HEAT INSULATING EXTERNAL WALL FOR BUILDINGS

Abstract: The invention relates to a heat-insulating external wall (1) for a building, wherein the wall includes an outer facing layer (3), an outer air gap (5), an insulating layer (6), an inner air gap (7) and an inner facing layer (8). The outer air gap (5) communicates with the ambient air through an inlet opening (4), and the inner air gap (7) communicates with the building interior (9) through an outlet opening (11). According to the invention, the insulating layer (6) is comprised of a material which functions as a filter which extracts particles from the passing air. A distribution layer (10) is disposed on the outside and/or the inside of the insulating layer (6). The distribution layer (10) is comprised of a generally air-impermeable material which is porous or is provided with a large number of uniformly distributed small holes. A flow control device (12) is mounted in the outlet opening (11) to maintain a generally constant flow of air through the wall (1), irrespective of the pressure difference between the outside and the inside of the wall (1).

Description: HEAT -CMSULATING EXTERNAL WALL FOR BUILDINGS The invention relates to a heat-insulating external wall for a building, in accordance with the preamble of Claim 1. The basic technical requirements placed on convention¬ al external walls of buildings is that the walls shall function as a climate shell in the building, and that they possibly shall also have a load-bearing capacity. With regard to its function as a climate shell, the heat-insulating capacity of external walls has con¬ stantly increased in significance in recent years. In this regard, the heat-insulating capacity has been in- creased by increasing the thickness of the insulating layer in the wall. However, it is not always possible to enhance insulation with the aid of applied, thick insulating layers. This applies particularly when providing additional insulation internally in existing buildings, since this may change the moisture and heat balance of the wall unfavourably. With the intention of improving heat-insulation capac¬ ity without increasing the thickness of the insulating layer, it has earlier been proposed to lead an air- stream from outside the building in through the wall, so as to counteract the transmission of heat through the wall. However, this has been found difficult to achieve and problems encountered with guiding the air flow in earlier construction proposals have hitherto prevented so-called dynamic insulation concepts from being used generally in conjunction with walls. The object of the invention is to provide a heat- insulating external wall which is a further develop¬ ment of the aforedescribed concepts of dynamic insula¬ tion, and it is the intention that the inventive wall, in addition to improving insulation capacity, shall also be used for ventilating the building interior and for filtering and pre-heating the through-passing air, so that the ventilation air flowing into the building will be held attemperated and free from particles that may be harmful to people suffering from allergies. This object is achieved by constructing the wall in accordance with the features set forth in the charac¬ terizing clause of Claim 1. Suitable embodiments of the inventive wall are defined in the subordinate Claims. The invention will now be described in more detail with reference to different embodiments of an inven¬ tive wall and also with reference to the accompanying drawings, in which Figure 1 is a schematic cross-sectional view of a wall intended for a new building and constructed in accor¬ dance with a first embodiment of the invention; Figure 2 is a schematic, cross-sectional view of a wall intended for internal additional or supplementary insulation in existing buildings and constructed in accordance with a second embodiment of the invention; Figure 3 is a partially cut-away perspective view of a wall constructed in accordance with a third embodiment of the invention; and Figure 4 is a sectional view of the wall shown in Figure 3. Figure 1 is a cross-sectional view of an external wall 1 for a building, of which only parts of two floor structures 2 are shown together with said walls. The external wall 1 includes an outer lining or facing layer 3, which forms the outside of the wall and which is shown in Figure 1 to be a brick wall. However, the outer facing layer 3 may be built from other suitable materials, such as concrete, sheets of different kinds or wood panelling. The outer facing layer 3 is also provided with at least one inlet opening 4, which may be fitted with a grid or insect net (not shown) . Provided inwardly of the outer facing layer 3 is an outer air gap 5 which extends over the whole surface of the wall 1. Provided inwardly of the outer air gap 5 is an insulating layer 6 which forms the main insu¬ lation in the wall 1 and which is preferably comprised of mineral wool. Located inwardly of the insulating layer 6 is an inner air gap 7, which is delimited outwardly by an inner facing or lining layer 8, which forms the inside of the wall 1 and delimits the wall against the building interior 9. In accordance with the invention, there is also pro¬ vided a distributing layer 10, which in the case of the Figure 1 embodiment is disposed as the inner defining surface of the insulating layer 6. The inner facing layer 8 is a dense or impervious layer which is provided in the vicinity of its upper end with an outlet opening 11. Mounted in the opening 11 is a flow control device 12 which functions to control the flow of air through the outlet opening 11. The external wall illustrated in Figure 1 functions as follows: A subpressure is generated in the building interior 9 in a known manner. The devices used to this end form no part of the present invention and are therefore not shown in the drawings. As a result of the subpressure prevailing in the building interior 9, ambient air is drawn in through the inlet opening 4 by suction and is distributed in the outer air gap 5. The air passes from the gap through an outer layer 13, through the insulating layer 6 and through the distri¬ bution layer 10 and into the inner air gap 7, from where the air through the outlet opening sprays into the building interior 9. The flow is controlled by the flow control device 12, which also prevents the air from flowing in the wrong direction. The distribution layer 10, which in the case of the Figure 1 embodiment is disposed on the inside of the insulating layer 6, is comprised of a material which is generally i pervi- ous to air, and is provided with a large number of small perforations (similar to needle holes), which are distributed over the whole surface of the distrib¬ uting layer 10. These perforations are so formed that the airflow passing through the insulating layer 6 is distributed generally uniformly over the whole surface of the insulating layer 6. The inwardly directed flow through the insulating layer 6, said flow having a very low rate of flow, will absorb the heat which is transmitted through the wall 1 from the building interior 9. The inner air gap 7 will thus contain preheated air, which is then delivered to the building interior 9 through the narrow outlet opening 11. The heat-insulating capacity of the wall 1 is thus better than if the insulating layer 6 were to be used without a flow of air therethrough. When the insulating layer 6 is comprised of material that has good filtering properties, such as mineral wool for instance, the insulating layer 6 will also function as a filter for the passing air. This filter will have a very large surface area and thickness and the air moves very slowly through the filter, thereby imparting very good filtering ability to the filter. The air exiting through the outlet opening 11 will therefore be very clean. As will be understood from the aforegoing, the inven¬ tive external wall 1 will fulfil the conventional function of forming part of the shell of the building, and also the additional function of providing a highly effective filter for ventilation air passing to the interior of the building, wherewith the wall will also have an improved heat-insulating capacity because the ventilation air that passes through the wall will take up at least some of the heat which would otherwise be lost to the surroundings, whereby the inflowing air is also attemperated and delivered to the room in a soundless and draught-free fashion. Figure 2 illustrates an external wall 1 which is of the same principle construction as the external wall 1 illustrated in Figure 1. However, the external wall 1 of the Figure 2 embodiment is comprised of an external wall of an existing building with internal additional or supplementary insulation, in accordance with the invention. Those parts which find correspondence in Figure 1 have been identified in Figure 2 with the same reference signs, and the function of the wall shown in Figure 2 is the same as that of the wall shown in Figure 1. The main difference is that the outer facing layer is comprised of an outer layer 3a, an insulating layer 3b and an inner layer 3c which forms the inner side of the existing wall, which has been supplemented in accordance with the invention. Figures 3 and 4 illustrate an inventive external wall 1, wherein those parts that find correspondence in Figures 1 and 2 have been identified with the same reference signs. In the case of the embodiment illus¬ trated in Figures 3 and 4, the distribution layer 10 is disposed on the outside of the insulating layer 6, instead of on the inside thereof. In this case, the outer layer 13 is located outwardly of the distribu- tion layer 10 and functions as a first filter for extracting coarse particles from the air, so as to prevent clogging of the fine perforations in the distribution layer 10. The external wall 1 of the embodiment shown in Figures 3 and 4 is also provided with a third air gap 14 arranged between the inner air gap 7 and the inner facing layer 8. Located between the inner air gap 7 and the third air gap 14 is a thin intermediate layer 15 which is comprised of a material that has good thermal conductivity, for instance metal. The third air gap 14 is completely separate from the inner air gap 7 and the bottom of the gap 14 communicates with the building interior 9 through an inlet opening 16. The third air gap 14 is also open at the top of the gap, so as to form an outlet opening 17 to the build¬ ing interior 9. Also provided in the lower part of the third air gap 14 is at least one heating device 18 which functions to heat air that flows in through the inlet opening 16 and then rises up through the third air gap 14 and flows back into the building interior 9 through the outlet opening 17. In this way, there is produced a warm air flow through the third air gap 14, meaning that the inner facing layer 8 will be kept at a suitable temperature, therewith further reducing the risk of draughts or other discomfort in cold weather. The intermediate layer 15, which has good thermal conductivity, also contributes to further heating the ventilation air in the inner air gap 7, prior to said air exiting through the outlet opening 11. It will be understood that the aforedescribed embodi¬ ments of the inventive external wall can be modified in different ways within the scope of the invention. For instance, the insulating layer 6 can be made of so-called loose wool, i.e. mineral wool which is comprised of loose fibres in the absence of any bind¬ er. This alleviates the problem of possible departure of binder residues from the insulating layer 6. How¬ ever, when loose wool is used, it is necessary to provide some form of supportive layer (not shown) on both sides of the insulating layer 6, said supportive layers assisting the insulating layer 6 in retaining its correct form.

Claims: Claims 1. A heat-insulating external wall (1) for a build¬ ing, said wall including an outer lining or facing layer (3), an outer air gap (5) located inwardly of the outer facing layer (3), an insulating layer (6) located inwardly of the outer air gap (5), an inner air gap (7) located inwardly of the insulating layer (6), and an inner facing layer (8) located inwardly of the inner air gap (7), wherein the outer air gap (5) communicates with the ambient air through at least one inlet opening (4) in the outer facing layer (3), and the inner air gap (7) communicates with the building interior (9) through at least one outlet opening (11) in the inner facing layer (8), and wherein the insu¬ lating layer (6) is comprised of a material which is air-permeable at least in a direction away from the outer air gap towards the inner air gap (7), c h a r a c t e r i z e d in that the insulating layer (6) is comprised of a material which will func¬ tion as a filter for extracting particles from the passing air; in that a distribution layer (10) is disposed on the outside and/or the inside of the insulating layer (6), said distribution layer (10) being comprised of a generally air-impermeable materi¬ al and being provided with a large number of uniformly distributed perforations or comprising a material of correctly balanced porosity; and in that a flow con¬ trol device (12) is arranged in the outlet opening (11) or adjacent thereto for maintaining a generally constant flow of air through the wall (1) independent¬ ly of the pressure difference between the outside of the wall (1) and its inside. 2. A wall according to Claim 1, c h a r a c ¬ t e r i z e d in that the insulating layer (6) is comprised of mineral wool sheets. 3. A wall according to Claim 1, c h a r a c ¬ t e r i z e d in that the insulating layer (6) is comprised of mineral wool in the form of loose wool, wherein a supportive layer is provided on each side of the insulating layer (6) as a support for the loose wool. 4. A wall according to any one of Claims 1-3, c h a r a c t e r i z e d in that the flow control device (12) is a pressure controlled valve which adjusts the throughflow area automatically in depen¬ dence on the pressure difference between the outside of the wall (1) and its inside. 5. A wall according to any one of Claims 1-4, c h a r a c t e r i z e d in that the distribution layer (10) is comprised of a sheet which is perforated with holes that provide a suitably balanced air perme¬ ability. 6. A wall according to any one of Claims 1-5, c h a r a c t e r i z e d in that a filtering layer (13) is arranged outside the distribution layer (10) for extracting coarse particles from the passing air. 7. A wall according to any one of Claims 1-6, c h a r a c t e r i z e d in that a thin intermediate layer (15) and a third air gap (14) are provided between the inner air gap (7) and the inner facing layer (8), wherein both the intermediate layer and the third air gap communicate with the building interior (9) at the top of said layer and said gap. 8. A wall according to Claim 7, c h a r a c - t e r i z e d in that the intermediate layer (15) is comprised of a material of good thermal conductivity, for instance metal. 9. A wall according to Claim 7 or 8, c h a r a c ¬ t e r i z e d in that a heating device (18) is mount¬ ed in the third air gap.

Inventors: ANDERSSON KURT ALLAN, CARLSSON TAGE, ANDERSSON, KURT, ALLAN, CARLSSON, TAGE
Applicants: ANDERSSON KURT ALLAN, CARLSSON TAGE, SKANSKA TEKNIK AB, ANDERSSON, KURT, ALLAN, CARLSSON, TAGE
Application year: 1993
Main classification: E04B1
IPC codes: E04B1, F24D3, F24F5, F24J2