i think attics are a good place to vent small grows to diffuse the heat and the amount of heat being put into your attic wont show much if at all in the large area of space your attic may have
but im not sold on it as a secure place to have your lights set up in since it will show hot spots - heat will be stronger in one section vs another and your attic will not have even amount of heat sig. throughout
personally i think the flir/heat sig topic is only worth talking about if your planning on a medium size or larger grow
i think 3000 to 4000 watts(or more) would get me worried - anything less is not a concern if you vent into your attic
but my opinion isnt worth much -
if you are truely worried about heat sig - go with a completely sealed room and dont vent any heat at all- only problem with that is it can get expensive to supply and operate
co2, a/c, chiller, dehumidifier............... and extra electric consumption to run it all
this extra electric usage might be enough to tip the scales of paranio from heat sig. to ooh my god my electric bill is 4x all my neighbors
