In light of the new foot of snow we got here in Michigan, and drifts over my hives, I decided to see if I needed to go shovel my hives out or not. There have been plenty of people worried about the bees suffocating in their hives from all the snow this winter, so I decided to see what the math says.
First we need to figure out how much air is really in a hive. Since there is comb, honey, and bees (if we’re lucky) filling up most of the room, there really isn’t that much room for air in a hive! Let’s assume a 2 deep configuration (10 frames) with a bee space of 3/8” between each frame, let’s assume ½”between the frames 1 and 10 to the box bodies
Those gaps give a volume of about 4.3”total gaps x 19.25”T x 14.5”W = 1200 cubic inches.
Next I have to add the volume parts under the inner cover, between upper and lower body, and above the bottom board.
Those gaps total about 1.5” giving a volume of 1.5”thick x 14.5”W x 18.25”L = 396 cubic inches.
Adding these two parts we can a total hive air volume of 1596 cubic inches.
1 gallon = 231 cubic inches
So there is an air volume of about 7 gallons in a 2 deep hive.
Next I make a comparison between bees and humans to drive home the point that 7 gallons of air for the bees is really not that much! (Thomas, I know you always love to compare bees and humans)
A human eating an USDA diet of 2000 calories a day has an average energy output of 100 watts. That heat output comes from metabolizing the sugars that our foods are broken down to. The bees also generate heat by metabolizing sugars (i.e. honey). To convert the chemical energy in sugar into heat, you need oxygen in both cases. Sugar + O2 -> Heat out.
(Frameshift, yes I’m obviously skipping the detailed steps in that conversion: glycolysis, Krebs cycle, etc)
Converting sugars to heat require requires oxygen rather you’re a bee or a human. It’s chemical.
According to Finski’s reports from Canada, a bee colony generates from 20watts to 40watts of heat to keep the cluster warm in the winter (if you are using cold wooden hives). Let’s assume the bees are making 20 watts of heat for now. If the bees are outputting 20 watts of energy then they are generating 1/5 the energy output of a human (on average) and will need 1/5 the oxygen for the chemical conversion of sugar to heat.
If you invert that, you can see that a human burns 5 times the sugar of a bee hive and hence needs 5 times to air (oxygen) for our chemical reactions. Bare with me, this is where it gets interesting:
What that means, is if the bees are completely sealed in their hive by ice, they only have 7 gallons of air to breath. That would be similar to locking a human in an air tight box with only 35 gallons of air to live on. That’s like sticking your head in a large 35 gallon garbage can and seeing how long YOU can live!
We discovered during Apollo 13 that living with small volumes of air can be a problem! Actually we (and the bees) would croak from too much CO2 in the air long before we croak from a lack of O2. Either way, we really would not last long at the energy outputs we (and the bees) are generating.
The math (or I should say MY math) says your bees WILL suffocate if there is not an exchange of air in the hive in a timely fashion. Snow will not prevent an exchange of air, but an iced over hive might.
