Well… first of all, it depends on your definition of “ale” or “non-pastorianus”. I’ll provide lots of options to cover all the bases:
You can try fermenting with any yeast at cold temperatures, if you want. I’ve done so with Belgian and Bavarian hefeweizen yeasts to mute their character a bit. If you try this, you should double the pitch rate, same as you would do for any lager. Makes sense, right?! And it works – in my experience, even the most characterful yeasts will tend to produce an astonishingly clean product if fermented in the mid 50s to 60 F. They’ll chug along slowly, but contrary to some beliefs, they WILL still ferment cold. Just very slowly.
US-05 and Nottingham are known by many, including myself, to work well in the mid 50s F, but interestingly, will also often produce more peachy esters at colder temperatures, so it’s something to be aware of.
And now for some science geek stuff:
WLP800 Pilsner “Lager” yeast is actually Saccharomyces cerevisiae which means it’s technically an “ale” yeast that performs well at cold temperatures. I’m sure people have used it at temperatures as cold as the 40s and low 50s F with great success. It is closely related to the WLP320 American Wheat and Wyeast 2565 Kolsch yeasts.
Same with WLP838 Southern German “Lager” which is technically an ale yeast that people use cold. I’ve not used this one yet, warm or cold. WLP838 is closely related to S-04, which might explain (at least in my own mind) why S-04 is so dang clean and sometimes seems to behave more like a lager yeast, even though it is indeed an ale yeast.
Conversely, WLP029 German/Kolsch “Ale” yeast is technically Saccharomyces pastorianus, and as such, should perform well at colder temperatures but also ferments fairly clean at warmer temperatures. I have not tried fermenting cold with this one yet but would like to experiment more with it.
Same story for WLP051 California V “Ale” yeast, it’s actually a lager yeast. Again, more experiments would be appropriate to see what it will do when fermented cold.
Play around! Experiment! Try something wacky! It will make beer! And maybe, even GREAT beer!
Cheers.