how many bunnies to heat a sprouting room

I am brainstorming how I can keep my barley sprouting down in the barn over the winter. I have an old insulated 'tack' room that does not have a special use right now. It is fully insulated, about 4 feet by 10 feet, ten feet high. So... if I set up my fodder trays on the one side, and want to have my bunnies winter over from the tractors during the cold part of the year to keep my sprouting room between 60-70 degrees... how many bunnies would I want to winter over in this room?

We are in Puget sound in WA, so we do have a winter, not a severe one- but still

anyone heat a room with bunnies?

The amount of rabbits you would need would be inhumane, they need air and unless you heat that too it's going to be cold. The insulation is good but the circulation is wonky, but if you had a solar heater situation I could see 10 having an effect. There not chickens they burn way hotter, but with insulation and a daytime boost of solar heated fresh air... I think 60-70 is reasonable to expect. I don't like hanging cages but that's my affair, I think there practical and efficient for the human. Litter expansion is where things tilt to the uh oh, and ammonia management becomes critical in such a tight space. So ventilation overrides the sprouts and the temperature drops.

Rabbits overwintering in the greenhouse can be better for both and if you include the worms to manage the poo into the structure, you have enough rich soil to feed the rabbits, the sprouts and additional material for planting out. But that's a different project, I think you can do it if you have some solar ventilation and temperature moderation with the heater. I think I failed to ask if there was natural light or not? Rabbits heat in more of a bubble style, they insulate themselves in, where poultry dry themselves by radiating outwards while producing heat.

Best of luck, and when Im thinking rabbits I'm thinking a 10+ pound rabbits like my giant chinchillas, I don't have any authority on smaller rabbits.

oh my no! That is way way too many bunnies, you are right, way too many for that space