Use of Infrared Thermography Use of Infrared Thermography for Building Inspection for Building Inspection

Seminar on Building Diagnostic and Inspection – Testing & Certification

Association of Engineering Professionals in Society Ltd

K.K. Lee, Kenneth

IntroductionIntroduction

TheoryEquipmentSurveyConclusion

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DefinitionDefinition

Infrared thermography is a science of obtaining and analysis of thermal data or information by non-contact thermographic equipment.

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DefinitionDefinitionReal time◦ Capture fast moving targets◦ Capture fast changing thermal patterns

Non-contact◦ Remote sensing◦ Keep out of danger◦ Does not affect the targetTwo-dimension◦ Comparison between areas◦ Thermal patterns can be visualized for analysis◦ Good overview of the target 4

SpectrumSpectrum

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EmissivityEmissivity

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KirchhoffKirchhoff’’s Law s Law

EmissivityReflectivityTransmissivity

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OpaqueOpaque

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Reflective ObjectReflective Object

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Transmissive ObjectTransmissive Object

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ConductionConductionhot cold

Q/t = k x A x (T1 – T2) / L

Q = conductive heat transfer (J)t = time (s)A = area (m2)L = thickness (m)T1 – T2 = ΔT (K or °C)k (or λ) = thermal conductivity (W m-1

K-1)Q/t = heat flow (W)

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ConductionConduction

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ThermogramThermogram

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ThermogramThermogram

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ThermogramThermogram

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ThermogramThermogram

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ThermogramThermogram

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Thermal ImagerThermal Imager

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Equipment SystemEquipment System

Compact and lightweightFrom shoulder-supported to hand-held video cameraLensesFocusDetectorElectrical signal

• Amplified• Processed• Displayed• Eyepiece• LCD viewer• Memory card• Digital photos

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Basic PerformanceBasic Performance

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Basic PerformanceBasic Performance

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Basic PerformanceBasic Performance

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TelephotoLess than 25 °Fewer things can be includedHigh rise building inspection

• Wide-angle• Greater than 25 °• More things can be

included• E&M inspection in

limited space

• Standard lens – normally 25° (FOV)

Lenses Lenses

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Lenses Lenses

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OperationOperationFocusRangeSpanAuto-rangingLevelPalettesSpotAreaIsothermEmissivityDistanceAmbient temperature Reflected temperature

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SoftwareSoftware

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Quantitative AnalysisQuantitative Analysis

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ProblemsProblems

WorkmanshipMaterialWeatherApplication methodAgingRegular checking

• Environment• Usage• Design• Accident• Maintenance record

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Target BuildingTarget Building

External or internalShapeSizeDistanceMaterialsTextureThickness of finishesStains

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TrainingTraining

In-house trainingManufacturer tutorialRegional agent tutorialInfrared training organizationsAcademic backgroundOversea seminars

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EquipmentEquipmentFOV and IFOVThermal sensitivityThermogram resolutionLCD display and its resolutionDetectorTemperature rangeSpectral rangeThermal fusion

• Lenses• Picture in picture• Accuracy• Memory• File format• Weight and size• Environmental data• Battery• Back up• Accessory

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EquipmentEquipmentInfrared cameraLensesTripodDigital cameraDistance measuring deviceTelescopeAnemometer

• Thermocouple• Thermo hydrometer• Goniometer• Hammer/tapper• Range finder• Personal protective

equipment

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MethodologyMethodology

International standardsNational standardsRegional standardsIn-house methodGovernmental requirements

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EnvironmentEnvironmentTime◦ Day time◦ Evening◦ Peak time◦ Non-peak time◦ Availability of accessWeather◦ Sunny◦ After Raining◦ Wind◦ CloudySeason◦ Summer◦ Winter

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EnvironmentEnvironmentBackground noise◦ Metallic panel◦ Glass claddingObstacles◦ Advertisement◦ Road sign◦ Lighting pole◦ Trees◦ scaffoldingHeat sources◦ Air conditioner◦ Fluorescent lighting

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EnvironmentEnvironment

Cold sources◦ Leakage of conditioned air◦ Moisture

Activities◦ Cold storage◦ Restaurant◦ Crematorium◦ Hospital

Structural

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LimitationLimitation

Surface textureTemperatureShapeIR camera useEmissivityViewing angle

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ConclusionConclusionApplication of infrared thermography is common in external wall inspection (qualitative).It is a good option to have a preliminary condition of building external wall.Assist with other tests is suggested such as tapping, pull-off tests (tile, mortar, coating), etc.CanopyQuantitative analysis

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Thank You

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