A small alcohol burner is much better than no heat source, for sure. In the case I was recalling, I carried a Primus 71, fueled with white gas, definitely a miniature blast furnace, and which is much better for the minus zero temps we were facing

It wasn't carried as a space heater - its function was to melt the snow and heat the food and water that would have maintained the ability of our bodies to maintain 98.6 inside our clothing layers and inside our sleeping bags. The interior of the shelter, tent, or whatever, falls to the prevailing ambient temperature.

To answer your question specifically, the amount of fuel necessary to heat the interior of any shelter is more that I am willing or able to carry.