Sake is traditionally made in the winter. This is because it requires low temperatures (45 deg) for fermentation, and refrigeration was non-existent until relatively recently. It was always easier to heat up a room in the winter than cool it in the summer.
I used this logic for brewing my sake as well. My house is warm, my basement is a bit colder, and outside is very cold. I thought that I could move my fermentation vessel around based on the required temperatures. I did not figure in the fact that my house is 63 deg, the first week of fermentation should be 75 deg, and the the temperature on my back porch is 2 deg.
This presents some challenges. To heat up the mash, I have put the vessel directly in front of a heating vent. I can get the temperature up to 71 deg this way, which will have to do. Next week I'll have to cool it down, and I'm hoping that the coldest closet in my basement works for this, or I'll have to figure out a way to insulate the vessel and put it on my below-freezing back porch.
Stir twice, 12 hours apart
Check temperature: 71 deg
Smells like yeast and a tiny bit of alcohol