Use of Infrared Thermography
for Building Inspection
Seminar on Building Diagnostic and Inspection – Testing & Certification
Association of Engineering Professionals in Society Ltd
K.K. Lee, Kenneth
Introduction
Theory
y Equipment
y Survey
y Conclusion
y
2
Definition
y
Infrared thermography is a science of
obtaining and analysis of thermal data or
information by non-contact thermographic
equipment.
3
Definition
y
Real time
◦ Capture fast moving targets
◦ Capture fast changing thermal patterns
y
Non-contact
◦ Remote sensing
◦ Keep out of danger
◦ Does not affect the target
Two-dimension
◦ Comparison between areas
◦ Thermal patterns can be visualized for analysis
◦ Good overview of the target
y
4
Spectrum
5
Emissivity
6
Kirchhoff’s Law
Emissivity
y Reflectivity
y Transmissivity
y
7
Opaque
8
Reflective Object
9
Transmissive Object
10
Conduction
hot
y
y
y
y
y
y
y
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)
cold
Q/t = k x A x (T1 – T2) / L
11
Conduction
12
Thermogram
13
Thermogram
14
Thermogram
15
Thermogram
16
Thermogram
17
Thermal Imager
18
Equipment System
y
y
y
y
y
y
Compact and
lightweight
From shouldersupported to hand-held
video camera
Lenses
Focus
Detector
Electrical signal
•
•
•
•
•
•
•
Amplified
Processed
Displayed
Eyepiece
LCD viewer
Memory card
Digital photos
19
Basic Performance
20
Basic Performance
21
Basic Performance
22
Lenses
• Standard lens – normally 25° (FOV)
Telephoto
y Less than 25 °
y Fewer things can be
included
y High rise building
inspection
y
• Wide-angle
• Greater than 25 °
• More things can be
included
• E&M inspection in
limited space
23
Lenses
24
Operation
y
y
y
y
y
y
y
y
y
y
y
y
y
Focus
Range
Span
Auto-ranging
Level
Palettes
Spot
Area
Isotherm
Emissivity
Distance
Ambient temperature
Reflected temperature
25
Software
26
Quantitative Analysis
27
Problems
Workmanship
y Material
y Weather
y Application method
y Aging
y Regular checking
y
•
•
•
•
•
Environment
Usage
Design
Accident
Maintenance record
28
Target Building
External or internal
y Shape
y Size
y Distance
y Materials
y Texture
y Thickness of finishes
y Stains
y
29
Training
In-house training
y Manufacturer tutorial
y Regional agent tutorial
y Infrared training organizations
y Academic background
y Oversea seminars
y
30
Equipment
y
y
y
y
y
y
y
y
FOV and IFOV
Thermal sensitivity
Thermogram resolution
LCD display and its
resolution
Detector
Temperature range
Spectral range
Thermal fusion
•
•
•
•
•
•
•
•
•
•
Lenses
Picture in picture
Accuracy
Memory
File format
Weight and size
Environmental data
Battery
Back up
Accessory
31
Equipment
y
y
y
y
y
y
y
Infrared camera
Lenses
Tripod
Digital camera
Distance measuring
device
Telescope
Anemometer
•
•
•
•
•
•
Thermocouple
Thermo hydrometer
Goniometer
Hammer/tapper
Range finder
Personal protective
equipment
32
Methodology
International standards
y National standards
y Regional standards
y In-house method
y Governmental requirements
y
33
Environment
y
Time
◦
◦
◦
◦
◦
y
Weather
◦
◦
◦
◦
y
Day time
Evening
Peak time
Non-peak time
Availability of access
Sunny
After Raining
Wind
Cloudy
Season
◦ Summer
◦ Winter
34
Environment
y
Background noise
◦ Metallic panel
◦ Glass cladding
y
Obstacles
◦
◦
◦
◦
◦
y
Advertisement
Road sign
Lighting pole
Trees
scaffolding
Heat sources
◦ Air conditioner
◦ Fluorescent lighting
35
Environment
y
Cold sources
◦ Leakage of conditioned air
◦ Moisture
y
Activities
◦
◦
◦
◦
y
Cold storage
Restaurant
Crematorium
Hospital
Structural
36
Limitation
Surface texture
y Temperature
y Shape
y IR camera use
y Emissivity
y Viewing angle
y
37
Conclusion
Application of infrared thermography is
common in external wall inspection
(qualitative).
y It is a good option to have a preliminary
condition of building external wall.
y Assist with other tests is suggested such
as tapping, pull-off tests (tile, mortar,
coating), etc.
y Canopy
y Quantitative analysis
y
38
Thank You
39