WO2024008362A1

WO2024008362A1 - A system and method for controlling humidity in a defined space

Info

Publication number: WO2024008362A1
Application number: PCT/EP2023/063958
Authority: WO
Inventors: Robert ARNELL; Roger GILISTRAND
Original assignee: Munters Europe Aktiebolag
Priority date: 2022-07-04
Filing date: 2023-05-24
Publication date: 2024-01-11
Also published as: SE2250840A1; SE2250840A2

Abstract

The disclosure relates to a system (1) for controlling humidity in a defined space (2), the system (1) comprising: an active air conditioner (4) fluidly connected to the defined space (2); a control device (100) operably coupled to the active air conditioner (4); at least one hygrometer (6,14) arranged in the defined space (2) and operably coupled to the control device (100); a passive dehumidifier and humidifier (8) comprising hygroscopic material (10), which passive dehumidifier and humidifier (8) is configured to be accommodated in the defined space (2) and in contact with the air in the defined space (2). The control device (100) is configured to control the active air conditioner (4) for conditioning the air in the defined space (2) to a dewpoint target value (CDPt) based on information from the first hygrometer (6), and in that the passive dehumidifier and humidifier (8) is configured to suppress fluctuations from the dewpoint target value (CDPt). The disclosure further relates to a method for controlling humidity in a defined space (2) using a system (1).

Description

A system and method for controlling humidity in a defined space

Technical field

The present invention relates to a system for controlling humidity in a defined space and a method for controlling humidity in a defined space using the system. More specifically, the invention relates to a system for controlling humidity in a defined space, the system comprising: an active air conditioner fluidly connected to the defined space; a control device operably coupled to the active air conditioner; at least one hygrometer arranged in the defined space and operably coupled to the control device; a passive dehumidifier and humidifier comprising hygroscopic material, which passive dehumidifier and humidifier is configured to be accommodated in the defined space and in contact with the air in the defined space. The present invention also relates to a method for controlling humidity in a defined space using such a system.

Background art

Dehumidifiers, such as sorption dehumidifiers and condensate dehumidifiers, are used for separating and removing moisture from air. A sorption dehumidifier typically comprises a dehumidifying element in the form of a wheel or rotor holding desiccant material, which is effective in attracting and retaining water vapour. The desiccant rotor may be divided in two sections, a process section and a regeneration section. The airflow to be dehumidified, process air, will pass through the process section of the desiccant rotor, the desiccant material in the rotor extracts moisture from the process air, so that it can leave the rotor as dried air. Simultaneously, the desiccant material is regenerated by another air stream, which flows through the regeneration section, all the while the desiccant rotor may rotate slowly about its longitudinal axis. By means of the simultaneous dehumidification of the process air and regeneration of desiccant material, the dehumidifier can be operated continuously. US2007056307 discloses an example of a dehumidifier having a desiccant wheel.

Document US20200408425 Al discloses a device adapted to control temperature and humidity of the air in a room. The device consists of elements of a quantity of hygroscopic material and means for passing air past or through the elements. A fan provides forced convection of air in a desired path over or through the hygroscopic material in the elements. The system may stabilize variations in temperature and humidity by cyclic absorption and evaporation matching the changes in external humidity. Very dry air or ultra-dry air may be achieved if all or most of the moisture is removed from the air. Such dry air may be conveyed to a dry space or a dry room in which activities, such as manufacturing processes are performed having large demands on dry air in the surrounding space.

The known devices, which comprise elements or panels of hygroscopic material adapted to control temperature and humidity of air use active air flow generating means, such as fans or blowers for generating an air flow at the hygroscopic elements. An external device may be used in combination as complement with the hygroscopic elements for minimizing energy consumption or energy costs.

Active air conditioners, such as sorption dehumidifiers and condensate dehumidifiers, may be effectively used for separating and removing moisture from air, and also to create very dry air or ultra-dry air in dry spaces or dry rooms. However, there are also large demands in such dry spaces or dry rooms for very low humidity fluctuations. Depending on the characteristics of the active air conditioner and the conditions of the dry space or the dry room, it may be difficult for the active air conditioner itself to supress humidity fluctuations. Further, it may be difficult for the active air conditioner itself to maintain the humidity in the dry space or the dry room at a constant level.

Despite known solutions in the field, it would be desirable to develop a system and a method for controlling humidity, which overcome or alleviate at least some of the drawbacks of the prior art.

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem.

A further objective of the present invention is to achieve a system and a method for controlling humidity, which allow for a stable, reliable and effective treatment of air, and thereby improve the functionality/performance of a dry space or a dry room.

A further objective of the present invention is to achieve a system and a method for controlling humidity, which supress humidity fluctuations in a dry space or a dry room.

These objectives are achieved by the system initially defined, further comprising the features that that the control device is configured to control the active air conditioner for dehumidifying the air in the defined space to a dewpoint target value based on information from the at least one hygrometer, and in that the passive dehumidifier and humidifier is configured to suppress fluctuations from the dewpoint target value. These objects are also been achieved by the method for controlling humidity in a defined space using such a system.

An advantage is that the system allows for a stable, reliable and effective treatment of air, and thereby improves the functionality/performance of a dry space or a dry room. A further advantage is that the system may supress humidity fluctuations in a dry space or a dry room.

The defined space may be a dry space or a dry room in which the relative humidity and the Celsius dewpoint value is very low. In a dry space or a dry room, work may be performed which requires absence of moisture and wherein fluctuations in humidity must be very low. The system may create very dry air or ultra-dry air in the defined space. The active air conditioner may comprise an active dehumidifier, an active humidifier, an active air heater and an active air cooler. The active air conditioner may be driven by electric power or any other power source. The active air conditioner may actively dehumidify the air in the defined space. The defined space may be a room where the dewpoint and temperature must be maintained with narrow ranges, so that a combination of dehumidification, humidification, heating and cooling may be required. The active air conditioner may comprise a sorption dehumidifier or a condensate dehumidifier. The control device is configured to control the active air conditioner for dehumidifying, humidify, heat and cool the air in the defined space. This has the advantage that the controlling of the humidity and temperature in the defined space using the system may be performed automatically. The at least one hygrometer may be arranged at any position in the defined space. The at least one hygrometer may be arranged at a position in the defined space where demands are high regarding a low Celsius dewpoint value and low humidity fluctuations. The hygrometer may be a dewpoint sensor. The dewpoint sensor may be a cooled optical device that detects when dew or frost is formed on a surface, such as a mirror surface being in contact with the air. The passive dehumidifier and humidifier may be arranged on walls, a ceiling, a floor or on furniture in the defined space. Further, the passive dehumidifier and humidifier may be arranged as a freestanding screen in the defined space. The hygroscopic material in the passive dehumidifier and humidifier is configured both to dehumidify and humidify the defined space. Moisture in the hygroscopic material in the passive dehumidifier and humidifier may be released to the defined space. Moisture in the defined space may be absorbed by the hygroscopic material in the passive dehumidifier and humidifier. The dewpoint target value may be set depending on the demands on the defined space. If the defined space is a dry space or a dry room, the dewpoint target value may be very low. Further, depending on the demands on the defined space, the accepted fluctuations from the dewpoint target value may be low.

The dewpoint target value may be in the range of -100 CDP to +12 CDP (Celsius dewpoint). A dewpoint target value in this range in the defined space may fulfil demands on a dry space or a dry room. A dry space or a dry room with a dewpoint value of -100 CDP may contain ultra-dry air. The dewpoint target value in the range of -100 CDP to +12 CDP may result in that work can be performed which requires absence of moisture and wherein fluctuations in humidity must be very low.

The passive dehumidifier and humidifier may be configured to suppress fluctuations in the range of 0,1 CDP - 2 CDP from the dewpoint target value. Fluctuations from the dewpoint target value in the range of 0,1 CDP - 2 CDP may lead to a stable dewpoint value in the defined space. Such low fluctuations from the dewpoint target value may result in that work can be performed which requires low fluctuations in humidity.

The system may comprise a supplementary air condition device fluidly connected to the defined space and operably coupled to the control device. The supplementary air condition device may condition the air in the defined space. Alternatively or in combination, the supplementary air condition device may condition ambient air from outside the defined space and emit the conditioned air in to the defined space.

The supplementary air condition device may be configured to regulate the temperature in the defined space. Demands may be set for a temperature setpoint value. The supplementary air condition device may be configured to increase or decrease the temperature in the defined space in order to reach and maintain the temperature at the temperature setpoint value.

A first hygrometer may be arranged in the defined space and a second hygrometer may be arranged at the passive dehumidifier and humidifier, wherein the first and second hygrometers are operably coupled to the control device, and wherein the control device is configured to control the active air conditioner based on information from the first and second hygrometers. The first hygrometer may be arranged at a position in the defined space where demands are high regarding a low Celsius dewpoint value and low humidity fluctuations. Such position in the defined space may be a position where work is performed with high demands on low humidity and a humidity of a constant level. The second hygrometer may be arranged at the passive dehumidifier and humidifier. The second hygrometer may be arranged in the near vicinity, i.e. at the passive dehumidifier and humidifier. The first and second hygrometers may be arranged as first and second dewpoint sensors.

The passive dehumidifier and humidifier may comprise a housing, which accommodates the hygroscopic material, wherein the housing may comprise at least one perforated wall. The housing may facilitate the arrangement and mounting of the passive dehumidifier and humidifier on walls, ceiling, floor or on furniture in the defined space. The housing may protect the passive dehumidifier and humidifier from external physical influences. The passive dehumidifier and humidifier may release and absorb moisture to and from the defined space through the at least one perforated wall of the housing. The second hygrometer may be arranged at or on the at least one perforated wall of the housing. Moreover, the second hygrometer may be arranged on the inside or the outside of the at least one perforated wall of the housing.

The hygroscopic material of the passive dehumidifier and humidifier may comprise structured media with a corrugated or honeycomb structure. A corrugated or honeycomb structure of the structured media of the hygroscopic material of the passive dehumidifier and humidifier may increase the exposed surface of the structured media. A large exposed surface of the structured media may increase the absorption capacity of the hygroscopic material of the passive dehumidifier and humidifier.

The method according to the present disclosure comprises the steps of: determining the Celsius dewpoint value in the defined space by means of the at least one hygrometer; controlling the active air conditioner, based on the determined Celsius dewpoint value, to conditioning the air in the defined space to a dewpoint target value; and suppressing any fluctuation from the dewpoint target value by means of the passive dehumidifier and humidifier.

An advantage is that the method allows for a stable, reliable and effective treatment of air, and thereby improves the functionality/performance of a dry space or a dry room. A further advantage of the method is that humidity fluctuations in a dry space or a dry room may be supressed.

The dewpoint target value may be set depending on the demands on the defined space. If the defined space is a dry space or a dry room, the dewpoint target value may be very low. The step of determining the Celsius dewpoint value in the defined space by means of the at least one hygrometer may be determined at a position in the defined space where demands are high regarding a low Celsius dewpoint value. The determined Celsius dewpoint value may be transmitted to the control device. If the determined Celsius dewpoint value is above dewpoint target value, the air in the defined space should be dehumidified. The step of controlling the active air conditioner, based on the determined Celsius dewpoint value, to conditioning the air in the defined space to a dewpoint target value may be performed by the control device if the determined Celsius dewpoint value is above or below the dewpoint target value. When reaching the dewpoint target value, the active air conditioner may have difficulties to maintain the Celsius dewpoint value at the dewpoint target value. Therefore, the step of suppressing any fluctuation from the dewpoint target value by means of the passive dehumidifier and humidifier may maintain the Celsius dewpoint value at the dewpoint target value. The step of controlling the active air conditioner, based on the determined Celsius dewpoint value, to conditioning the air in the defined space to a dewpoint target value, comprises dehumidifying or humidifying the air in the defined space to a dewpoint target value.

The at least one hygrometer may comprise a first hygrometer arranged in the defined space and a second hygrometer arranged at the passive dehumidifier and humidifier, wherein the method may comprise the further steps of: determining the Celsius dewpoint value at the hygroscopic material of the passive dehumidifier and humidifier by means of a second hygrometer; and controlling the active air conditioner based on the determined Celsius dewpoint valueat the passive dehumidifier and humidifier. The knowledge of the Celsius dewpoint value in the hygroscopic material of the passive dehumidifier and humidifier may determine how activity of the active air conditioner should be modulated. If the Celsius dewpoint value in the hygroscopic material of the passive dehumidifier and humidifier is high, moisture from the may be released to the defined space. Therefore, it may be determined that the active air conditioner should be modulated or activated in order to reduce or increase the Celsius dewpoint value in the hygroscopic material of the passive dehumidifier and humidifier. Thus, the knowledge of the Celsius dewpoint value in the hygroscopic material of the passive dehumidifier and humidifier may facilitate the ability to quickly reach the dewpoint target value and to maintain the Celsius dewpoint value at the dewpoint target value.

The method may comprise the further step of: controlling the supplementary air condition device to regulate the temperature in the defined space. Since the temperature in the defined space may affect relative humidity value, the control device may control the supplementary air condition device to regulate the temperature in the defined space. A temperature sensor arranged in the defined space, which is connected to the control device, may form the basis for activating the supplementary air condition device at a certain level.

The dewpoint may be measured near or in the near vicinity of, i.e. at the hygroscopic material of the passive dehumidifier and humidifier. The hygroscopic material itself will have different humidity at different depths unless the system has reached equilibrium. The hygroscopic material may carry much more moisture than the surrounding air. The hygroscopic material is supposed to act very quickly. When a door to the dry space or dry room is opened the moisture increases in the hygroscopic material, so that the dry space remains only a little about target dewpoint. The active air conditioner is then modulated or activated in order to reach the Celsius dewpoint target value. Since the hygroscopic material now carries more moisture than it can at target air dewpoint, it must slowly release moisture back to the room. The active air conditioner depresses this moisture until the system finally is back at equilibrium humidity.

According to an example, the Celsius dewpoint value in the defined space and the Celsius dewpoint value at the passive dehumidifier and humidifier are both at the dewpoint target value at the equilibrium humidity. When the humidity in the defined space suddenly increases, due to an opened door or window to the defined space. The first hygrometer detects, senses and determines the increased Celsius dewpoint value in the defined space. The control device receives information about the determined Celsius dewpoint value. The control device controls the active air conditioner, based on the determined Celsius dewpoint value, to dehumidify the air in the defined space to a dewpoint target value. Due to the increased Celsius dewpoint value in the defined space also the Celsius dewpoint value at the hygroscopic material of the passive dehumidifier and humidifier increases. The ability of the passive dehumidifier and humidifier to attract humidity in the air in the defined space will, together with the active air conditioner, decrease the Celsius dewpoint value in the defined space. As the active air conditioner continues to decrease the Celsius dewpoint value in the defined space, also the Celsius dewpoint value at the hygroscopic material of the passive dehumidifier and humidifier decreases. The second hygrometer detects, senses and determines the Celsius dewpoint value at the passive dehumidifier and humidifier. The control device receives information about the determined Celsius dewpoint value. The control device controls the active air conditioner, based on the determined Celsius dewpoint value. Finally, the Celsius dewpoint value in the defined space will reach the dewpoint target value. The active air conditioner may however have difficulty to maintain the humidity in the dry space or the dry room at a constant level. A soon as the humidity in the dry space or the dry room reaches the dewpoint target value, the passive dehumidifier and humidifier suppresses fluctuations from the dewpoint target value in the defined space. During the suppressing of humidity fluctuations in the defined space, also the temperature in the defined space may be controlled by the supplementary air condition device, by detecting the temperature in the defined space.

Effects and features of the second aspect are to a large extent analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect.

Brief ions of the

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Fig. 1 schematically illustrates a dry space or a dry room comprising a system for controlling humidity according to an example;

Fig. 2 schematically illustrates in view of perspective a passive dehumidifier and humidifier according to an example;

Fig. 3 shows a flowchart of a method according to an example; and

Fig. 4 schematically illustrates a control device or computer according to an example.

Detailed description

The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Figure 1 schematically illustrates a defined space 2, such as a dry space or a dry room, comprising a system 1 for controlling humidity and/or temperature in the defined space 2. The system 1 comprising an active air conditioner 4, which is fluidly connected to the defined space 2. The active air conditioner 4 may comprise an active dehumidifier, an active humidifier, an active air heater and/or an active air cooler. A control device 100 is operably coupled to the active air conditioner 4. According to the example in fig. 1, the active air conditioner 4 comprises a sorption dehumidifier comprising a desiccant rotor 20. The airflow Fl to be dehumidified, process air, will pass through a process section of the desiccant rotor 20, the desiccant material in the rotor 20 extracts moisture from the process air, so that it can leave the rotor 2 as dried air F2. Simultaneously, the desiccant material in the rotor 20 is regenerated by another air stream, which flows through a regeneration section of the rotor 20 and leaves the defined space 2 as a regenerated airflow F3. As mentioned above, the active air conditioner 4 may also comprise an active humidifier, which humidifies the air. A passive dehumidifier and humidifier 8 comprising hygroscopic material 10, which passive dehumidifier and humidifier 8 is configured to be accommodated in the defined space 2 and in contact with the air in the defined space 2. The passive dehumidifier and humidifier 8 is configured to dehumidify and humidify the air in the defined space 2, which is indicated by a double arrow 26 in fig. 1.

A first hygrometer 6 is arranged in the defined space 2 and a second hygrometer 14 is arranged at the passive dehumidifier and humidifier 8. The first and second hygrometers 6, 14 are operably coupled to the control device 100. The control device 100 is configured to control the active air conditioner 4 based on information from the first and second hygrometers 6, 14.

The control device 100 is configured to control the active air conditioner 4 for dehumidifying the air in the defined space 2 to a dewpoint target value CDPt based on information from the first hygrometer 6. The dewpoint target value CDPt may be in the range of -100 CDP to +12 CDP. The passive dehumidifier and humidifier 8 is configured to suppress fluctuations from the dewpoint target value CDPt, which may be in the range of 0,1 CDP - 2 CDP from the dewpoint target value CDPt.

The system 1 comprises a supplementary air condition device 12, which is fluidly connected to the defined space 2 and operably coupled to the control device 100. The supplementary air condition device 12 is configured to regulate the temperature T in the defined space 2. Ambient air Al may be configured to flow in to an inlet 28 of the supplementary air condition device 12 and enter the defined space 2 as conditioned air A2 from an outlet 30 of the supplementary air condition device 12. A temperature sensor 22 is arranged in the defined space 2 and is connected to the control device 100. The defined space 2 may comprise an opening 24 such as a door and/or a window. Fig. 2 schematically illustrates in view of perspective a passive dehumidifier and humidifier 8 according to an example. The passive dehumidifier and humidifier 8 comprises a housing 16, which accommodates the hygroscopic material 10. The housing 16 comprises at least one gas permeable wall such as a perforated wall 18. The hygroscopic material 10 of the passive dehumidifier and humidifier 8 comprises a structured media with a corrugated or honeycomb structure.

Fig. 3 shows a flowchart of a method for controlling the humidity in a defined space 2 using the system 1 disclosed in figure 1. The method comprises the steps of determining slOl the Celsius dewpoint value CDPs in the defined space 2 by means of the at least one hygrometer 6; controlling sl02 the active air conditioner 4, based on the determined Celsius dewpoint value CDPs, to conditioning the air in the defined space 2 to a dewpoint target value CDPt; and suppressing sl03 fluctuations from the dewpoint target value CDPt by means of the passive dehumidifier and humidifier 8. The step of controlling sl02 the active air conditioner 4, based on the determined Celsius dewpoint value CDPs, to conditioning the air in the defined space 2 to a dewpoint target value CDPt, comprises dehumidifying or humidifying the air in the defined space 2 to a dewpoint target value CDPt. The at least one hygrometer 6, 14 comprises a first hygrometer 6 is arranged in the defined space 2 and a second hygrometer 14 is arranged at the passive dehumidifier and humidifier 8, wherein the method comprises the further steps of: determining sl04 the Celsius dewpoint value CDPp at the hygroscopic material 10 of the passive dehumidifier and humidifier 8 by means of a second hygrometer 14; and controlling sl05 the active air conditioner 4 based on the determined Celsius dewpoint value CDPp at the passive dehumidifier and humidifier 8. Further, the method comprising the step of controlling sl06 the supplementary air condition device 12 to regulate the temperature T in the defined space 2.

Fig. 4 schematically illustrates a diagram of a version of a device 500. The control device 100 described with reference to figures 2-3 may in a version comprise the device 500. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540. There is provided a computer program P which comprises instructions for carry out the above-mentioned method. The program P may be stored in an executable form or in a compressed form in a memory 560 and/or in a read/write memory 550.

Where the data processing unit 510 is described as performing a certain function, it means that the data processing unit 510 effects a certain part of the program stored in the memory 560 or a certain part of the program stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read/write memory 550 is adapted to communicating with the data processing unit 510 via a data bus 514.

When data are received on the data port 599, they are stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 is prepared to effect code execution as described above.

Parts of the methods herein described may be effected by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.

Claims

1. A system (1) for controlling humidity in a defined space (2), the system (1) comprising: an active air conditioner (4) fluidly connected to the defined space (2); a control device (100) operably coupled to the active air conditioner (4); at least one hygrometer (6, 14) arranged in the defined space (2) and operably coupled to the control device (100); a passive dehumidifier and humidifier (8) comprising hygroscopic material (10), which passive dehumidifier and humidifier (8) is configured to be accommodated in the defined space (2) and in contact with the air in the defined space (2); characterized in that the control device (100) is configured to control the active air conditioner (4) for conditioning the air in the defined space (2) to a Celsius dewpoint target value (CDPt) based on information from the at least one hygrometer (6), and in that the passive dehumidifier and humidifier (8) is configured to suppress fluctuations from the dewpoint target value (CDPt).

2. The system (1) according of claim 1, wherein the dewpoint target value (CDPt) is in the range of -100 CDP to +12 CDP.

3. The system (1) according to any of claims 1 and 2, wherein the passive dehumidifier and humidifier (8) is configured to suppress fluctuations in the range of 0,1 CDP - 2 CDP from the dewpoint target value (CDPt).

4. The system (1) according to any one of the preceding claims, further comprising a supplementary air condition device (12) fluidly connected to the defined space (2) and operably coupled to the control device (100).

5. The system (1) according to claim 4, wherein the supplementary air condition device (12) is configured to regulate the temperature (t) in the defined space (2). The system (1) according to any one of the preceding claims, wherein a first hygrometer (6) is arranged in the defined space (2) and a second hygrometer (14) is arranged at the passive dehumidifier and humidifier (8), wherein the first and second hygrometers (6, 14) are operably coupled to the control device (100), and wherein the control device (100) is configured to control the active air conditioner (4) based on information from the first and second hygrometers (6, 14). The system (1) according to any one of the preceding claims, wherein the passive dehumidifier and humidifier (8) comprises a housing (16), which accommodates the hygroscopic material (10), wherein the housing (16) comprises at least one gas permeable wall such as a perforated wall (18). The system (1) according to any one of the preceding claims, wherein the hygroscopic material (10) of the passive dehumidifier and humidifier (8) comprises structured media with a corrugated or honeycomb structure. A method for controlling humidity in a defined space (2) using a system (1) according to any one of the preceding claims, wherein the method comprises the steps of: determining (slOl) the Celsius dewpoint value (CDPs) in the defined space (2) by means of the at least one hygrometer (6, 14); controlling (sl02) the active air conditioner (4), based on the determined Celsius dewpoint value (CDPs), to conditioning the air in the defined space (2) to a dewpoint target value (CDPt); and supressing (sl03) fluctuations from the dewpoint target value (CDPt) by means of the passive dehumidifier and humidifier (8). The method according to claim 9, wherein the step of controlling (sl02) the active air conditioner (4), based on the determined Celsius dewpoint value (CDPs), to conditioning the air in the defined space (2) to a dewpoint target value (CDPt), comprises dehumidifying the air in the defined space (2) to a dewpoint target value (CDPt). The method according to claim 9, wherein the step of controlling (sl02) the active air conditioner (4), based on the determined Celsius dewpoint value (CDPs), to conditioning the air in the defined space (2) to a dewpoint target value (CDPt), comprises humidifying the air in the defined space (2) to a dewpoint target value (CDPt). he method according to any one of claims 9 - 11, wherein the at least one hygrometer (6,

14) comprises a first hygrometer (6) is arranged in the defined space (2) and a second hygrometer (14) is arranged at the passive dehumidifier and humidifier (8), and wherein the method comprising the further steps of: determining (sl04) the Celsius dewpoint value (CDPp) at the hygroscopic material (10) of the passive dehumidifier and humidifier (8) by means of a second hygrometer (14); and controlling (sl05) the active air conditioner (4) based on the determined Celsius dewpoint value (CDPp) at the passive dehumidifier and humidifier (8). he method according to any one of the claims 9 - 12, wherein the method comprising the further step of: controlling (sl06) the supplementary air condition device (12) to regulate the temperature (T) in the defined space (2).