As it starts to drop below freezing, I find myself wondering how low I can drop the thermostat during the day and while sleeping. This is our first winter with Mason. Last winter I would let it get down to 65 degrees inside during those times. Do you think this is too cold for an indoor dog like Mason? He seems like a trooper when we go for his nightly walk, despite the cold temps, but I want him to be comfortable when inside while not increasing my electric bill more then necessary.