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Author Topic: Hive Temperature Calculations  (Read 4660 times)

Offline BlueBee

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Re: Hive Temperature Calculations
« Reply #20 on: August 04, 2011, 11:10:44 PM »
MarkF, I haven’t looked at this thread for a while, so apologies on a late response.  I have not measured the things you ask, but I can report what I’ve read for what that’s worth.  I have read the bees consume the least honey when the temp in the hive is in the low 40Fs.  They are going to be in a cluster below about 55F.  In the north, they don’t raise much/any new brood until after the new year.

Grieth, what I do in the summer is short circuit my foam insulation system by leaving a crack at the top of the foam and the bottom of the foam.  The foam still acts as a Sun shield keeping the Suns heat out, but it doesn’t trap heat inside like it does in the winter.

In the summer you’ve got at least 3 sources of heat to be worried about:  The ambient air temp, the heat load from the Sun (electromagnetic radiation), and the heat the bees are generating by living.  We don’t have any control over the first and the last, but we can control the heat load from the Sun with a foam insulator or a good solar reflector. 

On a sunny day, the amount of energy hitting the surface of the Earth is about 100watts/sq foot.  A hive probably has about 4 square feet incident to the sun at a time and that means your hive is getting baked with an extra 400watts+ of heat ON TOP OF your ambient air temp.  If you can reflect that heat before it can get into your hive, or insulate the hive from the heat, you are doing the bees a big favor. 

I use 2” foam tops to insulate my hives from the summer sun.  Heat isn’t going to get thru 2” of foam very quickly.   I’ve seen photos of hives in tropical Australia that use large sheets of foam over the hives to block the sun from the wood hive below.  It also keeps some rain away too.

Just a side note:  If you do use the low density (high R value) foam from your local hardware store, be sure to coat it with paint.  Without paint, the UV rays from the Sun quickly turn the foam to dust!

Offline CapnChkn

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Re: Hive Temperature Calculations
« Reply #21 on: August 06, 2011, 01:53:47 AM »
Wowwee!

It seems the one thing I've heard Beekeepers disagree about the most are the mechanisms of heat!  Everyone gives conflicting information about how bees stay warm, and now about how they stay cool.

Bees are tropical by their nature.  Same as other highly successful lifeforms, they've developed an adaptation that allows them to survive in more varied environments around them.  Honeybees in Asia place their combs on open branches, keeping the temperature by covering it.  Mellifera and Cerana have taken to building inside cavities.

The reason for this, I'm sure, is as protection from predation rather than as a temperature control.  If temperature were that important, the Dorsata and Florea would have died out a long time ago.  Still, nesting in cavities allows them to manipulate the environment to some degree.  This isn't adapting the environment as Humans would, I.E. donning a "winter coat," if you will, rather than building a cabin.

Tropical varieties of Mellifera tend to find any cavity to shack up in, while the Temperate varieties will invariably look for hollow trees.  I hypothesise a living tree is a more controlled space than holes in the ground, or free hanging comb.

Trees transpire.  This helps to keep them in a temperature range.  The leaves shade the trunk and limbs so that the sun doesn't increase temperature until there's an absence, allowing the sun in to warm the dark colored bark.  The fact that Mellifera will build open combs in extreme environments is a testament to their heritage, not to their hardiness.

Humans built the "wooden box."  They've also built straw boxes, clay boxes, cow dung boxes, cement boxes, and glass boxes.  Wood just seems to be the easiest and cheapest method.  Problem is not re-inventing the bee, it's re-inventing the tree!
"Thinking is like sin, them that doesn't is scairt of it, and them that does gets to liking it so much they can't quit!"  -Josh Billings.

Offline derekm

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Re: Hive Temperature Calculations
« Reply #22 on: August 06, 2011, 08:29:39 AM »
If you want to use wood as an insulator - think log cabin.   Would you live in a login  cabin through winter or summer where the walls were not 9"+ thick?

A 3/4" wooden box is nothing more than a shelter from the wind  and  predators and then something to hang the frames on. The insulation value of thin wooden boxes  for a bee is close to zip, nada. A single skin  nylon frame Tent would be just as good. (the figures prove it) There's nothing good about thin wood,  thermally speaking.  Although the wood, when new, has anti fungal properties that will help with the condensation issues. If you have ever had the misfortune to camp in a single skin tent in anything like cool weather you will now how miserable it is having the cold wet rain fall on you inside,  on a dry cool morning. So a double skinned tent would be significant improvement for the bees over single thin wood!

 Thin  Wood doesnt even protect from all predators. There's nothing worth losing thermally from putting the bees in aluminium or steel, that would at aleast give the bears something to think about.


The fact that so many bee colonies do survive is a tribute to the survival mechanisms of the bee not our contruction of hives.
    
« Last Edit: August 06, 2011, 09:10:47 AM by derekm »
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline derekm

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Re: Hive Temperature Calculations
« Reply #23 on: August 06, 2011, 08:44:34 AM »

....... Problem is not re-inventing the bee, it's re-inventing the tree!

2" thick  polystyrene box = 9" thick hollow tree trunk
« Last Edit: August 06, 2011, 09:12:17 AM by derekm »
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline Grieth

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Re: Hive Temperature Calculations
« Reply #24 on: August 07, 2011, 08:42:45 AM »
I am convinced.  But now I am thinking:  What can I do that is an easy way to add at least some insulation? :-D

If I put 1/2" thick layers of foam on the insides of the hive boxes, like a foam sheet cut out in the shape of a frame, and placed next to the outside frames, but flush against the insides of the boxes, and high enough that they left no gaps between boxes, how much impact would that have on your calcs? :-\

Are there any other 'easy to implement' ideas out there?  8-)

With days where the air temp is higher than the bees want inside the hive, is increased ventilation helpfull to them, or does it just make life more difficult?  I have been wondering about this since i read about the solar powered extractor fan one beek designed for the hive cover (using a computer cpu fan (so it wasn't very strong), and with with a thermostat so it didn't come on if it is a cool day). :-P
"The time has come," the walrus said, "to talk of many things:
Of shoes and ships - and sealing wax - of cabbages and kings”
Lewis Carroll

Offline BlueBee

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Re: Hive Temperature Calculations
« Reply #25 on: August 07, 2011, 11:12:42 AM »
I have not tried forced ventilation in a bee hive yet, so I’m just speculating here. 

A CPU cooling fan does not seem very strong, but they are enough to remove the 100+ watts of heat modern CPUs generate.  That is a lot of heat.  What a top fan could do for the bees is pull humid air out the top of the hive and draw less humid air in the bottom.  Since the only mechanism the bees have to implement cooling is the evaporation of water, lowering the humidity inside the hive (via ventilation) should help them.  Evaporative cooling becomes ineffective when the humidity in the space being cooled become too high.  This is why we use refrigeration based cooling in the humid areas of the USA as opposed to “swamp” coolers.

I would probably try to block as much heat from getting into the hive in the first place (insulation or solar reflectors) before going the route of a solar top fan.  However being an experimenter, if I lived in a hot sunny climate, I would probably give one of those solar powered top fans a try  :)

Offline derekm

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Re: Hive Temperature Calculations
« Reply #26 on: August 07, 2011, 12:37:45 PM »
Cooling using solar power but no fan - chimney cooling. use the chimney effect - it was once used to ventilate mines.

Insulate and make reflective the hive. Erect a chimney on the top of hive (say 3ft high and 4" dia). Paint the top 2/3rds of the chimney matt black.
The chimney getting hot when the sunshines on it  will cause air in it to rise and draw air in to the hive from below. To stop rain entering the chimney at the top use a sleeve type cowl .

The bees need ventilation to cool the hive by evaporation. When temp gets too high they start fanning their wings to turn up  the evaporation cooling.... Thats burning honey.
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline Grieth

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Re: Hive Temperature Calculations
« Reply #27 on: August 09, 2011, 09:08:35 AM »
Thanks for the solar ideas!

Does anyone have any comments on the effect of adding foam running boards, or other easynways to add insulation?
"The time has come," the walrus said, "to talk of many things:
Of shoes and ships - and sealing wax - of cabbages and kings”
Lewis Carroll

 

anything