While individual home energy audits have been a very useful tool in helping homeowners discover where their homes are leaking energy, or which older lights and appliances should be replaced with more efficient ones, this technique is painstaking, expensive, and is done one house at a time.
Thermal imaging, on the other hand, addresses residential energy leaks on a more massive scale. Trucks with roof-mounted thermal imaging cameras (think Google street view) can scan up to 10,000 homes in a single night.