I know my appartment can get pretty cold during winter and once when one of my tank heaters broke the temp dropped to 19degrees- as long as you maintain temp at around 23/24degees you will be fine
I don't think it's a good idea... house temperatures fluctuate heaps. There is no set temp for this thing to regulate so it would have the temperature yoyo-ing up and down all day and night.
I say: spend a few extra bucks and get a thermostatically controlled heater. You can get really skinny ones that would be easy to hide behind a fake plant!