My hands get cold at 18,5 C, I tried to set it lower but I'm really not comfortable. I used fingerless gloves to work with the keyboard and this helped me to go a bit lower, maybe 17,5 but it's not ideal. When I'm moving it can be colder and when I'm in bed or sofa I use a blanket or anything so it can also be lower, but for using the PC I really need 18,5 C.