FR2946499A1 - Installation for maintenance of hydrous deficit of atmosphere of chamber for cultivation of plant, has treatment and control unit emitting control signals to control starting of outside air intake unit - Google Patents

Abstract

The installation has a treatment and control unit (8) to receive data issued from temperature sensors (3, 4) and relative humidity sensors (5, 6) at an inlet and to transmit control signals at an outlet for opening and closing of an opening frame (7) based on input data. A mechanical forced outside air intake unit is controlled by the control unit. The control unit is allowed to emit the control signals to control starting of the outside air intake unit, and for opening or maintenance of the opening frame in an open position. Independent claims are also included for the following: (1) a chamber for cultivation of plants (2) a process for maintenance of hydric deficit of an atmosphere of a chamber for cultivation of plants.

Description

The present invention relates to a method and an installation for maintaining the water deficit, the atmosphere of a plant growing enclosure provided with at least one opening with controlled opening, under conditions considered optimal for said culture, and that a culture chamber equipped with such an installation.

The water deficit has a major influence on crop development. Depending on the crop, the optimal values of the water deficit vary.

Thus in the case of tomato cultivation, the optimal water deficit should be between 4 and 8 g of water / kg of dry air. In most greenhouses today, this deficit is of the order of 3 g of water / kg of dry air. This water deficit is, in addition, very difficult to stabilize due to permanent changes in temperature and relative humidity inside said greenhouse.

So far to ensure this water deficit, the greenhouses are equipped with opening opening piloted according to the conditions of temperature and relative humidity inside the greenhouse. However, this circulation of air is insufficient to bring the water deficit within the desired optimal value ranges.

An object of the present invention to provide a method and an installation of the aforementioned type whose designs allow to vary the water deficit, in particular to increase significantly to achieve the desired water deficit values.

Another object of the present invention is to provide a method and an installation of the aforementioned type whose designs make it possible to stabilize the water deficit within a range of optimal values without harming the culture conditions.

Another object of the present invention is to provide a method and an installation of the aforementioned type whose designs make it possible to maintain the water deficit within a range of optimum values without increasing the production cost of the crops.

For this purpose, the subject of the invention is an installation for maintaining the water deficit, the atmosphere of a plant growing enclosure provided with at least one opening with controlled opening, under conditions considered optimal for said culture, the water deficit corresponding to the difference in the water content of the air of the enclosure and air saturated at 100 relative humidity under the same conditions of temperature and pressure, said installation comprising a unit of processing and control configured to receive at least input data from temperature and relative humidity sensors and output opening or closing control signals of the at least one opening at least according to said data of inlet, characterized in that the installation further comprises mechanical means for forced admission of outside air into said culture chamber, which can be controlled by means of actuation by the processing and control unit, said processing and control unit being configured to output controllable control signals in parallel with the operation of the mechanical forced air intake means. external opening or maintaining in the open position of said at least one opening.

Thanks to the presence of mechanical means forced admission of outside air in the enclosure, it is possible to recover the latent energy of evaporation of the outside air to dehumidify the interior of the culture chamber. The circulation of outside air less loaded with water in the culture chamber allows said air to be charged with water in the enclosure before being evacuated by the openings outside the enclosure. Thanks to this circulation of air, dehumidification takes place. The installation thus makes it possible to regulate the water deficit and not to undergo it.

It should be noted that by the expression "the processing and control unit being configured to output control signals able to control, in parallel with the start of mechanical means forced admission of outside air , opening or maintaining in the open position of said at least one opening "indifferently means: - either that the processing and control unit is adapted according to the input data and after processing of said data to be delivered or transmitted in output two independent control signals controlling one, the putting into operation of the mechanical means for forced admission of outside air inside the enclosure, the other, the opening or the holding in the open position of the least one opening of the enclosure, or that the processing and control unit is adapted according to the input data and after processing said data to deliver a first control signal controlling the setting operation of the mechanical means for forced admission of outside air inside the enclosure, then from the first signal a second control signal for opening or maintaining the open at least one opening. In this case, the processing and control unit controls the opening or keeping in the open position of the at least one opening at least when the mechanical means forced admission of outside air inside the enclosure are controlled in operation in the direction of a start. According to a preferred embodiment of the invention, the mechanical means for forced admission of outside air into the culture chamber comprise at least one activatable / deactivatable member for forced admission of air by blowing and / or aspiration. within the culture chamber and at least one porous air conduit disposed within the enclosure and supplied with air by said forced air inlet member.

This configuration of the mechanical means of forced admission of outside air makes it easy to create an air flow by convection without moving the leaves of the plants grown in the enclosure.

The subject of the invention is also a plant culture enclosure of the type comprising at least one opening with controlled opening and temperature and relative humidity sensors arranged inside the enclosure and outside the enclosure to deliver relative measurement signals, on the one hand, to the air temperatures in the enclosure and on the outside of the enclosure, on the other hand, to the relative humidity of the air in the enclosure and to the outside, characterized in that the enclosure further comprises an installation of the aforementioned type for maintaining the water deficit of the atmosphere of said enclosure under conditions considered optimal for said culture.

Preferably, the enclosure, of the type in which the mechanical forced admission means of air comprise at least one forcing admission member of air by blowing and / or suction inside the enclosure and the less a porous air duct disposed inside the enclosure and supplied with air by said air intake member, is characterized in that it is equipped, in the vicinity of the floor or floor of said enclosure, at least one longitudinal heating duct, the or each porous air duct of the forced mechanical admission means of air extending substantially parallel to the or a heating duct, in the vicinity of the latter, and having porosities oriented towards said heating pipe.

In this embodiment, the air is blown directly onto the heating pipes by means of porous air ducts whose pores formed for example by perforations of the textile duct constituting the air ducts are oriented in the direction of the ducts. heating pipes to create a convection current on the heating pipes which lowers the temperature of said pipes without moving the leaves of the plants, which would disrupt the culture. The efficiency of the heating is improved due to the convection current created. The savings achieved as a result of the increase in heating efficiency and crop production efficiency outweigh the expenditures made to provide the electrical power necessary for the operation of the mechanical means of forcing outside air into the interior. of the enclosure. The subject of the invention is also a method for maintaining the water deficit of the atmosphere of a plant growing enclosure provided with at least one opening with controlled opening under conditions considered optimal for said crop, the water deficit corresponding to the difference in water content of the enclosure air and air saturated at 100% relative humidity under the same conditions of temperature and pressure, said culture chamber comprising at least sensors of temperature and relative humidity of the air inside and outside the enclosure, a processing and control unit configured to receive at least at least the measurement signals of the temperature and humidity sensors relative and output of opening or closing control signals of at least one opening at least according to said input data, characterized in that said enclosure further comprising s mechanical means forced admission of outside air in said culture chamber able to be controlled in operation by the processing and control unit, said method comprises at least the following steps: a step of measuring the temperature and the relative humidity of the air in the enclosure and outside the enclosure, - a step of memorizing a psychrometric diagram and the value of the minimum water deficit permissible in said enclosure, 20 - a step of processing the stored data and / or measured to, initially, determine, from said data, the water contents of the air in the enclosure and outside, the water deficit in said enclosure, and secondly, to compare, on the one hand, the water deficit within the enclosure with the minimum allowable water deficit stored, on the other hand, the water content of the outside air with the water content of the enclosure air, - a step of issuing control signals for controlling, in parallel with the start-up of the mechanical means for forced admission of outside air, the opening or the keeping in the open position of the at least one an opening 30 of the enclosure.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which: FIG. 1 represents a simplified schematic view of a culture chamber equipped with an installation for maintaining the water deficit according to the invention;

FIG. 2 represents a simplified schematic view of a culture chamber according to the invention;

FIG. 3 represents an example of a psychrometric diagram from which the air moisture content and the dew point temperature can be determined knowing the temperature and relative humidity of said air.

As mentioned above, the installation, which is the subject of the invention, is more particularly intended to allow maintenance of the water deficit of the atmosphere of an enclosure 1 of plant culture 2 provided with at least one opening 7 controlled opening under conditions considered optimal for said culture.

It should be recalled that the water deficit of the atmosphere of the enclosure 20 corresponds to the difference in the water content between the air of the enclosure and the moisture content of air saturated with 100% humidity. relative under the same conditions of temperature and atmospheric pressure.

The installation, which is the subject of the invention, comprises at least one treatment and control unit 25 configured to receive at least at least one input from temperature and relative humidity sensors and to output signals control of opening or closing the at least one opening 7, at least according to said input data. Said plant is therefore intended to be associated with a plant culture enclosure of the type comprising at least one opening 7 with controlled opening and temperature and relative humidity sensors arranged in the enclosure and outside the enclosure. enclosure for delivering measurement signals relating, on the one hand, to the temperatures of the air in the enclosure and on the outside of the enclosure, on the other hand, to the relative humidity of the air in the chamber; enclosure 1 and outside.

In the examples shown, the culture chamber comprises two temperature sensors, one, represented at 3 in the figures, and sensing the temperature of the outside air, the other, represented at 4 in the figures, and sensing the temperature inside the culture chamber, and two relative humidity sensors represented one in 5 in the figures, and sensing the relative humidity of the outside air, the other, represented at 6 in the figures, and sensing the relative humidity of the air in the enclosure. These sensors are connected at input to the processing and control unit 8 to deliver their signals to said unit. Each time the temperature sensors used are analog room temperature sensors. The same is true of relative humidity sensors.

In a manner characteristic of the invention, the installation furthermore comprises mechanical means 9 for forced admission of outside air into said culture chamber 1, which can be controlled in operation by the processing and control unit 8. , said processing and control unit 8 being configured to control, in parallel with the start-up of the mechanical means 9 for forced admission of outside air, the opening or the holding in the open position of the at least one opening 7 .

In the examples shown, the mechanical means 9 for forced admission of outside air into the chamber 1 of culture comprise at least one member 9A activatable / deactivatable forced admission of air by blowing and / or suction to 25 inside the enclosure 1 culture and at least one conduit 9B porous air disposed within the chamber 1 and supplied with air by said member 9A forced admission of air.

Forced air admission member 9A is, for example, formed by a centrifugal fan disposed at one end of the pipe itself formed by a textile sheath provided with perforations. The chamber 1 of culture is, in turn, equipped in the vicinity of the floor or floor of said chamber 1 of at least one pipe 10 of generally longitudinal heating. The or each duct 9B porous air mechanical means 9 forced admission of air extends substantially parallel to the or a pipe 10 of heating, in the vicinity of the latter, and has porosities oriented toward said heating pipe 10. The or each porous air conduit 9B extends over a heating pipe.

Preferably, when the chamber 1 comprises culture tanks 11, the porous air duct 9B of the mechanical means 9 for forced admission of air are arranged between the culture tanks 11 and the heating pipes 10 .

In the examples shown, the forced admission of outside air inside the enclosure is performed using centrifugal fans providing a stirring rate of about 4 to 5 volumes per hour. Such an airflow requires on average thirty fans for a greenhouse of one hectare. Air from the porous air ducts is blown directly onto the heating ducts. The porous air ducts are in the form of textile-type ducts perforated with a row of small holes ensuring a laminar flow and creating a convection current on the heating ducts without disturbing or moving the leaves of the plants.

The lines 9B blowing textile are therefore located under the gutters formed by the culture tanks and parallel to said gutters. Generally the number of fans is substantially equal to the number of porous air lines.

The positioning of the porous air ducts and the heating ducts in the lower part of the enclosure makes it possible to optimize the circulation of the air 30 in the enclosure which is equipped in the upper part, at its ceiling or floor. its side walls, the opening or opening 7 to controlled opening. Each opening 7 is generally formed of a closure element, such as a window, moved mu by an actuator, such as a jack. To enable the control of the mechanical means 9 forced admission of outside air in the culture chamber under conditions able to allow in particular a dehumidification of the enclosure, said processing unit 8 and control is a computer system and / or electronic which comprises: - storage means at least a psychrometric diagram and the value of the minimum water deficit permissible in said enclosure 1, - data processing means configured to, in a first step, determine, the water content of the air in the enclosure, the water content of the outside air, the water deficit of the air in the enclosure, from the stored data and input data including at least the relative temperatures and humidity of the air in the chamber 1 and outside the chamber 1, and, secondly, comparing, on the one hand, the water deficit inside the enclosure with the hydric deficit a minimum permissible stored value, on the other hand, the water content of the outside air with the water content of the air of the enclosure 1, and 15 - means of transmitting control signals configured to control the operating control of the mechanical means 9 forced admission of air based on the results of said comparisons.

Thus, the control signal transmission means are configured to control the operating control of the mechanical means 9 for forced admission of air at least when the water deficit of the enclosure air is less than the water deficit. minimum permissible storage and that the water content of the outside air is lower than the water content of the air in the enclosure. The mechanical means 9 for forced admission of outside air inside the enclosure are therefore controlled in operation when the water deficit of the enclosure air is less than the minimum permissible water deficit stored and the The water content of the outside air is lower than the water content of the air in the enclosure.

Suppose, by way of example, that the temperature and relative humidity sensors deliver at the input of the control and processing unit the following values of temperature and relative humidity:

Outside air temperature: 15 ° C Relative external humidity: about 93% 5 Indoor air temperature: 21 ° C Relative humidity indoor air: about 85 0/0

Suppose, furthermore, that the stored reference data comprise a psychrometric diagram of the type shown in FIG. 3 and that the value of the minimum acceptable water deficit, memorized, is set at 0.004 kg of water / kg of water. 'air. It should be noted that the memorized psychrometric diagram generally corresponds to the memorization of curves or abacuses giving for different relative temperatures and humidities, at least the corresponding water content. From the stored psychrometric chart, it is therefore possible to determine the water content of the outside air and the water content of the indoor air knowing the temperature and relative humidity of said airs. Thus, the water content of the outside air is, as illustrated by the first bold line of FIG. 3, equal to 0.010 kg of water / kg of air while the water content of the air of the enclosure is equal to 0.013 Kg of water / Kg of dry air as shown in the second solid line. The water content of the enclosure air for a relative humidity of 100% and an air temperature of 21 ° C is equal to 0.0156 kg of water / kg of dry air, this value being new determined from the diagram of Figure 3 (see dashed line). The water deficit of the air in the chamber is therefore equal to 0.0156 ù 0.0130, ie 0.0026 kg of water / kg of dry air. If necessary, it can be determined from said values, similarly, the water deficit of the outside air which is here equal to 0.005 Kg of water / Kg of dry air.

As noted by the processing and control unit 8, the air deficit in the enclosure is less than the value of the stored minimum water deficit and the water content of the air at the The interior of the enclosure is greater than the water content of the outside air, so the mechanical means 9 forced admission of outside air in the enclosure 1 culture are put in It works. At the same time, the opening or the holding in the open position of the said openings 7 is controlled.

Preferably, the storage means are also able to memorize the maximum permissible air temperature in the chamber 1 and the data processing means are also configured to compare the air temperature of the chamber 1 received as input of the processing and control unit 8 and the maximum permissible air temperature in the stored enclosure, said control signal transmission means being configured to control the operation of the mechanical forced admission means 9 of air in said enclosure according to the result of the comparison.

Thus, the mechanical means 9 for forced admission of air into the enclosure 1 are also put into operation when the air temperature in the enclosure is greater than the maximum permissible air temperature in said enclosure. The mechanical means 9 for the forced admission of outside air inside the enclosure are then used as means of air conditioning or ventilation of the enclosure so as not to exceed in summer a predetermined temperature in the enclosure of the enclosure. culture.

More preferably, the installation comprises at least one infrared temperature sensor 12 capable of delivering, at the input of the treatment and control unit 8, the surface temperature of the culture sheets in said enclosure 1 and in that the means data processing are also configured to, in a first step, determine, from the stored psychrometric diagram and the input data relating to the temperature and the relative humidity of the air in the chamber 1, the temperature dew air in the chamber then, in a second step, compare said dew air temperature to the surface temperature of the sheets, and in that the control signal transmission means are configured to control the operation of the mechanical means 9 forced admission of air into said enclosure according to the result of said comparison.

Thus, the mechanical means 9 forced admission of outside air into said enclosure are controlled in operation, when the dew point temperature of the air in the chamber is strictly greater, for example greater than 1 ° C at least, to the surface temperature of the culture sheets delivered by the infrared temperature sensor 12.

In the example illustrated above, referring to the diagram of FIG. 3, the dew point temperature of the air in the enclosure is about 18 ° C. The mentioned diagram data therefore make it possible to determine also from a given temperature and relative humidity of an air, the dew point temperature of said air.

Finally, the installation comprises means for adjusting the power and / or the air flow rate of the mechanical means 9 forced admission of air inside said enclosure 1, in that the storage means are configured to storing a so-called minimum outside air temperature, in that the processing means are configured to compare the inlet temperature relative to the outside air temperature with the so-called minimum stored outside air temperature, in that the means control signal transmission means are configured to adjust the power and / or the flow rate of said mechanical forced admission means 9 of air inside the enclosure according to the result of the comparison.

Said mechanical forced air intake means outside the enclosure are thus actuated at power and at the maximum flow rate when the measured outside air temperature is greater than the minimum allowed outside temperature and are at the same time. operated at a predetermined power or flow rate lower than the maximum value when the outside air temperature is lower than the stored minimum outside air temperature. This stored minimum outside air temperature can be set, for example, at + 7 ° C. To allow all of the data processing mentioned above, it is necessary to set up the installation and to enter a certain number of data in the processing and control unit. Thus the setting of the installation can include: s 1- the setting of the lowest permissible outside temperature (example 7 ° C), 2- the minimum water deficit adjustment of the greenhouse (example 4 g of water / Kg dry air), 3- the parameterization of the proportion of mechanical means of forced admission Io of air which will be in operation if the external temperature is lower or equal to the value in 1-, 4- the unit rate of a fan in m3 / second of air, 5- the setting of the unit power of a fan, 6- the setting of the temperature not to be exceeded in summer in the culture chamber. In operation, if the water deficit in the culture chamber is less than the value programmed in 2- and if the outside temperature is equal to or less than 1, then the proportion of ventilation defined in 3- is activated. If the outside temperature is above 1 and if the water deficit is less than 2-, then the maximum ventilation is switched on.

If the water deficit is equal to or greater than the value defined in 2-, all ventilation is stopped except in the case where the temperature in the greenhouse is equal to or greater than the temperature programmed in 6, in which case the ventilation is switched on. In totality.

If the dew air temperature in the greenhouse is at least 1 ° C higher than the surface temperature of the culture sheet, the mechanical means are started to prevent condensation on the leaves. The installation may comprise means for displaying at least one of the

14 reference or input or processed data selected from the following group of data: - the outside air temperature - the relative humidity of the outside air - the temperature of the air inside the enclosure - the relative humidity of the air inside the enclosure - the measured value of the water deficit in the enclosure - the surface temperature of the crops in the enclosure lo - the display of the dew point temperature air in the enclosure - the proportion of power and / or flow rate of the mechanical means of forced admission of air - the value of the minimum allowable water deficit. 15

Claims (10)

REVENDICATIONS1. Installation for maintaining the water deficit, the atmosphere of a plant growing enclosure (1) provided with at least one opening (7) with controlled opening, under conditions considered optimal for said crop, the water deficit , corresponding to the difference in water contents of the enclosure air and air saturated at 100% relative humidity under the same conditions of temperature and pressure, said installation comprising a treatment unit (8) and control configured to receive at least input data from sensors (3, 4, 5, 6) of temperature and relative humidity and output opening or closing control signals of the at least one opening (7) at least as a function of said input data, characterized in that the installation further comprises means (9) 15 mechanical forced external air admission into said chamber (1) culture, suitable for to be ordered in actuated by the processing and control unit (8), said processing and control unit (8) being configured to output control signals capable of controlling, in parallel with the start-up of the means (9). mechanical 20 forced admission of outside air opening or maintaining in the open position of said at least one opening (7). 2. Installation according to claim 1, characterized in that the mechanical means (9) forced admission of outside air in the chamber (1) of culture comprise at least one member (9A) activable / deactivatable admission forced air blowing and / or suction inside the enclosure (1) culture and at least one conduit (9B) of porous air disposed inside the enclosure (1) and fed with air through said member (9A) of forced admission of air. 30 3. Installation according to one of claims 1 and 2, characterized in that said unit (8) for processing and control is a computer system and / or electronic which comprises: 15- memory means at least one diagram psychrometric and the value of the minimum water deficit permissible in said enclosure (1), - data processing means configured to, initially, determine the water content of the air in the enclosure, the content of external air water, the water deficit of the air in the enclosure from the stored data and input data including at least the relative temperatures and humidity of the air in the enclosure (1) and outside the enclosure (1), and, secondly, compare, on the one hand, the water deficit within the enclosure with the minimum permissible water deficit stored, on the other hand, the moisture content of the outside air with the water content of the air in the einte (1), and - control signal transmission means configured to control the operating control of the mechanical means (9) forced admission of air based on the results of said comparisons. 4. Installation according to claim 3, characterized in that the storage means are also able to store the maximum allowable air temperature in the chamber (1) and in that the data processing means are also configured to compare , the air temperature of the chamber (1) received at the input of the processing and control unit (8) and, the maximum permissible air temperature in the stored chamber, said means for transmitting control signals being configured to control the operation of the mechanical means (9) forced admission of air in said enclosure according to the result of the comparison. 5. Installation according to one of claims 3 and 4, characterized in that the installation comprises at least one sensor (12) of infrared temperature capable of delivering to the input of the unit (8) for processing and control the temperature surface of the culture sheets in said enclosure (1) and in that the data processing means are also configured to initially determine, from the stored psychrometric diagram and the input data relating to the temperature and the relative humidity of the air in the chamber (1), the dew point temperature of the air in the chamber and, secondly, comparing the dew point temperature of the air with the surface temperature sheets, and in that the control signal transmission means are configured to control the operation of the mechanical means (9) forced admission of air in said enclosure according to the result of said comparison . 6. Installation according to one of claims 3 to 5, characterized in that the installation comprises means for adjusting the power and / or air flow of the means (9) for forced admission of air to air. the inside of said enclosure (1), in that the storage means are configured to store a so-called minimum outside air temperature, in that the processing means are configured to compare the temperature of the input relative to the temperature outside air with the so-called minimum stored outside air temperature, in that the control signal transmission means are configured to adjust the power and / or the flow rate of said mechanical forced admission means (9); inside the enclosure according to the result of the comparison. 20 7. Enclosure (1) plant culture of the type comprising at least one opening (7) controlled opening and sensors (3, 4, 5, 6) of temperature and relative humidity disposed in the enclosure (1) and outside the enclosure (1) for delivering relative measurement signals on the one hand, at the temperatures of the air in the enclosure (1) and outside the enclosure (1) on the other hand, at the relative humidity of the air in the enclosure and outside, characterized in that the enclosure (1) also comprises an installation for maintaining the water deficit of the atmosphere of said enclosure under conditions considered optimal for said culture according to one of 3o claims 1 to 6. 8. Enclosure (1) according to claim 7, of the type in which the means (9) for forced admission of air comprise at least one member (9A) for forced admission of air by blowing and / or suction to inside the enclosure (1) and at least one duct (9B) porous air disposed inside the enclosure (1) and supplied with air by said member (9A) air intake , characterized in that said enclosure (1) is equipped, in the vicinity of the floor or floor of said enclosure (1), with at least one pipe (10) for heating, the or each conduit (9B) of porous air mechanical means (9) forced admission air extending substantially parallel to, or a pipe (10) for heating, in the vicinity of the latter, and having porosities oriented towards said pipe (10) of heater. i0 9. Enclosure (1) culture according to claim 8, of the type in which said enclosure (1) comprises trays (11) culture, characterized in that the or ducts (9B) porous air means (9) Forced admission of air is arranged between the culture tanks (11) and the heating pipes (10). 10. A method for maintaining the water deficit of the atmosphere of a plant culture enclosure (1) provided with at least one opening (7) with controlled opening under conditions considered optimal for said culture, the deficit water equivalent to the difference of the water contents of the air of the enclosure (1) and of air saturated at 100% relative humidity under the same conditions of temperature and pressure, said chamber (1) of culture having at least sensors (3, 4, 5, 6) of temperature and relative humidity of the air inside and outside the enclosure (1), a processing and control unit 25 configured to receive at least the measurement signals of the temperature and relative humidity sensors (3, 4, 5, 6) and to output opening or closing control signals from the at least one opening at least according to said input data, characterized in that said enclosure (1 ) further comprising mechanical means (9) forced admission of outside air in said culture chamber able to be controlled in operation by the unit (8) for processing and control, said method comprises at least the following steps a step of measuring the temperature and the relative humidity of the air in the enclosure and outside the enclosure, a step of memorizing a psychrometric diagram and the value of the water deficit minimum allowable in said enclosure, - a step of processing the data stored and / or measured for, in a first step, determine, from said data, the water content of the air in the chamber and outside, the water deficit in said enclosure and, secondly, to compare, on the one hand, the water deficit within the enclosure with the minimum permissible water deficit stored, on the other hand, the water content outside air ec the water content of the air of the enclosure, - a step of issuing control signals to control in parallel with the start of the means (9) mechanical forced admission of outside air, opening or holding open at least one opening 15 (7) of the enclosure (1).