In an interesting case from Georgia, James Brundige's attorney argues to the state's Supreme Court that "thermal imaging is not enough for police to obtain a search warrant." The case is a spin-off of the United States Supreme Court decision in Kyllo v. United States. In Kyllo, the Supreme Court found that "[w]here . . . the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a 'search' and is presumptively unreasonable without a warrant."
In the story (link above) "[p]olice contend the grainy video they got shows heat given off by grow
lights and energy consumption that was greater than in neighboring
homes, providing them with probable cause to get a second search warrant
to enter James Brundige’s Athens home."
The case is interesting considering what other uses people may have for heat lamps and other devices that emit an extra amount of heat/energy.