WO2015167338A1

WO2015167338A1 - Ventilated roof structure for greenhouse or warehouse

Info

Publication number: WO2015167338A1
Application number: PCT/NL2015/050298
Authority: WO
Inventors: Adrianus Gerardus van Deursen; Philippus Lucas VAN DER HEIDE
Original assignee: Van Der Valk Systemen B.V.
Priority date: 2014-05-01
Filing date: 2015-05-01
Publication date: 2015-11-05
Also published as: EP3136838A1; WO2015167338A4; NL2012731B1

Abstract

A roof structure for a greenhouse or warehouse comprising mutually parallel gutters (1) extending in a longitudinal direction and a raised cover (2) extending between the gutters. The cover comprises a support structure (3, 5) supported on the gutters, an outermost translucent cover layer (15) as well as an innermost translucent cover layer (7) which together delimit a cavity (8) and which are supported by the load-bearing structure (3, 5). The roof structure is provided with a ventilation duct (12) that extends along the cavity (8) and that is connected by at least one opening (11) to the interior of the cavity, wherein the ventilation duct is adapted for exchanging a gas as ventilation medium between the ventilation duct and the cavity through at least one opening, for ventilating the internal space of the cavity. At least one of the gutters (1) comprises a tubular shape which defines the ventilation duct (12).

Description

Ventilated Roof Structure for Greenhouse or Warehouse

TECHNICAL FIELD

The invention relates to a roof structure for a greenhouse or warehouse, comprising gutters extending mutually parallel and in a longitudinal direction and a raised cover extending between the gutters, which cover comprises a support structure supported on the gutters, an outermost translucent cover layer and an innermost translucent cover layer which jointly delimit a cavity. BACKGROUND ART

Such a roof structure is known from NL-A-8105447. The innermost cover layer thereof consists of a film which is tensioned between the mutually parallel frames adjacent to the gutter and the ridge. The cavity thus formed between the film and the outermost cover layer of rods and glass panels may be closed to achieve an insulation effect. This may considerably decrease the energy costs associated with heating the greenhouse. The cavity may also be open to discharge condensation water from it. To achieve the desired insulating effect, the cavity may not be very thick and have a thickness of a few centimetres at the most. Also, the thickness of the cavity may be uniform, although that is not necessary. In such a case, it is ensured that a stationary layer of air is formed in the cavity, which has a favourable effect on the insulation.

This known roof structure, however, also has various disadvantages. As a result of the insulating effect of the cavity, it is difficult to remove snow from the roof structure. In known roof structures with single-layer panels, the snow melts away under the effect of heat in the interior of the greenhouse. The insulating effect of the double cover layers prevents that. However, a snow layer considerably blocks the incidence of light, which hampers cultivation.

A further disadvantage is that, during the summer, the air in the cavity gets so hot that cooling in the evening and night proceeds too slowly. The hot air remains functional as a heat source for a considerable time. However, this is undesirable, as a rapid cooling of the culture overnight is desired.

Patent FR2600230 describes a greenhouse which is formed by a support structure with two layers of transparent film attached thereto. In between these film layers, a space is formed that is kept under pressure by the outside air, using a fan and a pipe system. The air may be circulated through the intermediate space and be heated if necessary to counteract undesirable moisture condensation on the inside of the greenhouse. The pipe system in FR2600230, however, is unnecessarily complex and installing it is labour- intensive.

BRIEF DESCRIPTION OF THE INVENTION

An object of the invention is to provide, according to a first aspect, a roof structure which, on the one hand provides advantages of good insulation and energy saving, and with which on the other hand the above-mentioned disadvantages can be avoided. The roof structure according to this first aspect comprises ventilation means which discharge into the cavity and are adapted for ventilating the internal space of the cavity. The term "ventilation" is associated herein with the displacement of gas, and air in particular (as "ventilation medium"). Normally, inside the cavity of the roof structure according to this aspect of the invention, a stationary layer of air is present, so as to ensure the desired insulation. However, if for whatever reason, the disadvantageous effects of this insulation have to be avoided, the ventilation means can be put into operation. The air in the cavity may then be replaced by relatively hot or relatively cold air, depending on the desired effect.

In connection with supplying or discharging the ventilation air, the roof structure is provided with a ventilation duct that extends along the cavity, and which is connected by at least one opening (preferably via a series of openings extending in the

longitudinal direction or a groove) to the interior of the cavity, wherein the ventilation duct forms part of the ventilation means for exchanging a ventilation medium between that channel and the cavity through the at least one opening.

Gutters exhibiting a tubular shape are known. This tubular shape provides the gutter with a certain desired strength and rigidity, at relatively low transverse dimensions. This promotes incidence of sunlight into the greenhouse. The tubular duct in the interior of the gutter has the advantage that it can be used to discharge condensation water from the inside of the cover layer. According to the first aspect of the invention, these tubular ducts may be exploited by also letting these function as ventilation channel, via which ventilation air can be supplied to, or discharged from, the cavity. The use of the already present gutter with tubular shape as a ventilation channel provides a simplification of the ventilation facility, and makes it possible to implement it more robustly.

If, according to one embodiment, a series of openings or a groove is applied, then the ventilation air may be supplied or discharged uniformly over the entire length of the cavity. Consequently, the outermost cover layer can also be uniformly heated to remove snow.

Preferably, the tubular shape of the gutter is also adapted for discharging condensation water from an interior side of at least one cover layer. In a particular embodiment, the gutter may be provided with a condensate receiving ledge beneath the outermost cover layer; in that case, the opening(s) or groove may be located at the level of this condensate receiving ledge.

Preferably, at least one of the cover layers comprises a film. In that case, the cover may comprise at opposite sides of the cavity a fastening section with an undercut chamber for the film. The film has a respective longitudinal thickening on opposite edges, so that each longitudinal thickening extends into the undercut chamber of the respective fastening section. The advantage of this embodiment is that the film may be attached in a relatively simple way by pulling the longitudinal thickenings in a longitudinal direction into the undercut chambers of the fastening sections.

According to a further possible embodiment, the cavity is compartmentalised in the transverse direction, in other words: provided with partitions oriented in the transverse direction of the ridge towards the gutter. This means that the cavity comprises several adjacent compartments extending in a transverse direction, inside each of which an air layer is located. Such a compartmentalisation has the advantage that inside these the formation of a stationary air layer is promoted more strongly. In fact, the greenhouse or the warehouse normally stands on (a very slight) slope, viewed along the longitudinal direction parallel to the gutters and the ridges. The reason for this is to improve drainage from the gutters. As a result of this slope, however, undesirable flows in the longitudinal direction may occur inside the cavity, which reduce the insulation capacity.

Such a compartmentalisation may be achieved in various ways. According to a first option, a compartmentalisation wall may extend in the transverse direction inside the cavity, which wall is connected to the outermost and innermost translucent cover layers. Such a compartmentalisation wall may, for example, be formed by a metal profile, or a foil strip or the like.

According to a second option, the compartmentalisation may be achieved without using such a separate compartmentalisation wall, if the film between both longitudinal edges thereof is attached to the other cover layer by means of a fastening construction which extends in the transverse direction. For example, the film may be fastened with suitable clamps to the rods of a cover layer consisting of rods and glass panels.

In a further embodiment, valve means are provided for opening or closing the ventilation means. When open, the cavity may be ventilated. When the valve means are closed, the air in the cavity is stationary, so that the insulating effect is ensured.

However, it is not always necessary to apply valve means. If the ventilation means have openings for supplying air to and discharging air from the cavity that exhibit a certain throttling effect, then it may be sufficient to switch the ventilation means on or off. Furthermore, supply and discharge openings may be provided at various height levels. The valve means for closing or opening the cavity may be implemented in various ways. Preferably, the cavity is delimited by a longitudinal seal running parallel to the gutter, in particular, a closing section extending in the longitudinal direction, with at least one closable or non-closable opening, preferably a series of closable openings or a groove extending in the longitudinal direction of the seal, which discharge(s) into the internal space of the cavity. Also in this case, the variant including a series of openings or a groove promotes the uniform flow of ventilation air through the cavity.

The cover of the greenhouse according to the invention may be implemented in several ways. One example is a greenhouse with two cover layers consisting of film, which are supported by rafters that extend between both gutters. These rafters may exhibit a curved shape, so that the highest point of the cover is located in the middle between the case, one gutter may function as supply for a ventilation medium, and the other gutter as discharge for that ventilation medium. A ridge may be located at the highest point of such a cover.

However, the cover may be implemented in other ways, such as with a ridge located between the gutters at a higher level, an outermost cover layer on opposite sides inclined downwards from the ridge and rods towards an associated gutter for translucent panels between rods parallel to each other and a gutter, in which the innermost cover layer extends under a series of rods and panels on one side or both sides of the ridge. The outermost cover layer may be made of glass panels or film. The innermost cover layer may also be made of film or glass panels. Preferably, the outermost cover layer consists essentially of glass panels and the innermost cover layer consists essentially of film, wherein the cavity is formed between the glass panels and the film.

The longitudinal closure may be located at various positions at a distance from the gutter. According to a first option, this longitudinal closure coincides with the ridge. It is also possible to implement the longitudinal closure with a separate section that is located adjacent to or abuts the ridge. According to a further possibility, the longitudinal closure may be implemented as a longitudinal beam or transom resting between the gutter and the ridge. In the latter case, a ventilation window may be provided that is hingedly connected on one edge to the ridge, and cooperates at an opposite edge with the longitudinal beam or the transom, or vice versa.

Preferably, this roof structure is implemented such that it is entirely provided with an innermost cover layer as described herein above. For this purpose, at each gable roof a further inner layer is provided that extends under the other series of rods and panels to the other side of the ridge, thereby forming a further identical cavity that connects on one side to the further gutter and on the opposite side to a further longitudinal seal, wherein further ventilation means that discharge into the further cavity are provided for ventilating the internal space of the further cavity.

Furthermore, the ventilation means may comprise an active fan for exchanging ventilation medium with the internal space of the cavity. This fan may be connected to the ventilation duct, for example to a tubular duct in the tubular channel mentioned above. The active fan may be implemented to be selectively switchable, so that during

thermal stabilisation time of the air flow may depend strongly on the locations of the ventilation openings and the heating and/or cooling elements, as well as on the thermal properties of the ventilation ducts used. This switchability of the fan allows adjustment of the air flows in such a way that the thermal stabilization time of and/or losses in the air flow can be reduced. However, it is not always necessary to apply an active fan. The desired ventilation would also be achievable if the ventilation means comprise the above-mentioned openings located at various heights.

Furthermore, the ventilation means may be adapted for exchanging the ventilation medium between the internal space of the cavity and the space enclosed by the roof structure and/or with the space outside the roof structure.

A second aspect of the invention concerns a method for operating a roof structure for a greenhouse or warehouse. The roof structure comprises mutually parallel gutters and a raised cover extending between the gutters, which cover comprises a support structure supported on the gutters, an outermost translucent cover layer as well as an innermost translucent cover layer, which together delimit a cavity and which are supported by the support structure, wherein the roof structure is provided with a ventilation duct that extends along the cavity and that is connected via at least one opening to the interior of the cavity, wherein at least one of the gutters comprises a tubular shape which defines the ventilation duct. The method according to this second aspect comprises:

- keeping the air in the cavity stationary during a first time period to provide an insulating effect of the cover, and

- during a second time period outside the first time period, supplying air in a first region of the cavity and discharging air from another region of the cavity at a distance from the first region to create a heating effect, a cooling effect and/or a drying effect in the cavity.

The air supplied into the cavity may originate from the interior of the greenhouse, for example, in connection with the melting of snow on the roof in winter. It is also possible to supply cold air or conditioned air.

The method may, to operate a roof structure wherein the ventilation means comprise an active fan for exchanging ventilation medium with the internal space of the cavity, comprise the steps of:

- keeping the active fan inoperative during the first time period,

- activating the fan during the second time period.

In such a method, it is not always necessary to provide the openings in the cavity - through which the air enters the cavity and/or leaves the cavity- with a valve or valves. The openings may exhibit a throttling effect that, on the one hand, enables passage of air under the effect of the pressure difference generated by the fan, but on the other hand ensures that the air remains in a more or less stationary state when the fan is inactive.

Furthermore, the method, in connection with operating a roof structure wherein valve means are provided for opening and/or closing ventilation means, may comprise the steps of:

- keeping the valve means closed during the first time period,

- keeping the valve means open during the second time period.

According to an embodiment, the supplying and discharging of air during the second time period comprises: discharging air from the cavity via the at least one opening and through the ventilation duct and supplying air directly from an inner part of the greenhouse or the warehouse into the cavity to create the heating effect, the cooling effect and/or the drying effect in the cavity.

In the case that the roof structure encloses or covers an inner region, heated or cooled air from this inner region may be drawn into the cavity by the underpressure. As a result, the air does not need to flow through the ventilation duct first, so that any thermal losses and/or supply delays may be reduced.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, wherein corresponding

components are indicated by corresponding reference symbols.

Figure 1 schematically shows one half of a roof structure according to an embodiment;

Figure 2 shows the detail II of Figure 1 at a larger scale, and

Figure 3 shows detail III of Figure 1 at a larger scale.

[0001] The drawings are only intended for illustrative purposes, and do not serve to restrict the scope of protection as laid down by the claims.

DESCRIPTION OF EMBODIMENTS

The part of a roof structure shown in Figure 1 consists of a gutter 1 and the cover indicated as a whole with 2, of which only part is shown. The gutter 1 may be supported by columns (not shown) in a known way. In turn, the cover 2 consists of rods 3 extending between the gutter 1 and the ridge 5. Between the gutter 1, the rods 3 and the transom 4 or the ridge 5, glass panels 15 are accommodated. Both on the gutter 1 and on the transom 4, undercut sections 6 are fastened, onto which a film 7 is suspended which extends underneath the glass panels 15 and the rods 3. For that purpose, the film 7 has thickenings 9 on the edges, which are accommodated in the chamber of the undercut sections 6. Thus, an essentially airtight cavity 8 is formed that essentially exhibits a uniform thickness.

In connection with the discharging of condensation which accumulates on the underside of the cover 2, the gutter 1 is provided with condensate ledges 10, wherein condensation discharge openings 11 are located. The gutter 1 has a tubular duct 12 in which the condensate moisture is discharged.

The stationary air inside the cavity 8 has an insulating effect on the cover 2.

Consequently, the energy requirement of the greenhouse on which the roof structure is located may be kept within bounds. Also, the insulating effect of the cover 2 may cause difficulties in removing snow via melting. Also, in the summer, the heat that accumulates in the cavity 8 cause disadvantages. With the aim of remedying these advantages, the cover 2 is implemented in such a way that the cavity 8 of the cover 2 is connected more or less airtight to the openings 1 1 in the condensation ledge 10 as shown in Figure 2. Furthermore, an active fan 13 is connected to the tubular duct 12 into which the openings 11 discharge. In the transom 4, a closable opening or series of openings 14 is provided as shown in Figure 3.

By means of this active fan 13, air can be supplied to the cavity 8 through the openings 11, and with opened valve(s) 17 air may be discharged there from through the closable opening(s) 14. Thus, the cavity 8 may for example be heated in connection with melting of snow located on the cover 2.

The active fan 13 may also be adapted for generating a reversed air flow, so that the air through the openings 1 1 can be withdrawn from the cavity 8, so that an underpressure is created inside the cavity 8. As a result of the underpressure, further air can be supplied through the closable opening(s) 14 via opened valve(s) 17 into the cavity 8. In the case that the roof structure encloses or covers an inner region, heated air may be drawn in from this inner region 8 into the cavity as a result of the underpressure. By applying this reversal, any heat losses and/or supply delays of heated air (for example, as a result of a heat capacity of the gutter 1 with tubular duct 12) may be reduced. The active fan 13 may even be implemented selectively switchable to reverse the air flow in a controlled way, for example in anticipation of or in response to changing environmental variables that may cause a change in the expected heat losses.

The ventilation window 16 is rotatably suspended on the ridge 5. When closed, this ventilation window 16 abuts upon the transom 4. If no ventilation is provided, the valve 17 may be closed so that a stationary layer of air is ensured in the cavity 8, which guarantees a good insulation.

It will be clear that the embodiments described herein above have been described by way of example only and in no way limit interpretation, and that various changes and adaptations are possible without departing from the scope of the invention as defined in the appended claims.

LIST OF REFERENCE NUMBERS

1 Gutter

2 Cover

3 Rod

4 Transom

5 Ridge

6 Undercut fastening section

7 Film

8 Cavity

9 Thickening on the film

10 Condensate receiving ledge

11 Opening in the condensation gutter

12 Tubular duct of the gutter

13 Active fan

14 Closable opening

15 Glass panel

16 Ventilation window

17 Valve

Claims

1. A roof structure for a greenhouse or warehouse, comprising gutters (1) extending mutually parallel in a longitudinal direction, and a raised cover (2) extending between the gutters, which cover comprises a support structure (3, 5) supported on the gutters, an outer translucent cover layer (6) as well as an innermost translucent cover layer (7) which together delimit a cavity (8) and which are supported by the support structure (3, 5), wherein the roof structure is provided with a ventilation duct (12) that extends along the cavity (8) and that is connected with the interior of the cavity via at least one opening (1 1), wherein the ventilation duct is adapted to exchange a ventilation medium between the ventilation duct and the cavity through the at least one opening for ventilating the interior space of the cavity, wherein at least one of the gutters (1) comprises a tubular shape, which tubular shape defines the ventilation duct (12).

2. The roof structure according to claim 1 , wherein at least one of the cover layers comprises a film (7).

3. The roof structure according to claim 2, wherein a fastening section (6) with undercut chamber is located on opposite sides of the cavity (8), wherein the film (7) has a respective longitudinal member (9) on opposite edges, and wherein each longitudinal member extends into the undercut chamber of the respective fastening section.

4. The roof structure according to any one of claims 1-3, wherein the ventilation duct (12) is connected to the interior of the cavity (8) by a series of openings extending in the longitudinal direction or a groove, and wherein the ventilation duct is adapted to exchange the ventilation medium between that ventilation duct and the cavity via the opening(s) or the groove.

5. The roof structure according to any one of claims 1-4, wherein the tubular shape that defines the ventilation duct (12) is also adapted for discharging condensation water from the inside of at least one of the cover layers (6, 7).

6. The roof structure according to claim 5, wherein the gutter (1) is provided with a condensate receiving ledge (10) beneath at least one of the cover layers (6, 7), wherein the openings (1 1) or groove is/are located at the level of the condensate receiving ledge.

7. The roof structure according to any one of claims 1-6, wherein the cavity (8) is compartmentalised in the transverse direction.

8. The roof structure according to claim 7, wherein a compartmentalisation wall extends inside the cavity in the transverse direction thereof, which is connected to the outermost and innermost translucent cover layers (6, 7).

9. The roof structure according to claim 7, as far as dependent from claim 2, wherein the film (7) between both longitudinal edges thereof is fastened to the other cover layer via a fastening structure which extends in the transverse direction.

10. The roof structure according to any one of claims 1-9, wherein the cavity (8) is delimited by a seal (4) with at least one closable opening (14), preferably a series of closable openings extending in the longitudinal direction of the seal or a closable groove, which opens into the internal space of the cavity.

1 1. The roof structure according to any one of claims 1-10, comprising an active fan (13) for exchanging ventilation medium with the internal space of the cavity (8).

12. The roof structure according to claim 11 , as far as dependent from claim 4 or 6, wherein the active fan (13) is connected to the ventilation duct (12) inside the tubular gutter (1).

13. The roof structure according to any one of claims 1-12, comprising at least one further opening (14) for supplying and/or discharging the ventilation medium to/from the interior of the cavity (8), wherein the at least one opening (1 1) and the at least one further opening (14) are located at different heights.

14. The roof structure according to claim 10 or 13, comprising at least one valve (17) for opening or closing at the least one opening (1 1) and/or the at least one closable opening (14).

15. The roof structure according to any one of claims 1-14, comprising a ridge located between the gutters but at a higher level, rods running on opposite sides of the ridge and inclined downwards towards an associated gutter, an outermost cover layer made of translucent panels between mutually parallel rods and a gutter, wherein the innermost translucent cover layer extends under a series of rods and panels on one side of the ridge.

16. The roof structure according to claim 15, wherein the cavity (8) is delimited by the ridge (5).

17. The roof structure according to claim 15, wherein the cavity (8) is delimited by a longitudinal beam (4) lying between the gutter and the ridge.

18. The roof structure according to claim 17, wherein a ventilation window is provided, which is hingedly connected on one edge to the ridge or the longitudinal beam, and which on the opposite edge cooperates with the longitudinal beam or the ridge.

19. The roof structure according to any one of claims 1-18, wherein the cavity (8) has a uniform thickness.

20. A method for operating a roof structure for a greenhouse or warehouse, which roof structure comprises mutually parallel gutters (1) and a raised cover (2) extending between the gutters, wherein the cover is provided with a support structure (3, 5) supported on the gutters, an outermost translucent cover layer (6) as well as an innermost translucent cover layer (7), which jointly delimit a cavity (8) and which are supported by the support structure (3, 5), wherein the roof structure is provided with a ventilation duct (12) that extends along the cavity (8) and that is connected via at least one opening (11) to the interior of the cavity, wherein at least one of the gutters (1) comprises a tubular shape which defines the ventilation duct (12), wherein the method comprises:

keeping the air in the cavity (8) stationary during a first time period to provide an insulating effect of the cover, and

21. The method according to claim 20, for operating a roof structure provided with an active fan (13) for exchanging a ventilation medium with the internal space of the cavity (8), wherein the method comprises:

keeping the active fan inoperative during the first time period,

activating the fan during the second time period.

22. The method according to claim 20 or 21, for operating a roof structure provided with a closable opening (14) for supplying and/or discharging a ventilation medium to/from the interior of the cavity (8) and providing at least one valve (17) for opening or closing the at least one closable opening (14), wherein the method comprises:

keeping the at least one valve closed during the first time period,

keeping the at least one valve open during the second time period.

23. The method according to any one of claims 20-22, wherein the supply and discharge of air during the second time period comprises:

discharging air from the cavity (8) via the at least one opening (11) through the ventilation duct (12) and supplying air from an inner part of the greenhouse or the warehouse into the cavity (8) to create the heating effect, the cooling effect and/or the drying effect inside the cavity.