EP1706549A1

EP1706549A1 - Method and system for ventilating a building provided with cavity walls.

Info

Publication number: EP1706549A1
Application number: EP04808781A
Authority: EP
Inventors: Rob Van Der Pluijm; Jacobus Cornelis Antonius De Kroon; Peter Walter Bouma; Johan Cornelis Phaff; Bastiaan Knoll
Original assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Current assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Priority date: 2003-12-12
Filing date: 2004-12-13
Publication date: 2006-10-04
Also published as: NL1025014C2; WO2005056945A1

Abstract

A method for ventilating at least one space in a building with outside walls, of which at least two are designed as cavity walls with an outer leaf, an inner leaf and a cavity, while on the one sfide, air is transported from the surroundings of the building finto the at least one space to be ventilated and, on the other sfide, air is transported from the at least one space to be ventilated to the surroundings. In order to make the ventilation highly independent from the direction of the wind and strength of the wind, a pressure differente between two cavities is equalized by air displacement from the one cavity to the other cavity and air is supplied from one cavity via provisions provided to that end through the inner leaf to the at least one space to be ventilated.

Description

Title: Method and system for va'ήffiatmg a building provided with cavity walls.

The invention relates to a method for ventilating at least one space in a building with outside walls, of which at least two are designed as cavity walls with an outer leaf, an inner leaf and a cavity, while, on the one side, air is transported from the. surroundings of the building through the outer leaf into a cavity and from a cavity through the inner leaf into a space to be ventilated and, on the other side, air is transported from a space to be ventilated to the surroundings, and to a system for carrying out such a method. Such a manner of ventilating is known from French patent application 2.614.637, wherein an outside wall is formed from at least three leaves mutually forming at least two cavities, which are interconnected by appropriate means. Thus, ventilation air from the surroundings can be supplied through the various leaves and cavities of the outside wall to a space to be ventilated situated therebehind. The operation of such a ventilating system depends strongly on weather conditions. When it is calm, insufficient ventilation occurs, particularly when, in that case, no operative discharge ventilator is present. When there is a strong wind, excess ventilation occurs, often experienced as a draught. This in turn, may lead to the ventilation provisions being shut resulting in too little ventilation, which can be detrimental to the health of the people present in the building. Yet, not closing the ventilating provisions when there is a strong wind can result in unhealthy living conditions too. When there is a strong wind, the supply at the weather side of the building may be greater than the discharge capacity. As a result, at the lee side, no supply of fresh ventilation air takes place but discharge via the ventilation provisions. When air is discharged via the ventilation provisions intended for supply, the risk of condensation in these ventilation provisions is great, resulting in the growth of micro-organisms. When the wind turns or when it blows more softly, then, as usual and as intended, air will be supplied via these ventilation provisions. This supplied air will then be contaminated with the referred-to micro-organisms, which greatly troubles and seriously harms the ever- increasing group of people with respiratory disorders. Another possible manner is balanced ventilation. Here, supply takes place via channels with grilles and supply ventilators, while the discharge too takes place via channels with grilles and discharge ventilators, while "balanced" implies that the supply and discharge of air are equal to each other. With this manner of operation, the air supply can be configured such that it will not be experienced as a draught while, if desired, this system can also be combined with air heating. However, as the supply and discharge are balanced, with wind excess pressure, the leakage losses via windows, slits and the like will be relatively great with the above described health risk when the airflow is reversed. Although, through the controlled supply and discharge of air via channels, this system offers the possibility for recovering heat from the discharged air and heating the supplied, fresh ventilating air with this recovered heat, this energetic advantage to be achieved is considerably limited by the relatively great leakage losses. This system also leads to a temperature equalizing in all spaces, which is considered undesirable, in particular in houses. The fact is that in modern houses, efforts are directed towards temperature zoning between, for instance, living and sleeping spaces, or between spaces at ground level and on the first floor. Furthermore, such a system is relatively expensive and occupies much space due to the channels required towards the various spaces. A third possibility is demand-controlled ventilation. Here, the actual airflows through the ventilation provisions are measured by means of sensors and are compared, in a central control unit, to the pre-set desired values per space. Depending on the result of this comparison, signals are emitted adjusting, or not adjusting, valves situated in the ventilation provisions. With this manner of operation, by automatically adjusting the valves, changing wind is taken into account, while also, leakage losses can be compensated to a certain extent, so that energetic losses and reversal of the airflow can be limited. However, such a system requires a considerable investment in necessary material such as channels, ventilators, computer, sensors, ducts etc. Furthermore, such a system is labour-intensive and vulnerable during construction and maintenance-prone during use. Although central discharge is involved, the supply is decentralized, which means that heat recovery from the discharged air is possible but that this recovered heat is not added to the supplied air but is to be used differently, for instance by supplying to a hot water boiler. The object of the invention is to render, with relatively simple means, the ventilation of a building as independent as possible from varying wind directions or wind force while, simultaneously, the leakage losses and reversal of the airflow are prevented. This is achieved according to the invention with a method of the type described in the opening paragraph in that a pressure difference between a first cavity in a first outside wall and a second cavity in a second outside wall is equalized by air displacement from the first or the second cavity, respectively, to the second or first cavity, respectively. Through these measures, natural wind pressure differences between the coupled cavities are averaged out, in other words, by coupling the respective cavities, in particular pressure differences between weather side and lee side can be equalized while the coupled cavities act as air distribution ring having, virtually independently of wind speed and wind direction, more or less uniform excess pressure relative to the spaces to be ventilated in the building. This, now, implies a highly improved control of the supply to the spaces to be ventilated, because the pressure difference across the inner leaf of a random space hardly varies when wind force or wind direction changes so that the traditional disturbance of the ventilation air supply by the wind is eliminated. Furthermore, this not only signifies that a uniform and reproducible ventilation per space is possible, but also entails the possibility of ventilating autonomously, per space, and hence advances greatly towards the more and more intended temperature zoning. On the one side, equalizing pressure in the coupled cavities also comprises reduction of peak pressures and, hence, reduction of leakage losses via the inner leaf and, therefore, energetic losses. On the other hand, equalizing pressure means prevention of reduced pressure and hence of reversal of the airflow, that is, prevention of airflow from the space to be ventilated to the cavity, and thus of condensation and growth of micro- organisms, which strongly promotes health. The extent of the pressure difference across the inner leaf can then be accurately regulated, when a central mechanical exhaust ensures that the pressure in a space to be ventilated is smaller than the equalized pressure in the cavities, while determining and checking this pressure difference by equalizing the pressure across the cavities can be carried out relatively easily. Temporarily increasing the discharge when cooking, showering et cetera is a matter of increasing the reduced pressure of the mechanical exhaust. Replenishing the air then occurs by itself in that the supplied airflow via the open provisions also temporarily increases. The thus virtually constant excess pressure in the cavity, which is characterizing for the present method, in view of the fact that the cavity extends behind a whole inner leaf, yields particular advantages with respect to the possibilities of supply of the ventilation air to the space to be ventilated, as the air from the cavity can be introduced, distributed over the surface of the inner leaf, into a space to be ventilated. This offers optimal possibilities for a draught-free supply of ventilation air, because the supply provisions are no longer coupled to the location and size of the windows with their cold trap or to the location of the supply channels. For instance, according to a further embodiment of the invention, it may be provided that the air is supplied to a space to be ventilated distributed over an upper edge area of an inner leaf, and preferably over its full width. For further refining ventilation and climate control in a space to be ventilated, it can be provided that heat is supplied to or extracted from air introduced from the cavity into a space to be ventilated. From an energetic viewpoint, it is then further preferred that heat be extracted from air discharged from a space to be ventilated, while heat extracted from the air discharged from a space to be ventilated is transferred to air supplied from the cavity to a space to be ventilated. When ventilating according to the present invention, if desired, the wish to meet temperature zoning can be satisfied relatively easily, if heat is extracted from the air discharged from all the spaces to be ventilated, which heat is transferred to the air supplied to a part of all the spaces to be ventilated. The ventilation method according to the invention can then be advantageously combined with balanced ventilation, when air to be heated is led from a cavity through a heat exchanging installation, where, also, the air from all the spaces to be ventilated is guided through, and is urged by mechanical transport means from the heat exchanging installation via at least one channel into at least one space to be ventilated. In this manner, the advantages of both ventilation methods can be optimally combined. During at least a large part of the heating season, a lower temperature is deemed more desirable in sleeping quarters than in a living room. In those situations, heating of the supplied ventilation air can be considered to be more of a nuisance than it is desirable. In contrast, in living quarters, often, a higher temperature is deemed desirable. This can be realized through the basic heating, for instance a floor heating. As, however, the ventilation air has sufficient heat content to serve as additional heating, it is possible, through the proposed measures, to recover heat from all the discharged air while simultaneously, temperature zoning can be realized. The heat recovered from all discharged air is transferred to the centrally drawn-in air which is guided to the living quarters via ducts. As the latter air is extracted from the pressure-equalized cavities as well, the leakage losses which are normally relatively great in case of balanced ventilation, with all the associated drawbacks, are limited and reduction of disturbing influences of the wind on the ventilation process is ensured too. The invention also relates to a system for ventilating at least one space in a building with outside walls, of which at least two are designed as cavity walls with an outer leaf, an inner leaf and a cavity, while inlet and outlet means for ventilation air are provided which are in communication with the surroundings, the inlet means thereof being arranged in the outer leaves and being in communication with supply means arranged in the inner leaves and ending up in a space to be ventilated, and the outlet means being in communication with discharge means for extracting air from a space to be ventilated. In order to prevent the influences of wind direction and wind force with such a system to a considerable extent, it is proposed according to the invention that at least two cavities located in different outside walls are mutually in open communication by connecting means. Through these relatively simple and inexpensive features, the outside walls provided with cavities form, as to pressure, an equalized cushion around the spaces to be ventilated, so that, largely independently of a locally varying wind pressure exerted on the outer leaves of the cavity walls, a virtually constant pressure difference prevails across the inner leaves resulting in a highly uniform ventilation in all the spaces to be ventilated. More in particular, it is then preferred that at least the cavities of two outside walls situated on opposite sides of the building are mutually in open communication, so that it can be effectively prevented that an excess pressure on the one side of a building and a reduced pressure on the other side could disturb the desired, uniform ventilation of the various spaces to be ventilated. To, then, set the degree of ventilation and keep it constant, it is further preferred that the outlet means be connected to a central, mechanical exhaust. By regulating the exhaust, the pressure difference across the inner leaves and hence the degree of ventilation can be regulated to the desired level. One cavity extends over the entire surface of the inner leaf so that at each location of the inner leaf, a potential source of ventilation is present. This can be used advantageously, in that the supply means can comprise passages extending through the inner leaf, which, therefore, cannot only be disposed at any desired location but also, and in a relatively simple manner, can be provided at any desired moment. In order to be able to block the supply of air during calamities outside, such as, for instance, an escaped gas cloud, it is further preferred that the passages can be sealed off to the space to be ventilated by means of a closing mechanism. Naturally, then, also the discharge ventilator needs to be switched off. Additionally, it can be noted that if one should forget to close off one single passage, the highly equalized pressure difference across the inner leaf ensures that the leakage flows remain much lower than with other known systems. The freedom offered by the system according to the invention as to the placing of the air supplies offers optimal possibilities for situating and designing the supply such that a draught-free supply is ensured at all times, even when unheated air is supplied. This can, for instance, be realized when the passages are situated in an upper edge area of the inner leaf adjacent a ceiling of a space to be ventilated, while it is further preferred that the passages be covered by a hollow baseboard comprising an open communication with the space to be ventilated. Thus, the supplies can be realized by drilling passages through the inner leaf and the insulation, after which on the inner leaf, by means of bolts, brackets are attached, with a center-to-center distance of, for instance 1 m whereupon the hollow baseboard is snapped onto the brackets. All this can be carried out in one go by one installer at the most suitable moment thereto. The hollow baseboard construction offers many further possibilities and advantages. For instance, it is possible that the closing mechanism is included in the hollow baseboard such that it can close off the open communication, which open communication is, for instance, of slot-shaped design in longitudinal direction of the hollow baseboard. When, further, the hollow baseboard extends over the entire width of the inner leaf, the distribution of the supplied air can be further refined and spread, which offers the possibility of further optimizing the climate in a space to be ventilated. To this end, additionally, it may be provided that the supply means between the cavity and the space to be ventilated comprise filter means, these filter means being accommodated in the passages and/or being borne by the hollow baseboard. In addition, the hollow baseboard can be used for many other purposes, more in particular, the hollow baseboard can for instance serve as supporting element for a plurality of different elements, such as cords, sensors, heat exchanging elements, paintings, curtains, et cetera. A further optimization of the climate in the spaces to be ventilated can be obtained when the supply means comprise a heat exchanging element, which is connected to a source of heat or coldness. Such a heat-exchanging element, which can for instance be accommodated in a hollow baseboard, can for instance be designed as a hose running to and fro many times and carrying a heat-transporting medium. In case heating of the supplied air is desired, heat can be added to the medium, which heat is extracted from the centrally discharged air. In case cooling of the supplied air is desired, the hose can be connected to a source of coldness, such as ground water. A combination of the advantages of the ventilation system according to the invention and the known balanced ventilation system can be obtained in that with a building with more than one space to be ventilated, or spaces to be ventilated situated on more than one floor, the supply of ventilation air to at least one space to be ventilated takes place via supply means in at least one inner leaf, and to at least one other space to be ventilated via at least one channel coming from an installation provided with mechanical air supply and discharge means, which installation is provided with an inlet for fresh air connected with the cavities which are mutually in open communication, with a further inlet connected with the discharge means of all spaces to be ventilated, and with heat exchanging elements for extracting heat from the air coming from the discharge means and supplying it to the fresh air drawn in via the inlet which can be supplied, mixed or not mixed with air coming from the discharge means, via the at least one channel to the at least one space serviced by it. Due to these features, with an optimal energy management, a temperature zoning can be realized and, despite the use of balanced ventilation, leakage losses and reversal of the airflow can be limited. At locations where no heating of the supphed air is desired, it is supplied directly from the cavity to the respective space. The air discharged from that space is guided, together with the discharged air from the other spaces to be ventilated, through a heat exchanging installation, so that heat loss via the discharged air is limited to a minimum, while in the heat exchanging installation, the recovered heat is added to air which is extracted from the pressure-equalized cavities, and is transported via this installation and ducts connected thereto to spaces to be serviced with pre-heated air. It is self-evident that within the framework of the invention as determined by the accompanying claims, many modifications and variants are possible. For instance, parts of an outside wall where no cavity is situated, for instance windows and doors, can be bridged by means of ducts, which are on both sides in open communication with the cavity walls which are mutually in open communication. If desired, these ducts can be provided with ventilation air supplies. Although a hollow baseboard is preferred, the supplies can be provided with air distribution and/or passage means in any suitable manner. It can further be considered to bring the cavity walls, which are mutually in open communication with each other, in open communication with spaces under floors and ceilings, in which spaces, in turn, supplies can be arranged. Naturally, the cavities which are mutually in open communication with each other can also be connected with hollow spaces in walls other than those indicated as cavities, such as, for instance, hollow partition walls and prefab partition walls. Bringing the various cavity walls into open communication can be realized in any suitable manner, while channels and ducts can be considered, but also a crawl space suitable to that end or hollow floors such as hollow core plate floors.

Claims

1. A method for ventilating at least one space in a building with outside walls, of which at least two are designed as cavity walls with an outer leaf, an inner leaf and a cavity, while on the one side, air is transported from the surroundings of the building through the outer leaf into a cavity and from a cavity through the inner leaf into a space to be ventilated and, on the other side, air is transported from a space to be ventilated to the surroundings, characterized in that a pressure difference between a first cavity in a first outside wall and a second cavity in a second outside wall is equalized by air displacement from the first or the second cavity, respectively, to the second or first cavity, respectively.

2. A method according to claim 1, characterized in that via a central mechanical exhaust it is ensured that the pressure in a space to be ventilated is smaller than the equalized pressure in the cavities.

3. A method a according to claim 1 or 2, characterized in that the air from the cavity can be introduced, distributed over the surface of the inner leaf into a space to be ventilated

4. A method according to claim 3, characterized in that the air is supplied to the space to be ventilated distributed over an upper edge area of an inner leaf.

5. A method according to claim 4, characterized in that the air is supplied to the space to be ventilated over the full width of the inner leaf.

6. A method according to any one of claims 1 - 5, characterized in that the heat is supplied to or extracted from the air introduced from a cavity into a space to be ventilated.

7. A method according to claim 6, characterized in that heat is extracted from the air discharged from a space to be ventilated.

8. A method according to claim 7, characterized in that heat extracted from the air discharged from a space to be ventilated is transferred to air supphed from the cavity to a space to be ventilated.

9. A method according to claim 8, characterized in that heat is extracted from the air discharged from all the spaces to be ventilated, which heat is transferred to the air which is supphed to a part of all the spaces to be ventilated.

10. A method according to claim 9, characterized in that air to be heated is led from a cavity through a heat exchanging installation, where the air from all the spaces to be ventilated is guided through as well, and is driven by mechanical transporting means from the heat exchanging installation via at least one channel into at least one space to be ventilated.

11. A method according to claim 10, characterized in that unheated air is supphed directly from the cavity to spaces where no heated air is driven to.

12. A system for ventilating at least one space in a building with outside walls, of which two have been designed as cavity walls with an outer leaf, an inner leaf and a cavity, inlet and outlet means for ventilating air which are in communication with the surroundings being provided, while the inlet means thereof are arranged in the outer leaves and are in communication with supply means arranged in the inner leaves and ending up in a space to be ventilated, and the outlet means are in communication with discharge means for extracting air from a space to be ventilated, characterized in that at least two cavities situated in different outside walls are mutually in open communication by connecting means.

13. A system according to claim 12, characterized in that the cavities of two outside walls situated on opposite sides of the building are mutually in open communication.

14. A system according to claim 12 or 13, characterized in that the outlet means are connected to a central mechanical exhaust.

15. A system according to any one of preceding claims 12 — 14, characterized in that the supply means comprise passages extending through the inner leaf.

16. A system according to claim 15, characterized in that the passages can be closed off to the space to be ventilated by means of a closing mechanism.

17. A system according to claim 15 or 16, characterized in that the passages are situated in an upper edge area of the inner leaf adjacent a ceiling of a space to be ventilated.

18. A system according to any one of claim 15 - 17, characterized in that the passages are covered by a hollow baseboard comprising an open communication with the space to be ventilated.

19. A system according to claims 16 and 18, characterized in that the closing mechanism can close off the open communication.

20. A system according to claim 18 or 19, characterized in that the open communication is of slot-shaped design in longitudinal direction of the hollow baseboard.

21. A system according to any one of claims 18 — 20, characterized in that the hollow baseboard extends over the entire width of the inner leaf.

22. A system according to any one of preceding claims 12 - 21, characterized in that the supply means between the cavity and the space to be ventilated comprise filter means.

23. A system according to claim 22, characterized in that the filter means have been accommodated in the passages.

24. A system according to claim 22, characterized in that the filter means are borne by the hollow baseboard.

25. A system according to any one of claims 18-22, characterized in that the hollow baseboard can serve as supporting element for a plurality of possible elements, such as cords, sensors, heat exchanging elements, paintings, curtains, et cetera.

26. A system according to any one of claims 18-23, characterized in that the hollow baseboard is mountable through coupling with brackets attached to walls surrounding the space to be ventilated.

27. A system according to any one of the preceding claims 12-26, characterized in that the supply means comprise a heat exchanging element, which is in communication with a source of heat or cold.

28. A system according to claim 27, characterized in that the heat exchanging element is in communication with a heat recovery installation, which is part of the outlet means and extracts heat from the air discharged to the surroundings.

29. A system according to any one of the preceding claims 12-28, characterized in that with a building with more than one space to be ventilated, or spaces to be ventilated situated on more than one floor, the supply of ventilation air to at least one space to be ventilated takes place via supply means in at least one inner leaf, and to at least one other space to be ventilated via at least one channel coming from an installation provided with mechanical air supply and discharge means, which installation is provided with an inlet for fresh air connected with the cavities which are mutually in open communication, with a further inlet connected with the discharge means of at least a number of spaces to be venti-lated, and with heat exchanging elements for extracting heat from the air coming from the discharge means and supplying it to the fresh air drawn in via the inlet which can be supplied, mixed or not mixed with air coming from the discharge means, via the at least one channel to the at least one space serviced by it.

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