Poly Hive in Bloody Cold Climate

[B+.]

my Latvia Beekeepers Assn friend will visit in Sep and answer my questions.

Local knowledge will be worth a lot more than anything we say at a distance.
Beware about information gathered from the US because they have even more diverse climate than we do. Information that would be good in the southern states would be terrible for the north. The same is true here (because we're an island).
My thoughts are that your poly hive will be better insulated than the traditional hives there. Does your friend have experience of those in your climate?

 

[KiwiLad]

My thoughts are that your poly hive will be better insulated than the traditional hives there. Does your friend have experience of those in your climate?

Yup, that's what gave me the confidence to return to beekeeping here. His first observations were: "Most beekeepers in Latvia use wooden beehives. Usually wooden brood box is double walled. Wooden beehives perform well in cold winters. Also polystryne beehives can be used successfully in Latvia."

And then: "Unfortunately I don’t have personal experience with polystyrene hives here in Latvia. I know that many beekeepers use polystyrene beehives successfully. Nevertheless I also know that living beings like ants, woodpeckers, martens and mice can easily damage beehive and such cases occur quite often. KS told to me that he has several Lyson polystyrene beehives in operation already for several years but his feedback was negative because so often boxes and colonies are damaged by living beings."

I'm relaxed about the wildlife threat as the village I'm in is more semi-urban than semi-rural. My particular well-fenced back garden location never sees anything more scary than big crows.

 

[B+.]

My particular well-fenced back garden location never sees anything more scary than big crows.

I imagined you keeping them out on a farm where livestock might knock them over or they'd fall prey to woodpeckers, etc but your back garden should provide shelter from these and the worst of the weather too. If it were me; I'd aim to get them into a double box, or at least up off the cold damp ground over winter. It sounds like you're going to be trailblazing so you have to be prepared to experiment a bit. The downside is that you could lose a few colonies in the process.