Do I have an opinion about screened bottom boards in winter nucs?
Opinions R Us. If you’re using a foam hive, a big hole (ie SBB) completely negates the purpose of the foam in the first place! The purpose of insulation is to retain as much of the heat energy the bees generate as possible. That’s just a few watts in a nuc. If you leave a huge hole in any foam container, it no longer acts as an insulator and you might as well use a wood hive in that case. Would a person leave the top off a foam lunch cooler in the summer and expect their Pop to stay cool? Same deal, if you have a big hole in foam hive, its value as an insulator is ruined.
My designs use R10 foam (I’m in Michigan after all) and small holes to let moisture out, CO2 out, O2 in, and most of the bees heat in.
Here I am checking on one of my home made foam nucs. I’ve tried dozens of designs, this one happens to be constructed of 2” polystyrene R10 foam with a laminated luan core. Bottom entrance (other side of photo), back vent near the top.
Yeah, this is my best side too :)