Infrared (IR) Thermography

Infrared photography, also called infrared thermography or IR thermography, has gained popularity in recent years in several industries that deal with home energy usage and energy efficiency. This technology is quite useful in finding areas of a home that are losing or gaining heat, such as from a lack of insulation, as well as finding roof, siding, and plumbing leaks or overheated wiring or HVAC equipment. Air infiltration (air flow into the home) or exfiltration (air flow out of the home) typically has specific patterns that the inspector would look for. WIN Home Inspection now offers Infrared (IR) Thermography as a service to home buyers, home owners, builders, contractors, etc.

These cameras work by capturing infrared energy that all objects give off (to varying degrees) and displays an image with a range of temperatures on a small screen. Finding areas of the home where heat is escaping or invading can be relatively easy to a properly trained professional. For example, in the winter, looking up at a ceiling below a poorly insulated attic would show where insulation is lacking by the fact that the camera would display a range of colors corresponding to various temperatures. The cold zones (often displayed as a dark blue) would be discernable next to the better insulated areas (often displayed as an yellow or orange. These cameras will also be able to show actual temperatures at various areas of the image. A qualified thermography must have a detailed grasp of energy and heat transfer as well as material emissivity. IR cameras look at a different wavelength of light outside of where humans can see. Our eyes see light in the visual spectrum whereas an IR camera sees light in the infrared (IR) spectrum. The infrared spectrum is a lower frequency (higher wavelength) than human eyes see.

Knowing where insulation is lacking in attics, walls, etc. can help identify locations where improvements can be made to help lower utility costs and increase interior comfort. Many professionals who perform energy audits also use infrared thermography. This technology can also help find problem areas with electrical wiring or HVAC ductwork as well since both deal with temperature. An overloaded wire junction in the wall may be able to be found before it starts a fire. Unsealed or uninsulated HVAC duct joints could be found and repaired to help save on energy costs.

Since water also varies in temperature (such as once it enters a wall or ceiling), finding evidence of roof and plumbing leaks can also be done with infrared photography. Water cools a surface due to evaporation.

To use this technology reliably, however, the user must be properly trained on the camera’s features as well as how to decipher the characteristics of heat transfer. An untrained eye could easily confuse leaks and missing insulation, or totally miss this phenomenon altogether, when looking at an image displayed on the infrared camera. The infrared camera manufacturers either provide courses for those purchasing these cameras or contract out to 3rd parties to provide the proper training.

In the home inspection industry, the Standards of Practice of the American Society of Home Inspectors (ASHI) has not directly addressed the use of infrared thermography. Rather, it is a new tool to use, just like a flashlight, moisture meter, or screwdriver. In most cases, if a home inspector were to use this technology, it would be to find areas of energy inefficiency or air/water leakage of some sort. The costs associated with infrared thermography and proper training has prevented many home inspectors from making the investment in this technology. Since a home inspection is a non-invasive visual inspection of the home’s major systems, there is some discussion within the home inspection industry as to how to use this technology, yet stay within the Standards of Practice. Some inspectors say this is simply another tool in the course of providing the inspection service. Others see this technology as being invasive and, therefore, beyond the scope of a home inspection. Many of the inspectors that use infrared thermography, offer this technology as an add-on service, just like Termite/WDI inspections, Radon testing, etc.

The various companies that provide Errors & Omissions (E&O) insurance in the home inspection industry see infrared thermography a little differently. Some of these companies say that, infrared is just another tool and that the inspector’s E&O covers the use of infrared thermography as long as the inspector is properly trained in the use of this technology. Some other E&O insurance carriers consider IR camera use outside the scope of a home inspection and may require additional E&O coverage for those inspectors performing infrared thermography. The additional insurance cost may also be a constraining factor as to whether a home inspector wants to offer this service or not.

An IR scan entails walking around the home's exterior and interior and scanning the home's walls, floors, ceilings, ductwork, wiring, etc. The process of taking and analyzing the images can take 30 to 90 minutes depending upon the home's size and what is found in the images. If indications are found of a leak (plumbing or roof), the inspector should confirm the leak(s) using a moisture meter, assuming the area of the leak is physically accessible.

An important fact that needs to be mentioned has to do with exterior temperature. Late in the afternoon on a sunny day, trying to use infrared thermography at the home's exterior that has had a long day of sun exposure can be tricky or impossible. This can prevent the usefulness of a full IR scan of the home. Ideally, early morning tends to provide the best time for doing such exterior work due to the inference of exterior temperature being less likely. Also, for a proper full home IR scan, furniture inside the home should be moved away from exterior walls as well as pictures and mirrors removed from exterior walls. These items can block heat flow in the area of the exterior walls, so these items should be removed approx. 12 hours prior to the IR scan. Also, a temperature difference of at least 12 degs F (18 degs F is even better!) between the interior and exterior of the home is recommended for a proper IR scan. This may entail the home owner running the furnace or A/C to a higher (or lower) degree for at least 4 hours (12 hours is even better) prior to the IR scan starting. Since IR thermography deals with temperature differences, properly 'conditioning' the home before the IR scan takes place is necessary for the technology to work properly. In occupied homes, however, properly preparing and conditioning a home prior to the thermal scan may prove difficult.

As the infrared thermography equipment costs continue to decrease, more home inspectors will undoubtedly add infrared thermography to their list of services. Currently, the smaller handheld infrared cameras generally run from $2,000 to $8,000. The larger more complex cameras can easily cost $10k~$40k. As with any service, the inspector has to decide whether the investment will lead to more business and how soon the equipment and training will be paid for by providing the service. Just how many potential home buyers would elect to pay for such a service is another issue that many home inspectors have continued to wrestle with. Most of the home inspectors that offer infrared thermography as an add-on service typically charge $200-$400 per thermal inspection. Of course, if you inform a client that you just found a hidden leak, missing insulation, or potential fire hazard that was previously hidden by a fixed wall or ceiling covering, they would be happy they invested in this add-on service.

The author of this article, Matthew Steger, is a Level 1 Certified Thermographer.

Infrared (IR) Thermography

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