I believe there have been several outdoor displays of native reptiles and amphibians here in the UK which have incorporated suitable hibernation sites. I think Paignton used to have an off-show facility for Hazel Dormouse which must have had hibernation sites - as these would just be the same boxes used in field conservation provision they would be simple to provide. Actually, this whole question is bigger than just hibernation for temperate zone animals - many species have reproduction and other behaviours keyed to seasonal changes in day length/ rainfall/ diet/ temperature etc and duplicating this in captivity may need more attention than it often receives.