Infrared Thermography as an Indicator of Heat Loss

There have been challenges in identifying and locating air leaks and evaluating insulation performance. Thermography is being used increasingly these days as an effective diagnostic tool and the results have been promising. The technique of thermography combines photography and infrared sensing. We measure apparent surface temperatures directly with infrared sensing. Infrared cameras are used to capture thermal information in the form of images called thermograms. If given proper training, a person can read the thermograms to locate gaps in insulation and air leaks which are revealed in the form of heat loss. The information collected guides us effectively in making necessary repairs and gauging how good those repairs have been.

With fuel costs rising steadily and rapidly, the identification of energy loss has become more important than ever before. Imperfections in insulation installation, windows and doors being fitted loosely, steam pipes having leakages, and roofs and walls leaking air should be identified without delay to prevent a steep hike in energy bills. Adequate sealing of air leaks in roofs and the walls and timely replacement of insufficient insulation need proper attention. All of this is indicated by heat loss captured by thermography. Let’s look into thermography to locate heat loss in more detail.

How thermography works

Infrared videos and still images are used in thermography to measure surface temperatures. These tools help in spotting light present in the heat spectrum. The images record the temperature variations on a surface caused by heat loss where white indicates warm regions and black indicates cooler ones. When these images show heat loss, it tells the auditor where repairs are needed. Thermography is also an effective tool in quality control telling us if the insulation has been done correctly or if there are shortcomings in the construction causing air leaks.

Thermographic inspections can be both interior and exterior surveys. Depending on weather conditions, the energy auditor decides which method is likely to give the best results. As warm air leaking out of construction doesn’t necessarily move in a straight line, interior scans are done more commonly. With air not moving in a straight line, heat loss that you detect in a certain area of the wall outside may be occurring at some other area inside. Again, detecting temperature differences that show on a building’s outer surface is harder when the weather is windy. Since the air movement is reduced inside the building, interior inspections are more common and accurate.

Energy auditors can check how effective the insulation has been. With the thermograms, an auditor can decide where in the building insulation is needed and where it isn’t. Wet insulation causes heat to conduct faster than dry insulation. Therefore, leaks in roofs can be detected by thermography.

The infrared inspection comes in handy even when you’re buying a new property as there might be issues in their thermal envelopes. You may make the infrared inspection a must through a clause in the contract. The reports acquired may be useful as evidence in court proceedings should any dispute arise.

The types of infrared devices used

During an on-site inspection, you may find the energy auditor using different types of devices for infrared sensing. The simplest one to use is the spot radiometer which measures heat loss at a certain spot at a given time through a simple meter reading. The auditor uses the device to scan an area and notes temperature differences that indicate heat loss.

Thermal line scanners reveal radiant temperatures captured along a line. The thermogram is a representation of the line superimposed on a picture of the area scanned. The process presents differences in temperatures along the line that’s been tested.

Now we come to the most accurate device used in infrared inspection. It’s a thermal imaging camera. These cameras produce the most accurate results in the form of 2-dimensional thermal images of an area that reveals heat loss. The images are in separate colors ranging from white that indicates warm spots to black, an indication of hot regions. You have to bear in mind that spot radiometers and thermal line scanners aren’t quite capable of giving you all the necessary details that help you make a thorough assessment of your property’s energy efficiency. The infrared films that a conventional camera uses don’t capture heat loss properly as they aren’t sensitive enough.

How to prepare for infrared inspections

Before preparing for a thermal scan inside the property, taking certain steps are necessary for accurate results. You may have to move some pieces of furniture away from the walls and also remove the drapes. Thermographic images are the most accurate when the difference in temperatures is large- at least 20°F or 14°C, between the air inside and outside the property. Thermographic inspections are generally done in the winter in the northern states. However, you’ll have to keep the air conditioners on in the southern states where the scans are conducted in the summer when it’s warm.

Due to a phenomenon referred to as “thermal loading,” you may need to create a specific difference in temperature between the inside and outside and then maintain it for up to four hours before the test. You’ll therefore have to run the air conditioner in warm regions and the central heating in cool regions. You’ll have to confirm with the auditor if it’ll be necessary before the test begins.


Infrared thermography is therefore not only accurate in detecting heat loss, but it’s also fast and clean, and safe. It’s an effective tool of non-destructive testing which makes it even handier as it removes the need for any dismantling or demolition. Thermography is being used increasingly in a variety of fields. Its extensive use in detecting heat loss has helped gauge the effectiveness of insulation work in properties telling owners and auditors where corrective action is needed. Infrared thermography also tells us how effective such corrective action has been. The advantages of infrared thermography are many and if done under ideal conditions, they are very accurate in spotting heat loss which indicates air leakage.

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