Condo Media - February 2013 - (Page 28)

by Bret Monroe and Lew Harriman TECHNOLOGY Heat Seekers Thermal Cameras and Commercial Building Inspections fter years of confusion and fear of technology, the worldwide interest in reducing energy consumption has put a new emphasis on diagnosing the location and extent of heat leakage into and out of building enclosures and on troubleshooting potential structural issues or damaged locations. Thermal infrared cameras have become standard tools for the building inspections focused on these issues. Consider a simple example of a hotel stairwell with an odor problem. The infrared camera shows a temperature pattern, which suggests that cool water is escaping the fan-coil unit’s drain pan and wetting the carpet. Such wet materials grow the mold and bacteria, which produce odors. The images below show an example of outward air leakage from the top of a tall building due to the stack effect during cold weather. Warm air escaping through open joints near the top of the building creates a slight suction at the base of the building. Cold air leaks in at the base of the building to replace the outward-flowing air at the top, resulting in wasted energy and cold drafts. A To understand the use and the limitations of infrared imaging for moisture detection, it helps to understand infrared energy and the cameras, which can see it. Thermal Cameras All surfaces above absolute zero emit electromagnetic waves in the infrared region. These wavelengths are almost all much longer than visible light, although at the edge of human perception, infrared laser pointers emitting light at about 0.75 microns are a familiar technology. Slightly beyond that wavelength are the near-infrared waves, which can be seen with “night-shot” image enhancement in conventional video cameras. Then, 10 times longer than those wavelengths and beyond the range of conventional optics are the middle infrared wavelengths between seven and 14 microns. This range is called “thermal infrared” because when surfaces are between -40° and +400°F they emit quite a bit of radiation in this range. The strength of their emission can be sensed and measured with special optics, and used to show surface temperature patterns. Infrared technology was developed originally for military purposes. It’s the basis of heat-seeking missile guidance systems. But the cost of thermal imaging cameras has come down as economies of scale have reduced manufacturing costs. For example, the cost of a camera with a low-res imaging array of 160 x 120 pixels has dropped from over $20,000 Warm air escaping from open joints shows the location and relative magnitude of heat leakage from a tall building during cold weather. 10 years ago to less than 28 CONDO MEDIA • FEBRUARY 2013 $3,000 today. And the cost of a highres camera with a sensor of 320 x 240 pixels has come down from $40,000 10 years ago to between $8,000 and $12,000 today, depending on which features they include. These more economical prices have made thermal cameras cost-effective for moisture inspections as well as more complex energy investigations. Inspection Examples Let’s suppose a pipe breaks in an office. After the obvious water is removed with wet-vacuums, the building is surveyed in preparation for drying. After water ponds on the floor, it wicks up into the wall board, pulled by capillary suction. The thermal camera shows the moisture pattern as a band of cool surface near the base of the wall. That’s because the evaporating moisture takes just a bit of heat from the wall itself. Modern infrared cameras can resolve a temperature difference of less than 0.2°F between adjacent pixels, so the fact that the moist area may be only 1.5°F cooler than the rest of the wall is no obstacle to forming the image. It’s interesting to note the insulating effect of the base molding. Of course the wall board behind that base molding is still wet. But that fact is not perceptible in the infrared image. This illustrates the important point that these cameras do not “see inside walls.” Nor do the camera images “penetrate” into the wall. Although it shows very useful images, an infrared camera can only see the patterns created by the emission of infrared energy from surfaces. Meters must be used to confirm the presence of excess moisture. Then the investigator’s skill must

Table of Contents for the Digital Edition of Condo Media - February 2013

Condo Media - February 2013
Table of Contents
From the CED’s Desk
Editorial Board
CAI News
CAI Regional News
Asked & Answered
Homeowner’s Corner
Blanket Coverage
Vendor Spotlight
2013 CAI-NE Insurance & Restoration Directory
Classified Service Directory
Advertisers Index

Condo Media - February 2013