We have acquired two guinea pigs ( males and bonded) that are currently outdoor guineas ... the lady who we are getting them from said they have been sleeping outside etc with plenty of hay, straw, cosies and an insulated hutch with cover - so we felt confident doing the same ( they would be in a shed area).
Whilst purchasing some equipment yesterday I was chatting with a cashier who said if they are outdoor guineas I can't bring them indoors ever because the change in temp would shock them 
I was planning on letting them have free reign of a room downstairs during the day whilst the little ones are out, plenty of social time and interaction then hutch at night as above ....
Is this not wise?