Internal dough temp and final rise time

Hi guys,

Anyone out there has a spread sheet showing the Relationship between rise time and dough temp. For instance my last rise on the sourdough is usually 2h30 at 76 degree. However if for some reason i am baking at a friends house and i cannot control my temp because i dont have my proofer how do i know how long to let rise at say 70 degree instead of 76.

Is there some kind of relationship between temp and time or a rule like for each degree you have to add 20 minutes.

Any help would be greatly appreciated

Tks

Dan in Montreal