California Center for Sustainable Energy

Envelope leaks may be keeping your energy costs high

Look as hard as you like, but you can’t readily see if inadequacies hidden in and around your home’s walls, ceilings, windows, doors and air ducts are wasting energy and keeping your energy costs high. The good news is that you can either hire a professional to find leaks or borrow equipment to do it yourself at CCSE’s Energy Resource Center.

Building construction technicians know about the secret weapon in the war against heating and cooling loss that allows them to “see what you cannot see,” and the dramatic visual results can be used to greatly improve energy efficiency, according to Peter Hopkins, vice president of United Infrared Inc., a national marketing and training company.

Hopkins led a CCSE workshop in June on energy monitoring with infrared (IR) technology for homeowners, business owners and construction contractors that demonstrated that discovering building defects is about as simple as taking a photograph – in fact, exactly like taking a photo, but one that allows you to see thermal images in the infrared spectrum that human eyes cannot detect. Thermal imaging has been around for decades, in use by firefighters, soldiers, scientists and physicians, but its use has really taken off in the home and building inspection industry the past few years.

The basics of thermal imaging are fairly simple, if you skip the underlying physics and the laws of thermodynamics. All objects with temperatures above absolute zero (–460° F) produce IR radiation that is invisible to us. At certain levels, IR radiation can be seen without illumination by a process called thermography, which shows variations in temperature with higher temperatures emitting higher levels of radiation. When viewed through an IR imaging camera, warm objects (yellow) stand out against cooler areas (purple) – remember the movie “Predator”? The monster chased Arnold Schwarzenegger around the jungle, tracking him with alien thermography, and there was that great scene when Schwarzenegger hid in a mud wall. Well, with IR vision the monster would have easily seen him, but that’s Hollywood.

IR cameras can’t see through walls, but they can see anomalies within a wall, under the right conditions. What the camera reveals are thermal patterns that indicate studs, conduits, pipes and other solid objects, but for energy efficiency purposes, you are looking for variations in heat that may be caused by cracks in window and door frames, by missing or compacted insulation or by poor construction. You can also locate water leaks, pests and electrical overheating hazards, Hopkins noted, which can help keep such problems from escalating into costly repairs.

Thermographic inspection can be done as either an interior or exterior survey, but interior imaging is more accurate because it reduces the effects of weather conditions. The types of things that are usually found are improperly insulated attic access panels, air leaks at room corners and around door frames, missing or compacted wall insulation, air infiltration at lighting fixtures and a host of other energy-wasting defects. Images can be made in conjunction with blower door testing, during which a panel with a calibrated fan replaces an exterior door and is used to create a small pressure difference between inside and outside. The cost of a basic home energy audit, including thermography, generally ranges from $300 to $500, depending on location and square footage. Your home should be energy inspected once to determine if problems exist and whenever a renovation is planned. The Department of Energy recommends you should have a scan done before purchasing a house because even new houses commonly have defects in the thermal envelope.

Infrared cameras come in various configurations, sensitivities and resolution, ranging in price from $3,000-$8,000 for a basic camera to $20,000 for one in the upper mid-level. High-end IR cameras for aerial surveys and other large-scale inspections run as much as $500,000. There are 10-15 manufacturers, but the majority of cameras sold are made by FLIR Systems, Inc. and Fluke Corporation.

For those considering using thermal imaging to get into the home energy inspection business, there are classroom and online training and certification programs offered by companies such as the Infrared Training Center and the Academy of Infrared Training.

For those who like do-it-yourself projects, you can borrow an IR camera from the Energy Resource Center at CCSE for free for two days, choosing among the Testo Model 875, Fluke Model TiR, Fluke Model ST60 and FLIR Model B360. For check-out information and tool reservations, visit the Energy Resource Library website. You can also borrow a DVD about thermal imaging fundamentals.

In today’s world of rising energy costs, it is important to insure that we have the most energy efficient buildings and homes possible. Thermal infrared cameras for energy audits offer a perfectly easy way to detect and, with repairs, eliminate energy loss due to inefficient insulation or poor construction.

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