I try to keep my ambient room temp at 78 degrees. I use an oil filled space heater with a built-in thermostat (and I check the room multiple times daily to verify temps). I don't get much fluctuation in the room, generally never more than 3 degrees in either direction. The racks are all running flexwatt hooked to appropriate thermostats. I don't drop my temps at night.

Here are a couple of quick cell phone snaps from after I rearranged the room on Sunday. (ignore the messy shelves behind the racks. Those are getting cleaned off and out this weekend)



(You can see the heater in this pic...)