DE3724160A1 - Method of testing the water permeability of exterior walls and/or poor room ventilation and use of this method - Google Patents

Abstract

Method of testing the water permeability of exterior walls, primarily of brickwork, and/or poor room ventilation and use of this method. To answer, in a simple manner, the question whether there is present a lack of sealing in the facade or insufficient room ventilation it is proposed that the surface temperature be measured on the exterior wall, primarily on the room side, and the cold of evaporation or heat of condensation in or on the wall be determined together with the theoretical values derived from the exterior temperature and the room temperature, with cold of evaporation indicating water permeability and heat of condensation indicating poor room ventilation. Cooling, desirable in summer, of enclosed rooms can be achieved by, on hot days, besides the temperature-stabilising storage capacity of all walls, the water absorption and the re-evaporation giving effective degrees of cooling by means of targeted construction and coating of the outer walls.

Description

The invention relates to a method for testing the water permeability of external walls and other building boundaries and / or poor ventilation in building spaces.

It is not uncommon for outside walls to be enclosed in Form molds or water precipitation. If whose cause is condensation or wall leakage, can be explore practically only that the masonry on the infested Position to be checked deeply to see if that Masonry is damp throughout. Another visual inspection allowed at least not a sure conclusion whether the masonry is permeable to water is and therefore the mold or wall moisture originates or whether the room ventilation is insufficient and therefore Condensation is the cause.

The fact that the electrically measured Surface dryness of the affected walls is relatively low, the wrong one Conclusion that there is no moisture breakdown can.  

When using this method, however, it is overlooked that the Drying resistance on the inner wall surfaces due to physical reasons has a relatively low level, so that these surfaces are relatively dry at the expense of air humidification. So come it is preferably too high for liquid water penetration in rooms Indoor air humidity with inevitable signs of condensation at the coldest building limits, regardless of whether these now offer good or worse heat protection. In practice in the case of condensation, a more or less general Strong outside ventilation is suggested as a remedy, but it does the considerable water donation from leaky facades reaches its limit there finds where the heating expenditure becomes unacceptably high.

It is therefore an object of the invention to provide a method which is based on an easy way to answer the question of whether moisture damage in the area of external walls for facade leakage or insufficient ventilation of the living moisture.

The object is achieved in that after measuring the outside and room temperature with the roughly calculated heat transfer resistances for the outer wall and the k value, the surface temperature on the room side is calculated. At the same time, the actual surface temperature is measured, whereby markedly higher temperature values indicate condensation heat due to poor room ventilation and markedly low values indicate water permeability with evaporative cooling.

The invention therefore uses the thermodynamic effect that evaporating water in the area as so-called evaporative cooling Extracts heat or that on the other hand due to high room humidity Walls of condensing water, so-called condensation heat, delivers.  

Measurements have shown that the hourly evaporation / condensation a water film of 0.1 mm thickness immediately the considerable Energy amount of 63 W / m² is withdrawn / supplied.

Condensation of room humidity on walls outside the immediate summer, arises from a temperature gradient the lounge to the outside. The resulting temperature difference between the room air and the outside wall surfaces on the room side can with known heat transfer coefficients of the wall in question. There are noticeable differences between the setpoint and actual value, this can be explained with the above Paragraph discussed thermodynamic problems as follows:

• If the temperature drops too much, i.e. the temperatures on the inside of the outer wall are too low, the cause is to be found in evaporation phenomena, which is accompanied by considerable cooling (evaporative cooling).
  If the temperature drop is too low, that is, the temperature on the inside of the outer wall is too high, the cause is, however, condensation phenomena which, as stated above, result in considerable heating.

Deviations between the k-value-related and the actually measured temperature difference from the room air to the inside of the outer wall can be used to determine to what extent evaporation or condensation occurs. From the deviation, the amount of moisture turnover can be calculated quantitatively very reliably, because the temperature influences of the k value are far below those of the water influence.

The amount of evaporation is calculated according to the Molier equation of state as follows:

With

k = heat transfer coefficient of the wall in W / m² ° C ϑ _i = inside temperature in K ϑ _a = outside temperature in K ϑ _{W Ist} = temperature measured on the inside of the outside wall in K α _i = heat transfer resistance inside, usually α _i = 8 W / m² ° C

Depending on whether the measured wall temperature is too high or too low is compared to the expected temperature Water breakdown or excessive air humidity on the room side. The A specialist can then selectively either for external sealing, if necessary with Thermal insulation, or for better ventilation of the affected room to care.

According to a development of the invention, the method can also be used use to design a facade so that by targeted water absorption effective room cooling in summer using controllable additives is created. The degree of cooling of enclosed spaces without this influence, the size of the sun-stressed windows, based on the storage capacity of the room walls. Will According to the invention, layers are introduced into outer walls that are controllable the water intake rules and for a definitive evaporation care inside and out, so the resulting cooling leads to a significant drop in room temperature.  

In practice, e.g. B. on sensibly designed masonry facades a doubling of the cooling effect compared to what is achieved can be realized with the usual solid construction.

This means that, especially on masonry facades, targeted additional measures can be taken to ensure adequate water absorption and secondary drying with the appropriate cooling effect for the summer. By appropriately dimensioning the ventilation effect at the window joints (a values), it is possible to adequately dissipate the air humidification when the outside temperatures are cooler due to the season.

An embodiment of the invention is described below with reference to the Drawing explained, which is a schematic representation in cross section an outer wall termination shows.

Room 1 is located in a flat and has a ceiling 2 in the area of influence of a balcony 3 of the apartment 4 above. Above the window 5 , 5 moisturizations occurred on both sides of the window in the area of the masonry of the ceiling 2 .

The question arose whether this dampening was due to this were that they inevitably loaded with moisture Rooms were insufficiently ventilated or whether the moisture penetration occurred are due to rain leaks.

To answer the question asked, the surface temperatures on the damp walls were determined in room 1 . According to the invention, these temperatures can be compared with the temperatures that can theoretically be calculated from the heat transfer coefficient, to the extent that the under-temperature occurring during evaporation enables conclusions to be drawn about the amount of water evaporated or, conversely, about the amounts of condensation in the case of excess temperatures.

The measurement of the emission temperatures at the mold infested Outer wall gives the following balance:

Wall temperature in the damage area δ _{W Actual} = 9.4 ° C

As indoor and outdoor temperatures were at different, not massive elements lying in the temperature gradient and thus integrated measured for indoor and outdoor:

Room temperature δ _i = 19.3 ° C outside temperature δ _a = 2.1 ° C

The temperature balance shows that the examined outer wall towards the room has an under temperature of Δϑ = 9.9 ° C, while according to the heat transfer calculations with the measured outside and inside temperatures and the possible tolerance range of the k values (k = 1... 2 W / m²K) this difference is only Δϑ = 2.3. . . Should be 4.6 ° C. The only possible cause was evaporation with the corresponding cooling according to the laws of physics, which in the present case can only occur if water penetrates from the outside. Using the Molier equation, the moisture evaporation is calculated to be X _w = 85. . 100 g / m²h. Leakage can only be the cause of water penetration.

According to local findings, there is only a leak here on the upper balcony seal in question.  

When there is moisture on the balcony, water penetrates through it Leakage in the masonry underneath or in the lintel concrete.

Based on the knowledge gained according to the process, there is the moisture damage is not due to condensation of life moisture, so that the following without destructive tests for renovation can be recommended:

• a) removing the balcony screed including thermal insulation and Seal.
• b) Apply a new seal that is 15 cm at the edges over the upper edge of the thermal insulation to be subsequently installed and the wear layer must be pulled up. In this area is the seal with a loose / fixed flange construction to fix to the rising masonry.
• c) Relocating the balcony screed.

Claims (2)

1. A method for testing the water permeability of external walls and other building conditions and / or the poor ventilation of residential or commercial rooms, characterized in that on the outer wall, primarily on the room side, the surface temperature is measured and together with the resulting from the outside and Theoretically, values resulting from room temperature determine the evaporative cold or heat of condensation in or on the wall, an increased level of evaporative cold occurring indicating water permeability and an increased level of heat of condensation indicating poor room ventilation. 2. Use of the method for the production of external walls and other building limitations caused by targeted water absorption have a cooling effect in summer with controllable additives.