I've frequently seen it mentioned that the bees don't heat the entire hive, they just keep their cluster warm, and the rest of the hive is left cold. If this is indeed the case, what difference does it make if they have extra space inside the hive? 3 deeps, undrawn frames...if they're only going to cluster around stores, the stores are grouped together, and the rest is going to be as cold as the outside anyway, I don't understand why it matters.
I think the extra space would mean extra work to keep the cluster at the required/desired temperature. Remember warmer air rises and cooler air would move in to take its place
>what difference does it make if they have extra space inside the hive?
Have you ever stayed in a tent in the winter? Is a small tent warmer than a large tent? If you put a baby in a small room at 70 F is it warmer than the middle of a gymnasium at 70 F? No matter what anyone says, it makes a difference. I've wintered with more and less room and a really small cluster will not survive in a large space but will in a small space.
http://www.bushfarms.com/beesscientificstudies.htm#overwintering
A smaller space is more efficient.