Building Thermal Efficiency

Sarkis Agaian
November 15, 2011

Submitted as coursework for PH240, Stanford University, Fall 2011

Fig. 1: Thermal Imaging of Khmer Houses. (Source: Wikimedia Commons)

Climate change and increasing energy costs have drawn large attention to energy performance and efficiency. Buildings consume 40-50% of energy supply and about 50% of energy generated is wasted. [1] As a result, the demand for building envelope analysis, in which the physical separator of the building's interior and the exterior environment is evaluated, has increased. Rising energy costs, government regulations, new construction techniques and materials, growing concerns about occupant health are further boosting this demand. [2-5] One of the chief causes of unhealthy buildings comes from mishaps in air exchange. Air leakage, which can result from missing or damaged insulation or poor design that allows the air to move across the thermal perimeter, can account for up to half of its energy consumed. [1] In addition to making buildings energy inefficient, air leakage can substantially affect the building climate and reduce employee efficiency and occupant comfort. New technologies have been developed to combat problems like air leakage in order to construct buildings with high energy performance. [1] While specialized testing techniques are available to evaluate individual inspection components of a building, thermography is the only technology able to deliver the "big picture" of the building envelope as a complete system. [2,4,5]

Thermal images, or thermograms, display of the amount of infrared energy emitted, transmitted, and reflected by an object. [2] Every object generates heat radiation in the infrared part of the light spectrum, in which the intensity and spectrum distribution depend on the object's surface layer radiation properties and temperature. [4] Thermography measures surface temperatures using infrared video and still cameras (IRC). [2] The IRC visually shows temperature variations ranging from white in hot areas to black in cold places. [2] Infrared technologies are used in almost every industry, with applications in commerce, medicine, military, and recently building inspections. [1-6] Using IR cameras, inspectors can detect heat/air leaks, insufficient insulation, and moisture problems, as well as mold, pests, electrical hazards. [4,5] While thermal profile visualization prevents such problems from escalating into costly repairs, it presents different technological and economical challenges related to reliable inspection, camera cost, contractor expense, and training. [4,5] These barriers must addressed in adopting infrared thermography as the standard inspection tool in building diagnostics and monitoring. [4,5]

While infrared thermography is used ubiquitously, professionals are only beginning to understand its potential applications and benefits to building more efficient, energy-saving buildings. [1-6] Thermal imaging technology can play a powerful role in visualizing otherwise hard-to-detect building problems and help transform existing high energy-wasting buildings to energy-saving green buildings. [4,5] Future work in thermal imaging technology may also take into consideration various climate zones and environmental parameters to further develop a computer aided building energy saving system. [4,5]

© Sarkis Agaian. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] T. Y. Lo and K. T. W. Choi, "Building Defects Diagnosis by Infrared Thermography," Structural Survey 22, 5 (2004).

[2] X. P. Maldague and P. O. Moore, Nondestructive Testing Handbook: Infrared and Thermal Testing (Am. Soc. Nondestructive Testing, 2001), pp. 528-570.

[3] D. J. Titman, "Applications of Thermography in Non-Destructive Testing of Structures," NDT&E Intl. 34, 149 (2001).

[4] H. Kaplan, Practical Applications of Infrared Thermal Sensing and Imaging Equipment, 3rd Ed. (SPIE Press, 2007), pp. 9-29.

[5] C. A. Balaras and A. A. Argiriou, "Infrared Thermography for Building Diagnostics," Energy and Buildings 34, 171 (2002).

[6] J. Ruminski et al., "Thermal Parametric Imaging in the Evaluation of Skin Burn Depth," IEEE Trans. Biomed. Eng. 54, 303 (2007).