Yes. The thin Mylar aluminum coating with the low density fiberglass insulation will do its part to keep the heat undetected but not without sufficient expulsion of heat and a negative air pressure. I personally use 3/4" Polyshield (brand) white low density polystyrene foam board and 1-10" can fan combined with a can filter 150 for every 1200 watts of lamps and I beat detection. A member of my family actually saw a cop in an unmarked car pointing a heat gun at mine and my neighbors house and nothing happened (legally speaking) after that. That was 4 years ago and at the time I had 12-600 watt hps and 2-250 MH going. It also helps a little if the exterior finish of your home is brick. It's a cooler material than the plywood that is used under aluminum siding. A close second would be parex stucco.