the key here is to create a second layer
shielding the signature from being discovered
that's why you need to keep a space between the installation
flir can pickup sig on external walls only,
when creating a second layer with 2' beams
your adding the second layer the flir cannot pickup
the foil then blocks the IR from picking the heat sig behind it only
remember, your external walls will not stop being hot
they will still show hot on flir, but not a grow room sig
you also need to install the foil with the reflecting side of it facing your property to protect
this will help spread the heat evenly across, to prevent heat spotting from being detected
the reflective side will distribute the heat evenly inside,
making the heat sig that's picked up on the external walls seem even
if you hit the foil as the first layer with flir, it will completely block IR and show a black patch instead
it will not block or hide the heat sig between it and a median wall!!!
in this case and in general heavy insulation will resolve this
in states that mandate a 40R/45R insulation code, flir is useless in these areas for any indoor detection
spreading the hot air into the attic should work fine,
I'm killing my heat with a dedicated AC unit and an icebox
I've heard of folks with access who directed their hot air into the main sower line
hope this makes sense