If the temperature is -20 in your area, why not put the miner in home to get some heating out of the miner?
The amount of heat output is not enough to heat an ENTIRE house.
That really depends on many things:
1. The size of the house
2. How many miners you have
3. The temperature you want in the house
For example I'm okay with around +15C in my room so even one miner would be enough to make me feel comfortable. Of course I live in a flat surrounded by another flats which are warm.... so maybe tha's why ... Yep, for the entire single house one miner is definitely not enough.