Forecast

[madasafish]

They must live in the perfect beekeeping utopia.....simple feed if they need it, most important thing is to be on the ball enough to realise when they do

I think he lives in or near London so what he says of course is relevant to all England ,Wales ,N Ireland and Scotland of course... errr not.

When I read that FB site, I see an awful lot of opinions relevant only to the beekeeper's own locality only - so of limited use...

 

[Repwoc]

You might lose a few extra calories or KJ with extra space. The important bit is that it has no practical significance to the bees. But non of it is relevant if you are using open mesh floor; as you are doing the equivalent of matchsticks and crown boards. Are you overwintering on open mesh floors with the inserts out?
You don't build houses without floors just because heat rises.

So if the hive temp is immaterial, then so is any insulation? Since the insulation is only there to keep the hive warm.

 

[wightbees]

Temp here is just holding around 10C lots of bees flying, what a difference to you lot up north. Loads of trees in bloom.. Early this year compared to last.

 

[Beefriendly]

So if the hive temp is immaterial, then so is any insulation? Since the insulation is only there to keep the hive warm.

You miss the point.
Stop thinking about hives and think bees....
The cluster attempts to maintain it's own internal temperature regardless of whether insulation is present or not.
The main benefit of insulation in winter is less energy is needed by the bees to maintain their cluster temperature.
Adding a bit of extra space only equates to a few extra joules or calories being expended.....as I already said.

 

[The Poot in Somerset]

Thanks Beefriendly - I'm on the same page as you with this. I have kept the inspection trays in throughout the Winter. The hives are from Exmoor and when the trays are in they shut off all draft from the rear of the hive. So the only air in is through the entrance which I leave totally open, but with a mouse guard in place. I do have an eke with 50mm Celotex above the crown boards for the first time and this has cut down the dampness at the top of the hive significantly over prior years.
Again - regarding the air around the cluster - I think it will remain warmer in a DB as there would be little air movement caused by drafts?