Building
Building Infrared Thermography / Building Infrared Scanning / Building Infrared Survey

Building Envelope (External Wall) Infrared Analysis (Infrared Survey or Infrared Scanning)
Hong Kong has a high population density. Buildings here are high-rise in order to meet housing needs. Serious or fatal accidents may happen if these closely located buildings do not receive routine and appropriate maintenance. The external wall is one of the leading problems that can cause serious accidents.

Common non-structural external wall problems include cement rendering, mosaic tiles and tiles. Although these problems will not have an impact on the building structure in the short run, they pose a serious threat to the passers-by. Therefore, building envelope maintenance is a sine qua non of a safe living environment.

Assessing the condition of external wall
The condition of the external wall can be assessed in two ways: contact or non-contact. In contact testing, the tester needs to do the assessment in person, mainly by rapping on the wall. In non-contact testing, the external wall condition will be assessed by bare eyes or instruments and the most commonly used instrument is infrared thermography. The pros and cons of contact and non-contact assessments are as follows:

	Rapping	Bare eyes	Infrared thermography
Advantages	Accurate Comprehensive Can carry out repair instantly	Simple, cost effective Safe, quick Non-destructive	Cost effective, objective Safe, quick Provide objective data Non-destructive
Disadvantages	Expensive Long works duration Subjective Lack objective data	Low accuracy Subjective Confined to some locations Cannot examine internal problems Lack objective data	Confined to some locations Have environmental constraints

Theory
Loose areas will have slight air or moisture behind the wall. Air or moisture inside the wall will cause changes in thermal properties of the external wall. Thermography testing is capable of detecting evidence of air gap or moisture due to change in thermal conductivity and/or thermal capacitance of the external wall. Usually, the thermography test will conduct on sunny day.

Benefits

• locate defects quickly and accurately
• cost effective, non-destructive and scientific
• can ensure the quality of new building
• can estimate the area in need of repair
• can identify problems early before they become serious and costly (especially on LIFE damage)
• help extend the life of the existing roof
• document problems before the warranty expires
• provide facts for planning accurate budgets

Suggested procedures for external wall maintenance

Professional consultation
︾
Prepare tender
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Carry out infrared thermography
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Data analysis
(To decide whether further testing is needed)
︾
Further testing
(Use rapping or other methods to enhance the comprehensiveness and accuracy of the results)
︾
Maintenance works
︾
Carry out infrared thermography again
(To ensure all problems are fixed)
︾
Done