Most modern insulated windows are filled with Argon gas which provides more insulating properties then just plain air.  Over time, insulated window seal can fail causing the Argon to be lost and possibly letting humid air enter.  If condensation does not occur, widows that have lost the Argon gas are difficult to detect.  Under proper conditions, lost gas can be easy to see with the infrared camera.  When window seals fail they show a temperature difference from other windows in the home or office.   In a standard home and business infrared camera inspection, all windows will be checked over and any problems with the windows will be reported.

Window seal

window seal 2