The basement at the rim joist (some call it a band joist): 

The reasons for insulating the rim joist are important: the R-value of the this framing member is minimal (around R-1 per inch), there is often air movement from outside and between floors, and maintaining a more consistent temperature while reducing relative humidity is beneficial for comfort and building science reasons. 

During a recent energy audit, I noticed that the client had installed fiberglass batt insulation. Better than nothing? I suppose. The problem is that batt insulation is not an air barrier and therefore does nothing to stop air movement. And when it is not touching the rim joist, it is allowing pockets of air to change temperature. At right you'll see that this rim joist has a few areas where moisture has appeared.  Some of the insulation had become wet (left-most arrow) and was matted. 

With a cold rim joist, the warmer air in the area between the insulation and the joist cools as it moves from warm to cold (Second Law of Thermodynamics abbreviated: energy moves from hot to cold and never the reverse unless due to an outside force). 

When the warmer air cools and hits the nearest coldest surface - the rim joist - the air becomes more dense, reaches its due point and condenses. Now we have moisture trapped under insulation, which is not a good thing.  This is a relatively minor example, but the home is just 2 years old.  I'd hate to see it in 10 years.

Even a higher-end solution like using spray foam can yield poor results. In this photo from a recent inspection, you'll see that the foam has separated from the floor joists. 

In this case, one of a few things likely happened with the insulation contractor's installation: (1) The building components were too cold when the insulation was installed, which can prevent proper adhesion, (2) The insulation was applied too thick and layered too soon, which would prevent each layer from curing properly, or (3) Part A and B of the insulation mix was improper.  

That's an expensive call-back for the contractor.

In the summer, I frequently see insulation voids in ceiling. For the most part, rectifying the problem is just a matter of rearranging the insulation or removing the debris that is preventing the contact.  

Here's a thermal image of what this looks like. 

In this case, I crawled into the attic and a wad of old plastic wrapping was keeping the insulation from making contact with the attic floor.

In homes with sloped ceilings such as a cap cod, the area where the ceiling and the knee wall meet is often an area where insulation easily settles or is poorly installed in the first place.  

In this case, the batt insulation was not fastened at the top of the knee wall, had fallen backwards and was just hanging there.

You can see the heat from the crawlspace. It doesn't take much for it to conduct through the drywall and cause the room to be cooled even further.

The insulation simply needed to be refastened to the framing members.

The moral of the story? Make sure there is complete and uniform insulation contact for the best possible results.  Properly installed insulation, along with meticulous air-sealing, will give you a more comfortable home, saves you a few bucks and you'll increase the performance and longevity of your building.

A Residential Example:

Last fall a client asked me to verify that her home's walls were insulated according to the specifications laid out by the contractor.  And, for the most part, the work was up to snuff. Because it was a warm afternoon (around 80F), the client was cooling the home (around 68F). The resulting temperature difference was enough to provide some impressive images. 

In the picture below, the darker areas represent areas where insulation is installed properly. Therefore, the cool air that the client is paying for is staying where it should...indoors.  The lighter areas are where there is missing insulation. Heat (energy) from outside is conducting through the exterior wall assembly, convecting through the empty wall cavity, conducting through the interior drywall, and radiating off the drywall where the camera can detect the resulting emitted energy.

So, as you can imagine, the client was disappointed that this area was not insulated properly. Fortunately, the contractor agreed to come out and remedy the problem.

A Commercial Example:

Construction of a nearby office building is underway. When building concrete masonry unit (CMU) walls, there is a requirement that grout and rebar be installed under each area that will support a steel beam. The grout and rebar provide structural strength. If grout and rebar is missing, there is the potential for serious structural repercussions.

So while the general contractor would like to trust that these areas are being filled properly, they felt that verification would be time and money well spent.  And they were right.  Over the course of several imaging sessions we discovered several areas that lacked the necessary grout and rebar. We were also able to verify that many were also done correctly.

In the image below left, the arrow is pointing to cells below a beam pocket (black rectangle) that should be filled but are not. A filled cell (arrow, below right image) would be warmer due to being heated by the sun all day. The grout retains its thermal mass (not unlike a swimming pool with a solar cover keeping the water warm), and therefore shows warmer. Empty cells quickly cool when the sun goes down and display the cool pattern in infrared.

Fortunately, the cells were able to be repaired (filled) prior to the second and third floors being built and the construction manager and lead engineer are satisfied with the building's structural integrity.

While I am sometimes the bearer of bad news, it is very gratifying to be able to detect issues that have real consequences and do it while there is still time to rectify the problem. 

As the leading non-destructive, real-time inspection method, infrared thermal imaging technology makes this possible.