we moved into a split level rental house this July.
During the summer and fall the temperature inside was fine. Now that it's winter and we have the heat on, it's like zero degrees downstairs and a million degrees upstairs.
when I'm downstairs playing with lo we both freeze!
I've attached a pic to show what I mean by split lvel.
how can I even things out? there's a gas fire downstairs but in afraid to use it for safety reasons.

suggestions?