Mines set at 17°C. However it's myself and DS (7) living here so sometimes - like now when he's playing Wii Sports it's warm enough. I do over ride it to 18/19°C when we're stationary, not in kitchen with oven on, having a bath etc.
I am lucky my flat is only 5 years old and very insulated.
With a 9 month old I'm sure I would want it warmer. (lived abroad until DS 22 months so no experience of this sorry.)