Wow! You have natural daylight available, too, I see. Have you covered the sliding doors with a layer of plastic to cut cold air leakage, or are you keeping the exit uncovered for outdoor access? Our outdoor temperatures in central Iowa are below 0 farenheit this past week. So my basment is about 48 degrees in the "new" section that is not insulated and about 58 degrees in the insulated section. Time to pull out an oil-filled electric heater for my birds. The 'chids look fine, so I will not worry about them unless we have power outages. I think you will find the lower temps may slow growth but won't cause permanent damege.