Mining for Heat

So as winter is coming I have begun mining with my PC again. The reason I started again is it's cold and I usually use a space heater to heat my room. So mining actually doesn't spend any extra energy. Unless it lights up or moves something any power used by a computer is directly translated to heat. So that means any power used to mine can be used as my space. So even though a computer can't mine very well any more, it doesn't really matter, I'd be using the energy anyways.