Method and device for reducing a flow of soil air to indoor air in a building

Abstract

The present invention relates to a method for reducing a flow of soil air to the indoor air in a building (1), wherein the building comprises at least one wall (2), which wall comprises a permeable channel (23) connected with soil air, wherein the method comprises achieving a flow stop (24) for the soil air in the permeable channel (23). The invention also pertains to a device to reduce the flow of soil air to indoor air in a building (1).

Claims

1. Device for reducing a flow of soil air to indoor air in a building (1), wherein the building (1) comprises at least one wall (2), and said device comprises a permeable channel (23) connected with soil air, a flow stop (24) for the soil air in the permeable channel (23) to reduce the flow of soil air, a faade (22) fitted on an inner part (21) of the wall (2), said faade (22) comprising said permeable channel (23), said permeable channel (23) containing an air volume, the flow stop (24) separating at least a part of the faade (22), to divide the air volume into a first upper air volume (25) and a second lower air volume (26), and comprising a recess in the faade (21) through the permeable channel (23), to distance a first part of the permeable channel (23) which includes the first upper air volume (25), and a second part of the permeable channel (23) which includes the second lower air volume (26), from one another, and said stop (24) positioned to suck ambient outdoor air through the faade (22) and into said first upper air volume (25) rather than from said second lower air volume (26).

2. Device according to claim 1, additionally comprising an object insertable into said recess (24).

3. Device according to claim 1, wherein said flow stop (24) is obtained by removing a part of the faade, which is connected with the ground.

4. Device according to claim 1, wherein the flow stop comprises a drip strip (27), which is fitted in the wall and arranged to protect the faade below the flow stop from rain and snow.

5. Device according to claim 4, wherein the drip strip is designed with a drip protection part, which is integrated with the drip strip or which is moveable in relation to the drip strip and may be attached to it.

6. Device according to claim 1, wherein the flow stop is integrated with the faade.

7. Device according to claim 1, wherein the flow stop comprises a seal between the wall and a baseplate of the building.

8. Device according to claim 1, wherein the flow stop (24) is arranged level with or lower than a floor on the ground floor of the building.

9. Building comprising at least one wall with a device according to claim 1.

Description

DRAWINGS

(1) The invention is described in detail below with reference to the enclosed drawings, wherein

(2) FIG. 1 shows a plane view of a building into which soil air leaks through floors and walls;

(3) FIG. 2a shows a cross sectional view of a house wall with a recess in the faade, according to a preferred embodiment of the present invention;

(4) FIG. 2b shows a cross sectional view of a house wall where a part of the faade connected with the ground has been removed;

(5) FIG. 2c shows a cross sectional view of a house wall where an object has been inserted as a flow stop;

(6) FIG. 3 shows a perspective view of a building with a device according to the invention;

(7) FIG. 4 shows a cross sectional side view of a wall where a permeable part is inside the wall;

(8) FIG. 5 shows a cross sectional side view of the wall in FIG. 4, with a preferred embodiment of an alternative method to reduce radon concentration by removing air from the wall; and

(9) FIG. 6 shows a cross sectional view of a wall and a baseplate of a building, where a flow stop is inserted between the same.

DETAILED DESCRIPTION

(10) FIG. 1 shows a building 1 with walls 2, a baseplate 3 and a roof 4, into which soil air, which may contain among others radon from radon contaminated soil, leaks. As has long been known in the art, soil air oozes up toward the baseplate 3 and penetrates into the building through cracks or leaks and merges with the indoor air in the building. This is illustrated with dashed arrows toward the baseplate 3 in the figure. The conventional manner of reducing the radon level has been, as illustrated in the figure, to drill holes, so-called radon extractors 31, through the baseplate 3 and connect them to pipes 32 connected to an extractor device 33 with a fan that blows the radon gas out of the building, thus reducing the amount of gas present below the building. However, this evacuation only creates a reduction of soil gas between the outer foundation walls that function as barriers and prevents evacuation of soil gas beyond these.

(11) Please note that the use of terms such as up, down, top or bottom herein relate to the directions that are normally up and down on a building, i.e. up towards a roof and down toward the ground on which the building stands. Please also note that radon is specified here as an example of harmful substances in soil air, and that the invention is also advantageously used to reduce the level of other substances (humidity).

(12) The figure also illustrates the second and hitherto unknown manner in which radon penetrates into the building. Inside the wall 2 there is generally an inner part 21, which is load bearing in at least some part of the wall, and a faade 22, which is attached to the inner part 21 and designed to provide insulation and a water-proof surface layer to prevent water from penetrating into the wall 2. Often, the faade 22 runs along the inner part 21 all the way down to the ground, to achieve a uniform appearance. In the faade 22 there is also a permeable channel 23 in which an air volume may move, often in the form of a pre-cast or plaster surface. Radon may penetrate into a wall from the surrounding ground and merge with the air volume, rising through thermal movement and penetrating into the building via leaks or penetrations in the inner part 21 of the wall 2, so that it merges with the indoor air. A permeable channel is thus an elongated area in the wall, which may be penetrated by air, in this case soil air containing radon gas.

(13) FIG. 2a-c shows the wall 2 in more detail, where the inner part 21, the faade 22 and the permeable channel 23 are visible. In FIG. 1, there is an air volume in the permeable channel 23, able to move freely therein, but FIG. 2a-c also illustrates different versions of a flow stop 24, to achieve an obstacle to the movement of the soil air up through the wall.

(14) In FIG. 2a the flow stop 24 is in the form of a recess in the faade 22, all the way in through the permeable channel 23 to the inner part 21. Thanks to the flow stop 24 the air volume is divided into a first air volume 25 in the permeable channel 23 on one side of the flow stop 24, and a second air volume 26 in the permeable channel 23 on the other side of the flow stop 24. A flow stop 24 thus prevents a connection between the first air volume 25 and the second air volume 26, so that they are separated from each other. The second air volume 26 is located in the lower part of the faade 22 and therefore contains soil air with radon, while the first air volume 25 is located in an upper part of the faade 22, above the flow stop 24, and is accordingly radon free. Thanks to the flow stop, air sucked into the first air volume 25 is taken from the ambient outdoor air rather than from the second air volume 26.

(15) The flow stop 24 may thus be designed in many different ways, and in its simplest form it is a distance between the first air volume 25 and the second air volume 26, sufficiently large to allow circulation of outdoor air in the recess, which distance is within the interval 2 to 15 cm.

(16) In FIG. 2b, the flow stop 24 is in the form of a recess made where the bottom part of the faade, connected with the ground, has been removed. Accordingly, air in the permeable channel 23 is taken from the surrounding environment rather than from the ground.

(17) In FIG. 2c the flow stop 24 is in the form of an object, for example a plate or similar, which is inserted into the faade and cuts off the permeable channel 23, preventing the flow of soil air.

(18) When the flow stop 24 is in the form of a recess as in FIG. 2a, it is advantageous also to add a drip strip to be fitted at the inner part 21 of the wall 2 and running out from the wall 2 essentially perpendicular in relation to said inner part 21. The drip strip 27 is attached with fixings and is preferably angled downwards in an external part to prevent water from rain and snow entering into the faade 22 in the bottom part. In order to secure the thermal buoyancy in the permeable channel 23 above the flow stop 24, the drip strip 27 is fitted at a distance from the faade so that air may easily flow between the faade 22 and the drip strip 27 and penetrate into the permeable channel 23 to merge with the first air volume 25. This is illustrated in FIG. 3, with a building 1 where a recess has been made to form a flow stop 24. Furthermore, a drip strip 27 has been fitted along at least two walls 2. The flow stop 24 is essentially horizontal and without interruptions, which prevents radon contaminated air from the ground from penetrating past the flow stop 24 and continuing up into the first air volume 25 above the flow stop 24. It is thus obvious that it is advantageous for a flow stop 24 to be made along all the walls 2 of the building 1, or at least along all the walls 2 where the faade 22 runs all the way down into the ground, or at least along an entire wall 2 from a first end to a second end, but it is also possible that a reduction of the radon level may be achieved by way of a flow stop 24 along only one wall 22 or even a part of a wall 22.

(19) If the flow stop 24 is a recess, the recess is preferably approximately 2-15 cm high, depending on the load bearing capacity of the wall and its construction at a given building, but it is obvious that other height measurements or depth measurements may be suitable at certain buildings, depending on their specific characteristics.

(20) Since the flow stop 24 is arranged at the same level or lower than a floor on the ground floor of the house, the soil air is efficiently prevented from penetrating into the ground floor and thus also into higher floors. It is thus very advantageous for the flow stop to be placed level with or lower than the floor, even if other placements may also be considered, depending on the design and characteristics of the wall, in particular the placement of the permeable channel.

(21) FIG. 4 shows an alternative embodiment of a wall 2, where the wall's inner part 21 is heterogeneously designed and sufficiently porous for a permeable channel 23, extended to form a permeable area, to fit inside the inner part 21 itself. An example of a material with such heterogeneous and porous characteristics is concrete, but other materials may also be applicable. Radon gas may thus penetrate up into and through the inside of the wall 2 from the underlying ground, and may then ooze into the building 1 from there. In order to reduce the radon concentration in indoor air, a hole 41 may be created, for example by way of boring from the inside of the house, from the surface and into the inside of the wall 2, and an extraction device 42 may be connected to such hole, with a fan 43 arranged to extract radon-contaminated air from the wall 2, wherein an under-pressure is created in the wall 2. This is illustrated in FIG. 5.

(22) FIG. 6 shows an embodiment where soil air leaks up through the insulation, which may for example consist of Heraklith insulation boards, i.e. through an area where the baseplate 3 of the house is attached to the wall 2. The flow stop 24 is thus achieved thanks to a seal between the baseplate 3 and the wall 2.

(23) Please note that the above description referring to one embodiment may also be freely combined with other embodiments, as a person skilled in the art will realise.