Patent Application
20130193220
The invention relates to a measuring and regulating method for ventilating a building, comprising at least one ventilation system and at least one control and regulating unit, wherein the ventilation system generates at least one regulated supply air stream, which flows into the building via at least one separate building opening and/or at least one regulated exhaust air stream, which flows out of the building. Such methods are typically coupled to a heat recovery.
DE 20 2007 018 549 U1 describes a heat recovery module for the central ventilation and deaeration of buildings and homes. The basic principle of the application relating to this technology will be explained in detail below.
Energy savings goals for the building area and growing demands on an increased tightness of the outer building shell lead to an increased use of building technology measures, which serve for the controlled, automated home ventilation. The used room air is hereby removed from the different living and working spaces as so-called exhaust air via ventilation ducts, is guided to a central fan and is blown to the outside as exit air. With reference to the fresh air supply, a distinction is made between central and decentral supply. Due to the pressure drop caused by the fan, outside air flows through a plurality of supply air valves in the outer walls into the building and replaces the exhaust air, which is exhausted, in the case of the decentral fresh it supply. In contrast, a central fan draws in outside air and distributes it to the rooms as so-called supply air via ventilation ducts in the case of the central fresh air supply.
In the summer, exhaust air and outside air or supply air, respectively, are warm. A sufficient air exchange, which ensures a hygienic room air quality, which is not polluted by odors, pollutants and humidity, is attained with both methods of fresh air supply.
During the heating period in the winter, the exhaust air is warmed and the outside air is cold. The energy savings goals are attained by returning the heat contained in the exhaust air back into the building. Heat recovery modules, the core of which is an air/air heat exchanger, serve this purpose. The heat contained in the warm exhaust air is transferred to the entering colder outside air in the heat exchanger and is fed back to the building again with the supply air, while the exhaust air, which has now cooled down, leaves the building as cold exit air.
In the case of such heat recovery systems, it is also known to adjust only supply or exhaust air operation as so-called summer ventilation. In this type of operation, the heat recovery is turned off and ventilation takes place only to bring the cool air into the building in the morning and to blow out the stuffy air in the evening. These types of operations are supported by means of open windows.
DE 20 2007 012 044 U1 describes a supply air device for a room of a building, which ensures a pressure compensation for the low pressure, which is generated in the room, by means of an exhaust air fan. The supply air device encompasses a heat exchanger, which transfers heat energy from the exhaust air to the outside air, which flows into the supply air device, so as to heat the supply air, wherein the exhaust air fan can be connected or is connected to the heat exchanger of the supply air device in a fluidic manner.
The exchange of air in the building is also accomplished by means of fans, for example in the basement, in the attic or on the patio of a building. Moisture-controlled supply air elements, which are able to distribute the inflowing supply air to the corresponding rooms as a function of the actual demand, are also known for this purpose in a corresponding housing opening.
DE 10 2008 057 787 B3 describes a regulating device for systems relating to ventilation and air-conditioning, which encompasses the most varying supply and exhaust air ducts and fans as well as controllable supply and exhaust air butterfly control valves. In exchange for a flow regulator, provision is thereby made for a pressure sensor, which captures the room pressure in the room, which is to be climatized, wherein the room pressure forms the direct reference value for the open position of the supply and exhaust air butterfly control valves.
The invention is based on the object of embodying and arranging a ventilation system for buildings such that structural damages at the structure and at the insulation caused by moisture and mold are eliminated.
The object is solved in that at least a first current value for a temperature Ti1 and/or a corresponding absolute internal humidity fi1 and/or a corresponding relative humidity φi1 and/or a corresponding partial water vapor pressure Wi1 of the room air are determined in the interior of the building and simultaneously a temperature Ta1 and/or a corresponding absolute external humidity fa1 and/or a corresponding relative humidity φa1 and/or a corresponding partial water vapor pressure Wa1 of the outside air are determined outside of the building and are fed to the control and regulating unit. A relative overpressure or a relative underpressure including a pressureless state is then regulated by means of the ventilation system in the building as a function of the magnitude of the differences of at least one pair of the respective values. Determined means measured and/or calculated by means of the control and regulating unit based on measured parameters. “1” quantifies a first of a plurality of values, which is to be determined.
The main cause of structural damages is the leakiness of the building shell, in particular of the interior building shell, which is also called air-tightness. The leakiness leads to an air flow from the inside to the outside or from the outside to the inside, depending on climatic conditions and depending on the thermally caused pressure difference in and on the building. No building is completely air-tight, which is shown by the blower door measurements. In particular older buildings suffer from poor air-tightness and the intelligent control is particularly advantageous and helpful here, so as to generate a healthy room climate.
When warm and humid air flows into a structural design of a building due to the leakiness, which is more or less, but always present, and cools down progressively within the construction, the relative humidity is increased. A moisture increase within the structure above 60% humidity promotes the growth of mold fungus and thus the health burden and initiates wood-destroying processes. This danger of a moisture increase in the structure is even larger, the slower the air flows. The ventilation system thus fulfills two functions: it conveys air, provided that it is necessary to build up a differential pressure opposite thermals and wind and is controlled in the conveying direction such that air having a lower moisture flows through the structure and insulation.
In the case of a corresponding regulation, it can be attained by means of the method that the inside air or the outside air, which becomes colder when passing through the insulation and structure, only passes through the insulation and structure when it its relative moisture does not increase to the extent that a critical moisture value is reached. In the event that a critical moisture value is calculated by means of the determined values, the regulation and the pressure level, which is generated, if applicable, makes it possible that the air flowing into or out of the building through the insulation and structure always flows into the insulation and structure from that direction, with which the air becomes warmer and thus inevitably drier with reference to the relative humidity.
In an inside-outside comparison, the air having a lower temperature or having a lower partial water vapor pressure and thus the air having the lower relative moisture or also the air having an absolutely lower moisture is thereby actively pressed through the insulation and structure by means of a corresponding pressure regulation opposite to the natural temperature and vapor pressure drop. The air flow, which is necessary to generate the overpressure or underpressure, is thereby guided into the building or out of the building through a separately planned building opening, such as an air duct, for example. The air volume flow can also serve as control variable for the pressure. The insulation and structure is thus always only so humid that critical moisture values and certainly not a saturation are reached. Irrespective of a general air exchange demand, the insulation and structure of the building is protected against the entry of moister air from the inside and from the outside. Whether the difference of one or a plurality of the measured parameters is significant for the pressure regulation can be relevant prior to or also only after the determination and evaluation.
The partial water vapor pressure is adjusted locally, as a physical phenomenon as a function of the respective temperature and the respective relative humidity. In the case of a 100-percent saturation, thus 100% humidity, this is referred to as water vapor saturation pressure. In the case that different partial water vapor pressures prevail in two rooms, which are defined by a shell, due to different temperatures and/or due to different relative humidity, the water molecules will move in the direction of the lower vapor pressure area, so as to follow the natural vapor pressure drop, until a vapor pressure compensation might possibly take place. This also applies to a housing shell, which defines the interior against the atmosphere, thus the exterior.
This uniform distribution is supported by the temperature drop from warm to cold, largely having the same direction, because the higher partial water vapor pressure is for the most part coupled to a higher temperature and because the lower partial water vapor pressure is for the most part coupled to a lower temperature, which, however, does not exclude the exception that a relative lower partial water vapor pressure prevails in response to a relative higher temperature.
The partial water vapor pressure is determined on the basis of the values according to DIN 4108-3 and by measuring the respective temperature and the respective relative humidity.
According to the invention, the relatively cool and thus relatively dry inside air in moderate climate zones, for example, is pressed out of the building through the insulation and structure to the outside by means of overpressure, so that the relatively warm moist outside air cannot penetrate into the interior into the insulation and construction. For this purpose, the inside air can be dehumidified. During the cold season, however, the relatively cool and dry outside air is pulled inwardly into the building through the insulation and structure by means of underpressure, so that the relatively warm moist inside air cannot penetrate to the outside into the insulation. For this purpose, the inside air can be humidified.
Depending on the climate zone, a change of direction can thus also be necessary between day and night and several times within 24 hours, depending on how the respective parameters for the temperatures and partial water vapor pressures change. In particular in the case of rapid weather changes at the borders to high-low pressure areas, changes of direction of the temperature and vapor pressure drop can be identified frequently. However, the boiler room and living room climate, which is intentionally or unintentionally created by the inhabitants in accordance with their usage behavior, contributes to an increase and to a change of the temperature and partial vapor pressure drop.
Depending on the magnitude of the leakages or leakiness, respectively, the moisture input can be so high that several liters or water are introduced into the insulation of a building during a cycle of 24 hours, during which the entire building volume of air is exchanged four times or several times due to natural leakage, when the natural temperature and vapor pressure drop is not counteracted.
It is an essential feature that the respective determined values for a calculation of at least the following values of the control and regulating unit are supplied in the case of the method:
a) based on Ti1 and φi1 assuming a constant absolute moisture fi1 a corresponding temperature Ti1,x, in the case of which the relative moisture φi1,x encompasses a value of X and/or
b) based on Ta1 and φa1 assuming a constant absolute moisture fa1 a corresponding temperature Ta1,y, in the case of which the relative moisture φa1,y encompasses a value of Y and
c) the relative overpressure (P+) or the relative underpressure (P−) are regulated as a function of the magnitude of the differences of the values Ta1 and Ti1,x or of the values Ti1 and Ta1,y. It is attained through this that, based on the actual situation of the air on the inside and outside, it is initially calculated, which state the air would have, if it were to pass through the insulation and structure in the direction of the colder temperature. In the case that the air were to reach a critical relative moisture X or Y in this way, the passage through the pressure regulation is prevented. The change between overpressure and underpressure can take place with a time delay or immediately.
It is also advantageous for this that the values X and/or Y are between 0.6 and 1.0, preferably 0.8. A formation of mold is prevented even for a permanent period of time with a value of less than 0.8.
It is advantageous for the method that a relative overpressure is generated when the respective difference D, formed of at least one of the following value pairs, exceeds a certain maximum positive amount B:
Ta1 minus Ti1=B1; D1:
fa1 minus fi1=B2; D2:
Wa1 minus Wi1=B3; D3:
Ta1,y minus Ti1=B4. D4:
According to B1 to B3, it is warmer on the outside, the absolute moisture and the relative humidity are higher. According to B4, the critical temperature, in response to which the outside air would have reached a relative moisture of Y, is higher than the temperature on the inside, so that the critical temperature would be reached on the way through the insulation and structure and the relative moisture would become larger than Y (for example 0.8). All of the cases can be countered with overpressure, so as not to allow the outside air to penetrate to the inside through the insulation and structure due to the leakiness in the housing shell. A pressure regulation must not necessarily be carried out below the respective maximum value.
In particular when overpressure is to be generated in the building, the relatively moist outside air can be dried, for example via an air-conditioning system, before it is guided into the building for generating overpressure.
In the opposite situations, it is advantageous that a relative underpressure is generated, when the respective difference D, formed from at least one of the following value pairs, exceeds a certain maximum positive amount B:
Ti1 minus Ta1=B5; D5:
fi1 minus fa1=B6; D6:
Wi1 minus Wa1=B7; D7:
Ti1,x minus Ta1=B8. D8:
According to B5 to B7, it is warmer on the inside, the absolute moisture and the relative humidity are higher. According to B8, the critical temperature, in response to which the inside air would have reached a relative moisture of X, is higher than the temperature on the outside, so that the critical temperature would be reached on the way through the insulation and structure and the relative moisture would become larger than X (for example 0.8). All of the cases can be countered with overpressure, so as not to allow the inside air to penetrate to the outside through the insulation and structure due to the leakiness in the housing shell. A pressure regulation must not necessarily be carried out below the respective maximum value. In particular when underpressure is to be generated in the building, it can be advantageous to moisten the interior air, e.g, via the ventilation system, so as to counteract a drop of the relative humidity in the room.
It is also advantageous that, in the case that the differences D1 to D8 are smaller than the maximum amounts B1 to B8, the difference values are compared quantitatively and an overpressure or an underpressure or a pressure balance is adjusted by means of the ventilation system. In the case of a pressure balance, the supply air stream and the exhaust air stream are even.
It is also advantageous that the measure of the overpressure or of the underpressure is regulated as a function of one or a plurality of respective current prevailing values of the atmospheric pressure around the building and/or of the internal building pressure in the building, wherein the atmospheric pressure results from the dynamic pressures prevailing at the building and the internal building pressure results from the static pressures prevailing in the building.
For example, the static pressure is temperature-independent and results from the upwardly decreasing tightness of the upwardly warmer air and thus from the temperature difference. The dynamic pressure is generated from the wind, for example, which flows past the exterior of the building, so that back pressure on the side facing the wind and suction on the side facing away from the wind must be considered, whereas a dynamic pressure on the inside must be neglected for the most part, because any relevant air movements do not take place.
The building opening, which is relevant for the overpressure or underpressure in the building, which must be adjusted, can be positioned with reference to the static and dynamic pressure situation, which can be different, depending on the pressure ratios. In response to cold exterior climate, a static overpressure, which changes across the pressureless center of the building towards the very bottom to the static underpressure, which has the same amount of underpressure, would prevail in the roof area It goes without saying that, where an overpressure prevails on the inside, it might be easier to convey air out of the building to the outside and vice versa.
The dynamic pressure ratios are significant from the outside, so that it can be easier to adjust an overpressure through a building opening on the building side, which faces the wind, and vice versa.
The tightness of the building, which can be measured by means of a differential pressure measuring method (Blower Door Test), for example, can also be relevant for the calculation of the measure of over and underpressure. The leakiness is a measure for the dimensioning of the air volume flow or of an air volume flow difference, respectively, by means of which the required pressure level can be reached.
A constant air exchange through supply air streams and exhaust air streams of different sizes can be advantageous independent on an overpressure or underpressure in the building, wherein provision would be made for this purpose for a second building opening, which is also connected to the ventilation system.
Advantageously, provision can be made for a first building opening in the roof area and for the second building opening on the building as low as possible, and, depending on the distribution of the interior building pressure, each of the two building openings can be used for the supply air stream and/or for the exhaust air stream.
This method provides an extremely cost-efficient possibility to avoid structural damages on buildings, which are not insulated in an air-tight manner. In the case of such buildings, such as old buildings, in particular, the moister air can enter into the structure and insulation in an unhindered manner. Such an intelligent ventilation system is more cost-efficient than a renovation of old buildings, so as to avoid critical moisture values and mold.
However, the method according to the invention is also advantageous for modern buildings, which are sealed in an air-tight manner, because a 100-percent seal can never be reached and because structural damages can occur locally in the structure and insulation, in the case of such buildings even with well-executed air-tightness, in particular in the case of component layers, which are diffusion-tight on the outside, such as in the case of green roofs or gravel roofs, which are also extremely problematic in moderate climate zones in view of the formation of mold.
The moisture-variable air-tightness, which is used in these structures, also does not offer protection anymore when moisture enters into the structure due to the smallest leaks and the natural static pressure differences, in particular also in the case of exterior shading or also in the case of diffusion-inhibiting interior component layers, both of which prevent a back diffusion of the moisture located in the structure through the moisture-variable vapor barriers or air-tightness, respectively. The advantage offered by modern buildings is that the measure for the air volume flow must not be as large as in the case of old buildings, because the leakages in the building shell and also of the modern windows is considerably lower. This is why a system consisting of a diffusion-tight or diffusion-open, moisture-variable air-tightness is advantageous for the inside and the outside of buildings comprising a ventilation system.
Further advantages and details of the invention are explained in the patent claims and in the description and are illustrated in the figures:
In practice, a plurality of the afore-described variables are measured directly at a building 1 by means of corresponding sensors or are calculated by means of a corresponding logic in the regulation.
The following example is to clarify this. Assumption:
It follows from this:
It is to now be determined, how the air flow is to be forced through the ventilation system 2. When considering only the critical relative humidity of 0.8, it can then be determined that the inside air would reach a critical moisture value when passing through the insulation and structure, underpressure P− would thus be necessary to prevent this. However, due to the partial water vapor pressure drop, overpressure P+ would be necessary, because the drop is directed to the inside. The influences through the dynamic atmospheric pressure Pa (wind) and the static interior building pressure Pi are also oriented in opposite direction. An optimal determination, whether and how much overpressure P+ or underpressure P− must be generated or whether no pressure must be generated, is thus a function of the amount of the respective determined variables and of a relativization of the variables relative to one another. In the order, the pressure regulation results last after the determining and examining.
Further different situations are illustrated in
In
Due to the temperature differences across the height of the building 1, a pressure drop of the static internal building pressure Pi arises from top to bottom, which changes from positive to negative in the same amount. Depending on the temperature difference and depending on the height of the building 1, the pressure difference from top to bottom can be between 0.5 and 15 Pascal. This pressure drop is considered in response to the generation of underpressure P−, in that the exhaust air flow 5 is discharged in the area of the roof, which is not considered in the schematic drawing according to
In the exemplary embodiment according to
According to
The exemplary embodiment according to
The described method can be realized by means of an intelligent ventilation system 2, which determines the outside and inside values of the respective current parameters, such as temperature, relative humidity and/or partial water vapor pressure and which regulates the supply air stream 4 and/or the exhaust air stream 5 via a building opening 10. On principle, the method can be combined with an afore-described heat recovery module, in the case of which an overpressure or an underpressure P− can be generated simultaneously by means of a constant air exchange.
In the case of such a combination, the supply air stream 4 and the exhaust air stream 5 could be conditioned via the aggregate 3, so that the desired temperature and moisture level remains in the building 1 due to the constant air exchange, even in response to the generation of underpressure P−.
The values of the temperatures Ti, TA and of the relative moistures φi, φa and of the resulting partial water vapor pressures Wa, Wi, which are determined for the measuring points K1, K2, L1 and L2 marked in
The two values of the measuring points K1 and K2, which apply for the moderate climate, show a sign change in the case of the difference Dw of the two partial water vapor pressures Wa and Wi for outside and inside. Here, the pressure drop changes from the direction to the outside to the direction to the inside within 4 to 5 days.
The measuring values L1 and L2 shows that even though the direction of the pressure drop remains the same within one month, the extent of the pressure drop and of the difference Dw, with which the relative moisture φ presses from the outside to the inside into the building 1, changes. In accordance with the vapor pressure change, the overpressure P+ can be controlled in consideration of further parameters in the building 1, which are not described in more detail in this exemplary embodiment.
The values of the temperatures Ta, Ti of the relative moisture φa, φi as well as of the resulting partial water vapor pressures Wa, Wi, which are determined for the measuring points Mi to M4 marked in
It can be seen that a sign change relating to the difference Dw of the respective partial water vapor pressures Wa, Wi takes place three times within 72 hours, so that a change between overpressure P+ and underpressure P− must be made three times, so as to avoid structural damages. The climatic conditions can change every 24 hours and the basis for the decision, whether overpressure P+ or underpressure P− must be generated in the building 1 thus changes.
The advantages of a prompt change from overpressure and underpressure in a random frequency, which is a function of the outside climate, up to several times a day become clear when considering that several liters or condensate can be precipitated each day in the insulation and structure, depending on the situation and depending on the quantity and quality of the leakiness of the building shell. A dependency on the outside climate can be assumed, because the inside climate is relatively stable for the most part with values of between 20 and 23° C. and 50 to 58% humidity.
As described above, the differences of different temperature and moisture values are also determined and are included into the regulation in addition to the differences of the partial water vapor pressure. Mere diagrams, which are based on the difference of temperatures, are not illustrated, but a temperature drop from the inside to the outside or vice versa is a daily state, which can be determined worldwide.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 013 085.0 | Mar 2010 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/054745 | 3/28/2011 | WO | 00 | 4/10/2013 |
