Dec. 1, 2012
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The U.S. Army Engineer Research and Development Center (ERDC) is demonstrating a new technology that enables rapid, high-resolution detection of building envelope energy losses. Developed by the Massachusetts Institute of Technology (MIT) and Eye-R Systems with ERDC’s support, the technology combines an innovative vehicle-mounted kinetic super resolution (KSR), long-wave infrared (IR) imaging system with conventional hand-held thermal imaging.
The imaging system is mounted on a van equipped with a controlling laptop computer, real-time viewing screens, data storage and a real-time GPS. The resulting multiple, staggered images are automatically time-synched with video feeds from the cameras, and the data is merged to greatly enhance the resolution of every pixel of the scene. The KSR technology allows rapid thermal imaging of multiple buildings in a way not currently possible with conventional thermography.
Building energy losses are often caused by missing or inadequate insulation and thermal bridges that are difficult to assess except by IR thermography. Thermal bridges account for about 10 percent of the energy loss in a typical building, and infiltration causes about 40 percent. Damaged or missing insulation accounts for another 40 percent, and the remaining 1 percent is due to energy loss through window glazing.
Because warm objects emit long-wave IR radiation, IR thermography can help detect problems invisible to the naked eye. Examples are missing, damaged or improperly installed insulation within walls and roofs; thermal bridges; and poor seals. While conventional handheld thermography provides a detailed assessment of building envelope energy losses, it is a slow, meticulous process. KSR enables high throughput assessment of the energy loss from hundreds of building envelopes based on scans taken in just a few hours via drive-bys along the street where the buildings are located.
ERDC and MIT conducted super KSR thermographic and conventional thermography imaging at Fort Drum, N.Y., under the Installation Technology Transition Program sponsored by the Office of the Assistant Chief of Staff for Installation Management. The IR images are being combined with other imaging and structural information so that each detected energy leak can be automatically assigned a predicted energy cost, a parts and- labor repair cost and recovered energy savings. The resulting data can then be presented on a Google Street View map of the installation that color-codes each building according to the amount of the calculated energy loss.
Since thermographic procedures must be conducted when inside and outside temperatures differ by at least 20 degrees Fahrenheit, the Fort Drum thermography scans were taken during the winter months. IR thermographic images were analyzed to quantify energy losses via infiltration, damaged building components, inadequate insulation and thermal bridges. Energy losses by large building clusters were quantified and mapped.
The results identify buildings that appear to have the greatest energy loss and need closer inspection, for example, by using conventional hand-held thermography and blower door tests. Using this information, the cost and benefits of upgrades can be determined more accurately.
Based on closer inspections, energy upgrades can be recommended, as is being done for a Fort Drum building for which thermographic images indicated energy losses around windows and doors and at steel seams and fasteners. The building could be retrofitted with an emerging insulation material, such as closed-cell spray polyurethane foam, and the building rescanned to compare energy losses before and after the retrofit. In this case, thermographic imaging serves as a quality assurance and control tool to validate that the retrofits work.
During the next year, ERDC will launch more demonstrations under the Department of Defense Environmental Security Technology Certification Program. Sites will include the U.S. Military Academy, West Point, N.Y.; Scott Air Force Base, Ill.; and Camp Lejeune, N.C.
POC is Larry D. Stephenson, 217-373-6758, larry.d.stephenson@usace.army.mil. Larry D. Stephenson is a research metallurgist and materials scientist, and Jeffrey Lattimore is an engineering technician (materials), ERDC’s Construction Engineering Research Laboratory, Champaign, Ill.
This article was published in Public Works Digest, Vol. XXIV, No. 5, October/November/December 2012, p. 35.