Air leak detection system visualizes building drafts with the click of a camera

https://www.ornl.gov/news/air-leak-detection-system-visualizes-building-drafts-click-camera 

"fast accurate readings including leakage amounts... air flow schlieren photography... walls, windows, doors, dryer vents, outdoor faucets, vent fans, dropped ceilings, plumbing vent stacks, crawl spaces, attic hatches, duct registers... small shifts in background of sequence of imagesusing refraction, where fluid with different refractive index than surrounding area visualized based on distortion of background... algorithms measure velocity and flow rate... looking for air wiggles with leak detection temperature limit 12 to 15°C (goal: 5°C)"