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Derek Mitchell's research indicates that top ventilation in heavily insulated hives is detrimental.
To save me reading that - what is the basis of that 'research' ? DM has only been beekeeping for a couple of years and afaik has very few colonies. His wife is an experienced beekeeper of course ...

Is perhaps what you describe as 'research' based on the findings of other people ?
LJ
 

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LJ, I don't understand the question, but when I said "research" I meant Derek's.

I read Derek's articles that he wrote for ABJ and Bee Culture. Somone else (can't remember off the top of my head) also wrote an article for Bee Culture about wintering hives and referenced Derek's experiments in it.

I can't access Derek's original papers because they are behind a paywall.

Mitchell D. 2016 Ratios of colony mass to thermal conductance of tree and man-made nest enclosures of Apis mellifera: implications for survival, clustering, humidity regulation and Varroa destructor. Int. J. Biometeorol. 60, 629–638. (doi:10.1007/s00484- 015-1057-z)
 

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LJ, I don't understand the question, but when I said "research" I meant Derek's.
A misunderstanding then. Mitchell and I have crossed swords in the past about the premises upon which his theories are based. For a moment there I thought that he'd actually generated some hard data from a real-world experiment, and I was curious as to how he'd achieved this - that's all. :)
LJ
 

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JoshuaW, you are pointing out that better thermal protection permits earlier spring buildup. Note that narrow frames and small cell foundation also correlate with earlier spring buildup. You have to do due diligence to figure out if earlier swarming is manageable with your setup.

What I would really like to see would be 200 colonies set up in poly for winter with half having a small upper entrance about 1/2 inch diameter and the other half with only the lower entrance. This would tell me much more about the effectiveness of poly for wintering bees.
FP,

I've managed to winter one strong hive with polystryrene boxes and a lower-only entrance. Using squarepeg's modifications of Walt Wright's Checkerboard/Nectar managment method prevented swarming. To my surprise, the colony superseded a year-old prolific queen in accord with one of Mr. Wright's predictions.

Not statistically significant, but interesting.

I wonder if anyone in Scandinavia has done a large-scale experiment with poly hives, comparing top vs bottom entrances?
 

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Who drew "first blood" LJ ? I pay pretty close attention to this particular subject, top vents and humidity. In particular "Derek Mitchell's research indicates that top ventilation in heavily insulated hives is detrimental." is not claim by Dreck Mitchell I have come across. I may have to buy the "mass.." article soon. I will have to think about how a heavily insulated hive could negatively affect the dew point inside a hive. Heavily needs to be quantified, maybe to the point of near nil heat loss which causes internal overheating followed by the need for evaporative cooling by the bees resulting in excessive moisture and vapor pressure flowing out on below zero F, very high RH day could cause ice formation at the bottom entrance thus causing closure of the exit for moisture diffusion, and draining of CO2. Rambling on....... ran into this hiking in winter with breath causes my eyes and nostrils to ice up......
 

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Juhani asked "Did the both groups have similar structure concerning upper entrances?"
Me: Yes: no upper entrances on any hives.

clong: yes, that's one article.

The main article is in ABJ Volume 157 No. 8 August 2017 "Honey Bee Engineering: Top Ventilation and Top Entrances". It's a simplification of Derek's earlier work: Mitchell D. 2016 Ratios of colony mass to thermal conductance of tree and man-made nest enclosures of Apis mellifera: implications for survival, clustering, humidity regulation and Varroa destructor. Int. J. Biometeorol. 60, 629–638. (doi:10.1007/s00484-015-1057-z)


Good luck!!
 

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Think about the impact or airflow / boundary layer around the body when flying, heat and moisture loses, sensors etc. The electrostatic buildup and discharge question is a good one as when we did some stuff off a helicopter we had to drop a ground wire into the ocean first then deploy instruments. My question is why is the queen's top thorax are apparently hairless?
 

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Thanks for the reinforcing information clong,

We have similar experiences in different environments with a small time shift. I am at the 8 to 11 hive apiary stage and do not intend to grow. My observations are the similar to yours. I have had a weird event during Fall feeding with moisture. I will have to look at it next Fall. You get the benefit of a large statistical base.
 

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Thanks JoushaW more reinforcement,

Early hive expansion was also reported by Owen in his massive thermocouple study in the 1950s ( I shall reread and study his isotherms this winter as I am more aware now). He concluded that early brood raising was the prime advantage but also he iterated the concept of a looser cluster was able to move easier to stores. He was very focused on defining minimal survival requirements. Of course humidity sensing was beyond his capabilities.

This past season I standardized my hive configuration in early Spring after removing insulation ( a design issue). I also heavily fed and weighed hives in the Fall, nothing in winter or Spring, to an eclectic group of old and young queens in nucs, hives and what I call intensive care units. All survived the winter two were lost in mid-Spring to queen issues. One became an intensive-care unit. All were winter OAV treated. Honey flow and foraging was amazing this year but the most incredible occurrence was the lack of swarm cells - not one hive swarmed nor produced a swarm cell. I wish I knew what I did or it was pure luck. One hive expanded early as well as foraging in cooler weather, all day (Saskatraz characteristic?). This hive was ready for early tree foliage; 100 lb. of my favorite light honey - simply incredible! She wen ton to become Super Woman.

I am trying to define requirements for a hive design for my old-age ( not far away) and focusing on heat transfer and moisture or the water cycle . The effects of propolis is not to be ignored. I use 12 oz. duck cloth as an inner cover and rough sawn pine for hive boxes. Bees really propolized the cloth and wood heavily. Propolis it turn out is some what like Gortex as it seems to make the duck cloth water proof but is permeable to water vapor. From experience I am well aware of permeability of materials, changes in dielectric properties, absorption, etc. I am imagining a design that is composed of polyisocyanate foam bonded to a pine box. I assume the wood will not retain free water and rot but the box to box joint issues bother me. The alternative is an insulating structure with a an air gap between wood and foam with a low resistance permeable path for the air gap to the environment (very similar as to what Hesbach wrote about in BJ).
I have used a poly-hives to get nucs going, affects are kind of obvious on a small colony. I will build some. I am working on an easily removed insulated, 5-sided box, R10 box to slip over my "standardized brood chamber" composed of a medium-deep-medium. I reserve, keep cold, the screened bottom as a volume for diffusion based moisture exchange and condensation of vapor. This design will hopefully make access easy anytime for inspection. I seem to need to verify queen status and brood laying early to avoid colony loss in Spring due to queen issues. Early inspection will help me respond to a failing cluster or "intensive care unit" (ICU); move them to a poly unit or shrink size of standard brood chamber and feed. One ICU gave me a super of honey this year by what may be a four year old queen.

Ventilation or moisture control is needed but best left to the bees. The easy concept is to visualize is a "top vent", match sticks under top covers and the like. Punching holes in structure, especially on various surfaces, is dangerous for the bee as differential pressures caused by wind aerodynamics will create forced convection cooling and unwanted effects. Controlling the dew point, vapor pressure and material permeability characteristics is more difficult to imagine and understand but it seems the bees can do it if given the chance. Now if I could just find a cheap method of sensing humidity accurately over the 50-100% range at multiple points manually or via high tech recording/ transmission.
 

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I am trying to define requirements for a hive design for my old-age ( not far away) and focusing on heat transfer and moisture or the water cycle . ... I am imagining a design that is composed of polyisocyanate foam bonded to a pine box. I assume the wood will not retain free water and rot but the box to box joint issues bother me.

Now if I could just find a cheap method of sensing humidity accurately over the 50-100% range at multiple points manually or via high tech recording/ transmission.
Robert,

Here is one approach to insulating existing hive bodies:
https://www.beesource.com/forums/showthread.php?350601-clong-2018-2019-Treatment-Free-Experience&p=1696903#post1696903

For temp/humidity sensing, have you considered the Broodminder?
https://broodminder.com/collections/products/products/broodminder-th
 

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I wonder if anyone in Scandinavia has done a large-scale experiment with poly hives, comparing top vs bottom entrances?
I haven´t seen any studies, and it is maybe because nobody uses top entrances here in Scandinavia. The bottom ventilation and polystyrene hives is the norm, and even wooden boxes are without top entrances.
 

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Juhani Linden,
I wonder if the low relative humidity (RH) - cold air can cause a dyhration problem if allowed to vent vertically through a hive. Similar to trying to keep the RH up when running the wood stove. ( not to mention heat loss)
 

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Juhani Linden,
I wonder if the low relative humidity (RH) - cold air can cause a dyhration problem if allowed to vent vertically through a hive. Similar to trying to keep the RH up when running the wood stove. ( not to mention heat loss)
Lunden= natural type of park
Linden= lind= lehmus= tree

In the old days, most of the beekeepers in Finland had American style Langstroth boxes (brood and honey same type) with upper entrances and vertical ventilation. 40 years ago that started to change, when styrofoam hives and bottom ventilation came. Plus beekeepers did not want to get so many queens laying above excluders. (In wax circulation and swarm prevention systems brood was lifted above excluder.)
 

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From the book "Beekeeping for all" by Abbé Warré:

"To my great surprise, I noticed straight away that the bees consumed less of their stores in the
hives with single walls where they would feel the cold still more in winter. This is however normal. In
single-walled hives, the bees are torpid; they are as if in a continuous sleep. Now, who dines in that
condition? With hives with warm walls, the bees are active for longer, and thus have need of
sustenance. The single-walled hive thus economises on wood and stores"
 

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From the book "Beekeeping for all" by Abbé Warré:

"To my great surprise, I noticed straight away that the bees consumed less of their stores in the
hives with single walls where they would feel the cold still more in winter. This is however normal. In
single-walled hives, the bees are torpid; they are as if in a continuous sleep. Now, who dines in that
condition? With hives with warm walls, the bees are active for longer, and thus have need of
sustenance. The single-walled hive thus economises on wood and stores"
Abbé Warré hails from a location compatible to USDA Zone 6-7 (by the most extreme winter temps possible) and his own local humidity/wind profiles.
Keep this in mind and don't use his finding as if applicable to you.
Most likely they are not.

What is important - the wintering is the most optimal at steady 4-5C (~40F) - the sweet spot.
I understand this number refers to the average temperature of the air that surrounds the bee cluster.
The colder temps cause more stores to be used for maintaining the cluster temp.
The warmer temps cause more stores to be used due to the bees being more active.

Enough academic-grade material available to support this optimal wintering temp.
Implement this wintering model and be happy (less important how you do it - be it a triple-wall OR a conditioned shed OR a poly-hive).
 

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Abbé Warré hails from a location compatible to USDA Zone 6-7 (by the most extreme winter temps possible) and his own local humidity/wind profiles.
Keep this in mind and don't use his finding as if applicable to you.
Most likely they are not.

What is important - the wintering is the most optimal at steady 4-5C (~40F) - the sweet spot.
I understand this number refers to the average temperature of the air that surrounds the bee cluster.
The colder temps cause more stores to be used for maintaining the cluster temp.
The warmer temps cause more stores to be used due to the bees being more active.

Enough academic-grade material available to support this optimal wintering temp.
Implement this wintering model and be happy (less important how you do it - be it a triple-wall OR a conditioned shed OR a poly-hive).
I´m only saying it was very interesting to find that a beekeeping person that famous as Warré, from France(?) anyhow much milder climate than mine, has come up exactly the same conclusion as me, from the latitude of Alaska.
 
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