Thermal Imaging: Is that a ghost?!

Nick BakerBy Nick Baker, EIT, CCP, GPCP, LEED AP BD + C

Wood Harbinger’s engineers have been blogging since 2013! This Throwback Thursday series features posts from back in the day that are just too good to stay at the back of the blog. Enjoy this post from Nick Baker, originally published on October 31, 2013:

Thermal Imaging is used in a variety of industries, even in television.  But what is it the images are really saying?  The first thing you notice when looking at a thermal image is the colors, what is red and yellow  or “hot” and what is blue or “cold”.  But what does that really mean? How hot is hot? And vice versa how cold is cold?  Why are parts hot or cold?  And since this is the month of haunted houses and paranormal activity, why is there a ghost in the window?  And what is that hell spawn in the picture below?!

 No, that’s just a thermal image of a co-worker’s daughter.

First, a couple of definitions:

Thermography is the science behind thermal imaging.  Everything above 0 Kelvin emits infrared radiation; infrared thermography and thermal imaging are the study and capturing of that radiation.

Emissivity is the relative emission of radiation of an object to that of a black body.  A black body has an emissivity equal to one; every real object has an emissivity of between zero and one.  The more reflective a material the lower its emissivity is.  This is why images of glass and metal can appear to have a ghost, but we’ll discuss that more later.

To begin viewing a thermal image there are three important things to keep in mind.  First, what is the temperature scale, this is our “how hot is hot? or cold in cold?”  Second, what is it I am looking at and what do I expect to see?  Third, what, if any, anomalies are present in the image and are they real or not?

Below are three different thermal images from around my office with the accompanying digital image and explanation of findings.

Just a chair, but what’s that red spot?

In these first images the thermal image is showing that my coldest spot is 72 degree F, in this image cold is actually room temperature.  Looking at the digital picture this is an image of a chair against a wall.  The anomaly is an 80 degree F hot spot on/in a 72 degree F room.  Is this something paranormal? This is the moment that further investigation is required.  I found on the opposite side of the wall an outlet, then looking above the drop down ceiling found the conduit serving this outlet warm to the touch.  At this point I needed to enlist some help, because I am not an expert in Electrical systems, so turned to Sean Bollen P.E. of the Electrical Engineering Group in my office.  We used the building’s electrical plans and traced the circuit serving this outlet and found it was shared with the front desk; I went to see the load used by the front desk and found a small unit heater plugged in leading to the increased temperature of the conduit.

The images above are of one of the other circuit panels in the office.  I found the #4 and #26 circuits to be 5-10 °F warmer than the rest.  Again with further investigation and Sean’s help we found that these too were caused by the use of unit heaters also.

Is that a ghost?

These final pictures look like I found a ghost in Wood Harbinger’s office. Obviously there’s no one standing in front of the pictures, so why do we see a person in the thermal image? This picture actually shows the reflective properties of materials especially glass, highly reflective, compared to other materials such as gypsum board, low reflectivity.  As seen in the digital image the surfaces are of a wall with a picture framed with glass.  Being highly reflective, the glass surface reflects the image and radiation of me in the area with the picture but not on the wall next to or below the picture.  The image even captures a three degree F temperature difference between my reflected head (spot 3) and the area of the picture (spot 1).

So thermal images can be extremely useful but at the same time require interpretation by a qualified person and then may also require some additional investigation and assistance from others with specialize knowledge.  Next time you watch a paranormal hunting show, think about what you’re seeing in the thermal image; is it really a ghost or a camera man standing in front of some reflective surface?

Follow Nick on Twitter @NBaker_WH

This entry was posted in All Insignts, Commissioning, Mechanical Engineering and tagged , , , . Bookmark the permalink. Post a comment or leave a trackback: Trackback URL.

One Comment

  1. Jeff Yirak
    Posted October 31, 2013 at 8:51 am | Permalink

    Excellent explanation and investigation. So is it legal to have space heaters in the commercial office environment?

One Trackback

  • […] The obvious next step was to use Wood Harbinger’s very expensive and fancy thermal imager to see this transformation in a video of colorized infrared radiation. The result is a very close approximation of the temperature being emitted by the subject. A thermal imaging camera is often used for commissioning and evaluation exercises like motor inspections, electrical distribution panel analysis, building envelope investigation, and much more. […]

Post a Comment

Your email is never published nor shared. Required fields are marked *

You may use these HTML tags and attributes <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>