47 degrees and my shivering causes random keystrokes that emit perfect code, slack messages and reviews. Seriously though if I notice that I’m feeling extra warm or cold then that is distracting so I change the thermostat.

75-77F (24-25C Approximately). We have multiple standing A/C units. There have been several thermostat wars where partisans run units in the opposite thermal direction to balance out any actual or perceived imbalances.

"Maximum productivity temperature" is whatever doesn't have me shivering or sweating. In the winter (PNW, west of Mt. Tahoma) we keep our house at 59-61F, and in the summer we let it get up to 76-78F before cooling it down (will use fans to cool us down, though, if it's not too humid).

If it's just me in an outbuilding I'll put on a hat and coat and be okay in 41F (the lowest I've noted while also being comfortable enough typing). "Optimal" in that case includes the cost to heat the space, which I'd rather not do if I don't have to.

It used to be that anything about 71F was unbearable to work in.

I have since moved to a drier climate and have found the thermometer can creep up to 77F without noticing.

Even subtle changes in humidity can have huge impacts.

Productivity is a spook, but I like it around 75°F

70. Not for productivity, just for comfort.

Under 28C

80F

75 degrees