This topic has been on my mind, as the outside temps got below freezing earlier this week. Inside my house, the temp in the mornings was mid 50s. I did not turn on the heat, but I wore Smartwool socks, sweatpants, a long sleeved cotton shirt, another thicker Patagonia long sleeved shirt, fingerless ragg wool gloves, a Buff, a balaclava, a hat, and a down vest. And I occasionally dropped to the floor and did a set of 25 pushups! I'd like to make it until at least 10/15 with no heat.