Alternating, decentralized, regenerative ventilation installation

The subject-matter of this invention is a alternating, decentralized, regenerative ventilation installation in particular for the purpose of ventilating apartments. According to the invention, the ventilation installation is suitable for providing sufficient volume of appropriate air quality for the bounding constructed structures and users in buildings with doors and windows of high air-tightness (primarily apartments), the simple, energy- saving and cost-efficient implementation of air exchange, and thereby avoiding condensation and the resulting mould growth.

In buildings constructed with conventional wall structures (small bricks, B30, Porotherm, Ytong...) and conventional doors and windows of low air tightness (box-type, Tessauer windows ...), there is no problem posed by the removal of the several liters of daily generated internal humidity under normal use in the winter heating period. The large majority of this humidity, at least 95% on the average leaves with the hourly 1-1 .5-fold air change rate, by way of natural airing, via the gaps of doors and windows, while the remaining part via the wall structures, by way of steam diffusion. Therefore, ventilation has a key role in the winter humidity transport, and if for some reason the air change rate drops significantly, wall structure cannot take over this function, support the considerably increased volume of ventilation and vapour discharge. One well-known consequence - if no ventilation is provided in any other manner - is the accumulation of the relative humidity of internal air, which in extreme cases leads to vapour condensation from the wall corners with thermal bridges, and then directly to mould growth. Mould is not simply un- aesthetic, but hazardous to health, as well. It is difficult to remove, and in the lack of proper ventilation it re-emerges in a short while.

Modern, energy-saving doors and windows incorporated in new buildings or installed in older buildings during reconstruction works feature highly air-tightness in comparison to their conventional counterparts. According to literary data, natural air exchange taking place under such circumstances has just a 0.1-0.2-fold hourly value, i.e. only approximately one-tenth of the air exchange occurring with conventional structures, and just a fraction of the 0.5-fold air change rate recommended as the health threshold value. Naturally, there are considerable benefits accompanying the use of these doors and windows: reduced heat load in winter-time (or cooling load in the summer), decrease in external noises, while ventilation is not "spontaneous", but can be performed wherever and how-

ever one likes - yet, it calls for carefully designed, installed and operated ventilation. With some exaggeration, it can be claimed that windows featuring highly air-tightness are not designed for ventilation! They still can be used for ventilation purposes when opened manually, but definitely they cannot ensure proper ventilation, and thus other solutions should be sought for.

In order to avoid condensation and the resulting mould growth with doors and windows of high air-tightness, and provide for the penetration of fresh air needed for health purposes, there have been several solutions worked out and applied. Naturally, when letting the external, cold ventilation air in it should be heated in some (possibly energy-saving) way, which requires heating energy, and therefore entails significant costs. It is especially true in the light of the associated requirements, as with the application of bounding structures (walls, floor structures, doors and windows ...) with improved heat transmission coefficients the transmission heat demand of buildings tends to decrease, and concurrently the proportion of ventilation heat demand rises.

As concerning the widely known solution, first the so-called "ventilation" radiator of the Purmo company is to be mentioned. Here, the external, fresh and dry air flows via an inlet pipe installed by breaking through the wall and a filter to the surface of the radiator, and then to the room after being heated. This solution does not call for any separate supply air fan, as the heating of the air generates a small difference of pressure to ensure the inflow of the external air - yet, provisions should also be made for having the internal air leave the building. This latter flow is driven by extract fan(s) that in general can be found in the toilet, bathroom or kitchen. These appliances are primarily used in the Nordic countries, especially in Finland to a large extent, but they have also entered the Hungarian market. They generate no noise, filter the inlet air, yet no capable of sparing heating energy. Extract fan(s) usually with intermittent operations consume electric power, and therefore has certain operating costs.

The second group of appliances is constituted by the most frequently used, so-called air inlet structures (the products of e.g. Aereco, Kamleithner... company) that are mounted on windows (or sometimes external walls), and lead the external, fresh and dry air in, thus reducing the humidity of the internal air. They also call for the application of separate extract fan(s) to ensure sufficient pressure difference for the inflow of external air, and therefore proper air exchange is in place only during the operating time of the fan(s). Within the building, air should freely flow from e.g. the air inlet in the living room to the suction point in the bathroom, and therefore it is expedient to use cut-through doors. Air inlet structures have a so-called hygro-controlled version wherein the inlet cross-section is reduced by an air flap operated with a band whose length is variable in response to

any decrease in the humidity of internal air if less external fresh air is sufficient for reaching the proper level of relative humidity of internal air. This method has the potential of reaching partial energy saving, yet it is to be also ensured that the reduction of the volume of fresh air may not decrease to the detriment of health. External air can be filtered with a supplementary filter, and supplementary sound attenuators may as well be applied. Extract fan(s) usually with intermittent operations consume electric power, and therefore has certain operating costs. At the same time, the fan(s) installed within the apartments are active noise-emission sources.

In residential buildings, the third known method is the application of central ventilation units (e.g. Aides, Rosenberg, Kamleithner...). The central part of such appliances is an installation consisting of an extract and inlet fan, as well as a plate heat exchanger. The warm and highly humid air extracted from the side-rooms (kitchen, bathroom, WC.) transmits most of its heat to the plate heat exchanger to pre-heat the fresh and dry external air that are let in to the residential premises (living room, bedroom...) with the use of pipelines and air grills. Expediently, the extensive air duct network is installed in the suspended ceiling (or in the loft for high-pitched roof designs). Within the building, air should freely flow e.g. from the inlet fan in the living room to the extract fan in the bathroom, and therefore it is recommended to use cut-through doors again. The efficiency of air exchange can be 50-90%, which results a considerable savings in energy and heating costs. The use of such a central ventilation unit solves all the problems (provision of fresh air, avoiding condensation and mould growth, filtering of air), it is not too noisy when installed in the loft, yet its application is fairly expensive, and therefore this solution is not too wide-spread. In the summer, this appliance is also suitable for the so-called "free cooling" mode, which means that at nights it uses the colder, external air for the cooling and pre-cooling of apartments. In houses with outstanding heat insulation, the so-called passive houses, this ventilation unit with supplementary heating - e.g. heating cartridge - may as well replace the entire central heating system. The practically continuously operated fans consume electric power, thus entailing certain operating costs - yet the energy consumption of the inlet fan is utilized in heating.

The fourth known - but still not widely spread - method is the "inVENTer" decentralized ventilation system developed by the German Oko-Haustechnik inVENTer GmbH for regenerative ventilation in the individual premises. The system is primarily recommended to be installed in existing buildings to tackle the above-described problems, but it may as well be applied in new buildings. The point of the system is that each room is equipped with a separate ventilation unit that consists of a fan in two horizontally arranged openings bored in the external wall (or left hollow during the masonry works), as well as a

special, moulded, multi-holed ceramic heat-storing and heat-exchanger unit with a certain spacing in between the units. Of the two co-operated ventilation units, one functions as the extract unit, while the other is the inlet unit, but these functions are exchanged in every 70 seconds. Therefore, in the winter the first phase of the operation of one unit extracts and discharges the warm air of the room, and in the meantime by cooling this air down (utilizing the so-called "waste heat") heats up the ceramic heat-storing unit, and then in 70 seconds the second phase blows the external, cold air through the formerly heated heat-storing unit to heat the air, and conduct it to the room. The other unit performs the same process in a reversed phase. Thus, here heat exchange does not take place between simultaneously flowing media on the two sides of the bounding wall, but with a difference in time, by heating a heat-storing and heat-exchanger ceramic element (storing of heat), and cooling the same down (extraction of heat). This method of heat exchange is called as regenerative heat exchange in the associated literature. Alternating airflow (extraction-inlet) is supported by an axial fan of variable direction of rotation, equipped with a special electronic control. It is to be noted that this method does not ensure completely balanced ventilation (the quantity of extracted air is not equal to the quantity of air let in) - yet it would be desirable -, because the fan has a different airflow rate in the two directions of rotation. In general, the two ventilation units can be found in the same room, but the joint ventilation of two smaller, neighbouring rooms may as well be solved with the use of the above-mentioned cut-through door or wall-mounted air grills. According to documented measurements, the system can be operated very economically, with small energy consumption, cc. 90% efficiency, and furthermore it is also capable of "free cooling" operation in the summer, but it is very expensive. The practically continuously operated fans consume a relatively small quantity of electric power, thus entailing certain operating costs - yet the energy consumption of the fans is utilized in heating. At the same time, the fans are noise emission sources, and the acceptable level of noise can be achieved with a special, noise-attenuating anemostat.

The above-listed solutions rely on various patents, but the invention I have worked out does not involve any of them.

To summarize the problem briefly: with the application of doors and windows with high air tightness, the volume of fresh and dry external air naturally entering the building is significantly reduced, which in the winter may lead the surface condensation and consequential mould growth due to the extreme accumulation of internal humidity, and fails to satisfy the minimum fresh air demand of the users of the building, or provide for the appropriate indoor air quality.

Therefore, the objective set is: the provision of the necessary fresh air for the external bounding structures of the building and the users by any simple, energy-saving and economical means, in any manner being different from the known and above-described solutions with the concurrent minimization of the undesired side-effects, for instance noise.

From among the known and above-described solutions, I have taken the fourth, decentralized version with its small space demand to be the most appropriate starting point, as it offers the most wide-scaling advantages, benefits. It does ensure the required and expected functions, but I have found it to have a uselessly complex design, and be an excessively expensive solution. High costs are caused by the application of the special ceramic heat-storing and heat-exchanger element, as well as the unique, complex fan control. In the ventilation unit horizontally installed in the wall structure, there is no natural noise-attenuating deflection, and therefore a special noise-attenuating anemostat is to be used, which makes the solution even more expensive. Another less fortunate aspect is that the fan with variable directions of rotation cannot ensure the ideal, balanced ventilation. For this reason, I have been in quest for a solution that eliminates these deficiencies, disadvantages.

The solution has originated from the comparison of the ceramic heat-storing and heat- exchanger element of "inVENTer" and the common hollow burnt loam brick, the masonry block type that is the most frequently used for the masonry works of the external bearing walls of buildings nowadays. Both of them have a multi-holed, hollow structure and ceramic base, and therefore the hollow brick should be fundamentally - without any need of alteration - suitable for attending the above-described heat-storing and heat- exchanger function provided that air is conducted to the inside of the bricks - even with alternating airflow. On the other hand, such a solution is not too customary, and moreover during the masonry works vertical air ducts are usually closed with a cc. 1-1.5 cm bedding mortar layer to ensure the proper bonding of the masonry blocks, which blocks natural airflow in conventional walls. If, however, instead of the mortar, for instance, rubber, rubber foam or any other, similar material is applied round the edges of the fitted bricks placed on one another, continuous air ducts, a complete flue consisting of a number of parallel small channels can be developed in the wall, even across the entire headroom of the premises.

Nevertheless, there exists a more simple solution: manufactured with a ±0.5 mm height tolerance, the so-called "polished" bricks (e.g. Wienerberger Porotherm N+F Profi, Poro- therm HS Profi) have been used in Western countries for a while, and is in the phase of introduction in Hungary. When used for masonry works, only a 1 mm horizontal mortar layer is applied to these bricks to ensure proper bonding only on the peripheries and the

internal ribs, but not to close the vertical air ducts. As a consequence, even "normal" masonry works give rise to flue consisting of parallel, vertical small air ducts in the wall along the entire headroom of the premises from the floors (or intermittent floor structures) to the ceiling - without looking for any special solution for the development of the flues.

If with any of the applicable methods the vertical flue running in the external walls of the building is opened to the outdoor space on the bottom, and to the room (indoor space) on the top, such a ventilation flue will be available wherein the fan(s), air grills and filters) can be installed as required, and thus in a very simple manner such a regenerative ventilation unit will be in place that is similar to the one applied by "inVENTer", but whose heat-storing and heat-exchanger element is provided by the material of the wall itself in an inexpensive and simple design, as developed in a single and concurrent operation with the masonry works. There are always two of these ventilation flues operated simultaneously, but in certain intervals with a reversed direction of airflow, and thus they concurrently ensure appropriate inflow and extraction in the supplied room(s).

The details of the invention are presented in Figure 1 without applying any restriction.

Figure 1 shows the theoretical outline of the alternating, decentralized, regenerative ventilation equipment in a vertical section being perpendicular to the external wall, via one of the ventilation flues.

In Figure 1 , the alternating, decentralized, regenerative ventilation installation has two ventilation flues that have been formed from 1 masonry blocks, 2 bedding-bonding material, 3a lower flue elements and 3b upper flue element, all constituting integral parts of the external walls of the room(s). The 1 masonry block(s) contains a lot of parallel vertical holes. This 1 masonry block(s) is vertically linked to the 2 bedding-bonding material (if there are more than one), as well as the 3a lower flue element and 3b upper flue element in a manner where the vertical holes of the 1 masonry block(a) are not blocked by the 2 bedding-bonding material, and thus they are connected as contiguous vertical holes, air ducts. Forming parts of the ventilation flue, the 3a lower flue element and 3b upper flue element ensure that the vertical holes are connected with the outdoor space, as well as the room via the 5 air grills. In the ventilation flues, appropriate airflow is provided by the controlled 4 fan(s), and there are 5 air grills for the inlet and outlet of ventilation air, as well as 6 air filter(s) as required. The location of the 4 fan(s) is not fixed, but can be expediently installed so that the natural noise attenuation properties of the flues could be exploited to the farthest extent.

Hereunder, the elements required for the installation of the equipment contemplated in this invention are discussed with their properties, designs and the associated requirements.

The 1 masonry block(s) is the common hollow burnt loam brick, the masonry block type that is the most frequently and generally used for the masonry works of the external walls of buildings, in which there are vertical, parallel air ducts separated by ribs. Originally in conventional walls, these air ducts are blocked with mortar in each of the brick rows to carry a heat-insulating function, but in this invention they are connected vertically to form a flue that is suitable for the transmission of air with the use of the 2 bedding-bonding material. From this perspective, it has no consequence whether the conventional or new, polished 1 masonry block(s) are used, they can be applied even in combination. The materials of the 1 masonry blocks is suitable for heat storing, as well as the extraction of the stored heat with the use of the airflow in the air ducts.

The 3a lower flue element and 3b upper flue element primarily serves the connection of the ventilation flue to the outdoor space and the room, as well as the installation of the 5 air grills, but they can also accommodate the 4 fan(s) for the provision of proper airflow. They can be developed by means of cutting or carving from the 1 masonry block itself, but may as well be designed and manufactured for the given purpose. In this latter case, both of them should be dimensioned to the applied 1 masonry block, and the material is to be suitable for incorporation into the wall. Accordingly, they may be from stirofoam, expanded polyurethane, concrete, wood-concrete... that are widely used in construction industry - without the specification of the actual material properties, design of manufacturing properties. Both the 3a lower flue element and 3b upper flue element can be connected to either the outdoor space, or the room, yet it seems to be expedient to apply the arrangement shown in Figure 1. In this latter case, the 5 air grill is to be installed under the ceiling of the room, which is more favourable in view to the extraction and inlet of air.

The 2 bedding-bonding material serves the vertical connection of the 1 masonry block(s) (if there are more than one), as well as to the 3a lower flue element and 3b upper flue element so that it should not block the air ducts of the 1 masonry block(s) separated by their ribs, and thus a vertical flue being suitable for the transmission of ventilation air should be formed in the wall. In view to the material, it is the bonding mortar used for polished bricks that is the most appropriate solution, but may as well be rubber, rubber foam or any other, similar material applied round the edges of the elements of the ventilation flue.

The ventilation flue of the invention is constituted by the 1 masonry block(s), 3a lower flue element, 3b upper flue element and 2 bedding-bonding material, basically with the use of simple - though not fully "conventional" - masonry works, as integrated in the external wall. These ventilation flues ensure alternating airflow between the room(s) and the outdoor space, and at the same time serve as the heat-storing and heat-exchanger unit. Generally, two of such ventilation flues are installed in the same room, but in the case of smaller rooms a pair of flues may service two rooms connected by means of air flow. The height of the ventilation flue depends on the number of the 1 masonry block(s) placed on one another: it should be at least three unit high (of which one is the 3a lower flue element and another is the 3b upper flue element), and its maximum height may extend to the headroom of the given premises. The width of the ventilation flue is not predefined, either, but it is expedient to design it in the width of one or more 1 masonry blocks so that it could be easily incorporated in the wall.

The ventilation flues are to accommodate the 4 fan(s), 5 air grills and 6 air filter(s) as required.

The 4 fan may rely on a solution that is similar to the above-described "inVENTer" (axial fan with special electronic control and variable direction of rotation), yet the periodically variable direction of air flow can be solved in other ways, as well. If two simple 4 fans are installed as facing one another, always one of them should be operated at any time with the other stopped, and thus they can ensure completely identical airflow rates towards well-balanced ventilation. The two described solutions can be used jointly, they are not exclusive. The 4 fan(s) can be installed anywhere within the flue (with proper respect to the requirements of simple installation, as well as maintenance-servicing), but lower installation seems to be rather expedient, as in the case the ventilation flue considerably attenuates the noise generated by the fans. There is no constraint in connection with the type of the 4 fan (axial, radial, cross-flow) or the applied power supply (direct or alternating current) and voltage, but in view to proper controllability, touch protection system, small power need, long lifetime, low maintenance requirements and low noise, as well as favourable prices it is the direct current, extra-low voltage, axial design seems to be the most appropriate at the current state of art.

Owing to the system presented as the invention, i.e. the alternating, bi-directional airflow there is a special demand for the use of the 5 air grills and 4 air filter(s) as required: the 5 air grills should be suitable for attending both inlet and extraction functions, whereas the 6 air filter(s) should be capable of filtering and storing air pollutants even in the case of the alternating, bi-directional airflow.

After the individual elements, the operation of the alternating, decentralized, regenerative ventilation installation constituting the invention is discussed hereunder.

The alternating, decentralized, regenerative ventilation installation contains two cooperated ventilation flues wherein the controlled 4 fans ensure proper airflow. One of the ventilation flues operates as an extraction unit, whereas the other is the inlet unit, but these functions are alternated from time to time. In the winter season, the first phase of the operation of one unit extracts and discharges the warm air of the room, and in the meantime heats up the ventilation flue also serving as the heat-storing and heat- exchanger unit with the resulting "waste heat". After a certain period of time, the second phase - with a reversed direction of airflow - blows the external, cold air through the formerly heated ventilation flue to heat the air and cool the flue, and then the air enters the room. The other ventilation flue performs the same process in a reversed phase. Thus, here heat exchange does not take place between simultaneously flowing media on the two sides of the bounding wall, but with a difference in time, by heating the ventilation flues also serving as the heat-storing and heat-exchanger units (storing of heat), and cooling the same down (extraction of heat). This method of heat exchange is called as regenerative heat exchange in the associated literature. The appropriateness, efficiency (besides several other heating and flowing technical properties, such as the heating capacity and the mass of heat storing element, the air speed, dimensions...) of the solution depends on the length of the heating and cooling periods; the related optimal values can be established with calculations and measurements.

In the summer, the above-described ventilation installation is also suitable for the so- called "free cooling" mode, which means that at nights it uses the colder, external air for the cooling and pre-cooling of apartments.

In the light of the invention worked out on the basis of the underlying idea, I have built a pilot installation, and performed the related measurements. The experience earned in the course of construction and operations, as well as the measurement results have been convincing. The construction of the installation with the ventilation flues built from the 1 masonry blocks (the material of the wall itself) and integrated in the wall has been a simple, quick and inexpensive process. The pilot installation has provided air exchange to the room in line with the relevant health requirements, ensured well-balanced air exchange with the 4 fans facing each other, reduced the humidity of internal air in the winter to avoid the occurrence of condensation, led to a heat recovery of 70...85% efficiency in the various operating modes, and run with very little noise.

In summary, as relying on the idea described in the foregoing the objective set has been accomplished with such alternating, decentralized, regenerative ventilation installation that has two, alternating inlet and extraction ventilation flues operated in a reversed phase. These flues are made from the vertical, hollow 1 masonry block(s), 2 bedding- bonding material, 3a lower flue element and 3b upper flue element that all form integral parts of the external walls of the room(s), and serve as the regenerative heat-exchanger and heat-storing units. In the flues, there are controlled 4 fan(s) that provide for appropriate airflow from the outdoor space to the room(s), as well as from the room(s) to the outdoor space via the 5 air grills and 6 air filter(s) as required.