IR Thermography


Infrared Thermography is a space age military application that has been successfully applied to energy analysis work. Hand-held cameras similar to camcorders can detect and record small variations in temperatures.

When properly used by skilled professionals, IR Thermography can detect missing insulation, air leaks, wet insulation, electrical hazards, pending equipment failures, and a wide variety of other non-energy related functions that involve temperature variations.



The best way to use IR Thermography is on a cold winter night, several hours after the sun has gone down. This is because it is important that the camera detect heat loss from the house, and not heating variation affects from the sun or other human activities. The next best way to use an IR Camera is in conjunction with a blower door running. Using a blower door amplifies and reverses the air leaks making them MUCH easier to find, than with the older traditional method of using smoke sticks. Using a blower door with an IR Camera makes it possible to do a scan during the daytime, but any walls that has sunshine on them will still give a distorted result.


The equipment is expensive and the opportunity for use is somewhat limited. Newer cameras with higher sensitivity can be used in the summer time too, if the house has air conditioning and can be cooled down to 10 – 15F cooler than the outside. This generally results in a fairly expensive fee to have a house thermogram. ($150 to $500 per house.) Training and integrity are important credentials, as a thermography camera can be adjusted in a way to show normal activity (heat loss) as an abnormal event. It may be best to have a thermogram done by someone not also selling weatherization services.

Sample IR Audit Findings

Uninsulated attic access panel in winter

With a blower door running, cold air is being drawn in from the attic through wood paneling that has no sheeting or air block behind it

The attic has no air baffles installed at the soffit vents; the wind has blown back the insulation resulting in cold spots in the ceiling

These cold spots are actually water leaks; there is a small area of paint peeling but the wet area is much larger

The end wall of the cathedral ceiling that faces an upper attic is not insulated; it shows cold in the winter

That same end wall from the attic side shows as hot, as the attic is much colder than the heated space below/inside

Recessed ceiling light fixture is drafting because it is not sealed on the attic side

Doesn’t matter if the ceiling is wood or drywall, air leaks through

Recessed light fixture from the attic side; older-style fixtures can not be covered tight in insulation due to heat build-up and fire hazard. They can be covered, but must maintain a clearance around the fixture – typically at least 3″. Switching to CLF lamps will significantly reduce the heat build-up and further reduce the fire hazard. Newer recessed fixtures are internally vented and CAN be covered directly with insulation.

The fixture on the left is not sealed on the top side. On the right is the same kind of fixture with an insulated cap/box around it and sealed to the ceiling

This skylight chase is not insulated

The same skylight chase from the attic side shows hot compared to the colder attic

Note the colder (blue) colored band is a stud-wall cavity missing insulation; the house was retrofitted with blow-in insulation and this section of stud wall cavity was missed.

This section of wall was insulated with blown-in insulation, but it has settled, leaving the darker (colder) areas at the top of each stud cavity section

This basement wall is painted white and the underside of the floor above is painted black. It is pretty clear in the image which section of wall is above grade and which section is below grade. Also not the darker areas in the bandjoist showing the air leaks (blower door was running)

The basement wall above shown on the outside. Note how the snow has melted back. The section of wall to the right is the garage, which is not heated and shows as cold. The middle-orange color above the concrete part of the basement wall is the uninsulated bandjoist and the darkest blue are is the insulated stud wall.

An uninsulated basement wall shows both snow melt in the visible photo and heat loss in the IR image

With the blower door running, it is easy to see air leaks around windows and doors with the IR Camera

IR_BasementWindowA basement window has been covered with foam board insulation, but is still leaking a lot of air around the foam board

The fireplace has glass doors, but with the blower door running it is easy to see all the leaks. Normally these would be spots where hot air is leaking through the doors and up and out the chimney

This IR image shows water behind stucco; this may or may not be a problem depending on the quality of the water seal used behind to stucco to protect the house sheeting/wall. IR Cameras are often used to detect moisture behind stucco and thin masonry, and under roofing membranes of flat roofs, such as industrial buildings (see TechPro-EM for more about non-residential applications of IR Cameras)



IR_Camera_FlirBCAMFLIR Systems
America’s Main Office, USA
Telephone: 1-800-GO-INFRA (464-6372) or 978-901-8000

Go to their web site at






6920 Seaway Blvd.
Everett, WA USA 98203
Telephone: 1-800-760-4523

Go to their web site at


IR_Thermogram_CameraSierra Pacific Corp.
284 Sea Rim Ave
Las Vegas, NV   89148    USA
Telephone: 702-369-3966

Go to their web site at








Source: Text Bob Fegan 12/2008; IR Images from Sierra Pacific web site 9/2003; rev 9/2005; photos and IR images in the Table all by Bob Fegan, revised 5/2008;


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