I saw Windfalls Ice Box effect in action again today.
Our day temps have been below freezing for a week or two now, but today it got up to 50F. I went out to check on my super insulated bees and found a lot of bees out pooping all over, including on me. The hives with top entrances were very active while most of the hives with bottom entrances (and small top vents) were virtually dormant. Those appear to be experiencing an ice box effect.
They were perfectly alive, just mostly in cluster.
Interestingly it appears to me that the bees can easily heat up a super insulated hive if they want; be it a top entrance or a bottom entrance design. When enough bees decide to get active (for whatever reason) they can heat these super insulated hives up to 87F/30C in a hurry (even when it’s 32F/0C outside). So maybe the ice box effect I see with the bottom entrance hives has more to do with those bees deciding not to get active when the top entrance bees do?
Speculating here; but maybe the bees in a top entrance hive detect the outside weather (and sunlight) quicker than their sisters in a bottom entrance hive. The bees move up in the winter and hence they are more likely to be around a top entrance than a bottom entrance. Maybe the top entrance bees see good flying weather sooner, communicates that with the cluster, and wake them up. Once the cluster decides to become active, they can easily heat up a super insulated hive and start flying all around.
(This hypothesis probably wouldn’t have applied to Windfall’s bees since he just didn’t have enough bees to make enough heat over overcome the heat capacity of the cold slabs of honey).
My jury is still out on top vs bottom entrances for my super insulated experiments, but so far I have seen nothing but good news from my top entrance designs.