Building Services Management-Solutions For Today's Facility Maintenance Professional

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Infrared Thermography
Getting to the Source of HVAC Energy Loss

Whether a home or commercial building, getting to the bottom of energy loss can have a big impact on monthly energy costs.

Professional thermographer and owner of Infrared Survey Company, John Cannamela, has found that the culprit for much of a building’s energy loss has to do with the HVAC (heating, ventilation and air conditioning) system.

Knowing how to determine the HVAC issue is where infrared becomes Cannamela’s most important tool. In some of today’s most well designed and architecturally pleasing buildings, the mechanical rooms where HVAC systems are located are often small, restricted spaces.

These small spaces can be problematic for proper airflow needed for HVAC systems to run efficiently.

In many cases, when energy loss has become an issue, Cannamela is asked to do a general or insulation-specific audit. “People are often surprised to learn from these audits that half of the loss is HVAC,” said Cannamela.

Evenly distributed air (also referred to as laminar flow) through the air handler is key to an effective, efficient HVAC system. Air handlers deliver the air that is used to heat and cool a space. Heat is either removed or introduced into the air stream by mechanical means (e.g., chilled water coil, DX coil, or electric strip heaters).

But achieving this evenly distributed air movement can require using ducts of several different diameters. A certain amount of velocity is also needed in order to utilize the entire cross sectional of the coil.

Sounds straightforward, but when space is limited, equipment often gets downsized and ends up not being the right size needed for proper airflow. When this happens, energy is wasted and systems can fail.

Solution

The most common cause for poor airflow is the lack of distance between the return air plenum and the face of the device (such as the coil) that is the transfer medium. In order to understand the airflow, the temperature of the air in the HVAC system is measured.

Prior to infrared, several temperature data collectors would be placed across a coil at different heights across the air stream in order to characterize the air stratification. This earlier method would take several days to gather and analyze the necessary data.

By using an infrared camera, in a matter of seconds, Cannamela is able to measure the temperature of air in the HVAC system. And unlike the old method, once a problem is identified using the camera, Cannamela has an image to show and help explain the problem to his customer.

Without infrared to easily identify the HVAC system problem, it was a common mistake to spend money on suspect problem areas that were not the main cause of the energy loss. Cannamela points out that most people are unfamiliar with infrared and what it can do. But once they see the image and with the help of a professional thermographer, the problem is clear and the right improvements can be made.

“Having infrared images is not enough,” said Ronald Lucier, a thermography instructor for FLIR Systems’ Infrared Training Center (ITC) in North Billerica, MA. “It requires an understanding of the science in addition to having experience in the area you are working in. Whether it’s assessing water damage on roofs, energy audits, or an HVAC application, it requires experience and an understanding of thermography.”

Infrared thermography can be used extensively to identify problems and perform quality checks in building diagnostics, construction, roofing, facility inspection and energy auditing.

Infrared cameras produce images of invisible infrared or “heat” radiation and provide precise non-contact temperature measurement capabilities.

Nearly everything gets hot before it fails, making infrared cameras extremely cost-effective and valuable diagnostic tools in many diverse applications.

Infrared cameras can detect even minor variations in temperature that can signal electrical or moisture problems. For example, infrared cameras can detect moisture accumulating out of sight in a roofing system, electrical components that are overheating, and other problems. For more on thermography and thermal imaging, go to www.goinfrared.com or www.infraredsurvey.com. ❑