I don't think I'll be able to cut a vent hole out of the house. That's just not possible in my living situation. However, where I live the temperature is often around 0 degrees fahrenheit outside during the winter, so even cracking the nearby window a tiny bit would cool the plant off enough I would think. We're talking serious cold, sometimes 15 or more below zero. So, based on your suggestions I think I'm gonna do the following:

Extend the height of my box by a foot or two (I have to check what's the tallest I can make it).

Cut a couple of holes toward the bottom of the box for intake

Cut another big hole for my clip on fan to exhaust through, this one near the top.

Buy a wall mount oscillating fan and set that up inside as well.

Buy the HPS light kit with metal halide conversion bulb and mount that to the 'ceiling.'


The external room is a bedroom, but its occupant (my partner in crime) is very cold tolerant, so if the room is kept at 50 degrees (still major heating compared to 0 degree external), I would think my plants would be amply cool, no?

My only problem now is figuring out how to have ventilation without light leaks. The most light that is ever on in the outside room containing the grow box is a computer screen, but still, during flowering some of that light would have to penetrate through my ventilation holes, right? how do you folks manage to ventilate your grow spaces without creating potential light leak problems? Thanks for reading and any advice, again, much appreciated.