (110) comprises two adjacent subcavities (111, 112) which are arranged in a staggered manner with respect to one another.

6. Roof according to one of the preceding claims, wherein said profile has an inlet (13) to said cavities, said inlet being arranged in such a manner that it drains water away in the position of use.

7. Roof according to one of the preceding claims, wherein an insulating gas is provided between said film webs.

8. Cultivation space comprising a roof (4) according to one of the preceding claims as well as damp-proof side walls (2).

9. Cultivation space according to claim 8, wherein said side walls comprise polycarbonate material.

10. Cultivation space according to one of claims 8 or 9, comprising four posts (102) and beams (103) extending between the free ends thereof, in which said beams comprise attachment profiles, provided with a cavity for accommodating a retaining strip and a further retaining strip therein.

11. Cultivation space according to one of claim 8-10, wherein water sprayers (13) are arranged in said cultivation space.

12. Cultivation space according to one of claim 8-11, wherein the floor (17) of said cultivation space has a lower temperature than the remainder of said cultivation space.

13. Space unit comprising two adjacent cultivation spaces according to claims 8-12, wherein a common beam is provided comprising two attachment profiles which are spaced apart and a gutter situated in between.

14. Method for providing a sheathing in a supporting structure, which supporting structure is provided with an attachment profile designed to accommodate a retaining profile and a further retaining profile therein, to provide a roll (17) of cushion material comprising two webs of film material lying on top of one another and to provide a separate rolls (18, 19) of retaining strip material and ftirther retaining strip material, respectively, which retaining strip material is fitted in a cavity of said attachment profile and is fixed in said cavity of said attachment profile by said retaining strip material and further retaining strip material, respectively.

15. Method according to claim 10 wherein said roll of cushion material comprises a number of webs of film material which are connected to form a gas-tight loop.