| dc.description.abstract | Since the early 2000’s, the member states of the European Union (EU) and EuropeanEconomic Area (EEA), have been engaged in an effort to account for air infiltrationthrough the building envelope. Building infiltration is identified as a major contributorfor heat loss, and as one of the factors that have a great impact on the the airtightnessof a built environment. A standard the airtightness evaluation procedure is known as thefan pressurization method is established. An accurate evaluation of the airtightness level,however, demands an optimised estimation of the uncertainties related to the measurementmethod.Despite halve a century worth of application, a knowledge gap remains an untended con-cerning the quantification of uncertainties due to the impact of dynamic wind on fanpressurization method. The purpose of this thesis is therefore to investigate and char-acterize the airtightness of a building envelope with respect to varying wind conditions.Coefficient of determination, which qualifies the relationship between building pressureand the building leakage, is selected to quantify any observable dynamic wind impact andconsequences thereon.The experimental study was conducted at the field station for bio-climatic studies at theNorwegian University of Life Science (NMBU) in ̊As, Norway. A Minneapolis BlowerDoor system is used to measure the building pressures across the envelope. The BlowerDoor Test procedure known as a Multi-Point Test was performed in testing the buildingover a range of target pressures. The wind data in the dynamic condition was capturedby an ultrasonic anemometer device. It was located at a distance of 20m without anyobstruction within a radius of ca 18m, at a height of 2.2m above the ground. The winddata was further processed numerically by MATLAB@ programming software. Normaland Weibull probability density models were simulated to quantify and investigate thenatural distribution pattern. A spectral density estimation is also performed to quantifythe energy distribution of the dynamic wind signal in a frequency spectrum.The analysis of the results indicate that the impact assessment of dynamic wind conditionshall consider the following factors; 1)angular exposure of the blower door to the directionof the prevailing wind speed, 2) spectral energy distribution at low frequencies, and 3) thewind speed carrying the maximum energy. Further more, for an accurate description ofthe dynamic wind condition, the best fitting distribution function must be systematicallyselected. A good criteria for selection of such distribution function is suggested to combinethe wind speed and wind direction parameters. Finally, among the values of coefficients ofdetermination that were found to be satisfactory according to the current ISO9972:2015standard, mean wind speed up toVxy≈4.8m/swith corresponding wind speeds thatcarry maximum energy ofVxyMaxE≈5.8m/swere reported. this outcome implicates theapproach utilized by ISO9972 as a rather conservative design | en |
