I have searched a bunch for any info on this idea. I am considering a small grow op underneath my house but I am concerned with a few things. First, the last thing I want is my house to burn down. Second, I'm not sure how to get a standard electrical outlet under there without a cord trail. Obviously, stealth is very important. Third, it's winter. I think the temperature will even out because of the lights, but I dont know. I was thinking about using a rubbermaid grow box to help trap warmth. My local weather has been fluctuating quite a bit, ranging from 32 to 55 degrees F a day, so I dont know if ill be able to maintain the temp. I was thinking about using fluoros the whole time because of my first concern. I can deal with a lesser yield if it means my house doesnt burn down. But then there is much less heat to handle my third concern.
You would be better off in the closet, attic or basement. They all can have power that won't be seen and is accessible. Last thing you want to do is crawl under the house everyday.
you would need vents for one, but underground temperatures are alot more stable than above ground and its hotter in the winter underground than summer. the ground takes forever to have a temp change.