When I built my first TBH, I made extra bars. a couple were with 3/4 inch holes with screen, for ideas of allowing ventilation. I have about a 4 inch dead air space above the bars and below the top. And even though the top allows no light, the bees propolized every screen vent shut. I also made feeder bars that a feeder could sit on. You can make them with the standard bar and use the 2 liter plastic soda feeding method, or you can just made a "feeding bar" which is just an oversized wide bar, with a hole for a jar lid to insert. Although this is just a short feeding item as they will start building comb on this modified or larger bar, which you don't want permanently in the TBH - (although if built and measured properly you can do it)