They'll be fine without heat, unless they're in Antarctica or something.This is the only picture. The owner is being told they will not live thru winter without a heated enclosure. I corrected that for him but I didn't know what breed he had to be sure they were cold hardy.
Oh so it does get cold- as they are still young heat wouldn’t hurt but it will probably be ok to leave it for now. I visited ur area back in august I believe? Anyway it wasn’t cold so I couldn’t get a first hand impression on how it feels. My chickens do fine in our winter even if that is minimum 20 degrees lolIllinois, Chicago.
Just out of curiosity, what makes you say Production Red?I'd call it a production red not Rhode Island Red. Hatchery quality.
Ensure the coop has venting located high up. If a slant roof then vent lower and upper to allow air to rush in along roof line and exit moisture out high side. It's not the cold that injures chickens in winter, it's the moisture turning to frost on them that does. Proper venting out of moisture at roof line is all you need. No drafts on birds, clean air that wont develop frost.