All biological organisms need heat to live but what it must mean is that no additional ( i.e. no artificial and costly heating ) is required.

If that referes to Lynn Lake Manitoba then it is a few degrees higher in latitude than Noront's land. That means that we being in a warmer climate it should just as easily if not better be applicable to us.
Where biological organisms are concerned is that they are usually much slower in doing their job than straight chemical processes that do use enormous amout of heat. That heat is what speeds up the process. Economical often also means efficiency in speed of operation.

However it is an interesting possibility. Thanks for bringing up this subject.