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X-Ray Vision What Infrared Thermography Can Do For Your Building

X-Ray Vision

Time was, if a residential building was suffering heat loss, leaks, or other infrastructure problems, it was up to a team of engineers, contractors, and perhaps architects to investigate where the problem lay within the building's walls and to fix it - and that's only assuming anybody realized there was a problem in the first place. Slow leaks, mold contamination, faulty heat risers, and gaps in insulation can go undetected for years, compromising building residents' comfort and costing untold thousands in wasted energy and clean-up costs, and even developing into full-blown threats to building safety in the form of health and fire hazards.

Now, however, there is a method by which professionals can literally see through the walls of buildings of any size or description and identify potential problems before they become real crises. It's called infrared thermography - "IR" for short - and it's a tool of interest to building owners, managers, maintenance personnel, board members, contractors, engineers, and anyone involved in buying a building.

What It Is

In a nutshell, infrared thermography is a non-contact, image-based temperature measurement performed using an infrared sensitive camera. It's also referred to as thermal imaging, infrared imaging and in some fields, thermology. IR provides actual pictures of temperature, as well as accurate, detailed temperature measurements for objects of almost any size. The tool allows for rapid and direct understanding of any number of building systems and their behavior.

For a technology with such a simple description, IR has a remarkably wide range of applications. Single-family homes and commercial facilities can benefit from the technology every bit as much as a large apartment building, but here, we'll focus primarily on the applications of IR for multi-family managers and boards of directors.

How It Can Help

While words like "thermograph" and discussions of infrared technology may seem too high-tech and complicated for some building managers' and board members' comfort, the real-life, potentially beneficial applications of IR are things anyone involved with running a building day-to-day can relate to. The more specific, up-to-date information you have about your building, the better your position from which to negotiate on behalf of your board and/or shareholders. Applying thermography can be of help with building condition assessments and engineering reports prior to refinancing, re-negotiating insurance policies, or to determine what constitutes an adequate reserve fund.

IR can also help architects and engineers conduct surveys to locate subsurface building features such as wall studs, blocked doors or windows, voids, and pipes. This is useful not only for the sake of a board and building staff's general knowledge about the structure itself, but also for any residents wishing to renovate, combine apartments, or confirm that a construction job was completed properly and to their specifications.

Building superintendents and maintenance staff can utilize IR to aid in utility systems evaluations; the technology can be used to find the aforementioned "hot spots" in a building's electrical system, and can also be used to examine mechanical equipment and construction materials, like insulation, or heating and cooling equipment.

For legal and insurance purposes for both boards and shareholders, IR can also assist with identifying the location and extent of insulation gaps, moisture infiltration in walls or through the roof, delamination or separation of wall layers or other elements, air leaks, and all kinds of chimney problems.

Getting Technical

IR images are pictures of things we cannot see - like heat and relative temperatures - and they depend on interpreting the infrared radiation that all objects emit when above absolute zero temperature. Therefore, images in an IR report have to be presented in false color scales. These can be in varying shades of gray, or in any one of a number of color palettes. Grayscale images tend to look more like photographs, and it's generally easier to understand the geometry of the scene if it's rendered in grayscale. Color images, on the other hand, generally make it easier to see the various temperature differences. The best choice of color scale varies from case to case.

Items in an IR report are accompanied by temperature scales corresponding to the various colors or shades of gray in the photo image. Occasionally, the temperature range of an image has to be adjusted to several different levels in order to show the areas of interest. A narrow range at one level will reveal features that cannot be seen easily in a full-range image, but will hide other areas by saturating them at the top or bottom of the given temperature range.

How It's Done

In general, IR is performed using either a "passive" or an "active" approach. Passive IR involves observing fluctuations in a given building system based on the system's inherent temperature differences. An example of this would be finding "hot spots" in a building's electrical system by detecting areas of higher-than-average heat loss from overheated electrical connections.

By contrast, active IR involves introducing a variable, or "transient" to the system being observed. This is sometimes necessary if the features of interest do not have an inherent thermal signature of their own. It can also be used to emphasize differences that are hard to detect. The transients for active IR can be induced by utilizing the sun - called "solar loading" - or by more direct means, such as blowing hot air onto a surface. Possible applications for active IR might be the detection of delaminations in walls, or the detection of moisture in a roof or wall.

Many of the applications for IR in the real estate world are well served by simple thermal imaging that shows the approximate temperature and location of hot and cold areas.

There are also some restrictions in when and how some of these temperature surveys can be performed. Some of them - like roof moisture and delamination detection, and sometimes detection of water in walls - will require active IR (usually solar loading) to be effective. Others are weather dependent; building insulation surveys, for example, depend on a temperature difference between the interior and the exterior of the building.

What Might You Find?

Insulation keeps the warm side of a wall warm and the cold side of it cold. The better the insulation performs, the closer the surface of the wall is to the surrounding air temperature, and the less it costs to heat or cool the building. When insulation fails or is missing entirely - especially in a limited area - IR will show a temperature anomaly. During the heating season, this will show up as a warmer spot on the exterior of the wall, or a colder spot on the interior.

Image 1 shows the exterior of a high-rise building with an insulation problem. It appears that one floor's worth of the pipe chase that runs along the outside wall was not insulated during construction - perhaps the work crew went to lunch after finishing the 9th floor and came back from lunch at the 11th floor. Whatever the cause, this building is losing heat to the outdoors and wasting money.

Moisture from leaks can sometimes be detected without doing anything special to the surface of a given wall, but in other cases, it is necessary to use active IR techniques - such as heating the wall - to coax the problem into view.

IR can be used to detect wet areas in the walls. Wet areas warm more slowly than dry areas, and therefore appear relatively cool in the IR image. The ends of the interior walls and floors also appear cool, but this is normal under the conditions of the survey and does not necessarily mean that those areas are wet. The areas around the windows, and those that are irregularly shaped are particularly suspicious for moisture.

Delaminated areas are not as firmly connected to the rest of the building, and therefore heat up more than the other parts of the wall when the sun shines on them. They show up as hot areas in the images.

During the image survey, it was discovered that windows in the building had been removed and the areas sealed over. The column of windows on the left of the image used to be double-width, and the arch on the ground floor confirms this.

Other Benefits"¦and Limitations

Beyond saving money and curbing energy waste, IR surveys can improve building safety. Poor electrical connections - whether due to installation problems, accumulation of dirt and corrosion, failure of parts, or loosening of connectors - can easily overheat under heavy electrical loads. IR is a well-established method for finding these problems before they cause a complete power failure, or worse, a fire.

It's also worth pointing out that, where there's moisture infiltration, there will likely be mold growth. Given the wet summer here in the city and increased awareness of health problems possibly linked to mold contamination issues, interior moisture surveys can be of particular use in curbing the risk of mold growth in multifamily buildings.

Of course, while IR is a useful tool with many applications in buildings of all descriptions, it's important to remember that it's only a first step, and not a cure-all for everything. After all, just knowing a problem is there doesn't make it go away. The onus is still on boards and management to fulfill their obligation to identify and correct potentially problematic structural and maintenance issues, and IR technology is just one tool at their disposal to help execute that duty. IR surveys can be done easily and reliably and are generally very cost effective, but some instances, the technology may not be able to find or pinpoint the precise issue of interest to a client. The client has to be aware that - while IR is a very powerful item in their building maintenance arsenal - it is not an answer to everything.

Jack M. Kleinfeld, P.E. is president of Kleinfeld Technical Services, Inc., which offers infrared thermography and heat transfer analysis for a variety of applications.

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Comments

  • Can thermography be used to determine if a riser pipe needs replacing? If not what technology can be can be used assuming the pipe is not leaking.