Determining Neutral Plane Location
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Determining Neutral Plane Location
Tip written by: Infraspection Institute
Thermographically detecting air leakage sites within buildings is dependent upon proper site and weather conditions and imaging vantage point. Determining the location of a building’s neutral plane is key to ascertaining the correct vantage point for thermal imaging.
Air leakage can account for significant energy losses within buildings. Such losses occur as unconditioned air moves through the building’s thermal envelope into conditioned spaces. For heated low-rise structures, air typically infiltrates at lower elevations and exfiltrates at higher elevations. Simply defined, the neutral plane is the elevation within the structure where no air leakage occurs since indoor/outdoor air pressure is balanced.
Determining neutral plane location can often be more art than science. Among the many factors that influence the location of the neutral plane are: building construction, building height, inside/outside temperature differential, and the operation of the building’s HVAC system. Wind speed and direction can also influence the location of a neutral plane.
To help determine the location of a building’s neutral plane, use your thermal imager to investigate likely air leakage sites such as electrical receptacles on exterior walls. If you detect evidence of air infiltration at these sites, move upward to the next floor of the structure. Once above the neutral plane, evidence of air leakage sites will generally not be thermographically detectable unless a negative pressure is created with a blower door or the building’s HVAC system.
Infraspection Institute has been training and certifying infrared thermographers worldwide since 1980. Infrared inspection of building envelopes is covered in depth in all of our Level I training courses. For more information on our Certified Infrared Thermographer® or Distance Learning courses, call us at 609-239-4788 or visit www.infraspection.com.
