venting in cool enviroment

Ok, so i made my growbox out of 2 tupperware containers and everything looks good so far. but i live in NH and my growing spot is a little cold. My lights heat up the box to a usable temperature of 75-77 degrees. if i put fans in, im afraid the plants will get too cold. should i put one in, facing in or out or forget venting as im only growing one or two plants. any suggestions would be very appreiciated.

i also grow in a cold climate but am using HIDs which help heat things up.

one thing is to keep the system off the floor - put it on styrofoam or even wood would be better than sitting on a cold floor.

Ventilation and air circulation is as important to plant health and growth as nutrients, water or lighting so the size of your grow doesn't matter - you'll want to figure a way to get constantly circulating fresh air in there without cooling things down too much. Maybe put your intake near a heater?

i have a small space heater, and i was thinking that i could use that as the intake, and use a regular pc fan as the outake.

whatever you decide -- i would run the system with no plants for a few days and monitor the temperature/humidity (both lights on and lights off)

thanks a lot