From the first glance, ideal temperature is a subjective notion. It's a usual thing when some people open windows widely, while others wrap up themselves in sweaters and drink hot tea at one and the same room.
One badly tolerates heat, another is afraid of cold. When you are in a room, your comfort temperature depends not only on your physical peculiarities as of a human being, but also your comfort temperature is unique for every surroundings you are in.
The quality of isolation, the tasks you do at home, the amount of working equipment - there is a lot of factors which affect our perception of desired temperature. The comfort temperature is a balance between a wish to wrap up yourself in tons of clothes and a rush every 10 min to cold shower.