Get rid of the ventilation and try keep your temperatures above 60 deg F, otherwise you just will not see much in the way of growth below 60F. I'd get a thermostatic fan controller (about $30 at most grow shops) and connect it into your system (remove the glass from the ventilation hoods, if you haven't already as this will help).

This will be your biggest problem and I'd suggest running your lights during the night to off-set the temperature issues. I'd also get a small electric heater for the space during the off light period, and cut down on the cold air ventilation.

You will have some very nice color by the end.