Limits of recognizability of leakages by means of thermography!

Thermography is a helpful means at the visualisation of leakages on the wind and airtightness level. However on the one hand not always the theoretically necessaryphysical boundary conditions are available and on the other hand the constructionprogress not always the make an optimal building preparation possible. In principlealso a low n50-Wert during the air tightness measurement does not give a conclusionabout the wind tightness and about the construction unit qualities. As already manyclaims prove, the compliance with the air change rate, which represents anevaluation from energetic view, is not (alone) decisive for the function of aconstruction unit or a building. Deficiency complaints about bad or insufficientheatableness increase and end usually in a law suite.A reason is also the missing specialized knowledge of some Blower Doorspecialists, who neglect to inform there customers about the complete requirementsof construction physics. About requirements of construction physics, which areunknown to the not competent Blower Door tester. Particularly in the very low energyhouse or passive house range all needs of construction physics are important for thefunction and therefore also to be followed. But just there often substantial errorsappear, however only in the tenth part of a degree, and so it is not possible to findthese sources of error without sufficient knowledge of thermodynamics and buildingphysics.Which influence however the deficiencies have on the construction unit, which are ina great measure not noted and which are not recognizable exclusively by means ofair tightness measurement.In order to be able to illustrate the correlationes to some extent, a leckage patternwas fabricated and furnished with different errors. Afterwards we tried to seize theseerrors metrological.Likewise these errors were designed by means of a simulation routine for thermalbridges called FLIXO, to describe the necessary procedures on the inside and themetrological effects at the surface of the construction unit and/or to receivetheoretical approaches for further work.