EP4348121A1

EP4348121A1 - Method for ventilating a space, and ventilation system

Info

Publication number: EP4348121A1
Application number: EP22729032.7A
Authority: EP
Inventors: Hans Jorgen Christensen
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-27
Filing date: 2022-05-24
Publication date: 2024-04-10
Also published as: WO2022248003A1

Abstract

Disclosed is a method for ventilating a defined space (1). The method comprises the following steps:  detecting an outside air dewpoint of the air outside the defined space (1),  detecting an inside air dewpoint of the air inside the defined space (1),5  if the outside air dewpoint is higher than the inside air dewpoint by a predefined initial dewpoint margin, then o generating an air inflow into the defined space (1) from the outside of the defined space (1) by means of an inflow generator (2), o increasing the temperature of the inflow air by means of inflow air heating means (3) before the inflow air enters the defined space (1), o generating an air outflow from the defined space (1) to the outside of the defined space (1) by means of an outflow generator (4), o detecting a relative humidity of the exit air at the outflow generator (4), and o stopping operation of the inflow generator (2) and the outflow generator (4) if the relative humidity is above a predefined stop level A ventilation system (7) for ventilating a defined space (1) is also disclosed.

Description

METHOD FOR VENTILATING A SPACE, AND VENTILATION SYSTEM

Background of the invention

The invention relates to a method for ventilating a defined space and a ventilation system.

Description of the Related Art

Cellars, storage rooms, summer cottages or even privet home, public building or industrial buildings or in principle any other building or similar forming a defined more or less closed indoor space often need regular ventilation to ensure a pleasant indoor climate, to remove radon or other or such defined spaces can be exposed to moisture buildup if the defined space is not well ventilated. Moisture buildup can lead to rot, mold and other which can be damaging to the building structure and to the indoor environment. It is therefore well known to arrange ventilation in buildings to change the inside air and/or hopefully draw out some of the buildup moisture - e.g. by means of both a ventilation inflow and an outflow. However, particularly if the defined indoor space is not heated or only heated a little, there is a risk of the ventilation air condensing on colder surfaces in the defined space if e.g. hot moist air is introduced into a colder defined space.

Thus, from the European patent application EP 2 947 396 A1 it is therefore known to provide a ventilation system with means for detecting the dewpoint of the outside air and the dewpoint of the inside air and then ensure that a defined space is only ventilated when the outside air dewpoint is lower that the inside air dewpoint. In this way it is insured that the ventilation system does not being moisture into the defined space but it also means that the ventilation system is shut down a great amount of the time.

An object of the invention is therefore to provide for a more efficient technique for ventilating a defined space. The invention

The invention provides for a method for ventilating a defined space, the method comprising the following steps:

• detecting an outside air dewpoint of the air outside the defined space,

• detecting an inside air dewpoint of the air inside the defined space, · if the outside air dewpoint is higher than the inside air dewpoint by a predefined initial dewpoint margin, then o generating an air inflow into the defined space from the outside of the defined space by means of an inflow generator, o increasing the temperature of the inflow air by means of inflow air heating means before the inflow air enters the defined space, o generating an air outflow from the defined space to the outside of the defined space by means of an outflow generator, o detecting a relative humidity of the exit air at the outflow generator, and o stopping operation of the inflow generator and the outflow generator if the relative humidity is above a predefined stop level

Increasing the temperature of the inflow air before the inflow air enters the defined space is advantageous in that by heating the inflow air the relative humidity of the inflow air is reduced. In fact, by elevating the temperature of the inflow air by only 11° C the airs capacity for holding humidity is doubled. In this way it is possible to use the ventilation system even when the outside air dewpoint is higher than the inside air dewpoint. However, if the heated outside air stays too long in a colder defined space the temperature of the heated outside air could drop so much that the risk of the moisture condensing on cold surfaces in the defined space is increased. It is therefore advantageous to actively generating an air outflow from the defined space by means of an outflow generator and then monitor the relative humidity of the exit air at the outflow generator so that the operation of the inflow generator and the outflow generator can be stopped if the relative humidity is above a predefined stop level indicating that the risk of condensation in the defined space is too high. In this way the defined space can be ventilated substantially without risking moisture condensing in the defined space even when the outside air dewpoint is higher than the inside air dewpoint.

It should be noted that the dewpoint is the temperature at which the absolute humidity is equal to the amount of water that the air can actually hold, or the temperature at which the absolute humidity equals the relative humidity of 100%. Because the dew point is the temperature of saturation, it is the temperature at which condensation will normally occur. For a given temperature and pressure, the more vapor per cubic meter, the higher the absolute humidity and the higher the relative humidity. Adding water vapor increases the dewpoint temperature. This means that for very humid air the dewpoint is nearly as high as the temperature of the air unless the relative humidity is 100% and then the dewpoint is the air temperature. I.e., higher dewpoint means there is more moisture in the air.

Thus, detecting the exit air dewpoint or a relative humidity of the exit air to some extend is two sides of the same coin in that the measurement of the dew point is related to humidity. A rising dew point means there is more moisture in the air and a high relative humidity implies that the dew point is close to the current air temperature. A relative humidity of 100% indicates the dew point is equal to the current temperature and that the air is maximally saturated with water. When the moisture content remains constant and temperature increases, relative humidity decreases, but the dew point remains constant. Increasing the barometric pressure also increases the dew point but due to the ventilation, the barometric pressure inside and outside the defined space is substantially equal and the barometric pressure will therefore not affect the present method in any noticeable way.

It should be noted that the term “ defined space ” in this context should be interpreted as any kind of building, part of a building, room, container or other forming a defined space separated from the outside.

It should be noted that the terms “ inflow generator ” and “ outflow generator ” in this context should be interpreted as any kind of air flow generator suited for generating a flow of air, such as any kind of fan, pump, jet, hybrid ventilation means or other.

It should also be noted that the term “ heating means’ ’ in this context should be interpreted as any kind of heater capable of increasing the temperature of the inflow air - i.e. the term includes any kind of electrical heater, combustion heater, solar collector panel or other or any combination thereof.

It should also be noted that the predefined stop level is a predefined first level.

In an aspect of the invention, the method further comprises the step of detecting an exit air dewpoint of the exit air at the outflow generator and stopping operation of the inflow generator and the outflow generator if the exit air dewpoint is not higher than the outside air dewpoint.

Monitoring the relative humidity of the exit air and stopping ventilation if the relative humidity of the exit air becomes too high is advantageous in that the method can be used for ventilating the defined space even if outside air dewpoint is higher than the inside air dewpoint. However, when the outside air travels through the defined space the relative humidity of the air can rise because it absorbs moisture and/or because it is cooled down inside the defined space. I.e. if only the relative humidity of the exit air is monitored it is not possible to tell for sure if the system is actually dehumidifying the defined space or if it is actually increasing the relative humidity inside the defined space. It is therefore advantageous to also detect if the exit air dewpoint is lower than the outside air dewpoint - and stopping operation of the ventilation system if it is - in that as long as the exit air dewpoint is higher than the outside air dewpoint, the system will bring more humidity out of the defined space than into it and the system can therefore be used for dehumidifying the defined space even if the outside air dewpoint is higher than the inside air dewpoint which makes a ventilating according to the present method much more efficient and versatile. It should be noticed that this could also in an embodiment be monitored by monitoring changes in the inside air dewpoint

- i.e. stopping operation of the inflow generator and the outflow generator if the inside air dewpoint is rising after a predefined time period or if it is dropping (which would be advantageous in that means for detecting the inside air dewpoint is already present)

- but detecting the exit air dewpoint of the exit air at the outflow generator provides a more reliable result in that what leaves the defined space is compared to what enters the defined space.

In an aspect of the invention, the method further comprises the step of increasing the flow rate of the inflow generator and the outflow generator if the relative humidity is above a predefined second level, wherein the predefined second level is lower than the predefined stop level and/or if the exit air dewpoint is not higher than the outside air dewpoint by a first predefined exit air dewpoint margin.

When the outside air travels through the defined space it can absorb moisture and/or be cooled down to a point where the relative humidity rises to a critical level (i.e. a level where the ventilation could lead to condensation on surfaces in the defined space). Likewise, the exit air dewpoint could rise to a level indicating that too much humidity is absorbed in the defined space. One way of preventing this is to stop the ventilation process but it is advantageous to try to increase the flow speed of the outside air through the defined space (if the predefined second level is reached or if exit air dewpoint is not higher than the outside air dewpoint by a first predefined exit air dewpoint margin) before stopping the ventilation process in that increased flow speed will reduce the time the outside air is inside the defined space. I.e., the outside air will not have time to be cooled down as much and/or absorb as much moisture and the risk of condensation in the defined space is thereby reduced without having to stop the ventilation system.

In an aspect of the invention, the method further comprises the step of decreasing the flow rate of the inflow generator and the outflow generator or stopping operation of the inflow generator and the outflow generator if the relative humidity is below a predefined third level and/or if the exit air dewpoint is higher than the outside air dewpoint by a second predefined exit air dewpoint margin.

If the outside air is heated as it travels through the defined space or if the inside air is so dry that it will dehumidify the outside air as it travels through the defined space it is advantageous to decreasing the flow rate to save energy if ventilation is still needed for other reasons - i.e. oxygen level, radon removal, temperature regulation, increasing relative humidity in the defined space or other - or the ventilation system can be stopped to further save energy if it has no influence on the humidity in the defined space or if it is actually increasing the relative humidity level inside the defined space.

It should be noted that the predefined third level in this case obviously is lower than the previously mentioned predefined stop level and predefined second level and that the second predefined exit air dewpoint margin is bigger than the first predefined exit air dewpoint margin. In an aspect of the invention, if operation of the inflow generator and the outflow is stopped because the relative humidity is above the predefined stop level and/or the exit air dewpoint is not higher than the outside air dewpoint, then operation of the inflow generator and the outflow generator is only started again if the outside air dewpoint is higher than the inside air dewpoint by a predefined second dewpoint margin, wherein the predefined second dewpoint margin is smaller than the predefined initial dewpoint margin.

If the ventilation system is started again under the same conditions as under the initial run the same result must be expected - i.e. that the system is stopped again because the exit air dewpoint is not higher than the outside air dewpoint or the relative humidity is above a predefined stop level which indicates that the risk of condensation in the defined space is too high. It is therefore advantageous to not restart until the startup conditions have improved - i.e. until the outside air dewpoint is higher than the inside air dewpoint by a smaller margin (the predefined second dewpoint margin) than the initial margin (the predefined initial dewpoint margin) so that the chance of the method actually dehumidifying the defined space is increased or so that the risk of condensing in the defined space is reduced. In this way the system will adapt itself to the present conditions and e.g. a newly installed system can adapt itself to run more optimally.

It should be noticed that in a further embodiment, if the system is started when the predefined second dewpoint margin is reached and this also leads to the system being stopped due to the relative humidity of the exit air is above the predefined stop level and/or the exit air dewpoint is not higher than the outside air dewpoint, this startup margin between the outside air dewpoint and the inside air dewpoint could be reduced even further to a smaller predefined third dewpoint margin before a third try and so on until the system is not stopped due to the exit air dewpoint or the relative humidity of the exit air is above the predefined stop level. In an aspect of the invention, the exit air dewpoint and/or the relative humidity of the exit air is not detected until a predefined time period after operation of the inflow generator and the outflow generator is initiated.

It will take time for the intake air to travel through the defined space and reach the outflow generator. It is therefore advantageous to not detected the exit air dewpoint or the relative humidity of the exit air until a predefined time period has passed to ensure that it is actually the dewpoint and/or the relative humidity of the intake air - and not just the existing air from the defined space - that is being detected at the outflow generator. Hereby a more precise and efficient method is achieved.

In an aspect of the invention, the inflow air heating means comprises a solar collector panel including a panel temperature sensor detecting a panel temperature in the solar collector panel, wherein the method further comprises only generating the air inflow by means of the inflow generator and only generating the air outflow by means of an outflow generator if the panel temperature is above an outside air temperature, measured by an outside air temperature sensor by a first predefined panel temperature margin.

In a solar collector panel the air is heated by the sun in that the energy from the sun, insolation, is captured by an absorbing medium and used to heat air. Making the inflow air heating means comprise a solar collector panel is advantageous in that this provides a free and readily available source for heating the inflow air. However, to ensure that the solar collector panel will actually heat the inflow air it is advantageous to provide the solar collector panel with a panel temperature sensor detecting the panel temperature in the solar collector panel, so that the ventilation system is only started when the panel temperature is above the outside air temperature, measured by the outside air temperature sensor, by a first predefined panel temperature margin so that the solar collector panel can heat the inflow air to a certain level to increase the efficiency of the method and the system. The panel temperature being above a predefined panel temperature level is enough to tell if the system will run efficiently in most circumstances. However, e.g. on very cold sunny days there is a risk that the system is prevented from starting due to the panel temperature being too low even if the system actually would run efficiently - at least for dehumidifying purposes - if it was started. It is therefore advantageous to compare the panel temperature to the outside air temperature and then only start operation if the panel temperature is a predefined panel temperature margin higher than a temperature of the outside air.

In an aspect of the invention, if operation of the inflow generator and the outflow generator is stopped because the relative humidity is above the predefined stop level and/or the exit air dewpoint is not higher than the outside air dewpoint, then operation of the inflow generator and the outflow generator is only started again if the panel temperature is a second predefined panel temperature margin above the outside air temperature, wherein the second predefined panel temperature margin is bigger than the first predefined panel temperature margin.

If the ventilation system is started again under the same conditions as under the initial run the same result must be expected - i.e. that the system is stopped again because the exit air dewpoint is not higher than the outside air dewpoint or the relative humidity is above a predefined stop level which indicates that the risk of condensation in the defined space is too high. It is therefore advantageous to not restart until the startup conditions have improved - i.e. until the panel temperature is above the outside air temperature by a second predefined panel temperature margin being bigger than the first predefined panel temperature margin so that the chance of the method actually dehumidifying the defined space is increased or so that the risk of condensing in the defined space is reduced. In this way the system will adapt itself to the present conditions and e.g. a newly installed system can adapt itself to run more optimally. In an aspect of the invention, the method further comprises increasing the temperature of the inflow air by means of the inflow air heating means more if the relative humidity is above a predefined second level, wherein the predefined second level is lower than the predefined stop level and/or if the exit air dewpoint is not higher than the outside air dewpoint by a first predefined exit air dewpoint margin.

If the inflow air heating means comprises an electrical heater, a combustion heater or other where the heating capacity can be adjusted it is advantageous to increase the temperature of the inflow air more if the relative humidity is above a predefined second level and/or if the exit air dewpoint is not higher than the outside air dewpoint by a first predefined exit air dewpoint margin to thereby increase the efficiency of the ventilation system and reduce the risk of condensation in the defined space.

In an aspect of the invention, the inflow generator and the outflow generator are operated synchronously.

Operating the inflow generator and the outflow generator synchronously is advantageous because this will enable a more precise and useful detection of the exit air dewpoint or the relative humidity of the exit air at the outflow generator in that the risk of the outside air mixing too much with the inside air is reduced. Furthermore, synchronous operation simplifies the system control.

The invention further provides for a ventilation system for ventilating a defined space. The ventilation system comprises outside air dewpoint detection means arranged for detecting an outside air dewpoint of the air outside the defined space and inside air dewpoint detection means arranged for detecting an inside air dewpoint of the air inside the defined space. The ventilation system also comprises an inflow generator arranged for generating an air inflow into the defined space from the outside of the defined space and an outflow generator arranged for generating an air outflow from the defined space to the outside of the defined space. Even further, the ventilation system comprises exit air relative humidity detection means arranged for detecting an exit air relative humidity of the air at the outflow generator, inflow air heating means located at the inflow generator, wherein the inflow air heating means are arranged to increase the temperature of the air inflow, and control means arranged for activating operation of the inflow generator and the outflow generator if an outside air dewpoint detected by the outside air dewpoint detection means is higher than an inside air dewpoint detected by the inside air dewpoint detection means by a predefined initial dewpoint margin. The control means are further arranged to stop operation of the inflow generator and the outflow generator if the exit air relative humidity is above a predefined stop level.

Providing the ventilation system with control means capable of only starting the ventilation system if the outside air dewpoint is higher than the inside air dewpoint by a predefined initial dewpoint margin and stopping the system again if the exit air relative humidity is above a predefined stop level is advantageous in that this enables that the system will only run if it can actually run safely and efficiently - i.e. only if the risk of condensation in the defined space is low.

It should be noted that the term “ dewpoint detection means’ ’ in this context should be interpreted as any kind of dewpoint detector capable of detecting the dew point of air. I.e. the term includes any kind of standalone device capable of measuring the necessary parameters and generating a output in the form of a dew point or a value indicative of the dew point or the term could include a separate temperature sensor and a relative humidity sensor and a unit for calculating the dew point based on input from the temperature sensor and humidity sensor e.g. in combination with a lookup table.

It should also be noted that the term “ relative humidity detection means’ ’ in this context should be interpreted as any kind of relative humidity detector capable of detecting the relative humidity of air. I.e. the term includes any kind of standalone device capable of measuring the necessary parameters and generating a output in the form of a relative humidity or a value indicative of the relative humidity or the term could include a separate temperature sensor and a humidity sensor and a unit for calculating the relative humidity on input from the temperature sensor and humidity sensor e.g. in combination with a lookup table.

It should also be noted that the term “ control means’ ’ in this context should be interpreted as any kind of controller capable of detecting the relative humidity of air. I.e. the term includes any kind of standalone device capable of starting, stopping or/and controlling operation of a ventilation system based on different input. I.e. the term includes any kind of PC, logical circuit, Programmable logic controller (PLC) or other or any combination thereof.

In an aspect of the invention, the ventilation system further comprises exit air dewpoint detection means arranged for detecting an exit air dewpoint of the air at the outflow generator and wherein the control means are further arranged to stop operation of the inflow generator and the outflow generator if the exit air dewpoint is not higher than the outside air dewpoint.

Monitoring the relative humidity of the exit air and stopping ventilation if the relative humidity of the exit air becomes too high is advantageous in that the system, then can be used for ventilating the defined space even if outside air dewpoint is higher than the inside air dewpoint. However, when the outside air travels through the defined space the relative humidity of the air can rise because it absorbs moisture and/or because it is cooled down inside the defined space. I.e. if only the relative humidity of the exit air is monitored it is not possible to tell if the system is actually dehumidifying the defined space or if it is actually increasing the relative humidity inside the defined space. It is therefore advantageous to also make the ventilation system comprise exit air dewpoint detection means arranged for detecting the exit air dewpoint of the air at the outflow generator - and arranging the control means to stop operation of the ventilation system if the exit air dewpoint is not higher than the outside air dewpoint - in that as long as the exit air dewpoint is higher than the outside air dewpoint, the system will bring more humidity out of the defined space than into it and the system can therefore be used for dehumidifying the defined space even if the outside air dewpoint is higher than the inside air dewpoint, which makes the ventilation system much more efficient and versatile. It should be noticed that this could also in an embodiment be monitored by arranging the control means to monitor changes in the inside air dewpoint - i.e. stopping operation of the inflow generator and the outflow generator if the inside air dewpoint is dropping after a predefined time period or if it is rising (which would be advantageous in that means for detecting the inside air dewpoint is already present) - but detecting the exit air dewpoint of the exit air at the outflow generator provides a more reliable result in that what leaves the defined space is compared to what enters the defined space.

In an aspect of the invention, the ventilation system further comprises an outside air temperature sensor detecting the outside air temperature, and the inflow air heating means comprises a solar collector panel including a panel temperature sensor detecting a panel temperature in the solar collector panel, wherein the control means is further arranged to only activate the operation of the inflow generator and the outflow generator if a panel temperature detected by the panel temperature sensor is above the outside air temperature by a predefined panel temperature margin.

Making the inflow air heating means comprise a solar collector panel is advantageous in that this provides a free and readily available source for heating the inflow air. However, to ensure that the solar collector panel will actually heat the inflow air it is advantageous to provide the solar collector panel with a panel temperature sensor detecting the panel temperature in the solar collector panel so that the ventilation system is only started when the panel temperature is above the outside air temperature by a predefined panel temperature margin so that the solar collector panel can heat the inflow air to a certain level above the ambient temperature to increase the efficiency of the system. In an aspect of the invention, the method is a method for operating a ventilation system according to any of the previously discussed ventilation systems.

Figures The invention will be described in the following with reference to the figures in which fig. 1 illustrates a defined space comprising a ventilation system, as seen from the side, fig. 2 illustrates a flow chart according to a method of a first embodiment of the invention, and fig. 3 illustrates a flow chart according to a method of a second embodiment of the invention.

Detailed description of the invention

Fig. 1 illustrates a defined space 1 comprising a ventilation system 7, as seen from the side. In this embodiment the defined space l is a single room building - such as a warehouse or a production facility - but in another embodiment the defined space could be a private home, an office space, a summer cottage, a cabin, a container or other or the defined space could be one or more connected rooms in a building, such as a cellar, an attic, an annex or other as long as the inflow generator 2 can be arranged to be in fluid communication with the the outflow generator 4 of the ventilation system 7 in the defined space 1.

In this embodiment the ventilation system 7 comprises an inflow generator 2 located at one end of the defined space 1 and an outflow generator 4 located at the opposite end of the defined space 1. However, in another embodiment the inflow generator 2 and/or the outflow generator 4 could be located differently in relation to the defined space such as closer to the ground, closer to the ceiling, in neighboring walls, in the floor, in the ceiling or other.

In this embodiment the inflow generator 2 and the outflow generator 4 are identical in capacity and both formed by a fan driven by an electrical motor. However, in another embodiment the inflow generator 2 and the outflow generator 4 could be different in capacity, in make, in drive units or other.

In this embodiment the ventilation system 7 comprises outside air dewpoint detection means 8 arranged on the outside of the defined space 1 near the inflow generator 2 to detect the dewpoint of the outside air. However, in another embodiment the outside air dewpoint detection means 8 could be placed in another location e.g. on the inflow air heating means 3, at or on the inflow generator 2, on another location on the defined space 1 or separate from the defined space 1.

In this embodiment the ventilation system 1 also comprises inside air dewpoint detection means 9 arranged inside the defined space 1 to detect the dewpoint of the inside air. Since the defined space 1 is ventilated by the ventilation system 7 the dewpoint inside the defined space will vary depending on where it is detected inside the defined space 1. However, it is advantageous to locate the inside air dewpoint detection means 9 away from the direct flow path between the inflow generator 2 and the outflow generator 4 to obtain a more correct dewpoint reading of the air inside the defined space 1 and not just a dewpoint of the air traveling through the defined space

1. Thus, in this embodiment the inside air dewpoint detection means 9 are arranged at the ceiling near the middle the defined space 1 to enable a more correct and average reading. However, in another embodiment the inside air dewpoint detection means 9 could be placed differently inside the defined space e.g. nearer to the inflow generator

2, nearer to the outflow generator 4, at ground level, on a wall or other. In this embodiment the ventilation system 1 also comprises exit air dewpoint detection means 10 including exit air relative humidity detection means 11 arranged at the outflow generator 4 for detecting the dewpoint and the relative humidity of the air at the outflow generator 4.

In this embodiment the dewpoint detection means 8, 9, 10 comprises a relative humidity sensor and a temperature sensor. I.e. in this embodiment the exit air relative humidity detection means 11 is forming part of the exit air dewpoint detection means 10 but in another embodiment the exit air relative humidity detection means 11 could be a separate sensor e.g. if the system 7 did not comprise exit air dewpoint detection means 10.

When the dewpoint detection means 8, 9, 10 comprises a relative humidity sensor and a temperature sensor the actual dew point can be calculated in a number of different ways known to the skilled person.

One calculation option is the following very simple approximation that allows conversion between the dew point, temperature, and relative humidity. This approach is accurate to within about ±1 °C as long as the relative humidity is above 50%:

Dewpoint temperature ~ Air temperature - (100 - Relative humidity )/5

In which the air temperature is in degrees Celsius and the relative humidity is in percent. This approximation does not factor in barometric pressure or any other pressure for that matter but since the calculated dewpoints in this embodiment are used relative to each other and since is it reasonable to assume that the barometric pressure is substantially equal inside and outside the defined space 1 this very simple approximation will in practice provide useful results. However, a more accurate approximation way to calculate the dew point from only the air temperature and the relative humidity is the Magnus formula which could also be used, or even more accurate formulas exist also involving the air pressure.

Since the dewpoint detection means 8, 9, 10 in this embodiment comprises a relative humidity sensor and a temperature sensor then the actual calculation of the dew point will in this embodiment be performed by the central control means 12 to which the readings of the sensors are fed. However, in another embodiment the calculation could take place at the sensors by means of a calculating unit (i.e. e.g. a dedicated logical circuit, a PLC or similar) or the calculation could be performed could be performed by another unit separate from the dewpoint detection means 8, 9, 10 and the control means 12.

In another embodiment one or more of the outside air dewpoint detection means 8, the inside air dewpoint detection means 9 and the exit air dewpoint detection means 10 could be formed as of-the-shelf dew point sensors available as a single unit from a multitude of different suppliers.

In this embodiment inflow air heating means 3 - in this case in the form of a solar collector panel 5 - is arranged just in front of the inflow generator 2 so that all the air being pumped into the defined space 1 by the inflow generator 2 is first drawn through the inflow air heating means 3 in which it is heated - in this embodiment by insolation.

In this embodiment the solar collector panel 5 comprises an air inlet 13 arranged at the bottom of the panel 1 and an air outlet 4 arranged at the back of the panel 1 so that the heated air is guided into the inflow generator 2. The air drawn in through the air inlet 13 travels up past a light absorber 14 which in this embodiment comprises a metal plate painted black . In another embodiment the light absorber 14 could be made from black felt through which the air travels or the light absorber 14 could be formed in another way. The light absorber 14 absorbs the radiation from the sun which will heat up the light absorber 14. The large surface of the light absorber 14 absorbs the radiation from the sun which ensures that this heat is efficiently dissipated to the passing air - thus heating the air before it is exhausted out into the defined space 1 by means of the inflow generator 2.

To protect the inner components of the panel 5 and to increase the efficiency of the panel 5 a transparent or translucent front plate 15 is provide at the front of the panel 5. In this embodiment the front plate 15 is made from polycarbonate but in another embodiment, it could be made from glass, another plastic material, a composite material or other.

In this embodiment the solar collector panel 5 is provided with a panel temperature sensor 6 detecting the air temperature inside the solar collector panel 5. The readings of the panel temperature sensor 6 are transmitted to the control means 12 so that the control means 12 may also control the ventilation system 7 on the basis of the solar collector panels 5 ability to heat the intake air. In this embodiment the panel temperature sensor 6 is located inside and at the top of the solar collector panel 5 but in another embodiment the panel temperature sensor 6 could be located closed to the inflow generator 2, closer to the middle of the solar collector panel 5 or at another location in or on the solar collector panel 5. In this embodiment the ventilation system 7 also comprise a separate outside air temperature sensor 16 located on the outside of the defined space 1. However, in another embodiment the outside air temperature sensor 16 could form part of the outside air dewpoint detection means 8 and/or it could be placed in another location e.g. on/at an outside surface of the inflow air heating means 3, at or on the inflow generator 2, on another location on the defined space 1 or separate from the defined space 1. The readings of the outside air temperature sensor 16 are transmitted to the control means 12 so that the control means 12 may also control the ventilation system 7 on the basis of the outside air temperature in relation to the panel temperature to determine the solar collector panels 5 ability to heat the intake air. However, it is known to the skilled person that a solar collector panel 5 can be designed in a multitude of other different ways e.g., with the air inlet placed at the top or on the backside, with channels prolonging the airs travel time through the solar collector panel 5, with a built in the air drying arrangement capable of reducing the absolute humidity of passing air - such as any kind of thermal condensation means, mechanical/refrigerative dehumidifiers, makeshift dehumidifiers, desiccant, ionic membrane dehumidifier or other -, the solar collector panel 5 could comprise a particulate filter, the inflow generator 2 could be incorporated into the solar collector panel 5 and/or the solar collector panel 5 could be designed in a number of other ways and/or include a number of other features.

Heating the intake air by means of a solar collector panel 5 is simple and inexpensive but a solar collector panel 5 is obviously only able to heat the intake air when the sun shines. Thus, in another embodiment the inflow air heating means 3 could also or instead comprise an electrical heater, a gas heater or another heat source that could be turned on and off and e.g., adjusted in heating capacity depending on the actual need.

In this embodiment the ventilation system 7 comprises control means 12 in the form of a small PLC arranged for activating operation of the inflow generator 2 and the outflow generator 4 (i.e. start, stop and/or adjust capacity) on the basis on input from the outside air dewpoint detection means 8, the inside air dewpoint detection means 9, the exit air dewpoint detection means 10, the exit air relative humidity detection means 11, the solar collector panel temperature sensor 6, the outside air temperature sensor 16 and/or other sensors according to the present system and method. However, the ventilation system 7 and the control means 12 can obviously also be used for other purposes than the ones defined by the present method. I.e., is could be used for heating the defined space 1, for controlling radon levels or C02 levels in the defined space 1, to dehumidify or simply ventilate the defined space even if the conditions of the present method is not fulfilled or other. In this embodiment all the components of the ventilation system 7 - i.e., the panel temperature sensor 6, the outside air temperature sensor 16, detection means 8, 9, 10, 11, airflow generator 2, 4, inflow air heating means 3 and or other components - are connected to the control means 12 by means of cables but in another embodiment one or more of the components could communicate with the control means 12 wirelessly and/or the ventilation system 7 could comprise more than one centrally arranged control means e.g. by means of distributed control means 12, a control bus or other. Fig. 2 illustrates a flow chart according to a method of a first embodiment of the invention.

In this embodiment the method comprises the first step SI in which the outside air dewpoint - i.e. the dewpoint of the air outside the defined space 1 - is detected by means of the outside air dewpoint detection means 8 and the readings of the outside air dewpoint detection means 8 is communicated to the control means 12 in the form of a dewpoint value or as temperature and relative humidity values by means of which the control means 12 can calculate the outside air dewpoint. In a second step S2 the inside air dewpoint - i.e., the dewpoint of the air inside the defined space 1 - is detected by means of the inside air dewpoint detection means 9 and the readings of the inside air dewpoint detection means 8 is communicated to the control means 12 in the form of a dewpoint value or as temperature and relative humidity values by means of which the control means 12 can calculate the inside air dewpoint.

It should be noticed that the first step SI and the second step S2 will in most cases be performed simultaneously although they could be conducted sequentially in any order. In a third step S3 the control means 12 evaluates if the outside air dewpoint is higher than the inside air dewpoint by a predefined initial dewpoint margin. This predefined initial dewpoint margin is in this embodiment 10 °C but in another embodiment, it could be lower - such as 8, 5, 3 °C or even lower - or it could be higher - such as 12, 15, 20 °C or even higher. If the outside air dewpoint is not higher than the inside air dewpoint by the predefined initial dewpoint margin the control means 12 could initiate operation of the inflow generator 2, the outflow generator 4, the inflow air heating means 3 and/or other anyway but this would just be according to a different control regime - or the control means 12 could be arranged to not start operation of the inflow generator 2, the outflow generator 4, the inflow air heating means 3 and/or other in this case.

If the outside air dewpoint is higher than the inside air dewpoint by the predefined initial dewpoint margin, then an air inflow into the defined space 1 from the outside of the defined space 1 will be generated by means of the inflow generator 2 in a fourth step S4 and an air outflow from the defined space 1 to the outside of the defined space 1 will be generated by means of an outflow generator 4 in a fifth step S5. In a sixth step S6 the temperature of the inflow air will be increased by means of the inflow air heating means 3 before the inflow air enters the defined space 1. In this embodiment the fourth step S4, the fifth step S5 and the sixth step S6 will be initiated simultaneously by means of the control means 12 but in another embodiment two or more of the steps S4, S5, S6 could be initialed sequentially in any order.

In a seventh step S7 the exit air dewpoint of the exit air at the outflow generator 4 is detected by means of the exit air dewpoint detection means 10 and/or the relative humidity of the exit air at the outflow generator 4 is detected by means of the exit air relative humidity detection means 11. In this embodiment the exit air dewpoint and/or the relative humidity of the exit air is not detected until a predefined time period after the third step S3 - i.e. until a predefined time period after operation of the inflow generator and the outflow generator is initiated. In this embodiment the predefined time period is 30 minutes but in another embodiment the period could be shorter - such as 25, 20, 15 minutes or even shorter or the period could be longer such as 40, 50, 60 minutes or even longer e.g. depending on the size of the defined space 1 or other. In this embodiment the predefined time period can be manually adjusted e.g. at setup so that it is ensured that exit air dewpoint and/or the relative humidity of the exit air is not detected until the outside air entered into the defined space 1 by the inflow generator 2 has actually reached the exit air dewpoint detection means 10 and/or the exit air relative humidity detection means 11.

In an eighth step S8 the operation of the inflow generator 2 and the outflow generator 4 is stopped if the exit air dewpoint is not higher than the outside air dewpoint and/or if the detected relative humidity is above a predefined stop level. I.e. the control means 12 monitor that the detected exit air dewpoint is not higher than the outside air dewpoint and/or that the detected relative humidity is not above a predefined stop level and then stops operation of the inflow generator 2, the outflow generator 4 if this is the case. In some embodiments - particularly if the inflow air heating means 3 comprise an electrical heater or a combustion heater - the operation of the inflow air heating means 3 would also be stopped or the inflow air heating means 3 could continue running at a minimum capacity level.

If the ventilation system 7 comprises only exit air relative humidity detection means 11, the predefined stop level could be 90% relative humidity of the exit air. I.e. if the relative humidity of the exit air is higher than 90% the control means 12 stop operation of the inflow generator 2 and the outflow generator 4 and possibly the inflow air heating means 3. As long as the relative humidity of the exit air is lower than 90% the risk of humidity in the inflow air condensing inside the defined space 1 is low and ventilation of the defined space 1 can therefore be performed substantially without risking condensing in the defined space 1 even when the outside air dewpoint is higher than the inside air dewpoint. However, if reduction of this risk is desired the predefined stop level for relative humidity of the exit air could be set to 80%, 70%, 60% or even lower or if a higher risk could be accepted the predefined stop level for relative humidity of the exit air could be set to 92%, 93%, 96% or even higher.

However, under certain circumstances the relative humidity of the inflow air could rise during its travel towards the outflow generator 4 simply because the inflow air is cooled down inside the defined space 1 before it reaches the outflow generator 4. Thus, if the method and ventilation system 7 according to the present invention is used for dehumidifying the air in the defined space it is advantageous to detect the exit air dewpoint of the exit air at the outflow generator 4 by means of the exit air dewpoint detection means 10. By detecting the exit air dewpoint - i.e. by including the temperature of the exit air into the equation - it is possible to deduce if the system 12 and method will draw more humidity out of the defined space 1 by the outflow generator 4 than what is entered by the inflow generator 2 by ensuring that the exit air dewpoint is not lower than the outside air dewpoint. I.e. in an embodiment step eight S8 includes stopping the operation of the inflow generator 2 and the outflow generator 4 if the exit air dewpoint is not higher than the outside air dewpoint.

Fig. 3 illustrates a flow chart according to a method of a second embodiment of the invention.

In this embodiment of the invention the method comprises a ninth step S9 arranged before the eight step S8 in which the flow rate of the inflow generator 2 and the outflow generator 4 is increased if the relative humidity is above a predefined second level and/or if the exit air dewpoint is not higher than the outside air dewpoint by a first predefined exit air dewpoint margin. In this embodiment the predefined stop level is 90% so in this embodiment the predefined second level is 80%. It is obvious that the predefined second level has to be lower than the predefined stop level but, in another embodiment, the predefined second level could be 75%, 70%, 65% or even lower. I.e., if the relative humidity detected by the exit air relative humidity detection means 11 at the outflow generator 4 is above 80% the control means 12 is arranged to increase the flow rate of the inflow generator 2 and the outflow generator 4 so that the air blow in by the inflow generator 2 is moved faster through the defined space 1 and thereby not cooled down as much or thereby not as much humidity is absorbed. Faster air flow also means less absorbing of humidity in the first part of the defined space, so the possibility of escaping the space without condensation is higher. Once the relative humidity of the exit air at the outflow generator 4 rises above the predefined second level the normal operation is resumed - i.e. the flow rate of the inflow generator 2 and the outflow generator 4 is reduced to the previous level.

In this embodiment of the invention, the method also comprises a tenth step S10 arranged before the eight step S8 in which the flow rate of the inflow generator 2 and the outflow generator 4 is decreased or stopped if the relative humidity is below a predefined third level and/or if the exit air dewpoint is lower than the outside air dewpoint by a second predefined exit air dewpoint margin. In this embodiment the predefined stop level is 90% and the predefined second level is 80% so in this embodiment the predefined third level is 50%. It is obvious that the predefined third level has to be lower than the predefined stop level and the predefined second level but, in another embodiment, the predefined third level could be 65%, 50%, 40% or even lower. I.e., if the relative humidity detected by the exit air relative humidity detection means I I at the outflow generator 4 is above 50% the control means 12 is arranged to decrease the flow rate of the inflow generator 2 and the outflow generator 4 so that the air blow in by the inflow generator 2 takes longer to travel through the defined space 1 and thereby it can heat the defined space 1 more or it has time to absorb more humidity. Or the control means 12 can simply stop operation of the inflow generator 2 and the outflow generator 4 if the relative humidity is below the predefined third level. Same method applies if exit air dewpoint is not higher than the outside air dewpoint by a second predefined exit air dewpoint margin. In this embodiment the second predefined exit air dewpoint margin is 10°C but in another embodiment, it could be 8°C, 6°C, 5°C or even less or 12°C, 14°C, 16°C or even more. Once the margin between the exit air dewpoint of the exit air at the outflow generator 4 and the outside air dewpoint is smaller than the second predefined exit air dewpoint margin again, the normal operation is resumed - i.e. the flow rate of the inflow generator 2 and the outflow generator 4 is increased to the previous level.

In this embodiment of the invention the method also comprises an eleventh step Sl l arranged after the eight step S8. In the eleventh step SI 1 the start-up conditions in the third step S3 are changed if operation of the inflow generator 2 and the outflow generator 4 has been stopped because the relative humidity is above the predefined stop level and/or the exit air dewpoint is not higher than the outside air dewpoint. I.e. in this embodiment the operation of the inflow generator 2 and the outflow generator 4 is only started again if the outside air dewpoint is higher than the inside air dewpoint by a predefined second dewpoint margin. In this embodiment the predefined initial dewpoint margin is 10°C and the predefined second dewpoint margin obviously has to be smaller than the predefined initial dewpoint margin, so in this embodiment the predefined second dewpoint margin is 8°C, but it could be bigger or even smaller.

If the inflow air heating means 3 comprises a solar collector panel 5 with a panel temperature sensor 6 the eleventh step Sl l could also or instead include that operation of the inflow generator 2 and the outflow generator 4 is only started again if the panel temperature detected by the panel temperature sensor 6 is above the outside air temperature - detected by the outside air temperature sensor 16 - by a second predefined panel temperature margin. In this embodiment the first predefined panel temperature margin is 20°C and the second predefined panel temperature margin is 25°C but in another embodiment the first predefined panel temperature margin could e.g. be 15°C or 25°C and/or the second predefined panel temperature margin could be 20°C or 30°C or higher depending on the conditions as long as the second predefined panel temperature margin is bigger than the first predefined panel temperature margin. It should be noted that in an embodiment the method could comprise a third predefined panel temperature margin being smaller than the first predefined panel temperature margin. This third predefined panel temperature margin could be chosen if the system is dehumidifying too much - i.e. as an alternative or a supplement to decreasing the flow rate of the inflow generator 2 and the outflow generator 4 or stopping operation of the flow generators 2, 3 if the relative humidity is below a predefined third level and/or if the exit air dewpoint is lower than the outside air dewpoint by a second predefined exit air dewpoint margin.

List

1. Defined space

2. Inflow generator

3. Inflow air heating means

4. Outflow generator

5. Solar collector panel

6. Panel temperature sensor

7. Ventilation system

8. Outside air dewpoint detection means

9. Inside air dewpoint detection means

10. Exit air dewpoint detection means

11. Exit air relative humidity detection means

12. Control means

13. Air inlet

14. Light absorbing means

15. Front plate

16. Outside air temperature sensor

Claims

1. A method for ventilating a defined space (1), said method comprising the following steps: detecting an outside air dewpoint of the air outside said defined space (1), detecting an inside air dewpoint of the air inside said defined space (1),

• if said outside air dewpoint is higher than said inside air dewpoint by a predefined initial dewpoint margin, then o generating an air inflow into said defined space (1) from the outside of said defined space (1) by means of an inflow generator (2), o increasing the temperature of said inflow air by means of inflow air heating means (3) before said inflow air enters said defined space (1), o generating an air outflow from said defined space (1) to the outside of said defined space (1) by means of an outflow generator (4), o detecting a relative humidity of the exit air at said outflow generator (4), and o stopping operation of said inflow generator (2) and said outflow generator (4) if said relative humidity is above a predefined stop level.

2. A method according to claim 1, wherein said method further comprises the step of detecting an exit air dewpoint of the exit air at said outflow generator (4) and stopping operation of said inflow generator (2) and said outflow generator (4) if said exit air dewpoint is not higher than said outside air dewpoint.

3. A method according to claim 1 or 2, wherein said method further comprises the step of increasing the flow rate of said inflow generator (2) and said outflow generator (4) if said relative humidity is above a predefined second level, wherein said predefined second level is lower than said predefined stop level and/or if said exit air dewpoint is not higher than said outside air dewpoint by a first predefined exit air dewpoint margin.

4. A method according to any of the preceding claims, wherein said method further comprises the step of decreasing the flow rate of said inflow generator (2) and said outflow generator (4) or stopping operation of said inflow generator (2) and said outflow generator (4) if said relative humidity is below a predefined third level and/or if said exit air dewpoint is lower than said outside air dewpoint by a second predefined exit air dewpoint margin.

5. A method according to any of the preceding claims, wherein if operation of said inflow generator (2) and said outflow generator (4) is stopped because said relative humidity is above said predefined stop level and/or said exit air dewpoint is not higher than said outside air dewpoint, then operation of said inflow generator (2) and said outflow generator (4) is only started again if said outside air dewpoint is higher than said inside air dewpoint by a predefined second dewpoint margin, wherein said predefined second dewpoint margin is smaller than said predefined initial dewpoint margin.

6. A method according to any of the preceding claims, wherein said exit air dewpoint and/or said relative humidity of the exit air is not detected until a predefined time period after operation of said inflow generator (2) and said outflow generator (4) is initiated.

7. A method according to any of the preceding claims, wherein said inflow air heating means (3) comprises a solar collector panel (5) including a panel temperature sensor (6) detecting a panel temperature in said solar collector panel (5), wherein said method further comprises only generating said air inflow by means of said inflow generator (2) and only generating said air outflow by means of an outflow generator (4) if said panel temperature is above an outside air temperature, measured by an outside air temperature sensor (16), by a first predefined panel temperature level.

8. A ventilation system (7) for ventilating a defined space (1), said ventilation system

(7) comprising outside air dewpoint detection means (8) arranged for detecting an outside air dewpoint of the air outside said defined space (1), inside air dewpoint detection means (9) arranged for detecting an inside air dewpoint of the air inside said defined space (1), an inflow generator (2) arranged for generating an air inflow into said defined space (1) from the outside of said defined space (1), an outflow generator (4) arranged for generating an air outflow from said defined space (1) to the outside of said defined space (1), exit air relative humidity detection means (11) arranged for detecting an exit air relative humidity of the air at said outflow generator (4), inflow air heating means (3) located at said inflow generator (2), wherein said inflow air heating means (3) are arranged to increase the temperature of said air inflow, and control means (12) arranged for activating operation of said inflow generator (2) and said outflow generator (4) if an outside air dewpoint detected by said outside air dewpoint detection means (8) is higher than an inside air dewpoint detected by said inside air dewpoint detection means (9) by a predefined initial dewpoint margin, and wherein said control means (12) are further arranged to stop operation of said inflow generator (2) and said outflow generator (4) if said exit air relative humidity is above a predefined stop level.

9. A ventilation system (7) according to claim 8, wherein said ventilation system (7) further comprises an outside air temperature sensor (16) detecting the outside air temperature, and wherein said inflow air heating means (3) comprises a solar collector panel (5) including a panel temperature sensor (6) detecting a panel temperature in said solar collector panel (5), wherein said control means (12) is further arranged to only activate said operation of said inflow generator (2) and said outflow generator (4) if a panel temperature detected by said panel temperature sensor (6) is above said outside air temperature by a predefined panel temperature margin.

10. A method according to any of claims 1-7, wherein said method is a method for operating a ventilation system (7) according to claim 8 or 9.