I'm sure it would vary with what you're used to. I for one probably do more errors at 25C, as that's just too hot for me. I also read somewhere that our brain works best when the room temprature is 14C. 20C is perfect working temprature for me, in general I like to have it about 1-2C colder than my workmates. Then again, I'm from Iceland. :-)
Ragnar
Ragnar