Jorge (if I remember correctly) advises against growing in an outbuilding because the FLIR guys don't need any kind of warrant to survey a non-attached structure on your property. And, they can use that surveillance evidence to get a search warrant, or convict you in court.
If the garage is attached to your house... without a search warrant, they aren't "supposed" to use ANY type of surveillance equipment. No binoculars, no FLIR, only the naked eye. If you get busted, a good attorney can prove the warrant was obtained illegally and the evidence won't be admissible in court. (in the U.S.A.) not sure about the laws in your neck o' the woods.
Sounds like it's attached to your house, boiler and chimney and all, unless your planning a tent-in-your-garage style "Cannabis Factory", I'd say happy growing brother :)