planning:refurbishment_with_passive_house_components:thermal_envelope:airtightness
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| planning:refurbishment_with_passive_house_components:thermal_envelope:airtightness [2022/02/15 19:37] – admin | planning:refurbishment_with_passive_house_components:thermal_envelope:airtightness [2024/07/25 15:10] (current) – [See also] yaling.hsiao@passiv.de | ||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ====== Airtightness | + | ====== Airtightness |
| + | |||
| + | ===== Basic and airtightness in existing building===== | ||
| ===== Airtightness – how and why? ===== | ===== Airtightness – how and why? ===== | ||
| - | There are many disadvantages of air flowing in through joints and gaps in the building envelope. A large percentage of building damage is caused by leaks in the building envelope. | + | There are many disadvantages of air flowing in through joints and gaps in the building envelope. A large percentage of building damage is caused by leaks in the building envelope. Sound insulation is reduced, drafts cause discomfort for occupants and there are high heat losses. That is why airtightness standards have been set for many years and why we still have them in current regulations. |
| It is still widely beleived that poor airtightness ensures good ventilation in dwellings. However air movement is greatly dependent on outside wind speeds and the stack effect within the building (where warm air tends to rise). There are substantial drafts in poorly airtight old buildings even at moderate wind speeds but during periods of mild and calm weather air flows are inadequate. The air flow rate is too variable to maintain a consistant hygienic level of air exchange and high ventilation heat losses are inevitable. | It is still widely beleived that poor airtightness ensures good ventilation in dwellings. However air movement is greatly dependent on outside wind speeds and the stack effect within the building (where warm air tends to rise). There are substantial drafts in poorly airtight old buildings even at moderate wind speeds but during periods of mild and calm weather air flows are inadequate. The air flow rate is too variable to maintain a consistant hygienic level of air exchange and high ventilation heat losses are inevitable. | ||
| Line 12: | Line 15: | ||
| In particular, airtightness has the following advantages: | In particular, airtightness has the following advantages: | ||
| + | |||
| * prevention of moisture related building damage | * prevention of moisture related building damage | ||
| Line 23: | Line 27: | ||
| An adequate level of airtightness is the basis for: | An adequate level of airtightness is the basis for: | ||
| + | |||
| * the use of a variable demand-oriented ventilation (functioning with directed air flows) and | * the use of a variable demand-oriented ventilation (functioning with directed air flows) and | ||
| Line 29: | Line 34: | ||
| Two similar terms should be clarified: the __wind__tightness of a building component protects it from external air flowing in through the thermal insulation, which would otherwise impair the insulating effect and lead to increased energy consumption. This should not be confused with __air__tightness that is being discussed here, which is used for the movement of air through the building envelope, from the inside towards the outside or vice versa. | Two similar terms should be clarified: the __wind__tightness of a building component protects it from external air flowing in through the thermal insulation, which would otherwise impair the insulating effect and lead to increased energy consumption. This should not be confused with __air__tightness that is being discussed here, which is used for the movement of air through the building envelope, from the inside towards the outside or vice versa. | ||
| - | __Wind__tightness is completely different from __air__tightness, | + | __Wind__tightness is completely different from __air__tightness, |
| - | \\ | + | |
| ===== Testing the airtightness ===== | ===== Testing the airtightness ===== | ||
| - | The airtightness of a building can be measured by means of an air pressure test (airtightness test or “blower door test”) which determines the overall remaining leakage of a building. | + | The airtightness of a building can be measured by means of an air pressure test (airtightness test or “blower door test”) which determines the overall remaining leakage of a building. A fan is installed into a door or window to create a negative pressure in the whole house. The fan has a measuring device which gives the air flow rate for the pressure being tested. Flow rates are recorded for pressure differences at several points between 10 and 70 Pascals (Pa) negative pressure. The value at 50 Pa is calculated from the range of readings. The whole process is then repeated using a range of positive pressures [[.: |
| - | \\ | + | \\ |
| - | |{{ : | + | |{{ : |
| - | |//**Figure 1: Basic measurement setup for testing airtightness; | + | |
| - | \\ | + | |
| - | The negative and positive air pressure test results at 50 Pa are then averaged to give a single result, the leakage rate n< | + | |
| - | Pressure test results of old buildings that have not been modernised are often in the range between 3 and 6 h< | + | |//**Figure |
| - | With professional planning and implementation of the airtightness measures using the appropriate materials, permanently high airtightness values of the building can be expected | + | Pressure test results of old buildings that have not been modernised are often in the range between 3 and 6 h< |
| - | \\ | + | |
| + | With professional planning and implementation of the airtightness measures using the appropriate materials, permanently high airtightness values of the building can be expected ([[.: | ||
| ===== Airtightness measurement in refurbishment projects ===== | ===== Airtightness measurement in refurbishment projects ===== | ||
| - | Depending on the refurbishment project (partial or complete refurbishment), | + | Depending on the refurbishment project (partial or complete refurbishment), |
| + | |||
| + | __Example: | ||
| - | __Example: | + | At the same time, the initial value of the project |
| - | At the same time, the initial value of the project is documented which will then be used to ascertain the improvement after implementation of the modernisation measures. Even during the initial measurement for the planning, the building components that will represent the airtight layer must be specified. If specific areas prove to be airtight enough (e.g. intact interior plaster), they can be incorporated into the new concept.\\ | ||
| - | \\ | ||
| ==== Notes for implementation ==== | ==== Notes for implementation ==== | ||
| - | If a particularly low level of airtightness is expected for a building (many leaks) or if the building is particularly large, the pressure test can be carried out using several blower fans. In accordance with the [[planning: | + | If a particularly low level of airtightness is expected for a building (many leaks) or if the building is particularly large, the pressure test can be carried out using several blower fans. In accordance with the [[.: |
| In order to reduce the volume to be tested in large buildings it is possible to divide the building into several zones and test them one after another. It must be made sure that dividing the building is technically feasible. In most buidlings it will not be possible to achieve a perfect airtight separation of the zones. In this case the leakage between the zones will affect the measured value. To prevent this leackage the zones that are not tested at that time can be pressurized by another fan to the same preasure as the tested zone (guard-zone-measurement). Because of the huge extra effort dividing a building into several zones and testing them seperately this method is only recommended in special situations. | In order to reduce the volume to be tested in large buildings it is possible to divide the building into several zones and test them one after another. It must be made sure that dividing the building is technically feasible. In most buidlings it will not be possible to achieve a perfect airtight separation of the zones. In this case the leakage between the zones will affect the measured value. To prevent this leackage the zones that are not tested at that time can be pressurized by another fan to the same preasure as the tested zone (guard-zone-measurement). Because of the huge extra effort dividing a building into several zones and testing them seperately this method is only recommended in special situations. | ||
| - | Measurements should take place in the state of use. This means that during the preparation of the building for the test, only those openings should be sealed which would normally be closed tight. Supply air openings for a non-room-sealed fireplace (e.g. apartment heating or coal stove) may not be closed or sealed for the test. These openings are essential during operation and always remain open and therefore influence the airtightness of the building and its thermal assessment. | + | Measurements should take place in the state of use. This means that during the preparation of the building for the test, only those openings should be sealed which would normally be closed tight. Supply air openings for a non-room-sealed fireplace (e.g. apartment heating or coal stove) may not be closed or sealed for the test. These openings are essential during operation and always remain open and therefore influence the airtightness of the building and its thermal assessment. |
| + | |||
| + | During the measurement it is always advisable to carry out a series of negative AND excess pressures so that the building’s performance can be better represented and to increase the measurement accuracy. A major part of the time is required for the preparation of the building and for detecting leaks; in contrast, the actual test normally takes only about 30 to 40 minutes, therefore saving time here wouldn’t be appropriate. \\ | ||
| - | During the measurement it is always advisable to carry out a series of negative AND excess pressures so that the building’s performance can be better represented and to increase the measurement accuracy. A major part of the time is required for the preparation of the building and for detecting leaks; in contrast, the actual test normally takes only about 30 to 40 minutes, therefore saving time here wouldn’t be appropriate.\\ | ||
| - | \\ | ||
| ==== Calculation of the volume ==== | ==== Calculation of the volume ==== | ||
| - | The volumetric flow of the leakage V< | + | The volumetric flow of the leakage V< |
| - | <WRAP center 60%> | + | <WRAP center 60%> $$ \Large{n_{50} = \dfrac{V_{50}}{V} \: [\dfrac{1}{h}]} $$ </ |
| - | $$ | + | |
| - | \Large{n_{50} = \dfrac{V_{50}}{V} \: [\dfrac{1}{h}]} | + | |
| - | $$ | + | |
| - | </ | + | |
| This does not depend on the size of the building and can be used for comparisons between buildings or for comparisons before and after the modernisation. The actual heated volume of the building is the result of the heated living space multiplied by the clear room height. | This does not depend on the size of the building and can be used for comparisons between buildings or for comparisons before and after the modernisation. The actual heated volume of the building is the result of the heated living space multiplied by the clear room height. | ||
| - | The volume in a wall that results from the installation of a window or a door is not taken into account for the calculation of the building volume. For suspended ceilings only the clear measurement up to the suspended ceiling is considered. This always applies regardless of how airtightly the suspension has been carried out. Among other things, this stipulation according to [[planning: | + | The volume in a wall that results from the installation of a window or a door is not taken into account for the calculation of the building volume. For suspended ceilings only the clear measurement up to the suspended ceiling is considered. This always applies regardless of how airtightly the suspension has been carried out. Among other things, this stipulation according to [[.: |
| Beams, visible rafters etc. are not deducted. The actual size of the volumes under sloping ceilings etc. are taken into account. If there are staircases inside the airtight layer these are also added with their base area and clear height without considering the stairs themselves (i.e. as a simplification the volume of the steps is not subtracted from the building volume). | Beams, visible rafters etc. are not deducted. The actual size of the volumes under sloping ceilings etc. are taken into account. If there are staircases inside the airtight layer these are also added with their base area and clear height without considering the stairs themselves (i.e. as a simplification the volume of the steps is not subtracted from the building volume). | ||
| Line 83: | Line 82: | ||
| The volume must be determined by the inspector himself and must be documented comprehensibly, | The volume must be determined by the inspector himself and must be documented comprehensibly, | ||
| - | For large buildings (greater than ca. 4000 m³) it is always easier to implement low n< | + | For large buildings (greater than ca. 4000 m³) it is always easier to implement low n< |
| - | <WRAP center 60%> | + | <WRAP center 60%> $$ \Large{q_{50} = \dfrac{V_{50}}{A} \: [\dfrac{m³}{hm²}]} $$ </ |
| - | $$ | + | |
| - | \Large{q_{50} = \dfrac{V_{50}}{A} \: [\dfrac{m³}{hm²}]} | + | |
| - | $$ | + | |
| - | </ | + | |
| The q< | The q< | ||
| - | The calculation for the envelope surface is given in [[planning: | + | The calculation for the envelope surface is given in [[.: |
| - | \\ | + | |
| - | |{{: | + | |
| - | |//**Figure 2: Interrelation of the q< | + | |
| - | \\ | + | |
| - | | ^V\\ [m< | + | |
| - | ^Building 1| | + | |
| - | ^Building 2| | + | |
| - | ^Building 3| 4 080 | + | |
| - | ^Building 4| 9 000 | + | |
| - | ^Building 5| 25 200 | + | |
| - | ^Building 6| 62 500 | + | |
| - | //**Table 1: Data for the 6 buildings shown in Figure 2.**//\\ | + | |
| - | \\ | + | |
| - | ===== Basic principles | + | |//**Figure 2: Interrelation of the q< |
| + | ^Building 1| 200 | 210 | 1.05 | **0.6** | ||
| + | ^Building 2| 360 | 312 | 0.87 | **0.6** | ||
| + | ^Building 3| 4 080 | 1 568 | 0.38 | **0.6** | ||
| + | ^Building 4| 9 000 | 2 820 | 0.31 | **0.6** | ||
| + | ^Building 5| 25 200 | 5 500 | 0.22 | **0.6** | ||
| + | ^Building 6| 62 500 | 10 000 | 0.16 | **0.6** | ||
| - | There are two central planning fundamentals for implementing an airtight building envelope (based on [[planning: | + | There are two central planning fundamentals for implementing an airtight building envelope (based on [[.: |
| - | \\ | + | \\ |
| - | ^1. The “pencil rule”: it must be possible to trace the airtight layer of the envelope in the plan (for each building section) using a pencil without lifting the pencil – except for any planned ventilation openings. | + | ^1. The “pencil rule”: it must be possible to trace the airtight layer of the envelope in the plan (for each building section) using a pencil without lifting the pencil – except for any planned ventilation openings. ^ \\ |
| - | \\ | + | \\ |
| - | ^2. There must be only one single uninterrupted airtight layer. | + | ^2. There must be only one single uninterrupted airtight layer. Leaks CANNOT be remedied by another airtight layer before or after the first one (e.g. double lip seals at windows, vestibule door behind the front door). A comparison to illustrate this point: water won’t stop leaking from a bucket with a leak if the bucket is placed inside another bucket with a leak. ^ \\ |
| - | \\ | + | \\ |
| - | Besides the basic principles, the following guidelines are helpful for successful planning of the airtightness – whether for a new construction or for a refurbishment of an old building (based on [[planning: | + | Besides the basic principles, the following guidelines are helpful for successful planning of the airtightness – whether for a new construction or for a refurbishment of an old building (based on [[.: |
| - | * **simplicity**: | + | |
| - | * preferably **large uniform** areas with a simple basic construction | + | |
| + | | ||
| * selection of reliable and proven basic construction techniques – it is not necessary to develop completely new or exceptional sealing systems | * selection of reliable and proven basic construction techniques – it is not necessary to develop completely new or exceptional sealing systems | ||
| - | * **adherence to common principles** when planning different connections | + | * **adherence to common principles** |
| + | * in principle, any **penetrations** | ||
| - | * in principle, any **penetrations** of the sealing envelope | + | When planning an airtight building, three construction elements |
| - | \\ | + | |
| - | ===== Planning basics ===== | ||
| - | |||
| - | When planning an airtight building, three construction elements should be specified and taken into consideration: | ||
| - construction techniques for airtightness in **standard surfaces**, | - construction techniques for airtightness in **standard surfaces**, | ||
| - | - airtight **connections** of building components (along a “line”), | + | - airtight **connections** |
| - | - airtightness of **penetrations** through building components or at the corners where more than two components meet together (at a “point”).\\ | + | - airtightness of **penetrations** |
| - | \\ | + | |
| - | + | ||
| - | ==== Airtightness in surfaces ==== | + | |
| - | During the planning stage, the airtight layer for each external building component must be clearly specified. | + | During the planning stage, the airtight layer for each external building component must be clearly specified. It does not matter which layer of a component (load-bearing structure, interior cladding, etc.) is used as an airtight layer, but care should be taken that it can be connected as easily and securely with the airtight layers of the adjacent building components as possible. |
| - | The determination of the precisely defined airtight layer depends on the materials used, i.e. the structure of the walls, roof or floor. | + | The determination of the precisely defined airtight layer depends on the materials used, i.e. the structure of the walls, roof or floor. Common construction materials have varying degrees of permeability. Four material groups can be used to implement an airtight layer: |
| - PE sheets/ | - PE sheets/ | ||
| - Interior plaster | - Interior plaster | ||
| - Concrete | - Concrete | ||
| - | - Wood-based panels\\ | + | - Wood-based panels \\ \\ Airtightness concepts of all kinds usually consist of a combination of these materials. In principle it should be possible to use these materials without any joints or to seal the joints permanently without great effort. |
| - | \\ | + | |
| - | Airtightness concepts of all kinds usually consist of a combination of these materials. | + | |
| Interior plaster is normally used as the airtight layer in **solid constructions**. A continuous layer of plaster is necessary because an unplastered brick wall generally isn’t airtight. The uninterrupted interior plaster should be applied from the unfinished floor (before applying the screed!) right up to the unfinished ceiling and joined together tightly. It is important to ensure that “invisible” areas, like those behind stairs and prewall installations in bathrooms, are correctly plastered. This is necessary for an airtight application of the plaster and not for decorative reasons. For such areas, it has proved to be practicable if a smooth layer of cement is applied on the unfinished surface as a “preliminary layer”. Force-fitted interconnected concrete elements are the only supporting structures that are airtight by themselves. | Interior plaster is normally used as the airtight layer in **solid constructions**. A continuous layer of plaster is necessary because an unplastered brick wall generally isn’t airtight. The uninterrupted interior plaster should be applied from the unfinished floor (before applying the screed!) right up to the unfinished ceiling and joined together tightly. It is important to ensure that “invisible” areas, like those behind stairs and prewall installations in bathrooms, are correctly plastered. This is necessary for an airtight application of the plaster and not for decorative reasons. For such areas, it has proved to be practicable if a smooth layer of cement is applied on the unfinished surface as a “preliminary layer”. Force-fitted interconnected concrete elements are the only supporting structures that are airtight by themselves. | ||
| Line 153: | Line 133: | ||
| For **lightweight or mixed constructions**, | For **lightweight or mixed constructions**, | ||
| - | A reliable solution for lightweight constructions is the “double use” of the vapour barrier [[planning: | + | A reliable solution for lightweight constructions is the “double use” of the vapour barrier [[.: |
| - | \\ | + | |
| ==== Linear airtight connections ==== | ==== Linear airtight connections ==== | ||
| - | If basic airtight constructions have been chosen for the different building components, the airtight connections between the building components must also be carefully planned, because this is where significant leaks are often found later on. Even a compact single-family house with a simple layout can be used as an example: depending on the type of construction, | + | If basic airtight constructions have been chosen for the different building components, the airtight connections between the building components must also be carefully planned, because this is where significant leaks are often found later on. Even a compact single-family house with a simple layout can be used as an example: depending on the type of construction, |
| - | In the publication [[planning: | + | In the publication [[.: |
| === Example: Installation of a window or door frame in an external masonry wall === | === Example: Installation of a window or door frame in an external masonry wall === | ||
| - | //**Common errors:**// the attempt is made to connect the frame “tightly“ with the bare brickwork using construction foam, filling, sealing tape or adhesive tape. This will not succeed; it is not a question of the materials used, but rather an error in the specification of the airtightness layers. In an external masonry wall, the brickwork is not the airtightness layer. The whole brickwork area is interconnected through a network of gaps and hollow spaces containing air – in other words, the brickwork is an air conducting layer. Therefore the airtight layer of a component abutting a brickwork wall cannot be connected to the bare brickwork; instead, it must be connected to the airtight layer – which is usually the interior plaster.\\ | + | //**Common errors: |
| - | \\ | + | |
| - | //**Correct method: | + | - Identification of the airtight layers of the components to be connected, these are for example: \\ For window frames: the inside surface of frames. \\ For external brickwork: the interior plaster extending into the reveal. |
| - | - Identification of the airtight layers of the components to be connected, these are for example:\\ For window frames: the inside surface of frames.\\ For external brickwork: the interior plaster extending into the reveal. | + | |
| - Airtight connection of these airtight layers with each other. | - Airtight connection of these airtight layers with each other. | ||
| - | Since the frame and plaster can move in relation to each other as a result of the different thermal expansion coefficients and mechanical strain (weight of window or door wing when opened), the airtight connection must be able to accommodate relative movements of up to 2 mm without tearing. Therefore direct plastering in of the frame is not possible. Better solutions would be: | ||
| - | **I.** Adhesive tape applied securely to the plaster which is stuck to the frame and can be plastered over later (fleece-laminated adhesive tape).\\ | + | Since the frame and plaster can move in relation to each other as a result of the different thermal expansion coefficients and mechanical strain (weight of window or door wing when opened), the airtight connection must be able to accommodate relative movements of up to 2 mm without tearing. Therefore direct plastering in of the frame is not possible. Better solutions would be: |
| - | **II.** A plastic plastering strip, one side of which has a a flexible airtight sealing insert with enough give (≥ 2 mm) which is glued to the window frame, the other side of which is rigid and is plastered over inside the interior plaster.\\ | + | |
| - | **III.** A plaster end-strip which is applied at a distance of ≥ 8 mm from the window frame, creating a defined groove between the plaster strip edge and the frame. Tape (e.g. consisting of paper or fabric) is inserted into this groove to prevent the joint filler from sticking to the brickwork of the reveal. Then the space between the plaster end-strip and frame is filled with the flexible joint filler (silicone or acrylic filler) so that it adheres to the plaster end strip and the frame (two-flank bonding).\\ | + | **I.** |
| - | \\ | + | |
| - | |{{ : | + | |//**Figure 3: The possibilities (see above (I) to (III)) for a permanently airtight \\ connection of the window frame in plastered solid masonry \\ (adapted from [[.: |
| - | |//**Figure 3: The possibilities (see above (I) to (III)) for a permanently airtight\\ connection of the window frame in plastered solid masonry\\ (adapted from [[planning: | + | |
| - | \\ | + | \\ Based on the basic principle given in the example described in [[.: |
| - | Based on the basic principle given in the example described in [[planning: | + | |
| - | \\ | + | |
| ===== Penetrations of the airtight layer ===== | ===== Penetrations of the airtight layer ===== | ||
| Line 185: | Line 161: | ||
| Therefore, in new constructions as well as in modernisations, | Therefore, in new constructions as well as in modernisations, | ||
| + | |||
| * Preliminary planning | * Preliminary planning | ||
| Line 191: | Line 168: | ||
| * Time schedule | * Time schedule | ||
| - | * Monitoring of implementation\\ | + | * Monitoring of implementation |
| - | \\ | + | |
| ====== See also ====== | ====== See also ====== | ||
| - | [[planning: | + | [[planning: |
| - | + | ||
| - | [[planning: | + | |
| + | [[.: | ||
| + | [[.: | ||
planning/refurbishment_with_passive_house_components/thermal_envelope/airtightness.1644950234.txt.gz · Last modified: 2022/02/15 19:37 by admin