Everybody understand, this is for energy conservation or saving some money. You don't want to test the limit, do you? I believe, 12-13 degree should be OK.
Agree what ray-ca said.
Every house and its insulation are different, it is really up to you and your house. For my house and my neighbors, since basement is colder than upper floor, and I do want to make sure my water pipes are ok after the long winter, I must set the temperature higher.