The good news is that it is 50 degrees inside when it is 25 degrees outside. Much easier to get out of bed at 50 than 25.
Practical considerations for that climate is to put air tubes through the berm and a solar collector on the south side to drive heat through the berm in the summer. Air temperature well above 110 every day in direct contact with the dirt instead of having to pass through the insulation of the logs. The heat slowly works its way through the dirt toward the logs during the summer while the cool dirt next to the logs is still cooling the wofati during the summer heat. The radiant heat inside the berm traveling toward the logs maintains radiant warmth inside the wofati during the winter. the radiant heat traveling out from the inside of the berm prevents the cooling of the dirt next to the logs. My goal would be to keep the radiant temperature of the logs 65 to 70 degrees all year. They need to stick a
compost thermometer between the logs so that the berm temperature can be monitored. I am guessing from the graff that it is probably about 45.
My factory built house holds a 10 degree difference with the outside so a 25 degree difference is pretty good.