Mylar is the 99% IR proof material, AKA space blankets, all mylar is is a very thin sheet of aluminum and the only reason that would help you is if your grow room was very hot, which you would be venting to somewhere that can cool itself off, so unless u want to mylar your house house, that wouldn't help, but if you put a copper mesh it will interrupt any digital signal meaning telephone, wifi, and all other forms of forward looking image devices. If you research the FLIR, they cant see into your house just the heat that is coming out of it, so just vet throughout your house and your whole home will be just slightly warmer. My aunt is an agent over in AZ and she said the only busts that they get drawn to without any notification is large warehouse grows with tons of electricity. Having lights, even a 1k light isnt that much, most microwaves are around 1100watts, and even though that isnt on all the time, if you just wisely cut back things (even just turning off lights and not watching TV as much will help) theres nothing really they can see.