Issues associated with the use of infrared thermography for experimental testing of insulated systems

Infrared scanning radiometers are used to generate temperature maps of building envelope components (windows, insulation), which may assist in evaluating their thermal performance. Accuracy of an IR scanner for laboratory-based surface temperature measurements was evaluated and details for achieving max accuracy identified. Minimum uncertainty in IR temperature measurement is {+-}0.5 C. Using an external reference emitter to scale the absolute value of IR scanner temperature measurements can improve the accuracy from 2 C to as low as 0.5 C for a 5 C span, which is comparable to accuracy of type T thermocouples. Operational procedures can easily increase errors; actual accuracy of an IR measurement will vary with test speciment geometry, temperature gradients, and scanner settings (emissivity, etc.). Future efforts for standard IR thermographic test procedures that should address standardization of various items are outlined. A database of temperature maps for a range of window systems is being created; representative data are presented for two insulated glazing units with different spacer systems.