I had an interesting brief chat with a neighbour in regards to CO2 levels in his wintering shed. He had bought a CO2 monitoring device and has been monitoring everything from his office to every room in his wintering facility. His main shed is at 950ppm but his other shed is at 3500ppm. The conversation lead to optimal CO2 levels and where that equilibrium is at. 1700ppm seemed to be the common wisdom passed onto us by someone else...
CO2 is an important factor when wintering honeybees. They use it as part of their dormancy control and maintain a certain elevated level of it within their insulating shell, 1700ppm had been suggested.
So in regards to maintaining an indoor wintering rooms c02 levels, high levels might just kill them, trying to maintaining levels comparable to outdoor levels might just be wasted effort.
More importantly however is the wintering room air circulation. Too much air movement within the room can disrupt the hives CO2 sheid and interfere with dormancy. Turn those ceilIng fans down too much and pockets of deadly gasses and air layering will form.
I think it's time I start monitoring CO2 levels and stage my mid winter exhaust fans according to CO2 levels aswell as temp