The demand for energy-efficient construction has significantly increased in recent times. Developments in the field of energy, together with the demand for pleasant indoor environments, have resulted in ever-greater significance having to be attached to both the function of a building's thermal insulation and air tightness and the efficiency of its heating and ventilation systems.
Defective insulation and tightness in highly insulated and airtight structures can have a great impact on energy losses. Defects in a building's thermal insulation and air tightness do not merely entail risk of excessive heating and maintenance costs; they also create the conditions for a poor indoor climate. Lets us know dig deeper into the insulation factors encountered in buildings.
A buildings degree of insulation is often stated in the form of a thermal resistance or coefficient of thermal transmittance, the former being expressed in an "R" value and the latter in a "U" value. However, the stated thermal resistance values rarely provide a measure of the actual energy losses in a building. Air leakage from joints and connections that are not airtight and insufficiently filled with insulation often gives riser to considerable deviations from the designs and expected values.
Certification that individual materials and building elements have the promised properties is provided by means of laboratory tests. Completed building have to be checked and inspected in order to ensure that their intended insulation and air tightness functions are ACTUALLY achieved; enter infrared technology and thermal imaging inspections. With a basic understanding of the difference between laboratory certification and actual performance of building materials we will turn to field analysis of buildings using infrared and thermal imaging equipment.
In its structural engineering applications, thermography is used to study temperature variations over the surfaces of a structure. Variations in the structure's thermal resistance can, under certain conditions, produce temperature variations on its surfaces. Leakage of cold or warm air through the structure also affects the variation in surface temperature. So by now you may be thinking, what does all this mean? To bring theory into alignment with practice this means that insulation defects, thermal bridges and air leaks in buildings enclosing structural components can be located and surveyed to better understand the ACTUAL performance.
That being said, thermography itself does not directly show the structure's thermal resistance or air tightness; it is a qualitative analysis tool meaning visual depiction of surface anomalies that will need further investigation (quantification) by means of additional measurements and analysis.
Of equal importance is the inherent fact that accurate thermographic analysis of buildings relies on certain prerequisites in terms of temperature and pressure conditions across the structure. Generally, the greater the temperature difference between the exterior and interior (Delta T) of a structure will yield the best qualitative information. Details, shapes, and contrasts in the thermal image can vary quite clearly with changes in any of these parameters. The in-depth analysis and interpretation of thermal images therefore requires thorough knowledge of such aspects as material and structural properties, the effects of climate and the latest measuring techniques. For assessing the results of measurements, there are special requirements in terms of the skills and experience of those individuals taking the measurements. The picture below shows a comparison and infrared view of the ceiling in a kitchen below a second story bathroom. The picture validates a toilet that was leaking through the floor flange, although no water was visible in the bathroom area.
That's just a quick taste of several aspects of Building Science. For more information or additional assistance feel free to give us a call or send an email.
Jeremiah
JB Anderson Inspections Inc.
http://www.jbandersoninspections.com/
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