I really need to test this,but...
the bottom of the cone usually is almost cold whilst you cannot hold your hand at the top. So I figure that the heat loss at the bottom is minimal (?)
However, to avoid having the ground working as a heat sink, I would suggest putting some insulation under the stove in cold condition. I use a 3M kitchen scourer for that,(the green stuff) cause I have it with me anyway.
(you can see that in the "how to store the cone" thread)