This is a regular question, and to be often it is often not understood.

There are several thermography companies that do thermography and ignore wind totally. Several others only take it into account by woking below a preset limit, like 10 m/s. This limit of 10 m/s is to some extent the fault of trainers, that often quote 10 m/s as a cut off point, and don’t really explain beyond this. I agree totally that 10 m/s is a cut off point, and that above this level of wind speed thermography should not be undertaken. However, wind will affect your images and mesasurements even below this limit.

To demonstrate this, I have taken a heated plate, switched it on for a couple of hours. I then took a series of images, beginning with no wind, and then with a wind speed of 1 m/s, 2 m/s, 3 m/s, 4 m/s, 5 m/s, 6 m/s, 7 m/s, 8 m/s, 9 m/s and 10 m/s. There is only about 20 seconds between each image. Finally I produced a temporal plot of the cooling affect, which is in the last image.

The images show, that even with only 1 m/s of a wind speed there was sufficient cooling to cause measurement errors. If these errors are being input into some sort of quantification methodology, this means that if the measurements are wrong, so too will the quantification. This is particularly important with buildings, if thermographic images are being relied upon to provide U or R values, and there is a wind, then the results will be incorrect. If there has been some kind of cost quantification, then the temperature error, will cause erroneous costs to be quantified. Where people have limited themselves to working below 10 m/s, the results become even more questionable. In the 9 m/s image, the wind has caused almost 8 degrees of cooling. An input error like this will cause a very significant erroneous result.

The problem with working outdoors is that wind is not a constant, it varies constantly, and it is really impossible to take it into account fully. Quantification of results taken under anything other than near steady state is a serious error that many thermographers make, including some very experienced people, and some high profile thermography companies. At best, several other pieces of equipment should be used to verify the results, and thermography alone should not be used.

No wind above

1 m/s wind above

2 m/s wind above

3 m/s wind above

4 m/s wind above

5 m/s wind above

5 m/s wind above

6 m/s wind above

7 m/s wind above

8 m/s wind above

9 m/s wind above

10 m/s wind above

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