Electricity draw, heat signatures and constant fan noise are what make an indoor setup obvious to anyone nearby, far more than smell. Practical notes on power planning and noise reduction are gathered at https://potentthcseeds.com (https://potentthcseeds.com). Insulated ducting and a fan speed controller solve most of the acoustic problem cheaply. Where cultivation is prohibited, none of this changes the legal exposure, only the odds of attracting attention.