A device and a method for determining the air permeability of a building

Abstract

A device (1) configured for determining the air permeability of a building and comprising an air moving device, AMD, (2), a pressure measuring device, PMD, (3), an air flow rate measuring device, AFRMD, (4), a temperature measuring device, TMD; (5) and a data processing device (6; 8), the device being configured to: conducting (401-403), using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprising m measurement points, each measurement point comprising a plurality of n measurements, and generating, using the data processing device (6; 8), an air leakage curve comprising a correlation coefficient, r2. A check of whether the correlation coefficient, r2, is larger than or equal to 0.98 is performed. If the correlation coefficient, r2, is not larger than or equal to 0.98 the series of flow rate measurements are repeated and a new check of the correlation coefficient, r2, is performed for all 2m measurement points. If the correlation coefficient, r2, is still not larger than or equal to 0.98, the measurement point comprising the largest deviation from an air leakage curve formed by the 2m measurement points is removed, and a new check of the correlation coefficient, r2, is performed for all remaining 2m-1 measurement points. If the correlation coefficient, r2, is larger than or equal to 0.98 the check is considered completed.

Description

[0001] A device and a method for determining the air permeability of a building.

[0002] Technical Field

[0003] The present invention relates to a device and a method for determining the air permeability of a building.

[0004] As used herein, the air permeability of a building refers to the air leakage into or out of an envelope of a building. As used herein, the term "envelope of a building" is intended to encompass any envelope of a building, such as a wall, a floor, a roof, a ceiling, a membrane provided in a wall, a floor, a roof or a ceiling, and a moisture barrier provided in a wall, a floor, a roof or a ceiling.

[0005] Background Art

[0006] Determining the air permeability of a building is a requirement per law in many countries. When determining the air permeability of a building, it is, at least in Europe, a requirement that the ISO standard no 9972 is complied with.

[0007] Devices and methods for this purpose are known in the art. For instance, DK 181425 Bl discloses an apparatus for determining the air permeability of a building.

[0008] When determining the air permeability of a building a series of air flow rate measurements are performed and evaluated. This is also referred to herein as an "air permeability measurement". Such a series of air flow rate measurements comprise a number of measurement points, and each measurement point comprises a number of measurements.

[0009] Measurement results obtained with a device and a method for determining the air permeability of a building are generally presented in the form of an air leakage curve. Fig. 2 shows a graph featuring an exemplary air leakage curve depicting the air flow rate in cubic meters per hour (Y) as a function of the pressure difference in Pascal (X). The air leakage curve denoted A in Fig. 2 is the air leakage curve for pressurization, that is measured by creating an overpressure in the building envelope. The air leakage curve denoted B in Fig. 2 is the air leakage curve for depressurization, that is measured by creating an underpressure in the building envelope. The air leakage curve typically forms part of a report which may also comprise other data and information required by the ISO standard no 9972.

[0010] Amongst the requirements set forth in the ISO standard no 9972 is that for the data points forming basis for the air leakage curve, the slope of the curve, n, must be in the range from 0.5 to 1, and the coefficient of correlation, r2, must be larger than 0.98, that is r2> 0.98. However, many external factors may influence these two parameters, and especially the coefficient of correlation, r2. The result may be that the above requirements are not fulfilled and that the result of the measurement process or air permeability measurement performed is rendered invalid. One such external effect is wind gusts. If for instance the wind speed near the ground exceeds 3 m / s, or if the meteorological wind speed exceeds 6 m / s or reaches 3 on the Beaufort scale, it is unlikely that a satisfactory zero flow pressure difference can be obtained, which may lead to a too low coefficient of correlation, r2.

[0011] Using prior art devices and methods, the only solution in case the above requirements are not fulfilled is to disregard invalid air permeability measurements in their entirety and to perform new air permeability measurements. This leads to a longer and slower air permeability measurement procedure, which is cumbersome for the user, and which in turn leads to increased use of resources and increased wear on the device and may delay approval of buildings.

[0012] Also, checks for compliance with the ISO standard no 9972, including that the coefficient of correlation, r2, must be larger than 0.98, are in the prior art at least partly done manually by the operator. Therefore, professionally trained operators are as a rule required to perform the air permeability measurements.

[0013] It is therefore desired to provide a device and a method with which it becomes possible to fulfil the requirements set forth in the ISO standard no 9972, and especially the requirements that for the data points forming basis for the air leakage curve, the slope of the curve, n, must be in the range from 0.5 to 1, and that the co- efficient of correlation, r2, must fulfil that r2> 0.98, by means of a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0014] It is also desired to provide a device and a method with which it becomes possible for also persons not being professionally trained operators to perform the air permeability measurements, which in turn leads to a cheaper and quicker procedure.

[0015] Summary of Invention

[0016] The invention is defined in the independent claims. Advantageous embodiments are defined in the dependent claims.

[0017] It is therefore the object of the invention to provide a device and a method with which it becomes possible to fulfil the requirements set forth in the ISO standard no 9972, and especially the requirements that for the data points forming basis for the air leakage curve, the slope of the curve, n, must be in the range from 0.5 to 1, and that the coefficient of correlation, r2, must fulfil that r2> 0.98, by means of a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0018] It is a further object of the invention to provide such a device and method with which an air permeability report complying with the ISO standard no 9972 may be obtained in a simple and straight-forward manner. This also contributes to obtaining a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources and less wear on the device, and to a quicker approval of the building.

[0019] It is a still further object of the invention to provide such a device and method with which it becomes possible for also persons not being professionally trained operators to perform the air permeability measurements, which in turn leads to a cheaper and quicker procedure. These and other objects are in a first aspect achieved by means of a device configured for determining the air permeability of a building by measuring air leakage into or out of an envelope of a building, the device comprising an air moving device, AMD, a pressure measuring device, PMD, an air flow rate measuring device, AFRMD, a temperature measuring device, TMD, and a data processing device, the device being configured to:

[0020] conducting, using the AMD, PMD, AFRMD and TMD, a series of flow rate measurements comprising m measurement points, each measurement point corresponding to a pressure value, where m is an integer being seven or more, each measurement point comprising a plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using a predetermined sampling frequency, fs, a predetermined zero-flow pressure difference before checking, ApOl, and a predetermined time, t, over which the measurements are performed, where n = fs*t, and

[0021] generating, using the data processing device, an air leakage curve, the air leakage curve comprising a correlation coefficient, r2, and a slope, n, wherein generating an air leakage curve comprises:

[0022] a) (i) checking whether the correlation coefficient, r2, is larger than or equal to 0.98, and (ii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed, or (iii) if the correlation coefficient, r2, is not larger than or equal to 0.98:

[0023] b) (i) repeating conducting, using the AMD, PMD, AFRMD and TMD, a series of flow rate measurements comprising the m measurement points, where m is an integer being seven or more, each measurement point comprising the plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, and the predetermined time, t, over which the flow rate measurements are per- formed, where n = fs*t, such that the total number of measurement point is now 2m, (ii) checking, using the data processing device, whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points, (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed, or (iv) if the correlation coefficient, r2, is still not larger than or equal to 0.98:

[0024] c) (i) removing, using the data processing device, the measurement point among the 2m measurement points comprising the largest deviation from an air leakage curve formed by the 2m measurement points, (ii) checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-l measurement points, and (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed.

[0025] Thereby, a device is obtained with which it becomes possible to fulfil the requirements set forth in the ISO standard no 9972, and especially the requirements that for the data points forming basis for the air leakage curve, the slope of the curve, n, must be in the range from 0.5 to 1, and that the coefficient of correlation, r2, must fulfil that r2> 0.98, by means of a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0026] With such a device it further becomes possible to obtain an air permeability report complying with the ISO standard no 9972 in a simple and straight-forward manner. This also contributes to obtaining a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources and less wear on the device, and to a quicker approval of the building.

[0027] Additionally, it becomes possible even for workers not being specialized in air permeability measurements and the ISO standard no 9972 to perform air permeability measurements and obtain a report fulfilling the requirements set forth in the ISO standard no 9972. This in turn leads to a cheaper and quicker air permeability measurement procedure.

[0028] The following conditions may apply to the predetermined sampling frequency fs, predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed: If ApOl < 2, then t = 10 s and n = 10*fs; If ApOl < 3.5, then t = 15 s and n = 15*fs; If ApOl < 5, then t = 20 s and n = 20*fs; and If ApOl > 5, then t = 30 s and n = 30*fs.

[0029] Thereby, the number m of measurement points is automatically adapted to the baseline value. This in turn ensures that the sampling frequency is selected to be sufficiently high to ensure that the air permeability measurement is less susceptible to be invalid due to the correlation coefficient, r2, being too low, for instance due to wind gusts. This, in turn, contributes to obtaining a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0030] The predetermined sampling frequency, fs, may be between 2 Hz and 50 Hz, between 5 Hz and 25 Hz, or between 5 Hz and 10 Hz.

[0031] As an example, the predetermined sampling frequency, fs, may be 5 Hz, and the following conditions then may apply to the predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed: If ApOl < 2, then t = 10 s and n = 50; If ApOl < 3.5, then t = 15 s and n = 75; If ApOl < 5, then t = 20 s and n = 100; and If ApOl > 5, then t = 30 s and n = 150.

[0032] Conducting, using the AMD, PMD, AFRMD and TMD, a series of flow rate measurements may comprise selecting, by the data processing device, pressure values for the check by, by the AMD, building up a maximum pressure value, Pmax, in the building envelope, by the AFRMD, checking for a minimum air flow, and obtaining pressure values of the measurement points, wherein, if the minimum air flow is obtained, the pressure values are calculated such that the pressure values are equally distributed between the maximum pressure value, Pmax, and a predetermined minimum pressure value, Pmin, and such that the difference between two adjacent pressure values is not larger than 10 Pa, or, if the minimum air flow is not obtained, the pressure values are obtained by using a series of predefined pressure values.

[0033] Thereby, it is ensured that the choice of pressure values of each of the m measurement points is automatically adapted to the requirements of the ISO standard no. 9972. This in turn ensures that the sampling frequency is selected to be sufficiently high to ensure that the air permeability measurement is less susceptible to be invalid due to the correlation coefficient, r2, being too low, for instance due to wind gusts. This, in turn, contributes to obtaining a shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0034] The maximum pressure value, pmax, may be 65 Pa, the predetermined minimum pressure value, pmin, may be given as pmin = Ap01max*5 where ApOlmax is the largest value of the predetermined zero-flow pressure difference at a pressure of 10 Pa before the measurement process is initiated, and the minimum air flow may be 30 l / s at a pressure of between 60 and 70 Pa.

[0035] Using these values ensures an even shorter and quicker air permeability measurement procedure which complies with the ISO standard no 9972, and which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0036] If the result of step c) (ii) above is that the correlation coefficient, r2, is still not larger than or equal to 0.98 for all measurement points, then the device may further be configured to, by the data processing device: removing the measurement point among the 2m-l measurement points, which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value as the already removed measurement point among the 2m measurement points (i.e., the measurement point removed in step c) (i) above), checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-2 measurement points, and if the correlation co- efficient, r2, is larger than or equal to 0.98 considering the check completed.

[0037] It is noted that if the correlation coefficient, r2, is still not larger than or equal to 0.98 for all remaining measurement points, the device may be configured to repeating the procedure described in the paragraph just above one or more further times to remove one or more further measurement points as long as the data set still comprises at least one measurement point corresponding to each predetermined pressure value, and thus at least m measurement points.

[0038] Thereby, an even shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building, is provided.

[0039] Step (b) (ii) described above of checking, using the data processing device, whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points may comprise using baseline values and / or measurement points obtained in one or more previously conducted measurement processes.

[0040] Thereby, an even shorter and quicker air permeability measurement procedure which is easier to complete for the user, and which in turn leads to saved resources, less wear on the device and a quicker approval of the building.

[0041] In a second aspect, the above and other objects are achieved by means of a method for determining the air permeability of a building by measuring air leakage into or out of an envelope of a building, the method comprising: providing a device according to the present invention, conducting, using the AMD, PMD, AFRMD and TMD, a series of flow rate measurements comprising m measurement points, each measurement point corresponding to a pressure value, where m is an integer being seven or more, each measurement point comprising a plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using a predetermined sampling frequency, fs, a predetermined zero-flow pressure difference before checking, ApOl, and a predetermined time, t, over which the measurements are performed, where n = fs*t, and generating, using the data processing device, an air leakage curve, the air leakage curve comprising a correlation coefficient, r2, and a slope, n, wherein generating an air leakage curve comprises:

[0042] a) (i) checking whether the correlation coefficient, r2, is larger than or equal to 0.98, and (ii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed, or (iii) if the correlation coefficient, r2, is not larger than or equal to 0.98:

[0043] b) (i) repeating conducting, using the AMD, PMD, AFRMD and TMD, a series of flow rate measurements comprising the m measurement points, where m is an integer being seven or more, each measurement point comprising the plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, and the predetermined time, t, over which the flow rate measurements are performed, where n = fs*t, such that the total number of measurement points is now 2m, (ii) checking, using the data processing device, whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points, (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed, or (iv) if the correlation coefficient, r2, is still not larger than or equal to 0.98:

[0044] c) (i) removing, using the data processing device, the measurement point comprising the largest deviation from an air leakage curve formed by the 2m measurement points, (ii) checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-l measurement points, and (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed.

[0045] The following conditions may apply to the predetermined sampling fre- quency, fs, the predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed: If ApOl < 2, then t = 10 s and n = 10*fs; If ApOl < 3.5, then t = 15 s and n = 15*fs; If ApOl < 5, then t = 20 s and n = 20*fs; and If ApOl > 5, then t = 30 s and n = 30*fs.

[0046] The predetermined sampling frequency, fs, may be between 2 Hz and 50 Hz, between 5 Hz and 25 Hz, or between 5 Hz and 10 Hz.

[0047] As an example, the method may comprise obtaining the measurements using a predetermined sampling frequency, fs, of 5 Hz, wherein the following conditions apply to the predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed: If ApOl < 2, then t = 10 s and n = 50; If ApOl < 3.5, then t = 15 s and n = 75; If ApOl < 5, then t = 20 s and n = 100; and If ApOl > 5, then t = 30 s and n = 150.

[0048] The pressure values for obtaining the measurements may selected by, by the AMD, building up a maximum pressure value, Pmax, in the building envelope, by the AFRMD, checking for a minimum air flow, and obtaining pressure values of the measurement points, wherein, if the minimum air flow is obtained, the pressure values are calculated such that the pressure values are equally distributed between the maximum pressure value, Pmax, and a predetermined minimum pressure value, Pmin, and such that the difference between two adjacent pressure values is not larger than 10 Pa, or, if the minimum air flow is not obtained, the pressure values are obtained by using a series of predefined pressure values.

[0049] The maximum pressure value, pmax, may be 65 Pa, the predetermined minimum pressure value, pmin, may be given as pmin = Ap01max*5 where ApOlmax is the largest value of the predetermined zero-flow pressure difference at a pressure of 10 Pa before the measurement process is initiated, and the minimum air flow may be 30 l / s at a pressure of between 60 and 70 Pa.

[0050] If the result of step c) (ii) described above is that the correlation coefficient, r2, is not larger than or equal to 0.98 for all measurement points, then the method may further comprise, by the data processing device: removing the measurement point among the 2m-l measurement points, which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value as the already removed measurement point among the 2m measurement points (i.e., the measurement point removed in step c) (i) above), checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-2 measurement points, and if the correlation coefficient, r2, is larger than or equal to 0.98 considering the check completed.

[0051] It is noted that if the correlation coefficient, r2, is still not larger than or equal to 0.98 for all remaining measurement points, the method may comprise repeating the procedure described in the paragraph just above one or more further times to remove one or more further measurement points as long as the data set still comprises at least one measurement point corresponding to each predetermined pressure value, and thus at least m measurement points.

[0052] Step (b) (ii) described above of checking, using the data processing device, whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points may comprise using measurement points obtained in one or more previously conducted measurement processes.

[0053] Brief Description of Drawings

[0054] In the following description embodiments of the invention will be described with reference to the schematic drawings, in which:

[0055] Fig. 1 shows a schematic view of a device according to the invention.

[0056] Fig. 2 shows an exemplary air leakage curve obtained by a method according to the invention and depicting the air flow rate in cubic meters per hour as a function of the pressure difference in Pascal.

[0057] Fig. 3 shows steps of a method according to the invention.

[0058] Fig. 4 shows steps of a method according to the invention.

[0059] Fig. 5 shows steps of a method according to the invention. Description of Embodiments

[0060] Fig. 1 shows a schematic view of a device 1 according to the invention. The device 1 is a device for determining the air permeability of a building. Determining the air permeability of a building is generally done by performing a measurement of air leakage into or out of a building, particularly into and out of an envelope of a building, for instance through a membrane provided in a wall, roof, or floor of a building, and generating a report of such an air permeability measurement. The report is preferably a report in accordance with the ISO standard no. 9972. The device 1 comprises a device 10 for measuring air leakage into or out of a building.

[0061] The device 10 for measuring air leakage into or out of a building generally comprises an air moving device (AMD) 2, a pressure measuring device (PMD) 3, an air flow rate measuring device (AFRMD) 4, and a temperature measuring device (TMD) 5. The device 10 for measuring air leakage into or out of a building may further comprise a data processing device 6 and a data transmitter / receiver 7. The device 10 for measuring air leakage into or out of a building may further comprise a memory 11. The memory 11 may or may not form part of the data processing device 6.

[0062] Generally, the device 10 for measuring air leakage into or out of a building is configured to conduct a series of flow rate measurements following a method which will be described further below with reference to Figs. 3 to 5. The series of flow rate measurements comprises m measurement points, where m is an integer being seven or more. Each of the m measurement points corresponds to a pressure value. Each of the m measurement points comprises a plurality of n measurements, n being an integer being ten or more. Conducting the series of flow rate measurements comprises obtaining the measurements using a predetermined sampling frequency, fs, a predetermined zero-flow pressure difference before checking, ApOl, and a predetermined time, t, over which the measurements are performed, where n = fs*t.

[0063] The air moving device 2 is configured to induce a specific range of positive and negative pressure differences across a building envelope or a part thereof. The air moving device 2 is further configured to provide a constant air flow at each pressure difference for the period required to obtain readings of the air flow rate. The air moving device 2 may for instance be a pump configured to be connected to an opening in the building envelope by means of an air duct, such as a hose.

[0064] The pressure measuring device 3 is configured to measure pressure differences across the building envelope with an accuracy of ±1 Pa in the range of 0 Pa to 100 Pa.

[0065] The air flow rate measuring device 4 is configured to measure air flow rate with an error margin of within ±7 % of the reading. The reading of the air flow rate may be corrected according to air density.

[0066] The temperature measuring device 5 is configured to measure temperature with an accuracy of ±0.5 K.

[0067] The data processing device 6 is configured to receive and process measurement data from the pressure measuring device 3, the air flow rate measuring device 4 and the temperature measuring device 5. The data processing device 6 may further be configured to generate a report the received measurement data. The device, or the data processing device 6, may further save data, such as the measurement data or the report, in the memory 11.

[0068] Alternatively, or additionally, the device 10 for measuring air leakage into or out of a building may be configured to send the measurement data and / or the generated report to a data processing device 8. To this end the device 10 for measuring air leakage into or out of a building may comprise a data transmitter / receiver 7.

[0069] The data processing device 8 is external to the device 10 for measuring air leakage into or out of a building, but forms part of the device 1. The data processing device 8 may be configured to receive and process measurement data from the pressure measuring device 3, the air flow rate measuring device 4 and the temperature measuring device 5. The data processing device 8 may further be configured to generate a report the received measurement data. The data processing device 8, may further comprise a memory 12. The data processing device 8, may further save data, such as the measurement data or the report, in the memory 12.

[0070] The device 1 or the device 10 for measuring air leakage into or out of a building may further comprise an output device 9. The output device 9 may for instance be a display or a loudspeaker. The data processing device 8 and / or the data processing device 6 may further be configured to display the report generated on the output device 9, such as on a display. The output device 9 is shown in Fig. 1 as being external to the device 10 for measuring air leakage into or out of a building but forming part of the device 1. Alternatively, or additionally, the output device 9 may form part of the device 10 for measuring air leakage into or out of a building.

[0071] The data processing device 8 and / or the output device 9 may for instance be provided as a computer, a tablet or a smartphone being in data connection with the device 10 for measuring air leakage into or out of a building. The output device 9 may further be used to prompt a user during a measurement process.

[0072] The device 1 or the device 10 for measuring air leakage into or out of a building may further comprise an input device 13. The input device 13 is shown in Fig. 1 as being external to the device 10 for measuring air leakage into or out of a building but forming part of the device 1. The input device 13 may further be used by the user for inputting data into the device 1 or device 10 for measuring air leakage into or out of a building, such as a reply to a prompt during a measurement process. The input device 13 may for instance be a touch screen, a keyboard, a mouse pad, or a mouse.

[0073] Turning now to Figs. 3-5, a method according to the invention will be described. The method is a method for determining the air permeability of a building. Determining the air permeability of a building is generally done by performing a measurement of air leakage into or out of a building, particularly into and out of an envelope of a building, for instance through a membrane provided in a wall, roof, or floor of a building, and generating a report of such an air permeability measurement. The report is preferably a report in accordance with the ISO standard no.

[0074] 9972. The method is or may be carried out by a device 1 according to the invention as described above with reference to Fig. 1. In the following description, it is considered that measurements are made at seven measurement points with each measurement point comprising a plurality of n measurements, where n is an integer. More generally, the method is not limited to seven measurement points. Rather, measurements may be made at m measurement points, where m is an integer being seven or larger, and where each measurement point comprises a plurality of n measurements, n being an integer being ten or larger.

[0075] Referring first to Fig. 3, the method starts at 300 with beginning the measurement process. It is noted that prior to this, a baseline is calculated as follows. The opening of the AMD 2 of the device 1 is covered temporarily and the PMD 3 is connected to measure the pressure difference over the building envelope, that is between the inside and the outside of the building, known as the zero-flow pressure difference, ApOl. The values of the zero-flow pressure difference are recorded over a period of at least 30 seconds. A minimum of 10 measurement values are recorded. Based on these measurements, a baseline is then calculated. Then, a baseline check is conducted. If the baseline check reveals that the absolute value of ApOl is higher than 5 Pa, the check shall be declared not valid. If the baseline check reveals that the absolute value of ApOl is lower than 5 Pa, the check shall be declared valid. Then, the measurement process may begin.

[0076] First, at 301, pressure is built up in a building envelope using the AMD 2 of the device 1. The pressure in the building envelope is monitored using the PMD 3. The pressure built up may be an overpressure or an underpressure. Therefore, the measurement process or air permeability measurement to be described below may be performed for an overpressure or for an underpressure or for both. The pressure is increased until a maximum achievable pressure difference between the ambient pressure and the pressure in the building envelope is achieved. A set point for the maximum pressure difference is used for the pressure build-up. As an example, which will be used in the following description, the set point may be 65 Pa. However, more generally, the set point for the maximum pressure difference may be between 65 Pa and 70 Pa, or between 60 Pa and 70 Pa. When the pressure is increased until a maximum achievable pressure difference, a check is performed to establish whether the achieved pressure difference is a) below a first threshold value, c) above a second threshold value, or b) in between the first and second threshold value. By way of example, a check may be performed to establish whether the achieved pressure difference is, a) under 25 Pa, b) between 25 and 50 Pa, or c) over 50 Pa.

[0077] In case the pressure difference, that is the pressure in the building envelope as compared to the atmospheric pressure, remains below the first threshold value, here below 25 Pa, the method continues to 302 where the user may be prompted by the data processing device 6; 8 that the pressure is too low, and the measurement process is terminated.

[0078] Generally, when mentioned herein, prompting may be made on the output device 9, for instance visually on a display, or as a sound or alarm emitted by a loudspeaker, which is not shown on Fig. 1, but which may form part of the device 10 for measuring air leakage into or out of a building, or may be external to the device 10 for measuring air leakage into or out of a building, but forms part of the device 1.

[0079] In case the pressure difference is above the first threshold value, here above 25 Pa, but remains below the second threshold value, here below 50 Pa, the method continues to 303 where the user may be prompted to indicate whether it is desired to continue the measurement process. If the answer indicated by the user is "no" the measurement process is terminated. If the answer indicated is "yes", the method continues to 304, where pressure values for the measurement points are calculated by the data processing device 6; 8 as described further below.

[0080] In case the pressure difference, that is the pressure in the building envelope as compared to the atmospheric pressure, passes and therefore is above the second threshold value, here above 50 Pa, the method continues to 305 where a minimum flow check is performed by the AFRMD 4 and the data processing device 6; 8. The criterion applied to the minimum flow check may be that the flow of air over the building envelope at a pressure difference of between 60 and 70 Pa should be larger than or equal to 30 l / s.

[0081] If the criterion of the minimum flow check in 305 is fulfilled, that is if the pressure difference is above 50 Pa, the method continues to 304, where pressure values for the m measurement points are calculated by the data processing device 6; 8.

[0082] In 304, the pressure values for the measurement points are calculated by choosing m values equally distributed between a minimum pressure, pmin, and a maximum pressure, pmax, where the minimum pressure, pmin, is calculated as pmin = Ap01max*5 at 10 Pa, where ApOlmax is the largest value of the predetermined zeroflow pressure difference before the measurement process is initiated, and where the maximum pressure, pmax, is between 50 Pa and 65 Pa, depending on the pressure difference achieved in step 301 above. The method then continues to 401, where the actual air flow rate measurements are performed.

[0083] If the criterion of the minimum flow check in 305 is not fulfilled, the method continues to 306, where a series of predefined pressure values for the m measurement points are used. By way of example, the predefined pressure values may for instance be 45 Pa, 50 Pa, 55 Pa, 60 Pa, 65 Pa, 70 Pa and 75 Pa. Then, another minimum flow check is performed by the AFRMD 4 and by the data processing device 6; 8. If this minimum flow check reveals that the flow is below 5 l / s, the measurement process is terminated at 307. If, on the other hand, this minimum flow check reveals that the flow is above 5 l / s, the method continues to 401, where the actual air flow rate measurements are performed.

[0084] Referring now also to Fig. 4, before starting the measurements, a regulation check is performed at 403 by the PMD 3 and by the data processing device 6; 8. If the pressure is stable within 5 Pa of the desired pressure value for a period of 10 seconds, measurements are commenced at 401.

[0085] At 402, the number of measurements n for each of the m measurement points are determined by the data processing device 6; 8 based on the base line value calculated as described further above. A predetermined sampling frequency is used for the measurements and may be denoted fs. The number of measurements, n, may then generally be given as fs*t where t is the predetermined time, t, over which the measurements are performed. The predetermined sampling frequency, fs, may be between 2 Hz and 50 Hz, between 5 Hz and 25 Hz, or between 5 Hz and 10 Hz.

[0086] By way of example, if the sampling frequency fs = 5 Hz, the following conditions may apply to the predetermined zero-flow pressure difference before measuring, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed: If ApOl < 2, then t is set to 10 s and n = 50; if ApOl < 3.5, then t is set to 15 s and n = 75; if ApOl < 5, then t is set to 20 s and n = 100; and If ApOl > 5, then t is set to 30 s and n = 150.

[0087] At 401, the air flow rate measurements at the m measurement points with n measurements each are performed by the PMD 3 and the AFRMD 4. The measurement points may be completed in an increasing order according to pressure, with the measurement point at the lowest pressure first and the measurement point at the highest pressure last. The measurement process is completed at 404.

[0088] Referring now to Fig. 5, the result of the air flow rate measurements performed in 401-404 as described above undergoes a checking process. Initiated at 500, the air flow rate measurements performed in 401-404 as described above are checked by the data processing device 6; 8, for compliance with the requirement of the ISO standard no 9972 that the resulting air leakage curve exhibits a correlation coefficient, r2, being larger than or equal to 0.98.

[0089] If the correlation coefficient, r2, is larger than or equal to 0.98, the method continues to 501, where the checking process is considered completed, and the data processing device 6; 8 writes out the report. The report may be written out for instance to a file, which may be saved in the memory 11 or 12, or by showing the report on the output device 9.

[0090] If the correlation coefficient, r2, is not larger than or equal to 0.98 the method continues to 502 and 503, where the series of flow rate measurements, that is the measurement process at least in 401, and, if necessary, also in 402-404, described above, is repeated. The data set comprising all measurement points now comprises 2m, or in the example fourteen, measurement points. Then, at 504, a new check is performed of all 2m measurement points by the data processing device 6; 8, for compliance with the requirement of the ISO standard no 9972 that the resulting air leakage curve exhibits a correlation coefficient, r2, being larger than or equal to 0.98.

[0091] It is feasible that step 504 of checking, using the data processing device 6; 8, whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points may comprise using 507 baseline values or measurement points obtained in one or more previously conducted measurement processes. By previously conducted measurement processes is here intended measurement processes completed prior to measuring the first m measurement points in the ongoing measurement process as described in connection to Fig. 4 above.

[0092] If the result of the check in 504 is that the correlation coefficient, r2, is larger than or equal to 0.98 the method continues to 501, where the checking process is considered completed, and the data processing device 6; 8 writes out the report. The report may be written out for instance to a file, which may be saved in the memory 11 or 12, or by showing the report on the output device 9.

[0093] If the result of the check in 504 is that the correlation coefficient, r2, is still not larger than or equal to 0.98, the method continues to 505, where the data processing device 6; 8 removes from the data set the measurement point comprising the largest deviation from the air leakage curve formed by the 2m measurement points. The data set now comprises 2m-l measurement points. This may now be done without violating the requirements of the ISO standard 9972, since the total number of measurement points will still be larger than the minimum requirement set forth in the standard.

[0094] Then, still at 505, a new check is performed of all now remaining 2m-l measurement points by the data processing device 6; 8, for compliance with the requirement of the ISO standard no 9972 that the resulting air leakage curve exhibits a correlation coefficient, r2, being larger than or equal to 0.98.

[0095] If the result of the check in 505 is that the correlation coefficient, r2, is larger than or equal to 0.98 the method continues to 501, where the checking process is considered completed, and the data processing device 6; 8 writes out the report. The report may be written out for instance to a file, which may be saved in the memory 11 or 12, or by showing the report on the output device 9.

[0096] If the result of the check in 505 is that the correlation coefficient, r2, is still not larger than or equal to 0.98, the method continues to 506, where the data processing device 6; 8 prompts the user to indicate whether the checking process should be continued. If the answer indicated is "no", the checking process is terminated. If the answer indicated is "yes", the method continues to 501, where the checking process is considered completed, and the data processing device 6; 8 writes out the report. The report may be written out for instance to a file, which may be saved in the memory 11 or 12, or by showing the report on the output device 9. The report may include a note or remark, generated by the data processing device, that the correlation coefficient, r2, is not larger than or equal to 0.98.

[0097] It is noted that if the answer indicated in response to the prompt in 506 is "yes", it is also feasible that the method may return to 505, where the data processing device 6; 8 may then remove from the data set the measurement point among the 2m-l measurement points which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value as the already removed measurement point among the 2m measurement points. The data set will then comprise 2m-2 measurement points. This is on the provision that it may be done without violating the requirements of the ISO standard 9972, since the resulting total number of measurement points will still be larger than the minimum requirement set forth in the standard. Then, still at 505, a new check is performed of all now remaining 2m-2 measurement points by the data processing device 6; 8, for compliance with the requirement of the ISO standard no 9972 that the resulting air leakage curve exhibits a correlation coefficient, r2, being larger than or equal to 0.98.

[0098] If the result of the new check in 505 is that the correlation coefficient, r2, is still not larger than or equal to 0.98, the method continues to 506, where the data processing device 6; 8 prompts the user to indicate whether the checking process should be continued. If the answer indicated is "no", the checking process is termi- nated. If the answer indicated is "yes", the method continues to 501, where the checking process is considered completed, and the data processing device 6; 8 writes out the report. The report may be written out for instance to a file, which may be saved in the memory 11 or 12, or by showing the report on the output device 9. The report may include a note or remark, generated by the data processing device, that the correlation coefficient, r2, is not larger than or equal to 0.98.

[0099] It is also feasible that if the answer indicated in response to the prompt in 506 is still "yes", the method may repeat returning to 505, where the data processing device 6; 8 may now remove from the data set the measurement point among the 2m-2 measurement points which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value as the already removed measurement point among the 2m measurement points. The data set will then comprise 2m-3 measurement points. This is on the provision that it may be done without violating the requirements of the ISO standard 9972, since the resulting total number of measurement points will still be larger than the minimum requirement set forth in the standard. The method may then continue as described above.

[0100] It is noted that if the correlation coefficient, r2, is still not larger than or equal to 0.98 for all remaining measurement points, the method may comprise repeating the procedure described in the paragraph just above one or more further times to remove one or more further measurement points as long as the data set still comprises at least one measurement point corresponding to each predetermined pressure value, and thus at least m measurement points.

[0101] In case it is desired perform the air flow measurements for both an overpressure and for an underpressure, the above-described method may be repeated.

[0102] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. List of reference numerals

[0103] 1 Device

[0104] 2 Air moving device (AMD)

[0105] 3 Pressure measuring device (PMD)

[0106] 4 Air flow rate measuring device (AFRMD) 5 Temperature measuring device (TMD) 6 Data processing device

[0107] 7 Data transmitter / receiver

[0108] 8 Data processing device

[0109] 9 Output device

[0110] 10 Device

[0111] 11 Memory

[0112] 12 Memory

[0113] 13 Input device

[0114] 300-307 Method steps

[0115] 401-404 Method steps

[0116] 500-507 Method steps

Claims

P A T E N T C L A I M S1. A device (1) configured for determining the air permeability of a building by measuring air leakage into or out of an envelope of a building, the device comprising an air moving device, AMD, (2), a pressure measuring device, PMD, (3), an air flow rate measuring device, AFRMD, (4), a temperature measuring device, TMD; (5) and a data processing device (6; 8), the device being configured to:conducting (401-403), using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprising m measurement points, each measurement point corresponding to a pressure value, where m is an integer being seven or more, each measurement point comprising a plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using a predetermined sampling frequency, fs, a predetermined zero-flow pressure difference before checking, ApOl, and a predetermined time, t, over which the measurements are performed, where n = fs*t, andgenerating, using the data processing device (6; 8), an air leakage curve, the air leakage curve comprising a correlation coefficient, r2, and a slope, n, wherein generating an air leakage curve comprises:a) (i) checking (500) whether the correlation coefficient, r2, is larger than or equal to 0.98, and (ii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed, or (iii) if the correlation coefficient, r2, is not larger than or equal to 0.98:b) (i) repeating (503) conducting (401-403), using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprising the m measurement points, where m is an integer being seven or more, each measurement point comprising the plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtainingthe flow rate measurements using the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, and the predetermined time, t, over which the flow rate measurements are performed, where n = fs*t, such that the total number of measurement point is now 2m, (ii) checking (504), using the data processing device (6; 8), whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points, (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed, or (iv) if the correlation coefficient, r2, is still not larger than or equal to 0.98:c) (i) removing (505), using the data processing device (6; 8), the measurement point among the 2m measurement points comprising the largest deviation from an air leakage curve formed by the 2m measurement points, (ii) checking (505) whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-l measurement points, and (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed.

2. A device according to claim 1, wherein the following conditions apply to the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed:If ApOl < 2, then t = 10 s and n = 10*fs;If ApOl < 3.5, then t = 15 s and n = 15*fs;If ApOl < 5, then t = 20 s and n = 20*fs; andIf ApOl > 5, then t = 30 s and n = 30*fs.

3. A device according to any one of the above claims, wherein the predetermined sampling frequency, fs, is between 2 Hz and 50 Hz, between 5 Hz and 25 Hz, or between 5 Hz and 10 Hz.

4. A device according to any one of the above claims, wherein conducting, using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprises selecting, by the data processing device (6; 8), pressure values for the check by:by the AMD (2), building up (301) a maximum pressure value, Pmax, in the building envelope,by the AFRMD (3), checking (305) for a minimum air flow, andobtaining (304) pressure values of the measurement points, wherein if the minimum air flow is obtained, the pressure values are calculated such that the pressure values are equally distributed between the maximum pressure value, Pmax, and a predetermined minimum pressure value, Pmin, and such that the difference between two adjacent pressure values is not larger than 10 Pa, orif the minimum air flow is not obtained, the pressure values are obtained by using a series of predefined pressure values.

5. A device according to claim 4, wherein:the maximum pressure value, pmax, is 65 Pa.the predetermined minimum pressure value, pmin, is given as pmin = Ap01max*5 where ApOlmax is the largest value of the predetermined zero-flow pressure difference at a pressure of 10 Pa before the measurement process is initiated, andthe minimum air flow is 30 l / s at a pressure of between 60 and 70 Pa.

6. A device according to any one of the above claims, wherein, if the result of step c) (ii) (505) is that the correlation coefficient, r2, is not larger than or equal to 0.98 for all measurement points, then, by the data processing device (6; 8):removing the measurement point among the 2m-l measurement points, which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value asthe measurement point already removed in step c) (i) (505),checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-2 measurement points, andif the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed.

7. A device according to any one of the above claims, wherein step (b) (ii) of checking (504), using the data processing device (6; 8), whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points comprises using (507) baseline values and / or measurement points obtained in one or more previously conducted measurement processes.

8. A method for determining the air permeability of a building by measuring air leakage into or out of an envelope in a building, the method comprising:providing a device according to any one of the above claims, conducting (401-403), using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprising m measurement points, , each measurement point corresponding to a pressure value, where m is an integer being seven or more, each measurement point comprising a plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using a predetermined sampling frequency, fs, a predetermined zero-flow pressure difference before checking, ApOl, and a predetermined time, t, over which the measurements are performed, where n = fs*t, andgenerating, using the data processing device (6; 8), an air leakage curve, the air leakage curve comprising a correlation coefficient, r2, and a slope, n, wherein generating an air leakage curve comprises:a) (i) checking (500) whether the correlation coefficient, r2, is larger than or equal to 0.98, and (ii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed,or (iii) if the correlation coefficient, r2, is not larger than or equal to 0.98:b) (i) repeating (503) conducting (401-403), using the AMD (2), PMD (3), AFRMD (4) and TMD (5), a series of flow rate measurements comprising the m measurement points, where m is an integer being seven or more, each measurement point comprising the plurality of n measurements, n being an integer being ten or more, wherein conducting a series of flow rate measurements comprises obtaining the flow rate measurements using the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, and the predetermined time, t, over which the flow rate measurements are performed, where n = fs*t, such that the total number of measurement points is now 2m, (ii) checking (504), using the data processing device (6; 8), whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points, (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed, or (iv) if the correlation coefficient, r2, is still not larger than or equal to 0.98:c) (i) removing (505), using the data processing device (6; 8), the measurement point comprising the largest deviation from an air leakage curve formed by the 2m measurement points, (ii) checking (505) whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-l measurement points, and (iii) if the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed.

9. A method according to claim 8, wherein the following conditions apply to the predetermined sampling frequency, fs, the predetermined zero-flow pressure difference before checking, ApOl, the number of measurements, n, and the predetermined time, t, over which the measurements are performed:If ApOl < 2, then t = 10 s and n = 10*fs;If ApOl < 3.5, then t = 15 s and n = 15*fs;If ApOl < 5, then t = 20 s and n = 20*fs; andIf ApOl > 5, then t = 30 s and n = 30*fs.

10. A device according to claim 8 or 9, wherein the predetermined sampling frequency, fs, is between 2 Hz and 50 Hz, between 5 Hz and 25 Hz, or between 5 Hz and 10 Hz.

11. A method according to any one of claims 8 to 10, wherein the pressure values for obtaining measurements are selected by:by the AMD (2), building up (301) a maximum pressure value, Pmax, in the building envelope,by the AFRMD (3), checking (305) for a minimum air flow, andobtaining (304) pressure values of the measurement points, wherein if the minimum air flow is obtained, the pressure values are calculated such that the pressure values are equally distributed between the maximum pressure value, Pmax, and a predetermined minimum pressure value, Pmin, and such that the difference between two adjacent pressure values is not larger than 10 Pa, orif the minimum air flow is not obtained, the pressure values are obtained by using a series of predefined pressure values.

12. A method according to claim 11, wherein:the maximum pressure value, pmax, is 65 Pa.the predetermined minimum pressure value, pmin, is given as pmin = Ap01max*5 where ApOlmax is the largest value of the predetermined zero-flow pressure difference at a pressure of 10 Pa before the measurement process is initiated, andthe minimum air flow is 30 l / s at a pressure of between 60 and 70 Pa.

13. A method according to any one of the above claims 8 to 12, wherein, if the result of step c) (ii) (505) is that the correlation coefficient, r2, is not larger than or equal to 0.98 for all measurement points, then, by the data processing device (6; 8):removing the measurement point among the 2m-l measurement points, which (a) comprises the largest deviation from the air leakage curve formed by the 2m measurement points, and (b) is not corresponding to the same pressure value as the measurement point already removed in step c) (i) (505),checking whether the correlation coefficient, r2, is larger than or equal to 0.98 for all remaining 2m-2 measurement points, andif the correlation coefficient, r2, is larger than or equal to 0.98 considering (501) the check completed.

14. A method according to any one of the above claims 8 to 12, wherein step (b) (ii) of checking (504), using the data processing device (6; 8), whether the correlation coefficient, r2, is larger than or equal to 0.98 for all 2m measurement points comprises using (507) measurement points obtained in one or more previously conducted measurement processes.

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