I had made some insulation blankets for my hives when the temps got into the single digits earlier this winter. We just don't see single digits here typically. So being a 1st year beek I wanted to ere on the side of caution. Well a few weeks ago I took them off so I could inspect and left them off. Now we are suppose to get 6-12" snow. Temps are suppose to only get to high 20's. In my most productive hive I have a deep that has capped brood in at least 7 of the frames with lots of bees. Shuold I go put my blankets back on so the brood on the outside frames is not chilled?
Insulating hives
ramdino
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This is only correct if one has a draft going up through hive as a result of entrance size in bottom entrance and inner cover holes and top entrances. Again, in the study noted, what were the bottom and top entrance sizes?
A minimal bottom entrance of 5/8-1 inch by 3/8 restricts the air flow to minimal for ventilation and allows the cluster heat to warm the interior above ambient. If interior temp gets to 40F plus because of insulation and minimal air flow and black exterior paper, cluster is going to be better able to move to new stores. Just checked my hive and with 0F ambient, temp above the inner cover is 36F.
Minimal ventilation likely results in some condensation on comb and side walls and is a good thing to provide a winter water supply. Noted Ian in his indoor wintering of singles was looking for condensation on comb adjacent to cluster. Just don't want excess humidity and condensation overhead. In additio to top entrances, I added ventilated quilt boxes above my inner covers and they are very effective for venting moisture.
Insulation also will only moderate interior temp swings relative to exterior if there is minimal ventialtion. If there is a signficant draft going on, interior temp will closely follow exterior swings.
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While it is not the bees' intent,* heat does leak from the cluster and can heat the interior of the hive. In the case of a strong hive, this heat leakage can warm the hive interior by as much as 80F above the ambient air temps:
http://www.beesource.com/forums/showthread.php?291469-Winter-time-fun&highlight=winter+time+fun
I have a bunch more data that I have collected to enter. The general trend is pretty much the same for all the hives, so far.
*"intent" is used tongue-in-cheek, since insects can't form an "intent" as the word is commonly used
http://www.beesource.com/forums/showthread.php?291469-Winter-time-fun&highlight=winter+time+fun
I have a bunch more data that I have collected to enter. The general trend is pretty much the same for all the hives, so far.
*"intent" is used tongue-in-cheek, since insects can't form an "intent" as the word is commonly used
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I'm looking forward to getting my hives up and running and using my thermal imager on them. When they've deliberately warmed their flight muscles up (necessary for foraging) they can be as warm as we are. Attached is a thermal image I made last year of an individual forager on a bloom. The hot spot is the thorax, and it is unambiguously warmer that the environment or even the rest of the bee.
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Shinbone, 80F seems like a lot and I would think the probe is next to or within the cluster at 80F rise.
What size is the opening in your bottom entrance? Doesn't look like much more than 1/2 wide by?3/4 high. But minimal and corraborates my point about interior temp and how much ventilation is occurring. Ventialtion is greatly reduced but adequate.
Do you have shavings in the top vent box? I added a screen to the bottom of my vent boxes and layed a piece of burlap on top of the screen and filled with shavings. An area bee keeper was telling me that he wintered 15 out of 15 hives last winter(long and cold winter), and the only significant difference in winter preparation was that he used vented quilt boxes. Two of my four hives had died out.
What size is the opening in your bottom entrance? Doesn't look like much more than 1/2 wide by?3/4 high. But minimal and corraborates my point about interior temp and how much ventilation is occurring. Ventialtion is greatly reduced but adequate.
Do you have shavings in the top vent box? I added a screen to the bottom of my vent boxes and layed a piece of burlap on top of the screen and filled with shavings. An area bee keeper was telling me that he wintered 15 out of 15 hives last winter(long and cold winter), and the only significant difference in winter preparation was that he used vented quilt boxes. Two of my four hives had died out.
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All of my hives have interior temps above ambient temps, although there is substantial variation on just how high above ambient each hive is. The 80F example is the highest I have seen and that hive is always close to 80F, irregardless of the ambient air temps. The lowest is about 5F above ambient, and varies substantially with the ambient temps.
While one can argue that the high temps (or any of the above-ambient temps, for that matter) are due to the cluster having enveloped the sensor, that can't always be true because the cluster would eventually exhaust the honey resources in that area and would then move to another region hive and no longer be close to the sensor. In other words, the "close cluster" argument is only a temporary explanation, and one finally has to conclude that the bees are indeed heating the interior of the hive.
1/2" x 1/2" is a good approximation of the bottom entrances. Typical upper entrances vary from 1/2" x 1/2" to 3" x 1/2".
The tops are the Honey Run Apiaries All Season Inner Covers with a piece of foam insulation in place:
http://www.honeyrunapiaries.com/store/all-season-inner-cover-p-232.html
While one can argue that the high temps (or any of the above-ambient temps, for that matter) are due to the cluster having enveloped the sensor, that can't always be true because the cluster would eventually exhaust the honey resources in that area and would then move to another region hive and no longer be close to the sensor. In other words, the "close cluster" argument is only a temporary explanation, and one finally has to conclude that the bees are indeed heating the interior of the hive.
1/2" x 1/2" is a good approximation of the bottom entrances. Typical upper entrances vary from 1/2" x 1/2" to 3" x 1/2".
The tops are the Honey Run Apiaries All Season Inner Covers with a piece of foam insulation in place:
http://www.honeyrunapiaries.com/store/all-season-inner-cover-p-232.html
Local feral survivors in eight frame medium boxes.
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The thermodynamics of a bee hive are much more complicated that just measuring the temperature of the cluster and the temperature of the hive.
http://www.bushfarms.com/beesscientificstudies.htm#overwintering
http://www.bushfarms.com/beesscientificstudies.htm#overwintering
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Michael - So true!
The thermodynamics of a living entity are hugely complicated. My simple little measurements only serve to show the bees do heat the interior of the hive. My only intent with my measurements was to be able know when a hive died out over the winter by showing when a hive interior had cooled down to ambient temps.
The thermodynamics of a living entity are hugely complicated. My simple little measurements only serve to show the bees do heat the interior of the hive. My only intent with my measurements was to be able know when a hive died out over the winter by showing when a hive interior had cooled down to ambient temps.
Here is a post I wrote about how I insulate and wrap my hives. I was please with the results this year.
http://sidelinebeekeeping.com/2013/11/13/wrapping-hives/
http://sidelinebeekeeping.com/2013/11/13/wrapping-hives/
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The standing joke about physicists: "Assume a spherical cow ..."
Well, there must be something to insulating hives or so many beekeepers wouldn't continue to research the benefits or drawbacks insulating their hives, and we wouldn't be having this discussion. As I live in the coastal plain of North Carolina, we experience very hot and humid summers. I may be wrong, but I believe that a hive insulated year round with 3/4" foam board will help the hive to remain cooler in our hot and humid summers. As long as I provide adequate ventilation. More research on my part is called for.
This particular study did not give an exact entrance size, all it said was that it was a greatly reduced entrance. You can read into that whatever you want, if you think that the study was flawed because they used an entrance size that you assume was too large, and it caused excessive draftiness, which removed any beneficial whole hive heating, then there is nothing I can say to prove it otherwise.
How honey bees are able to withstand prolonged severe cold in uninsulated hives is something that always amazes me, so there definitely is some special thermodynamics going on in the hive that we can't always fully understand.
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Also, I am in the camp that thermal insulation (as opposed to wrapping a hive to seal out wind) does little if anything to help a hive survive cold temps in most locations.
As long as the hive is healthy and of reasonable size, and is in well maintained equipment, they will survive the winter unless they go off their winter stores. If they lose contact with their food, no amount of insulation will save them.
You'd have to go pretty far north or south before insulation becomes worthwhile.
Just the opinion of a newbie.
As long as the hive is healthy and of reasonable size, and is in well maintained equipment, they will survive the winter unless they go off their winter stores. If they lose contact with their food, no amount of insulation will save them.
You'd have to go pretty far north or south before insulation becomes worthwhile.
Just the opinion of a newbie.
shinbone, I have gone through most of your posts of your temperature readings, but I didn't see you mention what time of day you did the bulk of the readings (except a reference to readings taken one morning), I don't know if they were all taken about the same time of day on the days you did them or not. My questioning this is because when taking temperature readings during the daylight hours you are bound to get higher readings inside than ambient due to solar gain. Did you take any readings well after dusk or well before sunrise, those would be the more accurate readings as to whether or not the bees contribute heating to the whole of the hive? Maybe I just overlooked your reference to time of day as I was quickly scanning through your posts.
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jmgi - About half the readings were taken in the dark before sunrise (as I left the house for work), and about half the readings were taken in the early evening at dusk (when I came home from work).
My guess is that in the wintertime for hive box of a light natural pine color (which most of mine are), there is little solar gain. I also should note, that I see little difference between the hives that are wrapped in black insulation (Colony Quilt) and the hives that are unwrapped.
Although I may still set something up this year, next year I will set up an empty hive with a sensor in it to measure solar gain.
My guess is that in the wintertime for hive box of a light natural pine color (which most of mine are), there is little solar gain. I also should note, that I see little difference between the hives that are wrapped in black insulation (Colony Quilt) and the hives that are unwrapped.
Although I may still set something up this year, next year I will set up an empty hive with a sensor in it to measure solar gain.
shinbone, based on your observations then, it would seem to contradict the findings in the study I was referring to in the ABC and XYZ of Bee Culture, that being the cluster and immediately next to it were the only temperature probe readings that were much above ambient in the whole hive. That study appears to me on the surface to have been well done (massachusetts state college) and the results thoroughly recorded using over 118 sensors in a two story hive, so I don't know what the reason would be for their results to not be in line with your simpler experiment, you seem to have done a good job yourself with your small study. Either there is some solar heat gain or heat loss not being factored in somewhere with either experiment, or the bees themselves contribute more to hive heating than most think.
Reading your above link, many good points on thermodynamics to be sure, but still the question arises as to the predominant source of the heat gain in the wintering hive. We know the bees add some degree of heat generated by the cluster, and the solar gain obviously contributes heat, so we should accept that during daylight hours both sources work together at different degrees to raise internal hive temperatures. IMO, during daylight hours the solar gain is the biggest contributor, and quite possibly during nightime hours also because of the heat sink created in the stored honey.
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Respectfully, you obviously have no idea what you are talking about if you think solar gain can create an 80F temp differential in an uninsulated hive when ambient temp is 0F.
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I don't think it will on a wooden box, either, but you ought to see my Revere collectors at work on a sunny January day. On a summer day they can boil water.
My question is, have either one of you done more than measure a temperature or two? Installed any heat flow sensors? (I have 7 heat flow sensors within reach of me right now.) Assayed the various ways heat can be lost, including air flow, evaporation (and condensation), leaky insulation, i.e. all the things involved in a home energy audit? Done any thermography? Know how to construct a guarded calorimeter? Measured hive weight loss versus energy use? No? Me either, but I intend to.
What I expect to find is a superorganism exploiting stored energy to regulate temperature, but whatever I can actually measure must trump what I expect.
In support of shinbone, as a surrogate for a wooden hive, how about a 1440 square foot log cabin, with two 4'x8' solar hydronic heat collectors driving a radiant heat floor. The building still needs some insulation but it is better insulated than a hive, and with a far superior volume to surface area ratio. It faces south and gets full sun. I'm still hoping to get this system to the point where it won't freeze in the winter. I'm close, but not there yet.
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Phoebee - that all sounds impressive, but it is just words until you actually do all that to a beehive. How about you post the results for us to see when you are done?
jus say'n
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