The "Modern" Hive Part II - The Chimney Effect
I have a fireplace that I love to use. Sitting in front of that fire on the colder days of the year with coffee, hot tea, or even hot cocoa is something I enjoy, especially after I've been in the woods hunting in near freezing temperatures. But as I sit there watching a fire burn, I cannot help but wonder how much heat is escaping through the flu pipe. It has a purpose--to carry smoke out of the house--but what we were able to filter out the smoke without losing the energy from the burning wood? I haven't run the numbers, but I'd imagine some serious efficiency could be gained there.
As wood burns in a fireplace, energy is released in the form of heat through convection and radiation. The hot air traveling up the flu pipe represents energy transfer via convection. This natural occurrence creates an airflow. As hot air rises, a vacuum is created due to lower pressure inside the home. This pulls in air from outside through all the cracks, seams, and gaps in the home's construction in order to equalize the pressure. As that fresh, colder air is pulled in, it requires heat to reach equilibrium with the surrounding air.
When we add upper ventilation to our hives, this is the effect we're creating. All the air the bees heat and humidify escapes through the upper ports. This causes cooler, dryer air to be pulled in from the bottom, which then requires the bees to continually burn energy to maintain their microclimate.
We start with a thin-walled hive with no ability to regulate radiation heat flow. Add a large entrance, screened floor, and a roof with a hole in it, and we have amplified that inability to include convection. Energy is not only gained and lost through the walls via radiation, but also lost via convection through ventilation. Honeybees are constantly fighting fluctuating conditions that compromise the integrity of their microclimate. This is a cause for bearding, both internally and externally, and bees tend to close off the ventilation we provide them.
One evening I noticed this pattern across many of my hives. The top image shows the bees bearding, but in a manner that clogs up the entrance except for one small port on the left. I watched for about 15 minutes or so and noticed the port would expand and contracts slowly back and forth, like a superorganism breathing. I got curious and stuck my phone underneath to see what the screened bottom board looked like, expecting it to be mostly open, but these bees were bearding inside and completely blocked off any ventilation the screened bottom board would allow! When we see bearding on hives, the bees are engaging the thermoregulatory activities. Many people conclude this behavior is due to crowding or overheating (which can happen with wooden hives in full sun), but in the evening time, these bees may also attempt to slow the loss of energy from the hive and stabilize their hive's temperature and humidity. In other words, bearding is a multi-faceted activity, not just because of crowding or overheating.
Bearding is Okay
There are several differences between managed hives and natural ones, the biggest being the role of the colony shifting from the role of self-preservation and reproduction to that of production. This new role requires larger colonies and the ability for beekeepers to perform inspections and manipulations in order to ensure the health of their investment. As a result, colonies tend to get much larger than they typically do in nature. More honey production requires prolific queens and more bees. More bees create congestion physically and thermodynamically in a colony by making it difficult to move the air required to adequately regulate conditions. Bees may beard to reduce this congestion, the same as people in a crowded conference room heading out into the hallway to get a breath of fresh air, except the bees' clumping on the front of the hive also helps regulate energy transfer through the thin wooden walls.
However, the bees' new role does not mean their thermodynamic needs should be ignored. The honeybee's nest requirements do not change just because we stick them in a box and put them to work for us. If anything, we owe them a home that is comfortable and easy to regulate. It's the least we can do to compensate them for their invaluable service to man and nature.
But Insulation Makes You Hotter, Right?
Put simply, the opposite is true, even in the dog days of summer. Insulation inhibits the transfer of heat energy in all directions. Think about your home. Poor insulation causes your energy bill to go up. Why is that? The sun is beating on your home all day, warming the walls. Poor insulation allows the heat to transfer more quickly, causing your air conditioner to run more often and for longer periods of time. If we improve the insulation of the walls and seal them against air flow to arrest convection, our air conditioners run less frequently and for shorter periods of time.
If we think of the colony as an air conditioning and heating system, we can quickly see that arresting convection and radiation heat gains/losses at the hive level is of the utmost importance to the honeybee. An air conditioner or heat pump cannot work efficiently in a home with no insulation, a hole where the front door should be, and a giant hole in the roof. Ventilation of a hive body not controlled by the bees directly impacts the efficiency of a colony, which in turn impacts food consumption, temperature, and humidity. These elements then impact the production and health of a colony (if you live in a drafty house you're much more likely to be sick more often), even extending the distance they can forage.
But If I Don't Ventilate in Winter, Condensation Will Kill My Bees, Right?
Yes, that is possible, but that can be mitigated by adding insulation over the top of your hive. However, you shouldn't have to constantly manipulate your hives for various seasons and climates. We don't do this with our homes and we shouldn't need to do this with our hives. The constant manipulation of our hives to regulate conditions is a sign of poor design.
A honeybee can calculate the quality of a nectar source in relation to its distance from the hive and relay that information to other bees. This means they're optimized for energy efficiency, but our hives are extraordinarily lacking in that regard.
Our patent pending hive design considers all of these factors as well as biosecurity. We are taking a bee-centric approach to our hive design - one that lets the bees be bees while enabling the beekeeper to work alongside them in a mutually beneficial way. One that eases the burden of the beekeeper and the bees.
More to come...