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Air Leakage Detection in Building Façades by Combining Lock-In Thermography with Blower Excitation

Kölsch, Benedikt and Pernpeintner, Johannes and Schiricke, Björn and Lüpfert, Eckhard (2022) Air Leakage Detection in Building Façades by Combining Lock-In Thermography with Blower Excitation. In: Proceedings of the 42nd AIVC Conference, pp. 46-54. 42nd AIVC-10th TightVent & 8th Venticool Conference, 05.-06. Okt. 2022, Rotterdam, Niederlande.

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Abstract

Air leakage in building envelopes is responsible for a large portion of the building’s heating and cooling requirements. Therefore, fast and reliable detection of leaks is crucial for improving energy efficiency. This paper presents a new approach to determining air leakages in a building’s envelope from the outside, combining lock-in thermography and thermal excitation by a blower door system. The blower creates a periodic overpressure within the building, inducing periodic temperature variations of the surfaces near the leaks on the outside surface, the façade. With the temperature variations excited at a known frequency, Fourier transforms of the time-series of the thermal images at the excitation frequency result in amplitude and phase images highlighting the areas affected by leaks. Periodic excitation and detection by an IR camera is known as lock-in thermography and is widely used to characterize semiconductor devices and in non-destructive testing. Excitation is usually achieved by optical, electrical, or mechanical energy input. For this work, measurements of outside façades have been performed with three excitation cycles of a period of 40 seconds at a 75 Pa pressure difference, leading to a total measurement time of only 2 minutes. Measurements have been performed with air temperature differences of 5 to 7 K at highly variable conditions of irradiance, wind, and cloud cover. The measurements show higher detection quality and less impact from changing ambient conditions than the state-of the-art differential infrared thermography measurements. With the method highlighting the variations in the amplitude image only at the excitation frequency, variations caused by environmental effects are filtered out. A temperature difference as low as a few Kelvin is therefore sufficient, and large façades can be examined from the outside. This amplitude image is already clearer than an image created with differential thermography. A further reduction of unwanted artefacts in the image is demonstrated using phase-weighing of the amplitude by scalar product.

Item URL in elib:https://elib.dlr.de/188993/
Document Type:Conference or Workshop Item (Speech)
Title:Air Leakage Detection in Building Façades by Combining Lock-In Thermography with Blower Excitation
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Kölsch, Benediktbenedikt.koelsch (at) dlr.dehttps://orcid.org/0000-0003-3564-9822
Pernpeintner, JohannesJohannes.Pernpeintner (at) dlr.deUNSPECIFIED
Schiricke, BjörnBjoern.Schiricke (at) dlr.dehttps://orcid.org/0000-0003-0572-2048
Lüpfert, EckhardEckhard.Luepfert (at) dlr.dehttps://orcid.org/0000-0002-6207-975X
Date:October 2022
Journal or Publication Title:Proceedings of the 42nd AIVC Conference
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:pp. 46-54
Status:Published
Keywords:Lock-In, Thermography, Blower Door, Airtightness, Leak Detection, Building Envelope, Building Energy Efficiency
Event Title:42nd AIVC-10th TightVent & 8th Venticool Conference
Event Location:Rotterdam, Niederlande
Event Type:international Conference
Event Dates:05.-06. Okt. 2022
Organizer:AIVC
HGF - Research field:Energy
HGF - Program:Materials and Technologies for the Energy Transition
HGF - Program Themes:High-Temperature Thermal Technologies
DLR - Research area:Energy
DLR - Program:E SW - Solar and Wind Energy
DLR - Research theme (Project):E - Condition Monitoring
Location: Jülich , Köln-Porz
Institutes and Institutions:Institute of Solar Research > Qualifizierung
Deposited By: Kölsch, Dr.-Ing. Benedikt
Deposited On:26 Oct 2022 11:39
Last Modified:26 Oct 2022 11:39

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