Managers of commercial, industrial and institutional buildings are always on the lookout for ways to reduce their cost of operations, including maintenance expenses and heating and cooling bills.

For help, one powerful tool they’ve turned to is a handheld thermal imager, also known as infrared (IR) imagers or IR cameras.

Thermal imaging or thermography can capture two-dimensional representations of surface temperatures, including roofs, walls, doors, windows and construction joints. Often, these images reveal temperatures or differences in temperatures (Dts) that indicate conditions and inefficiencies contributing to the waste of heated or cooled air and energy.

While thermography may be used for tasks as diverse as detecting insect or animal infestations and discovering voids in poured concrete structures, they also can help lower a building’s maintenance and energy costs by checking roofs, walls, windows and doors for inefficiencies.

Flat roof structures are the standard in commercial, industrial and institutional buildings in the U.S., and billions of dollars are lost every year due to premature roof failure. By simply maintaining the roof, a great deal of money that is being lost could be put to better use. Infrared roof inspection can help prolong the life of a flat roof structure.

A flat (low-slope) roof consists of a deck, insulation and a membrane. Usually, the membrane consists of either built-up layers of roofing felts bonded together, or it’s a single sheet of glued down rubber or plastic further anchored by stone ballast. The membrane’s job is to keep out water. When a membrane leaks, water is exposed to the insulation.

Using methods outlined here, it is relatively easy to isolate moisture in or on insulation during an external inspection using an IR camera. In fact, one thermography expert says that finding water problems on a flat roof, especially finding water- saturated insulation is like “shooting fish in a barrel.”

Of course, wet insulation loses its Rrating, which means it loses its effectiveness as a barrier against heat and cold and should be replaced.

If a roof leaks but the insulation does not absorb water, then you need more than a passing knowledge of insulation types and of patterns caused by water infiltration to perform meaningful thermography yourself. Still, if you know that the roof construction on your building( s) is built up felts with absorbent insulation (e.g., perlite, wood fiber, cork or fiberglass), then an investment in an IR camera may be the way to go in guarding against heating or cooling losses and/or expensive roof repairs.

Walls

During an external scan of a building under the right circumstances, a thermal imager can pinpoint moisture in walls in much the same way it can in roofs. Of course, water in walls (or roofs) will lead to mold and mildew, adversely affecting occupants who are allergic to such spores. Also, in walls (as in roofs), wet absorbent insulation will have lost its effectiveness and should be replaced.

Detecting totally non-insulated walls poses a special problem because there is no insulated section with which to compare non-insulated sections. When thermal readings are uniform for a wall, a physical inspection of the wall’s interior may be required to confirm the presence of insulation.

To monitor for air leakage, which generally translates into cooling losses in summer and heating losses in winter, scan windows, closed doors, construction joints (soffits and transitions from concrete to frame walls), wall penetrations ( pipes and electrical entries) and roof penetrations (vents, ducts and chimneys). Under the right circumstances, an IR camera will detect temperature differences that signal heating or cooling losses.

In double-pane window systems, for example, vacuum seals inevitably erode over time, and moisture collecting between the panes of glass signal that condition. When that happens, an infrared camera scanning a bank of windows from the outside will confirm the seal loss by recording a surface temperature of the suspect window different from the other windows in the bank. The R-value of the window is different because the insulation seal is gone.

While infrared thermography is useful in finding seals that are broken or completely missing on window systems, there is a fairly long payback on repairing windows as compared to other ways of reducing the cost of operations.

As one experienced thermographer puts it, “There are usually bigger energy fish to fry somewhere else in the building.” That is, a savvy manager is probably going to start with fixes that represent the fastest return on investment, addressing roofing problems, for example, before dealing with windows that have lost their seals.

One other often-overlooked area of energy loss are doors at shipping and receiving docks. Nearly every commercial, industrial or institutional building, no matter how small an operation it supports, has a loading dock. Except in the rare case when the docks are not heated and cooled for the comfort of workers, the potential for wasting energy when a truck is at a dock is significant. Thermal images will help document the extent of any waste.

When and What to Look For?

Wet insulation is the primary cause of premature roof failures and high roof maintenance costs. Scan roofs after a hot day. Any detectable moisture will retain the heat of the day while surrounding structures and insulation cool.

In a report by Infrared Solutions Inc., now a Fluke company, Chaz Nabji notes that different types of insulation result in different thermal patterns. Therefore, knowing what type of insulation is in a roof and the thermal pattern it will create in the presence of water can be very helpful in detecting moisture in a roofing system.