If you're talking about anyplace in the U.S., they could see the heat signature of twenty 1k lights and not be able to do anything. The Supreme Court has already ruled that thermally imaging a person's house IN AND OF ITSELF constitutes a search, and is thus invalid without a warrant. In other words, if they already have a warrant, they could thermally image your home, but they can't use thermal imaging to get a warrant. And if they already have a warrant, it's much cheaper and easier to send five guys to your house and tear it apart than it is to send up a helicopter with thermal imaging equipment.