Thermal imaging is a tool I use for energy auditing, but it’s usefulness goes way beyond. I often use my camera during building projects and at my own home to help detect problems.
My camera is a Flir C3. A fairly basic and lower cost thermal imaging camera. I say lower cost, around $600. A drop in the bucket for a top of the line Flir, which can run over $20,000! The C3 has the features and resolution to meet my needs.
Thermal imaging is simply a photo of temperature differences. Most newer thermal imaging cameras overlay a digital photo over the thermal image to help sharpen the image.
The photo above is a good example of what a digital picture overlay can do for a thermal image. Below is that same image without the digital overlay.
Much easier to tell what you are looking at with the digital overlay.
My C3 has an 80 x 60 IR sensor and 640 x 480 pixel digital camera, which is fairly low in the thermal imaging community. That top of the line Flir for $20,000 has an IR sensor resolution of 1024 x 748 along with a 5 megapixel digital camera. Very sharp images, even without the digital picture overlay.
The thermal imaging photographs will need to be downloaded from the camera. I use the Flir Tools Software to create reports for my customers. I can also manipulate the thermal image photos. There are several color palettes to choose from. I prefer the iron palette. Cool areas in the photo are purple to black with warm areas orange, yellow and white. The pic below is of a poorly air sealed and insulated door shown in iron.
The next photo is the same door but using the arctic palette. The cooler areas are shown in blue with the warmer in yellow.
How about the rainbow palette.
And the grey scale palette.
Other ways I can manipulate a thermal image picture is by increasing the digital photo’s visibility and decreasing the thermal image. This gives a much clearer image of the subject matter but still allows the warm and cold areas in the photo to be visible. This option can be selected using any of the color palettes.
The final way I can view a pic is by using a picture in picture option. This shows an area of thermal image surrounded by the digital image.
OK, you’ve seen the different ways I can present a thermal image. How about the information the image contains. Let’s go back to the original door thermal image in the iron palette.
The temperature in the upper left hand corner of the image indicates the temperature of the circle in the center of the photo. The Flir software will allow me to move this circle anywhere in the photo to indicate the temperature of the surface in the center of the circle. The scale on the right side indicates all the temperatures within the photo, in this case from 10.8°F to 57.7°F. Very useful information. Without knowing the scale, the temperature difference could be very small and not much of a concern but look much worse in the photo.
Here is an example of small temperature scale, only 20 degrees. (There is nearly a 40°F temperature scale in the door photos above.) This basement is loosing heat through the concrete block, the photo makes the concrete block look like it is on fire when it’s actually only 13°F.
Another important consideration when conducting a thermal image scan of a home is the temperature outside compared to the temperature inside the structure. The time of the year is important.
The photo above was taken during the summer with a blower door in operation creating a negative pressure in the home. This is a wood paneled ceiling that is poorly air sealed in a log home. Warm air is moving out an attic space that the sun has been shining on, which is indicated by the yellow streaks on the ceiling. Notice the temperature scale, only 10°F difference. I didn’t have a large temperature difference between the inside of the home and the outside while conducting this energy audit.
The above pic was taken during the winter, cooler outside air was being drawn under the bottom wall plate during a blower door test in this home that was built in the 1930’s. Notice that the incoming air is purple in this photo.
Thermal imaging can sometimes detect water damage. When a surface is wet, it will typically have a different temperature than the surrounding surfaces. The picture below shows a ceiling that was wet after water leaked around a roof boot for a woodstove chimney.
The purple area near the temperature circle in the center of the photo is damp drywall. This water damage was a couple weeks old when this photo was taken, the photo would have been much more pronounced if taken during or right after the water leak.
One last thermal image, this one is of a floor with hot water radiant heat.
This picture was taken for a carpenter who needed to drill a hole in this floor and was worried about penetrating a heating tube. I was able to find each tube and give him a safe place to drill.
There are many other uses for thermal imaging in residential construction, my camera is one of my favorite tools I own. Did you know there are attachments to make your smart phone a thermal imaging camera? An entry level unit costs around $200. A low cost tool that both contractors and homeowners will find useful.