EP3020881B1

EP3020881B1 - Method and system for providing retrofitted insulation

Info

Publication number: EP3020881B1
Application number: EP15194514.4A
Authority: EP
Inventors: Erling Jessen
Original assignee: Saint Gobain Isover SA France
Current assignee: Saint Gobain Isover SA France
Priority date: 2014-11-14
Filing date: 2015-11-13
Publication date: 2020-08-05
Anticipated expiration: 2035-11-13
Also published as: PL3020881T3; FR3028537B1; EP3020881A1; FR3028537A1; FR3028538A3; DE202015106184U1; DK3020881T3

Description

The present invention relates to a system and a method for providing dehumidification of a retrofitted insulation of an interior side of a building envelope, such as an external wall/roof/floor of a building.
The requirements for energy efficient buildings are rising and in new buildings only very little energy is required to heat up the interior. The reasons for this are amongst others due to a different way of constructing the buildings and use of different materials as compared to earlier times. However, a great number of buildings are built before energy efficiency was an issue, and here a solution for retrofitting insulation would be welcomed. Although a number of solutions already exist they are not always suitable for all buildings. In particular many old buildings have beautiful facades and sometimes the buildings are listed, putting a restriction on what is allowed to change. The solutions presently available are to a wide extent directed at insulation of the facade from the outside. A few solutions are available for insulation from the inside, yet the solutions presently available present some drawbacks in particular in relation to moisture transfer through the walls. The amount of water that transfers through a wall in the form of liquid water and water vapour or from diffusion through building materials will vary with different types of construction. A problem with old buildings is usually that you have a cold wall inside the building and when attaching insulation to this wall, moisture will build up, and may lead to fungal growth and rot.
In EP 1 529 890 A2 is described a device and method for adjusting the temperature and ventilating rooms in a building. Here insulation is attached to the inside of an exterior wall and a hollow space is created between the insulation and an interior sheathing of e.g. concrete or dry wall. Cool or heated air may be sent through the hollow space in the wall in order to regulate the temperature in the room, and the air may subsequently be let out into the room. This solution and others where the insulation is attached directly on the cold wall will not be suitable for walls having a diffusion tight surface, such as a vapour barrier included in the wall or is painted with a diffusion tight paint, which most paints used today are.
Another example of a wall construction is disclosed in WO2008/128262 . It describes a plate-shaped facing element for a wall and wall facing, wherein in the facing element one or more channels are provided for allowing a heat transfer and/or cooling medium, preferably air, to flow through. The channels are preferably configured to be open to the outside.
In US2009/0025323 a moisture removal system is disclosed. The system is preferably added at the interior side of a concrete wall. Here insulation forms a hollow space with the concrete wall, and moist air is removed by channels within the hollow space that conduct the moist air from an inlet end to an outlet end. The system may comprise a fan, dehumidifier and a heater to replace the humid air in the channels with air that is drier than humid air under vacuum conditions.
In DE102013209257 a thermal insulation system is disclosed, wherein insulation may be provided on the inside or outside of a building. The insulation layer is attached to the wall and a hollow space is created between the insulation and the wall. If the system is provided on the inside of the house then moist air in the hollow is dried before being vented outside of the building.
The drawback of prior art systems is uneven distribution of the fluid throughout the hollow between the existing wall and the retrofit insulation system. Uneven fluid distribution leads to high airflow or uneven moisture removal effect due to poorly ventilated areas.
When looking at solutions particularly concerned with avoiding moisture building up in the wall when retrofitting insulation to cold interior wall surfaces, one solution includes a capillary insulation element that must not be sealed off by ordinary diffusion tight paint or wallpaper, in order for humidity to escape. Another marketed solution suggests that tapestry, paint and existing vapour barrier is removed before insulation may be attached to the inside of the exterior wall. These solutions are either not suitable for use when insulation is to be provided on the inside of the building, in particular to a cold exterior wall or surface, or they present some considerable drawbacks.
As a consequence, if a cold exterior wall or surface is not insulated, problems related to moisture are not the only concern, but also the utilization of the rooms is greatly decreased. Since the temperature and moisture conditions at the exterior wall or surface are not the same as in the rest of the room, the areas near the exterior wall or surface in old buildings are often not used or only to a limited extent due to draft and cold radiation problems causing thermal discomfort. This is of course a great disadvantage to the users of these buildings and rooms. Hence, there is a demand for a solution addressing the above-mentioned problems, and which adds better utilization of the interior space of a building and at the same time provide efficient removal of moisture at a cold exterior wall or surface.
It is therefore the object of the invention to provide a system and a method, where insulation is retrofitted to a building envelope, especially an external wall, from the inside, without removal of any parts of the existing wall and without the risk of mould fungus forming inside the wall, and by which better utilization of the interior of the building is provided. Only very fungus sensitive layers of organic material such as wall paper will be necessary to remove.
In a first aspect, this and further objects are achieved by a method for providing ventilation of a retrofitted insulation and dehumidification of the retrofitted insulation system according to independent claim 1, comprising the steps of attaching an insulation material to the interior side of the building envelope such that a hollow space for conducting a fluid is provided between at least a part of the interior side of the building envelope and the insulation material; sealing of the hollow space making it substantially fluid tight; providing the hollow space with a fluid inlet and a fluid outlet; providing means for entering fluid into the hollow space through the fluid inlet and for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid entering the hollow space through the fluid inlet, providing a humidity detector for detecting the humidity at one or more points between the interior side of the building envelope and the insulation material, and providing means for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid exiting the hollow space through the fluid outlet.
By entering fluid where its characteristics are controlled in a suitable manner, preferably by entering tempered dehumidified air, the moisture on the exterior wall is removed through ventilation. The inventive method of providing dehumidification of the retrofitted insulation makes it possible to optimize the dimensions of the insulation material and the hollow space by suitable control of the configuration and the operating conditions which in turn entails that the available space in the interior of the building is rendered more usable. Controlling the velocity results in an even distribution of the airflow throughout the hollow space.
The method parameters may be controlled in a number of ways dependent on for example inside and outside temperature, moisture content in the hollow space between the insulation material and the interior side of the external wall, etc.
The fluid is entered into the fluid inlet and into the hollow space by means of a perforated inlet ventilation duct having a predefined inlet length and inlet configuration, and the fluid may exit the hollow space through the fluid outlet by means of a perforated outlet ventilation duct having a predefined outlet length and outlet configuration.
According to one further embodiment of the method, at least one of the steps of controlling at least one of humidity, velocity and temperature of the fluid inflow through the fluid inlet and into the hollow space, and controlling at least one of velocity, humidity and temperature of the fluid exiting the hollow space through the fluid outlet is carried out by determining at least one of said inlet length, inlet configuration, outlet length, outlet configuration, and size and/or distribution of perforations in the perforated inlet and/or ventilation ducts.
The fluid, preferably ambient air, is preferably dehumidified and/or heated slightly in the step before entering the inlet such that it is able to absorb/transport a higher amount of moisture from the hollow space.
The velocity of the fluid is regulated both when entering the hollow space and exiting the hollow space. That way a substantially constant atmospheric pressure may be maintained inside the hollow space. Furthermore, if the hollow space is kept at substantially atmospheric pressure and the airflow is kept low, then the dimensions of the installations can be kept to a minimum. Hence, the thickness of the wall construction may be kept to a minimum. Thus, the rooms of the building to be retrofitted with the system according to the present invention can be utilized better. In turn, this renders the need to operate a moisture removal system at vacuum (as defined as a negative pressure slightly below atmospheric pressure) condition due to poor evenness of the airflow in the hollow space superfluous, as there is no need for a high airflow to get a satisfactory moisture removal. This of course requires larger dimensions of the installation and will take up more space in the room to be retrofitted. Alternatively, the system may only control the velocity of either the fluid entering or exiting the hollow space. For example dehumidified fluid may be blown into the hollow space and a vent may be positioned at an opposite side of the wall letting out air and moisture.
On the other hand fluid may be sucked out from the hollow space and a vent may let in fluid because of the pressure difference between the hollow space and the surroundings.
The fluid exiting the hollow space may be let out inside the building or let out on the outside of the building. Before the fluid exiting the hollow space is let out inside the building, the fluid is preferably at least heated to room temperature and preferably dehumidified if the amount of moisture is above a certain level. The fluid that is let out inside the building may furthermore be purified in case any dust or microorganisms are present in the hollow space.
The fluid may be circulated such that the fluid exiting the hollow space is heated and dehumidified before entering the system again.
The fluid inflow and the fluid outflow are coordinated such that a substantially atmospheric pressure is maintained inside the hollow space to create the substantially even air distribution throughout the hollow space. In this way a simpler, thinner and cheaper system may be obtained without compromising the moisture removal compared to applying vacuum in the hollow space.
In particular the inflow of fluid may be controlled in response to the detected humidity in the hollow space. With a very precise control it is possible to optimize the method even further.
In a second aspect, a system of retrofitted insulation is provided, having the features set forth in independent claim 6.
The provision of a number of elements in one and the same system renders the system easy and flexible to produce, transport and handle during installation, just as the desired improved utilization of the interior space is attained.
The inlet control means comprises a perforated inlet ventilation duct having a predefined inlet length and inlet configuration, and wherein the outlet control means comprises of a perforated outlet ventilation duct having a predefined outlet length and outlet configuration. This secures an even distributed airflow in the hollow space. This is important while an even airflow provides an optimal moisture removal and even moisture level in the exterior wall. Thus, no area will be left poorly ventilated and inefficiently dehumidified. Furthermore, the even air distribution will facilitate a minimum need of air flow. Hence, the running cost of the system can be kept low.
In a development of the presently preferred embodiment, the perforated inlet ventilation duct and/or the perforated outlet duct has a plurality of openings along said predefined inlet length and outlet length, respectively, the shape of said openings being circular, oval, rectangular or in the shape of trapezoidal slits.
In order to increase the efficiency and optimization of the system even further, the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet duct may have a substantially uniform cross-section along the respective predefined length, preferably rectangular, and wherein said plurality of openings has a varying size, shape and/or distribution along the respective predefined length.
As an alternative, the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet ventilation duct may have a varying cross-section along the respective predefined length, preferably in the shape of a conic frustum, and wherein said plurality of openings has a constant size, shape and distribution along the respective predefined length.
As a second alternative, the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet ventilation duct are achieved by relatively large duct dimensions in relation to the airflow to create a pressure chamber effect and wherein said plurality of openings has constant size, shape and distribution along the respective predefined length.
By providing perforated ventilation ducts of this kind to the system, no further regulation of the airflow is needed.
In one embodiment, which is particularly advantageous with respect to the total thickness of the system, and hence optimum available interior space of the room, the inlet configuration of the perforated inlet ventilation duct and the outlet configuration of the perforated outlet duct has a substantially uniform, rectangular cross-section along the respective predefined length, and wherein the thickness of the perforated inlet ventilation duct and of the perforated outlet ventilation duct is smaller than the combined thickness of insulation material and the hollow space.
In another embodiment, the perforated inlet and outlet ventilation ducts are placed in parallel with each other, preferably at two opposite sides of the interior side of the building envelope, in the case the building envelope is an external wall more preferably at the floor and the ceiling, respectively. In most building an end of a wooden beam is in contact with the exterior wall or the whole wooden beam is placed near an exterior wall, where there is an increased risk of the wooden beam being subjected to a moisture related degradation process. By placing the ventilation ducts along the floor and ceiling the risk is lowered, because the moisture level surrounding the wooden beam is lowered. Especially if the wooden beam is not isolated then the surrounding environment is not only drier, but the construction of the wall system enables the capillary properties of an exterior wall to transport the moist away from the wooden beam, thus providing a sufficiently moisture reduced environment for the wooden beams.
In an embodiment the insulation material is preferably in the form of slabs, provided with recesses forming said hollow space for conducting the fluid, and wherein 5-95%, or 10-90%, or 20-80%, or approximately 50% of a surface of the insulation material is in direct contact with the interior side of the building envelope. The more direct contact between the building envelope and the insulation material there is, the better the insulation properties. The less direct contact between the insulation and the existing wall the better distribution of the fluid flow and narrow recess thickness is achieved.
Alternatively or additionally, a plurality of spacers in the form of distance pieces may be provided between the interior side of the building envelope and the insulation material. The distance pieces may be pegs for attachment of the insulation material to the interior side of the external wall. The pegs may extend all the way through the insulation material. It may also be different elements for example polymer spacers. The distance pieces may be positioned in the corners of the insulation material. Alternatively, a sheet material provided with recesses, for example by having a wave form on one or both side(s), may also be used as a distance piece.
In one particular embodiment where a plurality of spacers in the form of distance pieces is provided, the cavity thickness between the exterior wall and the insulation material may be 5-50 mm and more preferably 10-25 mm. Due to the low air flow needed in the present invention only a narrow cavity is needed. Hence, making more room available for insulation and a better utilization of the room in which the insulation is retrofitted.
In a further development of the above-mentioned particular embodiment each spacer is provided as a profile element with openings. This allows the air to pass through without compromising the evenness of the air flow distribution. The opening(s) must therefore be large enough to secure an even airflow distribution, but at the same time have mechanical properties to withstand the stress from normal home activities or low force activities such as office activities. Preferably, the total opening area in the profile element is between 20-80 % and more preferably 35-50% of the cavity section. Large openings or a large total opening area are chosen in order to secure low flow resistance and non-sensitive to irregular wall surfaces. If necessary, the profile elements may be adjusted to level the wall, leaving additional openings for the air to pass by without jeopardizing the evenness of the airflow distribution. The profile element may be made from various materials such as metal, plastics, etc.
In another embodiment, the inlet control means comprises a dehumidifier and a fan. Providing these two as a unit has a number of advantages from particularly an installation and utilization point of view.
The unit comprising the dehumidifier and the fan may be provided integrated in the wall. This is advantageous for two reasons: First, the energy for running the system will affect the exterior of the wall by being transferred to the circulating fluid, typically air. This will heat the air and increase the moisture removal capacity of the air. Secondly, the energy will not affect the interior of the house which otherwise might lead to a measurable temperature increase which is not desired during the more humid and non-heating seasons. The control means unit may be thicker compared to the wall construction. In this embodiment the control means unit might be visible for a user standing on the interior side of the wall construction in the form of a box or cabinet on the wall. The control means unit may be thinner than the wall construction.
Alternatively, it is possible to provide the dehumidifier and the fan as a replaceable unit. It is furthermore possible to replace the control means without dismantling the retrofitted wall construction. In a system or wall construction of this kind it is expected that the control means have a shorter life time than the retrofit wall construction. Typically, the expected lifetime of the dehumidifier and fan unit is a decade or two, whereas the wall system itself is expected to last several decades. Hence, replacement of the control means must be done easily and conveniently without being too costly for the user as is the case of the present invention.
In one further embodiment, the unit of inlet control means including the dehumidifier and the fan has a combined thickness which is smaller than the combined thickness of insulation material and the hollow space. Here it is possible to neatly include the control means unit in the wall, and only a control panel is visible from a user standing on the interior side of the wall construction.
The interior side of the insulation material may be provided with sheathing, such as plywood, Cross-laminated timber, Medium Density Fibreboard, metal or Oriented Strand Board, suitable for receiving attachment means for holding elements mounted to the interior side of the building envelope and insulation material. The sheathing may provide a plane surface. Furthermore if the sheathing is dispensed with it may be difficult to hang up shelves or other heavier elements on the inside of the finished wall, if only a thin slab of drywall is attached to the insulation material.
Furthermore the interior side of the retrofit insulation system, preferably the interior side of a double sheathing, may be provided with a vapour barrier. The vapour barrier may be provided as a part of the insulation material or sheathing if for example it is laminated thereto or coated thereon.
Furthermore, the insulation material may be in the form of slabs, preferably provided with recesses along one or more edges. Recesses may be provided anywhere and in any number in the surface of the slab that is facing the interior side of the building envelope, both horizontally and vertically and across. Alternatively the slabs may have buttons, such that fluid is generally free flowing in the hollow space and the buttons serves as distance holders to the interior side of the building envelope or external wall. The slabs are preferably approximately 3-8 cm thick, more preferably 4-7 cm thick. As an additional feature a centre of the slabs may be marked for example with a cross. Pegs for attaching the slabs to the external wall are preferably positioned here.
When referring to "the interior side", it is the side of element that faces the inside of the building/room.
When referring to "system" or "wall construction" it should not be limiting of the scope of the present invention since the system may comprise embodiments to construct a wall construction or the wall construction may comprise a system.
When referring to length, width or thickness, the width should be understood as the length of the shorter side of an element, the length should be understood as the longer side of an element, and the thickness is defined as the third dimension, wherein a element may in this context be cavity space, building wall or insulation material but not limited to this.
Different embodiments and features may be combined freely.
In the following, the invention will be described in further detail with reference to the drawing in which:

Fig. 1a is a perspective view of a wall construction comprising the system of retrofitted insulation in a first embodiment not forming part of the present invention,
Fig. 1b is a cross section of a second embodiment of a wall construction,
Fig. 2 is a schematic drawing of the flow in a system not forming part of the present invention,
Figs 3a-3g are schematic drawings of different embodiments of slabs of insulation material,
Fig. 4 is a schematic perspective view of a further embodiment of the system of retrofitted insulation,
Figs 5a and 5b are schematic drawings of the flow in two systems according to the invention,
Figs 6a to 6c are schematic drawings of various embodiments of a slab of insulation material with spacers in still further embodiments of the system according to the invention,
Fig. 7 is a partial view, on a larger scale, of a detail of system corresponding to Fig. 4,
Figs 8a to 8f are schematic cross-sectional views of various shapes of the spacer of the Fig. 7 embodiment,
Figs 9a to 9c are perspective views of various shapes of a ventilation duct in embodiments the system according to the invention, and
Figs 10a and 10b are schematic cross-sectional views of a part of the system in two alternative embodiments of the invention.

One embodiment of system of retrofitted insulation 1 not forming part of the invention is shown in Fig. 1a.
An interior side of an external wall 11 forming part of a building envelope is provided with sealing tape 17 along the interfaces to the floor and ceiling. The same is done along window and door frames if any, in order to create a substantially closed space. A number of insulation slabs 12, preferably made of mineral wool, size 60 cm x 60 cm, and constituting the insulation material of this first embodiment is attached to the interior side of the external wall 11 by means of pegs 14. The pegs 14 do not go all the way through the insulation slabs 12. Instead they are only used as a means for attachments of screws that are screwed into the external wall 11.
Facing the interior side of the external wall 11 of the insulation slabs 12, a hollow space 13 is provided. In the first embodiment of Fig. 1a, the hollow space 13 is formed as a grid of channels provided by recesses in the insulation slabs 12. It is to be understood that such recesses may take any suitable form as will be described in further detail with reference to Figs 3a-3g.
In the specific embodiment shown in Fig. 1a, the insulation slabs 12 are provided with recesses 26 along the edges of the slabs, as is shown in the embodiment of Figs 3a and 3b. Putting the insulation slabs 12 together substantially above and beside each other thereby creates the grid of channels in which a fluid is directed. The ventilation channels are connected to ventilation means which is further described under Fig. 2.
On the interior side of the insulation slabs 12 a sheathing 15 is provided. The sheathing 15 is suitable for receiving attachment means, such that e.g. book shelves, lamps, pictures, etc. may be attached to the finished wall formed on the inside. The sheathing is in the embodiment shown made of plywood but may be made of other materials suitable for receiving attachment means.
The interior side of the sheathing 15 is provided with a vapour barrier 16, where sealing tape 17 likewise is provided along the edges, such as along floors, ceilings, windows and doors, in order to form a closed and controllable system in the grid of channels making up the hollow space 13. That way it is avoided that ambient air containing moisture is drawn in behind the insulation. The interior side of the vapour barrier 16 is then again provided with drywall panels 18 or other panelling, creating an even surface suitable for receiving tapestry, paint or wallpaper. The drywall panel could furthermore comprise a box or control panel (not shown) for controlling the control means. Additionally, the box or control panel make it easy to replace the control means (not shown) such as a fan or dehumidifier (not shown).
Fig. 1b shows schematically a second embodiment of a system of retrofitted insulation mounted to a wall construction represented by external wall 11. What differs from the first embodiment is that the insulation material 12 is not provided with recesses. Instead a plurality of spacers is provided in the form of distance pieces 24 provided between the external wall 11 and the insulation material 12. Hence, the hollow space 13 is provided by the total volume between the exterior side of the insulation material 12 and the external wall 11 minus the volume of the sum of the volume taken up by the distance pieces 24.
Fig. 2 shows a cross section of the hollow space 13 of an embodiment of a system not forming part of the present invention.
Here the recesses 13 in the insulation material 12 are shown forming the grid of channels for conducting the fluid in the operational condition of the system. A fluid inlet 27 and a fluid outlet 28 are provided at bottom and at the top of the wall in a room. The fluid inlet 27 and outlet 28 may be positioned vice versa or in a completely different way. The arrows show how the fluid flows in the hollow space 13. The fluid flow in this embodiment is advantageous when operating with a low airflow, atmospheric pressure in the hollow space and an even airflow to minimize the thickness of the wall construction.
Humidity detectors 19 are provided in the hollow space 13 either attached to the insulation material 12 or the external wall (not shown). Data on the detected humidity are sent, preferably wirelessly, to the control means 22 for controlling the characteristics of the fluid entering the hollow space 13 and/or the control means 23 for controlling the characteristics of the fluid exiting the hollow space 13. An inlet ventilator 21 and an outlet ventilator 20 are provided in connection with the control means 22, 23. A dehumidifier may be incorporated in the ventilator or provided separately. Instead of having a mechanically and/or electronically controllable ventilator at the outlet for drawing out fluid from the hollow space 13, a vent hole may merely be provided. The vent hole is preferably closable.
Figs. 3a-3g are schematic drawings of different embodiments of slabs of insulation material 12.
Figs. 3a and 3b are a back view and a front view, respectively, of a slab of insulation material 12, provided with recesses 26 along the edges. It is noted that the hollow space 13 indicated in Figs 1a and 2 is formed by the recesses 26, i.e. the flow channels of the grid for conducting the fluid are in this embodiment formed by two facing recesses 26 of adjacent insulation slabs 12 along the sides of the respective slabs.
Figs. 3c and 3f show slabs of insulation material 12, provided with recesses 26 horizontally and vertically, respectively. In order to form a grid of channels all slabs in a wall are preferably positioned such that the recesses are extending in the same direction.
By providing recesses 26 in both directions as shown in Figs 3e and 3g, the orientation of the slabs of insulation material 12 is irrelevant, but the slabs should be positioned right above and next to each other in order to form a grid of channels that may be ventilated.
The dimensions and configuration of the recesses 26 is chosen in accordance with the specific requirements and conditions. That is, the portion of the surface of insulation material in direct contact with the interior side of the building envelope may lie in the range 5-95%, or 10-90%, or 20-80%, or approximately 50%.
The embodiment of a slab of insulation material 12 as shown in Fig. 3d is not provided with any recesses so the insulation material 12 should be positioned at a distance from the interior side of the external wall or building envelope in order for ventilation to be possible. This may be done by means of distance pieces as previously described with reference to Fig. 1b. As in the first embodiment, a number of pegs 14 used for fixing screw or the like in the insulation material is positioned in the middle of the slab. It is shown that it extends all the way through and may function as a distance piece. It may also only extend partly through the slab of insulation material 12.
Referring now to Fig. 4, an embodiment of the system of retrofitted insulation according to the present invention will be described. Only differences relative to the embodiments of Figs 1a, 1b, 2 and 3 will be described in detail.
In the embodiment of Fig. 4, the inlet control means 22 comprises a perforated inlet ventilation duct 31 having a predefined inlet length and inlet configuration. The outlet control means 23 of this embodiment comprises of a perforated outlet ventilation duct 32 having a predefined outlet length and outlet configuration. Although not shown in detail, it is clear to the skilled person that the perforated inlet ventilation duct 31 is in connection with the fluid inlet 27, and the perforated outlet ventilation duct 32 is in connection with the fluid outlet 28. The connections may be carried out in any suitable manner known in the art.
With further reference to Figs 9a to 9c, showing partial perspective views of various shapes of the perforated inlet ventilation duct 31, a plurality of openings 35 is provided along the predefined inlet length. Correspondingly, the perforated outlet ventilation duct 32 is, in the embodiment shown, provided with a plurality of openings as well (not shown in detail).
The shape of the openings 35 is shown as circular in Figs 9a-9c. Other conceivable shapes include openings that are oval, rectangular or in the shape of trapezoidal slits.
In the embodiment of Figs 4 and 9a-9c, each of the inlet configuration of the perforated inlet ventilation duct 31 and the outlet configuration of the perforated outlet duct 32 has a substantially uniform cross-section along the respective predefined length. As shown in Figs 9a and 9b, the configuration may be substantially rectangular with predefined height and width dimensions and ratio therebetween. This may be combined with forming the plurality of openings 35 with a varying size, shape and/or AWA#136518 distribution along the respective predefined length. The skilled person will be able to choose suitable dimensions and ratios.
In a not-shown embodiment, the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet ventilation duct are achieved by relatively large duct dimensions in relation to the airflow to create a pressure chamber effect and wherein said plurality of openings has constant size, shape and distribution along the respective predefined length.
In a further not-shown embodiment, the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet duct has a varying cross-section along the respective predefined length, preferably in the shape of a conic frustum, and wherein said plurality of openings has a constant size, shape and distribution along the respective predefined length.
Turning now to Fig. 10a, a detail of the embodiment shown in Figs 4 and 9c is shown, namely that the inlet configuration of the perforated inlet ventilation duct 31 and the outlet configuration of the perforated outlet duct 32 has a substantially uniform, rectangular cross-section along the respective predefined length, and wherein the thickness of the perforated inlet ventilation duct and of the perforated outlet ventilation duct is smaller than the combined thickness of insulation material 12 and the hollow space 13.
Also indicated in Fig. 10a is a unit generally designated 40 which incorporates the inlet control means comprising a dehumidifier and a fan. The choice of suitable dehumidifiers and fans for this application is well within the skills of the skilled person.
In the embodiment of Fig. 10a, unit 40 is shown as integrated and has a combined thickness which is smaller than the combined thickness of insulation material 12 and the hollow space 13. Turning now to Fig. 10b, the unit 40 is shown as having a larger thickness and is provided as a replaceable unit.
It also emerges from Fig. 4 that the perforated inlet and outlet ventilation ducts 31, 32 are placed in parallel with each other, in the embodiment shown at two opposite sides of the interior side of the building envelope. Thus, in the present case in which the building envelope is an external wall, the perforated inlet and outlet ventilation ducts 31, 32 are positioned at the floor and the ceiling, respectively.
In the schematic overviews of Figs 5a and 5b, the flows of fluid such as dehumidified air are shown. The difference between Fig. 5a and Fig. 5b resides in the fact that the unit 40 in the Fig. 5a embodiment is embedded in the insulated retrofit system 1, whereas it is located externally thereof in the embodiment of Fig. 5b. At the top, air (or other fluid) is sucked into the perforated outlet ventilation duct 32 from the hollow space; the air is conducted to the dehumidifier which in turn sends the dehumidified air back into the hollow space through the perforated inlet ventilation duct 31 at the bottom.
Eventually, further developments of the embodiment of Fig. 4 will now be described in some detail with particular reference to Figs 6a-6c, 7 and 8a-8f.
As mentioned in the above, in a plurality of spacers 24 in the form of distance pieces is provided between the interior side of the building envelope 11 and the insulation material 12.
Such spacers 24 are used in those cases in which the hollow space 13 between at least a part of the interior side of the building envelope and the insulation material 12 is configured to have a thickness of 5-50 mm, preferably 10-25 mm. Typically, the thickness is about 15 mm.
As indicated in Fig. 4 and shown in more detail in Fig. 6a, the spacer 24 of this embodiment is provided as a profile element with a number of openings 25. The choice of dimension, size and distribution of these openings 25 may be chosen according to specific conditions. Typically, the total opening area of the profile element is 20-80 % and more preferably 35-50% of the cavity section, and in the embodiment shown approximately 40%.
In the alternative embodiment of Fig. 6b, spacers 24 are provided on the side of the insulation material 12 intended to face the wall 11 in the mounted condition of the system 1. The spacers 24 may be provided in any suitable manner, including fastening by adhesion to the insulation material.
In the embodiment of Fig. 6c, which corresponds to the embodiment of Fig. 3d described in the above, the spacers 24 are formed as pegs introduced from the other side of the insulation material 12 to protrude beyond the side of the insulation material 12 intended to face the wall 11 in the mounted condition of the system 1.
Finally, and referring in particular to Figs 7 and 8a-8f, conceivable cross-sectional configurations of the spacer as a profile element 24 with a number of openings 25 are shown as profile elements 24a-24f. It is to be understood that each profile element 24a-24f includes a set of openings 25 of suitable shapes, sizes and distribution.
Variations of the embodiments described in the above are of course conceivable. The means for entering fluid and the means for controlling one or more characteristics of the fluid entering the hollow space are in combination called inlet control means.
The means for entering fluid into the hollow space may be a fan or ventilator. The means for entering fluid into the hollow space may be connected to a dehumidifier incorporated therein or provided separately.
The means for controlling one or more characteristics of the fluid entering the hollow space through the fluid inlet may be a controller connected to the means for entering fluid and a dehumidifier. A heating element for heating the fluid before entering the hollow space may be present as well.
The insulation material is preferably made of a mineral wool.
The sealing is preferably provided by sealing tape along the edges of the insulation material and/or floor, ceiling and openings, such as windows, to prevent ambient air from inside the room from entering the hollow space.
In a further embodiment outlet control means for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid exiting the hollow space through the fluid outlet are provided.
Preferably a humidity detector for detecting the humidity at one or more points between the interior side of the building envelope and the insulation material is provided. That way it is possible to keep track of the moisture build up. The inlet or outlet control means may be controlled based on the detected humidity in the hollow space. For example if humidity above a certain limit is detected in the hollow space, the velocity of the fluid entering the hollow space may be increased. The fluid may be more dehumidified and/or possibly the outlet control means that may include a fan or ventilator for removing fluid or air from the hollow space may be activated increasing the flow of fluid in the hollow space. If no moisture is detected, the ventilation may be turned off. This could be relevant in the summer when the external wall or other external surface is heated by the sun.
As an alternative or in addition to the humidity detectors, the inlet or outlet control means may be controlled by a timer. For example certain times a day or during the year the ventilation is activated and the characteristics of the fluid entering and/or exiting the hollow space are controlled based on time. The timer could preferably be positioned in connection with or on the means for entering fluid into the hollow space.
A controller preferably controlling characteristics of the fluid entering and/or exiting the hollow space such as at least one of velocity, humidity and temperature, are preferably positioned in a utility room/closet controlling both the fluid entering and exiting the hollow space. Preferably several hollow spaces, in for example several walls, are controlled centrally. One controller controlling all characteristics of the fluid both in and out may be provided instead.
The system is generally described in relation to an external wall, but the system may be applied to roofs and floors as well.
It is to be understood that, throughout the description and claims of the specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

Claims

Method for providing dehumidification of a retrofitted insulation of an interior side of a building envelope, especially an external wall (11), comprising:
- attaching an insulation material (12) to the interior side of the building envelope such that a hollow space (13) for conducting a fluid is provided between at least a part of the interior side of the building envelope and the insulation material (12);

- sealing of the hollow space (13) making it substantially fluid tight;

- providing the hollow space (13) with a fluid inlet (27) and a fluid outlet (28);

- providing means for entering fluid into the hollow space (13) through the fluid inlet (27) and for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid entering the hollow space (13) through the fluid inlet (27),

- providing a humidity detector (19) for detecting the humidity at one or more points between the interior side of the building envelope (11) and the insulation material (12),

- providing means for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid exiting the hollow space (13) through the fluid outlet (28), wherein the following steps are carried out:

- entering fluid, preferably in the form of ambient air, more preferably from inside the building envelope, through the fluid inlet (27) and into the hollow space (13),

- controlling at least one of humidity, velocity and temperature of the fluid inflow through the fluid inlet (27) and into the hollow space (13), and AWA#136518

- controlling at least one of velocity, humidity and temperature of the fluid exiting the hollow space (13) through the fluid outlet (28), - regulating the velocity of the fluid both when entering the hollow space and exiting the hollow space such that a substantially atmospheric pressure is maintained inside the hollow space (13) to create a substantially even air distribution throughout the hollow space (13),
characterized in that,
the fluid is entered into the fluid inlet (27) and into the hollow space (13) by means of a perforated inlet ventilation duct (31) having a predefined inlet length and inlet configuration and wherein the fluid is exiting the hollow space (13) through the fluid outlet (28) by means of a perforated outlet ventilation duct (32) having a predefined outlet length and outlet configuration.
Method according to claim 1, wherein at least one of the steps of controlling at least one of humidity, velocity and temperature of the fluid inflow through the fluid inlet (27) and into the hollow space (13), and controlling at least one of velocity, humidity and temperature of the fluid exiting the hollow space (13) through the fluid outlet (28) is carried out by determining at least one of said inlet length, inlet configuration, outlet length, outlet configuration, and size, shape and/or distribution of openings in the perforated inlet and/or outlet ventilation ducts.
Method according to any one of the preceding claims, wherein the fluid, preferably ambient air, is dehumidified and/or heated slightly in the step before entering the inlet.
Method according to any one of the preceding claims, wherein the fluid is circulated such that the fluid exiting the hollow space is heated and dehumidified before entering the system again.
Method according to any one of the preceding claims, wherein the inflow is controlled in response to the detected humidity in the hollow space (13).
System of dehumidifying retrofitted insulation comprising:
- insulation material (12) configured to be attached to an interior side of the building envelope, especially an external wall (11), such that a hollow space (13) for conducting a fluid is provided between at least a part of the interior side of the building envelope and the insulation material (12);

- means for sealing the hollow space (13) making it substantially fluid tight,

- a fluid inlet (27) and a fluid outlet (28);

- means for entering fluid into the hollow space (13) through the fluid inlet (27),

- inlet control means (22) for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid entering the hollow space (13) through the fluid inlet (27),

- outlet control means (23) for controlling one or more characteristics, such as temperature, humidity and velocity, of the fluid exiting the hollow space (13) through the fluid outlet (28), and

- a humidity detector (19) for detecting the humidity at one or more points in the hollow space (13)

- the velocity of the fluid is regulated both when entering the hollow space and exiting the hollow space such that a substantially atmospheric pressure is maintained inside the hollow space (13) to create a substantially even air distribution throughout the hollow space (13),
characterized in that,
the inlet control means (22) comprises a perforated inlet ventilation duct (31) having a predefined inlet length and inlet configuration,and
the outlet control means (23) comprises of a perforated outlet ventilation duct (32) having a predefined outlet length and outlet configuration.
System according to claim 6, wherein the perforated inlet ventilation duct (31) and/or the perforated outlet ventilation duct (32) has a plurality of openings (35) along said predefined inlet length and outlet length, respectively, the shape of said openings (35) being circular, oval, rectangular or in the shape of trapezoidal slits.
System according to claim 7, wherein the inlet configuration of the perforated inlet ventilation duct (31) and/or the outlet configuration of the perforated outlet duct (32) has a substantially uniform cross-section along the respective predefined length, preferably rectangular, and wherein said plurality of openings (35) has a varying size, shape and/or distribution along the respective predefined length.
System according to claim 8, wherein the inlet configuration of the perforated inlet ventilation duct (31) and/or the outlet configuration of the perforated outlet ventilation duct (32) are achieved by relatively large duct dimensions in relation to the airflow to create a pressure chamber effect and wherein said plurality of openings has constant size, shape and distribution along the respective predefined length.
System according to claim 7, wherein the inlet configuration of the perforated inlet ventilation duct and/or the outlet configuration of the perforated outlet duct has a varying cross-section along the respective predefined length, preferably in the shape of a conic frustum, and wherein said plurality of openings has a constant size, shape and distribution along the respective predefined length.
System according to any one of claims 6 to 10, wherein the inlet configuration of the perforated inlet ventilation duct (31) and the outlet configuration of the perforated outlet duct (32) has a substantially uniform, rectangular cross-section along the respective predefined length, and wherein the thickness of the perforated inlet ventilation duct and of the perforated outlet ventilation duct is smaller than the combined thickness of insulation material (12) and the hollow space (13).
System according to any one of claims 6 to 11, wherein the perforated inlet and outlet ventilation ducts (31, 32) are placed in parallel with each other, preferably at two opposite sides of the interior side of the building envelope, in the case the building envelope is an external wall more preferably at the floor and the ceiling, respectively.
System according to any one of claims 7 to 12, wherein the insulation material is provided in the form of insulation slabs (12), each insulation slab (12) being provided with recesses (26) forming said hollow space (13) for conducting the fluid, and wherein 5-95%, or 10-90%, or 20-80%, or approximately 50% of a surface of the insulation material is in direct contact with the interior side of the building envelope.
System according to any one of claims 6 to 13, wherein a plurality of spacers in the form of distance pieces (24) is provided between the interior side of the building envelope (11) and the insulation material (12).
System according to claim 6, wherein the hollow space (13) between at least a part of the interior side of the building envelope and the insulation material (12) has a thickness of 5-50 mm, preferably 10-25 mm.
System according to claim 15, wherein each spacer or distance piece (24) is provided as a profile element with a number of openings (25), the total opening area of the profile element being preferably 20-80 % and more preferably 35-50% of the cavity section.
System according to any one of claims 6 to 16, wherein the inlet control means comprises a dehumidifier and a fan.
System according to claim 17, wherein the inlet control means including the dehumidifier and the fan is provided as an integrated unit (40).
System according to claim 18, wherein the inlet control means including the dehumidifier and the fan is provided as a replaceable unit (40).
System according to claim 18 or 19, wherein the unit (40) of the inlet control means including the dehumidifier and the fan has a combined thickness which is smaller than the combined thickness of insulation material (12) and the hollow space (13).
System according to any one of claims 6 to 20, wherein the interior side of the insulation material (12) is provided with a sheathing (15), such as plywood, Cross-laminated timber, Medium Density Fibreboard, metal or Oriented Strand Board, suitable for receiving attachment means for holding elements mounted to the interior side of the building envelope and insulation material (12).
System according to any one of claims 6 to 21, wherein the interior side of the retrofit insulation system, preferably the interior side of a double sheathing, is provided with a vapour barrier.