The invention relates to a horticultural or agricultural greenhouse for cultivating crops therein.

EP 2941952 discloses a greenhouse that is close to the roof provided with at least one horizontally suspended fabric screen which defines a cultivation space for cultivating crops therein under the fabric screen and a roof space separated from the cultivation space. The fabric screen comprises at least one passage between the roof space and the cultivation space. The greenhouse further comprises a ventilation system with air displacing means for displacing air in the cultivation space of the greenhouse. At least one of the air displacing means is situated close to the passage in the fabric screen and is configured to draw in and subsequently displace air from both the roof space and the cultivation space. The ventilation system is arranged below the passage of the fabric screen and is connected to the fabric screen.

SUMMARY OF THE INVENTION

A disadvantage of the known horticultural greenhouse is that in order to cool and/or dehumidify the cultivation space, ventilation windows in the roof of the greenhouse need to be opened to allow cool and/or dry fresh air to enter the greenhouse via the roof space. Therefore, during cooling and/or dehumidifying of the cultivation space the conditions of the air in the roof space may be negatively influenced. For instance, because the fresh air enters the greenhouse through the ventilation windows, the C02 level in the roof space is reduced, and the refreshed air in the roof space needs to be reheated.

It is an object of the present invention to overcome or to ameliorate the disadvantage of the known greenhouse.

According to a first aspect, the invention provides a horticultural greenhouse for cultivating crops therein, comprising: multiple rows of support columns forming a roof support construction; a roof that is supported by the roof support construction, and that separates the greenhouse from the environment, wherein the roof of the greenhouse comprises a roof passage; a fabric screen for at least partially darkening and/or thermally shielding the greenhouse, wherein the fabric screen extends in a horizontal separation plane within the greenhouse that divides the greenhouse in a cultivation space below the separation plane and a roof space above the separation plane; and a ventilation system comprising a first ventilation arrangement, wherein the first ventilation arrangement comprises a first ventilation device for displacing air within the greenhouse, and a first air duct with a first air inlet, a first air outlet, and a first air channel extending between the first air inlet and the first air outlet, wherein the first air channel debouches into the air outside of the greenhouse via the roof passage, wherein the first air channel passes through the separation plane, and wherein the first ventilation device is arranged for drawing air into the first air channel.

When the screens in the greenhouse according to the invention are closed, the roof space comprises a stock of air having specific and well measurable conditions. As the first air duct of the ventilation system passes through the separation plane and the roof space it is possible to draw fresh air into the cultivation space without altering the specific conditions of the stock of air in the roof space. The cultivation space can thus be ventilated without influencing the conditions of the air in the roof space, or without the need of indirect reheating via the cultivation space. Furthermore, as the first ventilation device is in direct air communication with the outside air of the greenhouse, the effectiveness of ventilating the greenhouse can be achieved independently of the position of the fabric screens, i.e. opened or closed. The air outside the greenhouse will have better conditions than the air inside the roof space with respect to air humidity for example.

In an embodiment the first air duct is connected to the roof passage in order to further optimize the air flow between the cultivation space and the outside air of the greenhouse.

In an embodiment the first air duct defines the roof passage. The first air duct is part of the roof construction in order to strengthen the roof construction near the roof passage.

In an embodiment the first ventilation arrangement comprises a first closing panel that is configured to move between a first position in which the first closing panel closes the first air channel, and a second position in which the first closing panel allows air to pass through the first air channel. The first closing panel can be opened when the outside air conditions are favorable to ventilate the greenhouse and can be closed when the outside air conditions are unfavorable to ventilate the greenhouse. In this way the efficiency of the ventilation system is further increased.

In an embodiment the first air duct comprises in the roof space a second air inlet to the first air channel, and a second closing panel that is configured to move between a third position in which the second closing panel allows air to pass through the second air inlet, and a fourth position in which the second closing panel closes off the second air inlet. The second closing panel can be opened to draw air directly from the stock of air in the roof space into the cultivation space. The second closing panel can be closed when air is drawn from outside of the greenhouse into the cultivation space. When air is drawn from outside of the greenhouse into the cultivation space the second closing panel can be opened or partly opened to simultaneously draw air from the stock of air in the roof space. In this way unfavorable conditions of the air from outside of the greenhouse may be altered by adding the air from the roof space thereto. For instance cold air from outside of the greenhouse may be warmed up by adding warmer air from the roof space thereto. This increases the conditioning flexibility of the greenhouse.

In an embodiment the first closing panel and the second closing panel are operably connected to each other for synchronized movement. In an embodiment the first closing panel is in the first position when the second closing panel is in the third position, wherein the first closing panel is in the second position when the second closing panel is in the fourth position. By operably connecting the first closing panel and the second closing panel the actuation arrangement of the ventilation arrangement is kept simple and robust.

In an embodiment the first ventilation device comprises a first fan connected to the first air duct at the first air outlet thereof for drawing air into the first air channel. By placing the first fan inside the cultivation space it can be serviced in a straightforward manner.

In an embodiment thereof the first ventilation device comprises a first air blender that is provided between the first air outlet of the first air duct and the first fan, wherein the first air blender comprises a first blender inlet that is in air communication with the first air outlet, a second blender inlet that is in air communication with the cultivation space, and a blender outlet that is in air communication with the first fan, wherein the first air blender is configured for providing an air blend from air from the cultivation space and air from the first air duct to the first fan. By providing the first air blender, the air drawn from outside the greenhouse and/or drawn from the roof space can be actively blended with air from inside the cultivation space. The desired conditions in the cultivation space can then be obtained more quickly.

In an embodiment the first air blender comprises blending flaps that are movable between a first position in which the first blender inlet is closed off, and a second position in which the second blender inlet is closed off. When the condition of the air within the cultivation space is as desired, it may be sufficient to just circulate the air within the cultivation space without adding air from outside the greenhouse. Otherwise, it may be necessary to draw air from outside the greenhouse into the cultivation space in order to adapt the condition of the air within the cultivation space. By providing the blending flaps the amount of air to be drawn from outside the greenhouse or the cultivation space can be regulated.

In an embodiment the first ventilation arrangement is provided with a first heat exchanger that is arranged for exchanging thermal energy with the air displaced by the first ventilation device. With the heat exchanger it is possible to adjust the temperature within the cultivation space while being less dependent of the temperature of the air from outside the greenhouse.

In an embodiment the first ventilation arrangement is arranged to blow air into the cultivation space in a direction parallel to the longitudinal direction of the greenhouse. In an embodiment thereof the ventilation system comprises a row of multiple first ventilation arrangements, wherein the row of multiple ventilation arrangements is arranged parallel to the transverse direction of the greenhouse. In a further embodiment thereof the ventilation system comprises multiple rows of first ventilation arrangements, wherein the rows of first ventilation arrangements are arranged at a distance from each other in the longitudinal direction of the greenhouse. In this arrangement it is possible to ventilate the complete area of the cultivation space in an efficient manner.

In an embodiment the ventilation system comprises a second ventilation arrangement, wherein the second ventilation arrangement comprises a second ventilation device for displacing air within the greenhouse, and a second air duct with a third air inlet, a second air outlet, and a second air channel extending between the third air inlet and the second air outlet, wherein the second air channel debouches into the roof space of the greenhouse, and wherein the second ventilation device is arranged for drawing air into the second air channel.

By adding the second ventilation arrangement to the greenhouse it is possible to draw air directly from the stock of air in the roof space into the cultivation space. Therefore the cultivation space of the greenhouse can be supplied with air from outside the greenhouse, air from the stock of air in the roof space, or air from both. This further increases the conditioning flexibility of the greenhouse.

In an embodiment the second ventilation device comprises a second fan that is connected to the second air duct at the second air outlet thereof for drawing air into the second air channel. By placing the second fan inside the cultivation space it can be serviced in a straightforward manner.

In an embodiment the second ventilation device comprises a second air blender that is provided between the second air outlet of the second air duct and the second fan, wherein the second air blender comprises a first blender inlet that is in air communication with the second air outlet, a second blender inlet that is in air communication with the cultivation space, and a blender outlet that is in air communication with the second fan, wherein the second air blender is configured for providing an air blend from air from the roof space and air from the cultivation space to the second fan. By providing the second air blender, the air drawn from the roof space is actively blended with air from inside the cultivation space. The desired conditions in the cultivation space can be obtained more quickly.

In an embodiment the second air blender comprises blending flaps that are movable between a first position in which the first blender inlet is closed off, and a second position in which the second blender inlet is closed off. When the condition of the air within the cultivation space is as desired, it may be sufficient to just circulate the air within the cultivation space without adding air from the roof space. Otherwise, it may be necessary to draw air from the roof space into the cultivation space in order to adapt the condition of the air within the cultivation space. By providing the blending flaps the amount of air to be drawn from the roof space or the cultivation space can be regulated.

In an embodiment the second ventilation arrangement is provided with a second heat exchanger that is arranged for exchanging thermal energy with the air displaced by the second ventilation device. With the heat exchanger it is possible to adjust the temperature within the cultivation space while being less dependent of the temperature of the air from the roof space.

In an embodiment the second ventilation arrangement is arranged to blow air into the cultivation space in a direction parallel to the longitudinal direction of the greenhouse. In an embodiment thereof the ventilation system comprises a row of at least one first ventilation arrangement and at least one second ventilation arrangement, wherein said row is arranged parallel to the transverse direction of the greenhouse. In a further embodiment thereof the ventilation system comprises multiple rows of at least one first ventilation arrangement and at least one second ventilation arrangement, wherein said rows are arranged at a distance from each other in the longitudinal direction of the greenhouse. In this arrangement it is possible to ventilate the complete area of the cultivation space in an even more efficient manner.

In an embodiment the ventilation system comprises a top beam extending parallel to the separation plane, wherein the first air duct or the second air duct is supported by the top beam. The top beam is connected to the roof support construction and suspends the air duct above the cultivation area in order to keep the cultivation area free of hindering objects.

In an embodiment the top beam comprises at least one top beam passage and the first air channel or the second air channel extends through the at least one top beam passage. The top beam is arranged in the separation plane. By including the passage in the top beam the air duct does not obstruct with the fabric screens.

In an embodiment the roof support construction comprises transverse frames for supporting the roof, wherein the top beam extends between subsequent transverse frames in a direction transverse thereto, and wherein the fabric screen is guided along the longitudinal sides of the top beam between the subsequent transverse frames. In this configuration the screens can move unobstructed between the open and closed position along the top beam.

In an embodiment the roof support construction comprises transverse frames for supporting the roof, wherein the top beam extends parallel along and is secured to one of the transverse frames, and wherein the top beam is arranged between the respective transverse frame and the fabric screen. In this configuration the screens can move unobstructed between the open and closed position. The transverse frame adds rigidity to the ventilation arrangement. In an embodiment the ventilation system comprises multiple first ventilation arrangements and multiple roof passages that are regularly distributed over the entire area of the cultivation space, whereby the climate in the cultivation space can be controlled over the entire area, independent from the size thereof. This allows the greenhouse to be scaled up to any size.

In an embodiment the ventilation system comprises a ventilation window assembly with multiple ventilation windows in the roof that are regularly distributed over the entire area of the cultivation space, wherein the ventilation windows are configured to move between an open position to allow outside air to enter the roof space, and a closed position. The ventilation window arrangement can be used for substantial evacuation of hot air from the cultivation space, whereby the climate in the cultivation space can be controlled or brought back under control over the entire area, independent from the size thereof. This allows the greenhouse to be scaled up to any size.

The cumulative flow area of the roof passages is preferably smaller than the cumulative flow area of the ventilation windows to enable a strong upward airflow during evacuation of the hot air.

According to a second aspect, the invention provides a ventilation system for use in a horticultural greenhouse according to the first aspect of the invention.

According to a third aspect, the invention provides a first ventilation arrangement for use in a horticultural greenhouse according to the first aspect of the invention, or in a ventilation system according to the second aspect of the invention.

According to a fourth aspect, the invention provides a method for climate control in a cultivation space in a horticultural greenhouse according to the first aspect of the invention, the method comprising the steps of: by the first ventilation device, displacing air within the cultivation space; by the first ventilation device, displacing air from outside the greenhouse into the cultivation space; or by the first ventilation device, displacing air within the cultivation space and from outside the greenhouse into the cultivation space.

In an embodiment when the ventilation system comprises the ventilation window assembly, the method further comprises the steps of: monitoring the air temperature or the air humidity or the concentration of carbon dioxide or oxygen in the cultivation space; keeping the air temperature or the air humidity or the concentration of carbon dioxide or oxygen in the cultivation space within a defined parameter range by means of the first ventilation arrangement; and opening the ventilation windows when the air temperature or the air humidity or the concentration of carbon dioxide or oxygen in the cultivation space comes outside the defined parameter range and closing the ventilation windows when the air temperature or the air humidity or the concentration of carbon dioxide or oxygen in the cultivation space comes within the defined parameter range.

In this embodiment the ventilation windows may be opened for a fast evacuation of hot air or humid air over a short time period, whereafter the air temperature or the air humidity or the concentration of carbon dioxide or oxygen in the cultivation space is kept within a defined parameter range by means of the first ventilation arrangement over longer time period.

In an embodiment when the first ventilation arrangement comprises the second air inlet and the second closing panel, the method further comprising the steps of: by the first ventilation device, displacing air between the roof space and the cultivation space; by the first ventilation device, displacing air within the cultivation space and between the roof space and the cultivation space; or by the first ventilation device, displacing air within the cultivation space, from outside the greenhouse into the cultivation space and between the roof space and the cultivation space.

In an embodiment when the ventilation system comprises the second ventilation arrangement, the method further comprising the steps of: by the second ventilation device, displacing air within the cultivation space; by the second ventilation device, displacing air between the roof space and the cultivation space; or by the second ventilation device, displacing air within the cultivation space and between the roof space and the cultivation space.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which: Figure 1 shows a schematic overview of a part of a horticultural greenhouse with multiple rows of support columns connected by transverse frames, and a ventilation system according to an embodiment of the invention;

Figures 2A-B respectively show an enlarged view and a side view of a first ventilation arrangement of the ventilation system according to figure 1;

Figure 2C shows an enlarged view of an alternative first ventilation arrangement of the ventilation system; Figure 2D shows an enlarged view of a further alternative first ventilation arrangement of the ventilation system; Figure 3 shows an isometric view of a second ventilation arrangement of the ventilation system according to figure 1; and

Figures 4A and 4B respectively show a part of the greenhouse of figure 1 having an alternative setup of the ventilation system, and an isometric view of a ventilation arrangement of the ventilation system of figure 4A. DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows an agricultural or horticultural greenhouse 1 according to an embodiment of the invention. The partially shown greenhouse 1 is in this example a Venlo type greenhouse, and comprises a number of identical metal columns 2, for example metal lattice columns, that are positioned spaced apart and in rows oriented in the longitudinal direction L of the greenhouse 1. The lattice columns 2 are connected by means of metal transverse frames 10 that extend in the transverse direction T of the greenhouse 1, for forming a supporting structure for a roof 40. The transverse frames 10 comprise a horizontal top bar 11, a horizontal bottom bar 12 extending below the top bar 11, and diagonal brace struts 13 there in between.

The roof 40 of the greenhouse 1 comprises multiple identical support gutters 41 that extend parallel to each other in the longitudinal direction L of the greenhouse 1. The support gutters 41 are in the transverse direction T of the greenhouse 1 alternately supported by the columns 2 or by the transverse frames 10. The roof 40 comprises multiple roof ridges 42 that extend parallel to the support gutters 41 in the longitudinal direction L of the greenhouse 1. The support gutters 41 and the higher situated roof ridges 42 alternate in the transverse direction T of the greenhouse 1. The roof 40 comprises multiple glass rods 43 that extend in the transverse direction T of the greenhouse 1 between the support gutters 41 and the roof ridges 42, and fixed glass panels 44 that are along their circumference supported by the support gutters 41, the roof ridges 42 and the glass rods 43. The roof 40 separates the greenhouse 1 from the environment.

The roof 40 comprises a ventilation window assembly 700 that comprises multiple ventilation windows 701. The ventilation windows 701 comprise glass panels 702 in frameworks 703 that are at the upper side hingeably connected with the ridge profiles 15. As shown in figure 1 the ventilation windows 701 are in this example shorter than the fixed glass panels 44. Therefore a horizontal window profile 704 is mounted between the two adjacent slanting glass rods 43 to form a rabbet for an additional fixed glass panel 44 below the ventilation windows 701. The ventilation windows 701 are regularly distributed over the roof 40, for example repeating alternating at the left side and right side of each roof ridge 42, wherein repeating a ventilation window 701 is provided after for example two fixed glass panels 44. The window arrangement 700 comprises multiple slide rail assemblies 705 that extends horizontally through the greenhouse 1 near the roof 40. The slide rail assemblies 705 comprise an elongate U-shaped rail profile with a top slit opening along its length, and a not visible elongate slide rod inside the rail profile that has protrusions that extend through the slit opening. The slide rail assemblies 705 comprise pairs of window push rods 706 that are hingeably connected to a first protrusion on the slide rod of the slide rail assemblies 705, and that are hingeably connected to the ventilation windows 701. The slide rod can be slidably driven with respect to the rail profile along its longitudinal axis by a not shown motor, to move the window push rods 706 and to therewith hinge the ventilation windows 701 between an open position and a closed position.

The greenhouse 1 comprises multiple screens 20 that are provided between pairs of subsequent transverse frames 10, and parallel guiding wires 21 that extend in the longitudinal direction L of the greenhouse 1 between the top bars 12 thereof. Each of the screens 20 is slidably supported and guided along one or more of the guiding wires 21. For the sake of clarity, only one screen 20 and two guiding wires 21 are shown, while in practice a plurality of parallel screens 20 and guiding wires 21 is provided.

The screens 20 are moveable along the guiding wires 21 between a shown open state, and a non-shown closed state by means of non-shown motors. In the closed state the screens 20 extend in a substantially horizontal separation plane S and bound, together with the roof 40, a roof space

6 that is located above the separation plane S, and bound, together with the non-shown side walls of the greenhouse 1, a cultivation space 7 that is located below the separation plane S. In the closed state the screens 20 darken and thermally shield the entire cultivation area of the greenhouse 1. The closed state of the screen 20 enables the roof space 6 and the cultivation space 7 to have different climate conditions, for example with respect to air temperature, air humidity, and concentrations of carbon dioxide and oxygen in the air.

The roof 40 has regularly distributed roof passage 45 of which one is shown in figure 1. In this example the roof passage 45 has a rectangular shape and is located near one of the roof ridges 42.

The horticultural greenhouse 1 comprises a ventilation system 5 that comprises the ventilation window assembly 700, and that comprises a first ventilation arrangement 30 for circulating air in the cultivation space

7 and for drawing fresh air from outside the greenhouse 1 into the cultivation space 7, and a second ventilation arrangement 330 for circulating air in the cultivation space 7 and for drawing air from the roof space 6 into the cultivation space 7.

As shown in figures 1, 2A and 2B the first ventilation arrangement 30 comprises a first top beam 31 extending between and substantially transverse to the two subsequent transverse frames 10 in the separation plane S. Subsequent screens 20 are guided substantially along both longitudinal sides of the first top beam 31.

As best shown in figures 2A and 2B the first top beam 31 has two oblique first top beam legs 32, 33 which merge into a first top beam center section 34. The first top beam 31 comprises an elongated first top beam passage 35 within the first top beam center section 34. The first ventilation arrangement 30 comprises a first bottom beam 70 which is provided below and substantially parallel to the first top beam 31 and that extends between and substantially transverse to the two subsequent transverse frames 10. The first bottom beam 70 has two oblique first bottom beam legs 71, 72 which merge into a first bottom beam center section 73. The first bottom beam 70 comprises an elongated first bottom beam passage 74 within the first bottom beam center section 73. The first bottom beam passage 74 is located directly below and is aligned with the first top beam passage 35. By means of the first bottom beam 70, it is possible to provide additional non-shown fabric screens within the greenhouse 1.

The first ventilation arrangement 30 comprises a first air duct 36 that is arranged at and supported by the first top beam 31 and the first bottom beam 70. The first air duct 36 comprises a first top duct section 37, a first intermediate duct section 38 and a first bottom duct section 39 which are arranged in series. The first top duct section 37 is mounted to the first top beam 31 around the first top beam passage 35 and extends therefrom towards the roof passage 45. The first top duct section 37 has a rectangular cross section, and converges in a first direction D from the roof 40 towards the first top beam 31. The first intermediate duct section 38 extends between the first top beam 31 and the first bottom beam 70 and is respectively mounted thereto around the first top beam passage 35 and the first bottom beam passage 74. The first intermediate duct section 38 has a rectangular cross section that is substantially constant in the first direction D. The first bottom duct section 39 is mounted to the first bottom beam 70 around the first bottom beam passage 74 and extends therefrom downwards into the cultivation space 7. The first bottom duct section 39 has a rectangular cross section and in the first direction D away from the first bottom beam 70 diverges substantially parallel to the transverse direction T of the greenhouse 1, and converges substantially parallel to the longitudinal direction L of the greenhouse 1.

The first air duct 36, at the end of the first top duct section 37 near the roof 40, defines a rectangular first air inlet 90 that is near and/or adjacent to the roof passage 45, and, at the end of the first bottom duct section 39 in the cultivation space 7, the first air duct 36 defines a substantially square shaped first air outlet 91. The first top duct section 37, the first intermediate duct section 38 and the first bottom duct section 39 of the first air duct 36 together define a first air channel 92 that extends between the first air inlet 90 and the first air outlet 91.

In this example the first air inlet 90 and the roof passage 45 are arranged near and/or adjacent with respect to each other. The first top duct section 37 of the first air duct 36 may also be part of the construction of the roof 40 and therewith define the roof passage 45 in the roof 40. The first top duct section 37 may also extend through the roof 40 and therewith define the roof passage 45 in the roof 40. The first air outlet 91 is located below the first bottom beam 70 in the cultivation space 7 of the greenhouse 1. The first air outlet 91 may also be located near or coincide with the first bottom beam passage 74 within the first bottom beam 70 or it may be located near or coincide with the first top beam passage 35 within the first top beam 31 adjacent to the cultivation space 7.

The first ventilation arrangement 30 comprises a first closing panel 46 that is hingeably attached to the roof 40 near the roof passage 45, and first closing panel actuators 47 that are attached between the roof 40 and the first closing panel 46. The first closing panel actuators

47 are configured to move the first closing panel 46 between a first position in which the first closing panel

46 closes off and/or seals the first air channel 92, and a second position in which the first closing panel 46 extends away from the roof 40 whereby it is open to allow fresh air to pass into the first air channel 92. In this example the first closing panel actuators 47 comprise a rotatable rod

48 that extends horizontally through the roof space 6 of the greenhouse 1 along the first top duct section 37 near the first air inlet 90. The first closing panel actuators

47 comprise a toothed rod 49 that is operably connected to the rotatable rod 48 by a geared connection, and that is hingeably connected to the first closing panel 46. The rotatable rod 48 can be rotatably driven around its longitudinal axis by a not shown motor to move the toothed rod 49 with respect to the rotatable rod 48. By rotating the rotatable rod 48 the length of the toothed rod 49 between the rotatable rod 48 and the first closing panel 46 can be adjusted and therewith the first closing panel 46 can be moved between the first position and the second position.

The first ventilation arrangement 30 is provided with a first ventilation device 50 comprising a first air blender 60 that is connected to the first air outlet 91, and a first fan 67 that is connected to the first air blender 60. The first air blender 60 comprises a first blender housing 61 that defines a first blender inlet 63 at the topside thereof and that is connected to the first air outlet 91, a second blender inlet 64 that is in air communication with the cultivation space 7, and a blender outlet 65 opposite to the second blender inlet 64 and that is connected to the first fan 67. The first blender housing 61 defines a first blending space 62 between the first blender inlet 63, the second blender inlet 64 and the blender outlet 65. The first air blender 60 comprises first blending flaps 66 that are provided parallel to each other within the first blending space 62. The first blending flaps 66 are rotatable about a rotation axis R substantially parallel to the transverse direction T of the greenhouse 1 by means of a not shown motor.

The first fan 67 in this example is an axial fan comprising fan blades that are rotatable by a motor. When the first fan 67 is activated, air is drawn into the first air blender 60. When the first blending flaps 66 are in a horizontal first position the first blender inlet 63 is closed off and air is drawn into the first blending space 62 from the cultivation space 7 to circulate, and when the first blending flaps 66 are in a substantially vertical second position the second blender inlet 64 is closed off and air is drawn into the first blending space 62 to be taken in from outside the greenhouse 1. By adjusting the orientation of the first blending flaps 66, the ratio of air from outside the greenhouse 1 and air from the cultivation space 7 can be regulated. The first air blender 60 then provides an air blend from air from outside the greenhouse 1 and air from the cultivation space 7 to the first fan 67.

The horticultural greenhouse 1 further comprises a first heat exchanger 80 that is arranged downstream of the first fan 65. Air from the first air blender 60 flows along the first heat exchanger 80 in order to cool or heat the passing air. In this example the first fan 65 and the first heat exchanger 80 are arranged downstream with respect to the first air blender 60. It is to be understood that the first fan 65 and/or the first heat exchanger 80 may also be arranged upstream with respect to the first air blender 60.

Figure 2C shows an alternative embodiment of the first ventilation arrangement 130. The alternative first ventilation arrangement 130 comprises substantially the same features as the first ventilation arrangement 30 as shown in figures 2A and 2B. Corresponding features are not reintroduced and are referred to with the same reference numbers.

The alternative first ventilation arrangement 130 comprises a second air inlet 182 to the first air channel 92. In this example the second air inlet 182 is defined in the first top duct section 37 of the first air duct 36. The second air inlet 82 is arranged in the roof space 6 and is in air communication with the roof space 6 and with the first air channel 92.

The alternative first ventilation arrangement 130 comprises a second closing panel 183 that is movably connected to the first top duct section 37 of the first air duct 36 near the second air inlet 182, and second closing panel actuators 184 that are configured to move the second closing panel 183 between a third position in which the second closing panel 183 is positioned away from the second air inlet 182 whereby it is open to allow air to pass from the roof space 6 into the first air channel 92, and a fourth position in which the second closing panel 183 is positioned in front of the second air inlet 182 to close off and/or seal the first air channel 92.

As shown in figure 2C, in the alternative first ventilation arrangement 130 the second closing panel 183 is embodied as a slide valve or sliding panel that is slidably connected to the inside of the first top duct section 37. The second closing panel actuators 184 comprise rigid rods 185 that are at a first end hingeably connected to the second closing panel 183 and that are at the opposite second end hingeably connected to the first closing panel 46. The second closing panel 183 is therewith operably connected to the first closing panel 46 for synchronized movement of the first closing panel 46 and the second closing panel 183. The second closing panel 183 moves with the first closing panel 46 when the first closing panel 46 is moved by the first closing panel actuators 47. Alternatively, the second closing panel 183 can be operated by the second closing panel actuators 184 independent of the first closing panel actuators 47. For instance by a dedicated rotatable rod arrangement that is similar to that of the first closing panel actuator 47 and that has a dedicated not shown motor for moving the second closing panel 183 between the first position and the second position thereof.

Figure 2D shows a further alternative embodiment of the first ventilation arrangement 230. The further alternative first ventilation arrangement 230 comprises substantially the same features as the first ventilation arrangement 30 as shown in figures 2A and 2B and as the alternative first ventilation arrangement 130 as shown in figure 2C. Corresponding features are not reintroduced and are referred to with the same reference numbers.

The further alternative first ventilation arrangement 230 comprises a second air inlet 282 to the first air channel 92. In this example the second air inlet 282 is defined in the first top duct section 37 of the first air duct 36. The second air inlet 282 is arranged in the roof space 6 and is in air communication with the roof space 6 and with the first air channel 92.

The further alternative first ventilation arrangement 230 comprises a second closing panel 283 that is movably connected to the first top duct section 37 of the first air duct 36 near the second air inlet 282, and second closing panel actuators 284 that are configured to move the second closing panel 283 between a third position in which the second closing panel 283 is positioned away from the second air inlet 282 whereby it is open to allow air to pass from the roof space 6 into the first air channel 92, and a fourth position in which the second closing panel 283 is positioned in front of the second air inlet 282 to close off and/or seal the first air channel 92.

As shown in figure 2D the further alternative first ventilation arrangement 230 comprises a first closing panel actuator 247 that comprises a slide rail assembly 248 that extends horizontally through the roof space 6 of the greenhouse 1 along the first top duct section 37 near the first top beam 31. The slide rail assembly 248 comprises an elongate U-shaped rail profile with a top slit opening along its length, and a not visible elongate slide rod inside the rail profile that has protrusions that extend through the slit opening. The first closing panel actuator 247 comprises a first push rod 249 that is hingeably connected to a first protrusion on the slide rod of the slide rail assembly 248, and that is hingeably connected to the first closing panel 46. The slide rod can be slidably driven with respect to the rail profile along its longitudinal axis by a not shown motor, to move the first push rod 249 and to therewith move the first closing panel 46 between the first position and the second position.

In the further alternative first ventilation arrangement 230 the second closing panel 283 is embodied as a hinged panel that is hingeably attached to the inside of the first top duct section 37 near the second air inlet 282. The second closing panel actuators 284 of the first ventilation arrangement 230 comprise second push rods 285 that are at a first end hingeably connected to the second closing panel 283 and that are at the opposite second end hingeably connected to a second protrusion on the slide rod of the slide rail assembly 248. By sliding the slide rod with respect to the rail profile in its longitudinal direction, the second closing panel 283 can be moved between the third position and the fourth position. As the first closing panel 46 and the second closing panel 283 are connected to the same slide rod of the slide rail assembly 248, the first closing panel 46 and the second closing panel 283 are operably connected to each other for synchronized movement of the first closing panel 46 and the second closing panel 283. The second closing panel 283 moves with the first closing panel 46 when the first closing panel 46 is moved by the first closing panel actuator 247.

As shown in figures 2c and 2D, when the first closing panel 46 is in the first position, in which it closes off and/or seals the first air channel 92, the second closing panel 183, 283 is in the third position, and when the first closing panel 46 is in the second position, in which it extends away from the roof 40 to allow fresh air to pass into the first air channel 92, the second closing panel 183, 283 is in the fourth position. When the first closing panel 46 is in a position between the first position and the second position, the second closing panel 83, 183 is in a corresponding position between its third position and its fourth position.

Alternatively, the second closing panel 283 can be operated by the second closing panel actuators 284 independent of the first closing panel actuators 247. For instance by a dedicated slide rod and-or slide rail assembly that is similar to that of the first closing panel actuator 247 and that has a dedicated not shown motor for moving the second closing panel 283 between the first position and the second position thereof.

When the first fan 67 is activated, air is drawn into the first air blender 60. When the first blending flaps 66 of the first air blender 60 are in the horizontal first position the first blender inlet 63 is closed off and air is drawn into the first blending space 62 from the cultivation space 7. When the first blending flaps 66 are in the substantially vertical second position the second blender inlet 64 is closed off and air is drawn into the first blending space 62 from the first air duct 36, that is from outside the greenhouse 1 and/or from the roof space 6, depending on the position of the first closing panel 46 and the second closing panel 183, 283. When the first closing panel 46 is in the second position and the second closing panel 183, 283 is in the fourth position, air is drawn into the first blending space 62 from outside the greenhouse 1. When the first closing panel 46 is in the first position and the second closing panel 183, 283 is in the third position, air is drawn into the first blending space 62 from the roof space 6. By adjusting the orientation of the first closing panel 46 and therewith adjusting the position of the second closing panel 183, 283, the ratio of air that is drawn from outside the greenhouse 1 and air that is drawn from the roof space 6 can be regulated. The first air blender 60 then provides an air blend from air from outside the greenhouse 1 and air from the roof space 6 to the first fan 67.

By adjusting the orientation of the first blending flaps 66 in combination with adjusting the orientation of the first closing panel 46, the ratio of air from outside the greenhouse 1, air from the roof space 6 and air from the cultivation space 7 can be regulated. The first air blender 60 then provides an air blend from air from the cultivation space 7 and air form the first air duct 36, that is air from outside the greenhouse 1 and/or air from the roof space, to the first fan 67.

As shown in figures 1 and 3, the second ventilation arrangement 330 of the horticultural greenhouse 1 comprises a second top beam 331 extending between and substantially transverse to the two subsequent transverse frames 10 in the separation plane S. Subsequent screens 20 are guided substantially along both longitudinal sides of the second top beam 331.

As best shown in figure 3 the second top beam 331 has two oblique second top beam legs 332, 333 which merge into a second top beam center section 334. The second top beam 331 comprises an elongated second top beam passage 335 within the second top beam center section 334. The second ventilation arrangement 330 comprises a second bottom beam 370 which is provided below and substantially parallel to the second top beam 331 and that extends between and substantially transverse to the two subsequent transverse frames 10. The second bottom beam 370 has two oblique second bottom beam legs 371, 372 which merge into a second bottom beam center section 373. The second bottom beam 370 comprises an elongated second bottom beam passage 374 within the second bottom beam center section 373. The second bottom beam passage 374 is located directly below and is aligned with the second top beam passage 335. By means of the second bottom beam 370, it is possible to provide additional non-shown fabric screens within the greenhouse 1.

The second ventilation arrangement 330 comprises a second air duct 336 that is arranged at and supported by the second top beam 331 and the second bottom beam 370. The second air duct 336 comprises a second top duct section 337 and a second bottom duct section 339 which are arranged in series. The second top duct section 337 extends between the second top beam 331 and the second bottom beam 370 and is respectively mounted thereto around the second top beam passage 335 and the second bottom beam passage 374. The second top duct section 337 has a rectangular cross section that is substantially constant in the first direction D. The second lower duct section 339 is mounted to the second bottom beam 370 around the second bottom beam passage 374 and extends therefrom downwards into the cultivation space 7. The second lower duct section 339 has a rectangular cross section and in the first direction D away from the second bottom beam 370 diverges substantially parallel to the transverse direction T of the greenhouse 1, and converges substantially parallel to the longitudinal direction L of the greenhouse 1.

The second air duct 336, at the end of the second top duct section 337 at the second top beam 331, defines a rectangular third air inlet 390 adjacent to the roof space 6, and, at the end of the second bottom duct section 339 in the cultivation space 7, the second air duct 336 defines a substantially square shaped second air outlet 391. The second top duct section 337 and the second bottom duct section 339 of the second air duct 336 together define a second air channel 392 that extends between the third air inlet 390 and the second air outlet 391.

In this example the second air outlet 391 is located below the second bottom beam 370 in the cultivation space 7 of the greenhouse 1. The second air outlet 391 may also be located near or coincide with the second bottom beam passage 374 within the second bottom beam 370 or it may be located near or coincide with the second top beam passage 335 within the second top beam 331 adjacent to the cultivation space 7.

The second ventilation arrangement 330 is provided with a second ventilation device 350 comprising a second air blender 360 that is connected to the second air outlet 391, and a second fan 367 that is connected to the second air blender 360. The second ventilation device 350 comprises substantially the same features as the first ventilation device 50 as shown in figures 2A and 2B. Corresponding features are not reintroduced and are referred to with the same reference numbers increased by 300.

The function of the second ventilation device 350 differs from the function of the first ventilation device 50 in that, when the second blending flaps 366 are in a substantially vertical second position the second blender inlet 364 is closed off and air is drawn into the second blending space 362 from the roof space 6. By adjusting the orientation of the second blending flaps 366, the ratio of air from the roof space 6 and air from the cultivation space 7 can be regulated. The second air blender 360 then provides an air blend from air from the roof space 6 and air from the cultivation space 7 to the second fan 367.

The horticultural greenhouse 1 further comprises a second heat exchanger 380 that is arranged downstream of the second fan 365 and that comprises substantially the same features as the first heat exchanger 80 as shown in figures 2A and 2B.

As shown in figure 1 the ventilation system 5 of the horticultural greenhouse 1 comprises the first ventilation arrangement 30, 130, 230 and the second ventilation arrangement 330 that are arranged in a row substantially parallel to the transverse direction T of the greenhouse 1, and that are arranged to blow air into the cultivation space 7 in the same direction substantially parallel to the longitudinal direction L of the greenhouse 1. It is to be understood that the first ventilation arrangements 30, 130, 230 and the second ventilation arrangements 330 of the ventilation system 5 may be arranged in alternative ways. For instance the ventilation system 5 may comprise only the first ventilation arrangements 30, 130, 230 or only the second ventilation arrangements 330. The first or second ventilation arrangements 30, 130, 230, 330 may be arranged to blow air into the cultivation space 7 of the greenhouse 1 in opposite directions. Multiple rows of first ventilation arrangements 30, 130, 230 or multiple rows of second ventilation arrangements 330 may be provided within the horticultural greenhouse 1. In that case, the rows of first ventilation arrangements 30, 130, 230 and the rows of second ventilation arrangements 330 are arranged at a distance from each other in the longitudinal direction L of the greenhouse 1.

Figure 4A partially shows a horticultural greenhouse 500 that is similar to the greenhouse 1 of figure 1, comprising a ventilation system 405 having an alternative setup for the second ventilation arrangement 430. Corresponding features are not reintroduced and are referred to with the same reference numbers.

The ventilation system 405 of the horticultural greenhouse 500 differs from the ventilation system 5 of figure 1 in that it comprises a second ventilation arrangement 430 for arranging multiple ventilation devices 450 in the greenhouse 500, in particular at one of the transverse frames 10 thereof. The second ventilation arrangement 430 comprises a U-shaped second top beam 431 extending over substantially the whole length of the respective transverse frame 10. The U-shaped second top beam 431 is provided between the respective transverse frame 10 and the screen 20, and is suspended to the respective transverse frame 10. The screen 20 is attached to the U-shaped second top beam 431 thereof.

As best shown in figure 4B the U-shaped second top beam 431 has two parallel second top beam legs 432, 433 which merge into a second top beam center section 434. The U-shaped second top beam 431 comprises elongated second top beam passages 435 within the second top beam center section 434.

The second ventilation arrangement 430 comprises, in this example, two second air ducts 436 that are arranged at and supported by the U-shaped second top beam 431. Each second air duct 436 is mounted to the U-shaped second top beam 430 around one of the second top beam passages 435 and extends therefrom downwards into the cultivation space 7. Each second air duct 436 has a rectangular cross section and in a first direction D away from the U-shaped second top beam 431 it converges substantially parallel to the transverse direction T of the greenhouse 500, and it diverges substantially parallel to the longitudinal direction L of the greenhouse 500.

Each second air duct 436, at its end at the U- shaped second top beam 431, defines a rectangular third air inlet 490 that correspond to the second top beam passage 435, and, at the opposite end, each second air duct 436 defines a substantially square shaped second air outlet 491. Each second air duct 436 defines a second air channel 492 that extends between the third air inlet 490 and the second air outlet 491.

The above described alternative second ventilation arrangement 430 is similar to the second ventilation arrangement 330 of figures 1 and 3 in that the third air inlets 490 are adjacent to the roof space 6. The second ventilation arrangement 430 can also be embodied similar to the first ventilation arrangement 30 of figures 1, 2A and 2B, wherein at least one of the air inlets 490 is near and/or adjacent to a roof passage that is provided in the roof of the greenhouse 500.

The horticultural greenhouse 500 may be provided with a heat exchanger similar to the first heat exchanger 80 and the second heat exchanger 380 of figures 1 and 3.

The ventilation system 5, 405 of the greenhouse 1, 500 is provided with a control system for controlling the climate inside the greenhouse 1, 500, in particular in the cultivation space 7 where the crops are growing by making benefit from the air in the roof space 6 and from the air outside of the greenhouse 1, 500.

The control system comprises a computer for so called data-based growing inside the greenhouse 1, 500 based on all the available data.

The computer is connected with a first group of multiple sensors that are distributed over the entire cultivation space 7, a second group of multiple sensors that are distributed over the entire roof space 6, and a third group of multiple sensors that are located outside near the greenhouse 1, 500. The sensors comprise air temperature sensors, air humidity sensors, and sensors for measuring specific gas concentrations in the air that are relevant for growing crops, for example the concentrations of carbon dioxide and oxygen in the air.

The computer is connected with the motors of the slide rail assemblies 705 of the ventilation window assembly 700 for opening and closing the distributed ventilation windows 701.

The computer is connected with the motors of the screens 20 for opening and closing the screens 20.

The computer is connected with the motors of the first closing panel actuators 47, 247, with the motors of the first fans 67, with the motors of the second fans 367 for individual control thereof, and, when present, with the motors of the second closing panel 183, 283.

The greenhouse 1, 500 is used for growing crops in areas having an outer climate, for example a colder outer climate, that is less suitable for growing a particular crop. The cultivation space 7 has a size of many hectares. The greenhouse 1, 500 is provided with a heating system based on burning of carbon fuel. During daylight the generated carbon dioxide is fed into the cultivation space 7 to optimize the growth of the crop. The generated heat is transferred to circulating water that is fed to the heat exchangers 80, 380 for heating the cultivation space 7, or to a buffer tank to be used at another moment, for example overnight for heating the cultivation space 7.

The climate in the cultivation space 7 is precisely controlled by means of the ventilation system 5, 405 during 24 hours per day to ensure an optimal and constant growth of the crop in the large cultivation space 7. The ventilation windows 701 are by default fully closed to keep the generated carbon-dioxide within the cultivation space 7 and the roof space 6. The first fans 67 and the second fans 367 are powered and the first blending flaps 66 and the second blending flaps 367 (when present) are in the first position for horizontal distribution and circulation of the air inside the cultivation space 7.

The air temperature in the cultivation space 7 is maintained at an optimal value by the ventilation system 5, 405. The air temperature can be controlled upwards by heating with the heat exchangers 80, 380, or controlled downwards by direct vertical introduction of outside air from outside into the cultivation space 7 by moving the closing panel 46 into the second position and by moving the first blending flaps 66 into the second position.

The air humidity in the cultivation space 7 is maintained at the optimal value. Usually the outside air is colder and therefore has the lowest air humidity, and the air inside the cultivation space 7 has the highest air humidity due to the higher temperature and because the crop is fed with water whereby it releases moisture. The air humidity in the cultivation space 7 can be controlled downwards by direct vertical introduction of outside air from outside into the cultivation space 7 by moving the closing panel 46 into the second position and by moving the first blending flaps 66 into the second position.

Depending on the circumstances, the screens 20 are closed for thermally shielding the cultivation space 7 from the roof space 6. When the outside air is substantially colder than the temperature to be maintained in the cultivation space 7, for example overnight, the screens 20 are closed to shield the cultivation space 7 from the roof 40. In this situation the cultivation space 7 has the highest air temperature and air humidity to be controlled. The outside air has the lowest air temperature and air humidity, and the roof space 6 has an air temperature and air humidity there between. The carbon dioxide that is fed into the cultivation space 7 diffuses via the screens 20 into the roof space 6 where it remains enclosed. When outside air is vertically introduced as described before to control the air humidity in the cultivation space 7 downwards, it bypasses the air inside the roof space 6, whereby the air in the roof space 6 does not need to be reheated and the carbon-dioxide remains enclosed.

Depending on the circumstances, the air inside the roof space 6 can be vertically introduced into the cultivation space 7 by setting the second closing panel 183, 283 in its third position whereby the air in the roof space 6 is vertically introduced into the cultivation space 7 below the screens 20. This can for example be performed at sunrise for a fast increase of the concentration of carbon dioxide in the cultivation space 7 while the cultivation area 7 is still heated with hot water from the buffer tank, that is without burning carbon fuel for generating carbon dioxide. In this manner the carbon fuel consumption over 24 hours can be reduced, as less heat is necessary to keep the cultivation space at temperature overnight and less carbon dioxide is necessary as it is already present in the roof space 6.

Above described steps are performed by the ventilation system 5, 405 for controlling the air temperature, the air humidity and the concentrations of carbon dioxide and oxygen inside the cultivation space 7 within small ranges, for example an air temperature of 20- 25 degrees. When it is not possible anymore to control within these small ranges, for example when the air temperature exceeds 26 degrees or more, the ventilation windows 701 and the screens 20 can be opened for large corrections. When the air temperature, the air humidity or the concentrations of carbon dioxide or oxygen are brought back within the small ranges, the ventilation windows 701 are closed again. The ventilation system 5, 405 according to the invention enables vertical introduction of outside air while bypassing the roof space 6, The ventilation system 5, 405 is a distributed system whereby the cultivation space 7 can be scaled up to any size without adverse effects to the accuracy of the climate control.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.