IRLab Thermography Experiments
The human eye can't see the heat that shines off of everyday objects. But with the help of infrared imagers, researchers can "see" and measure this heat which radiates from every surface. This data can produce images called thermograms that are based on the temperature of objects. Researchers Dariush Arasteh, Brent Griffith, Daniel Türler, Paul LaBerge, Howdy Goudey, and Christian Kohler of the Building Technologies Program have developed an Infrared Thermography Laboratory to measure and image the surface temperatures of windows and other insulated systems. This type of thermal testing has the advantage that large amounts of surface temperature data can be collected without disrupting the test situation. The data are collected as an image that allows for a quick understanding of the relative performance of various parts in the system.

Thermogram

This image is called a thermogram. Each pixel of a thermogram has a temperature value and the image's contrast is derived from differences in surface temperature. The specimen here is a normal dual pane window. Cold air is blowing along the back side. The scale at the bottom shows the relation between temperature and color. Note the cooler conditions around the perimeter of the glass, this is due to high heat flow through the aluminum spacer located between the two panes of glass.

 

 

Thermal Chambers and Lab Equipment

This photograph shows the the two chambers and a window specimen.  The chamber on the left produces cold, blowing air and the chamber on the right produces room temperature still air.  The windows are first mounted in a foam surround panel and then clamped between the warm and cold chambers. .

 

This photograph shows the main components of the Infrared Thermography Laboratory. The infrared imager is pointed into the warm chamber. The cold chamber is in the back. The computer data acquisition and control system is on the right. The flexible bellows and support structure allows varying the imaging distance from 1.5 to 4.0 meters.

The facility uses the two temperature-controlled chambers to create a steady flow of heat through the test specimens. Standard conditions used in building design for winter are typically used, -17.8°C or 0°F with high wind on the cold side and 21.1°C or 70°F on the warm side. The infrared imager measures the warm side surface of the specimen. A special reference emitter technique is used to improve the accuracy of the infrared temperature measurement with uncertainty estimated at ± 0.5°C. The test section size is about 1 meter square. The Infrared Thermography Laboratory is available to researchers outside of LBNL to solve scientific problems consistent with the facility's purpose. Testing is also available to window manufactures who are developing or proving major new products and design approaches; results are not to be used for commercialism.

More Details and Images

Selected Thermograms of various types of windows

Technical Papers on Thermography

Quantitative Thermography and Database of Window Surface Temperature Distributions


Accomplishments

The IRLab performs non-invasive surface temperature measurements of window systems under controlled laboratory conditions. In recent projects, researchers have analyzed:

  • Film coefficient and convection problems for the National Fenestration Rating Council
  • Vacuum Glazing prototypes produced by the University of Sydney
  • Double, triple, and quadruple glazings
  • Low conductivity spacers
  • Vinyl window frames
  • Wood casement windows
  • Double-hung windows
  • Integrated Window System prototypes produced by LBNL
  • Gas-Filled Panel opaque thermal insulation produced by LBNL

For more information on Infrared Thermography Laboratory research and facilities contact:

Howdy Goudey
Building Technologies Program
510-486-6046 (fax)