Insulation features of material/ heat transferring

[Finski]

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One guy said here that insulation of wood is zero.  It is not so.

Heat conductivity W through cubic metre

brick wall  0,6
wood 0,12
light gravel , Leca gravel  0,13

wood saw dust 0,08
mineral woo l  0,06
polyurethane 0,03
polystyrene insulation board  0,05


24 cm mineral wool has same insulation value as 2,4 metre brick wall.

1 cm polystyrene insulate as well as 4 cm wood.

In modern polystyrene boxes 3 cm wall has insulation value as good as   12 cm wood.
Not a log house but something like that.

If you have mesh floor totally open, insulation values do not help much.



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[hankdog1]

Finski your exactly right everything has a certain thermal mass to it.  The ability to retain heat and or cold.  Beehive is no exeption to the rule.  Makes me wonder what kind of insulation the comb actually adds too.

[windfall]

Finski, do you know if the value for wood is for pine or an average across common species? More commonly in US we find wood rated "in average"
Thanks for digging these up, I have been looking for a relative value on sawdust the last few weeks!

I will see if i can dig up the numbers for individual species...I used to have them. But I suspect most beehives are better than what finski has posted....dense hardwoods like oak and beech push the average away from the better insulating softwoods like cedar and pine more commonly used.

Hankdog1,
Thermal mass and thermal conductivity are related but different. Mass (heat sinks) will attenuate rapid changes but not necessarily slow heat transfer away from source as insulation will.
Certainly honey filled combs represent a substantial thermal mass, and empty comb should have an insulating value. I would be curious to know it too

[derekm]

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One guy said here that insulation of wood is zero.  It is not so.

Heat conductivity W through cubic metre

brick wall  0,6
wood 0,12
light gravel , Leca gravel  0,13

wood saw dust 0,08
mineral woo l  0,06
polyurethane 0,03
polystyrene insulation board  0,05


24 cm mineral wool has same insulation value as 2,4 metre brick wall.

1 cm polystyrene insulate as well as 4 cm wood.

In modern polystyrene boxes 3 cm wall has insulation value as good as   12 cm wood.
Not a log house but something like that.

If you have mesh floor totally open, insulation values do not help much.

The  conductance  value of PS foam is normally quoted at 0.03 to 0.035 PU foam at 0.021 oak at 1.4
An a box open at the bottom is a different case where we have to take into account stratification and convection currents. If warm air always escaped easily hot air ballons would not work. If we can keep the bubble of warm air in place above a column of cooler air then quite the opposite we have excellent insulation. Most insulation is just trapped air or gas.

Compared to 2 inches of PU foam 3/4"  hardwood conducts 17 times more heat that is a dramatic difference to  a bee cluster, it means the difference between 4 deg
c and 68 deg c.
I have a calculator that will work out the watts per degrees C for most hive designs and materials and give the max and minimum ambient temperatures that the bees can can control to brood temperature

[Finski]

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In the hive during winter the wood is quite wet. The weight may rise 30%. That adds heat conductivity.

Even plywood take in water that amount.

[windfall]

The insulation (conductivity) numbers I am finding have soft wood at R 1.41 per inch and Foam PS 5 and PU 6-7, I do not have the conversion handy for the European equivalent. A significant difference but not 16 fold.
Or are you referring to the heat capacity of the wood vs foam. certainly thermal mass might be that different and moisture in wood play in as Finski states.

[Finski]

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A pistol to search thermal leaks

that is a fine tool. You push a button and you get at once the te of object.

I looked last winter my cottage house, what transfers best the heat.
It was outside -20 C and it was inside +20 C.  the door temp was +6. Behind the door it was -4C.

The door is, as we call "mirror door".  Mirrors are only 4 mm ply.   so, it is clear job to insulate doors.

In our city flat I noticed that the wall towars home yard is only +14C. It means that it harly has insulation. The house is made 1952.  


i had in the cottage kitchen "half panell" on the wall. That again had +6 surface temp.
Air circulates behind the panel and practically it has no insulation purpose. It must must take panells off and I insulate the  wall - after 30 years!

[BlueBee]

The following Wikipedia page gives the thermal resistance of various materials in the "R-values" (and International SI units).  http://en.wikipedia.org/wiki/R-value_(insulation)

According to this data, a softwood has a thermal resistance of R 1.41 as Windfall quoted.  However that is for a full inch of wood.  Hives are ¾", so that drops the R value of most hives down to R 1.0. 

The "pink" or "blue" foam sold here in the USA has a R value of R 5 per inch of thickness.  I'm using 2" thick stuff on my hives and hence my hives are 10x more insulated than people using wood hives.  Derekm (I believe) is using 3" foam, so his R value is probably about R-18 (using our units).  So he is indeed 17x (or more) insulated than a standard wood hive.

When you have a top entrance, you do degrade the performance of your insulation due to "air infiltration" as noted on the wiki page.  Those of us who do use top entrances in the winter (myself included) are going to compromise our insulation to a degree because of air infiltration.  Packets of warm air flow out the top, and packets of cold are sucked in by the vacuum created.  My holes are small to limit the negative effects of air infiltration while maintaining a good exchange of gasses which I feel is important.  It is a compromise though. 

Derekm is trying to improve upon the conventional insulation approach by cutting out the air infiltration losses with an interesting design. 

[Finski]

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An English professional beekeeper ( nick name Hivemaker on forum) made an experiment. He took  a couple  bee boxes then he put inside a a weak heat sourge.

He researched the effect of mesh floor and solid floor as heat escaping.
Then he had a digital thermometer sencor in side the box in differen points. Holes in the wall.
He put very weak wind blow towards boxes.

The results are remarkarcable agaist mesh floor.

Same way we may measure the meaning  heat escaping from the hive with different variations.

[derekm]

The insulation (conductivity) numbers I am finding have soft wood at R 1.41 per inch and Foam PS 5 and PU 6-7, I do not have the conversion handy for the European equivalent. A significant difference but not 16 fold.
Or are you referring to the heat capacity of the wood vs foam. certainly thermal mass might be that different and moisture in wood play in as Finski states.

The difference is you dont use 2" of wood for a hive (weight).The common thickness for wood  I see is 3/4"  where as 2"  or more of foam is very feasable  . Using your figures wooden hive  0.75 * 1.41 = 1.0575 ,  PU  hive 2*7 =14
The natural habitat for a bee is a hollow tree this may be 6" to 12" of solid wood plus 1 to 3 inch of rotten wood insect damaged wood inside.  This rotten wood is light and full of a air ,a foam is you like. This means the natural habitat of a bee  has an R value between 14 and 32.

[derekm]

.
An English professional beekeeper ( nick name Hivemaker on forum) made an experiment. He took  a couple  bee boxes then he put inside a a weak heat sourge.

He researched the effect of mesh floor and solid floor as heat escaping.
Then he had a digital thermometer sencor in side the box in differen points. Holes in the wall.
He put very weak wind blow towards boxes.

The results are remarkarcable agaist mesh floor.

Same way we may measure the meaning  heat escaping from the hive with different variations.

I have a hive with a slotted floor( a form of open mesh) that with only 5 frames with brood on can maintain 19C down at the floor level in the  back corner, This is in light wind  with outside temperature at 4C. The top of frame temperature  was 40C. The entrance has an open area of 12mm by 300mm. However the design of whats under the floor and the entrance is crucial to making  a open mesh floor warm.

[hankdog1]

derekum it's been my experience with bee trees that the bees may have no more then a few inches of wood to insulate them in my area.  Just not too many trees around that are big enough to give the amount of wood around the colony cavity and still have that much wood and rotting wood around them.  

[derekm]

its those pesky people chopping down perfectly good bee trees :)
A typical hollow tree here is a willow which can with pollarding over the years can  make it a good 2m  diameter.

Never the less I think we can see that Bee heaven does not have an R value of 1 or anywhere near it.

[Finski]

. The top of frame temperature  was 40C. The entrance has an open area of 12mm by 300mm. However the design of whats under the floor and the entrance is crucial to making  a open mesh floor warm.

that 40 C is emergency temperature because the hive has been disturbed. It is too the high speed flying temp of bee thorax.

Normal temp of brood is 36C.

In winter, when the hive needs insulation, cluster core is 23C. When you disturbe the hive it quickly rises to 40C. It took almost 2 days again to settle down.

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[derekm]

Well when you measure the top of the hive its hotter than the brood. Its like have the thermostat in the living room and then finding its hot up stairs.

To keep the brood at 34C, the top of the hive has to be hotter than  34C  to offset the heat losses.

My measuresments show that  cooler morning  the  higher the  top of hive temperature. During the day the top of the hive in an insulated hive goes down to  34C as the floor temperture climbs to 26C

in uninsulated hives the this top of hive excess temp is more marked and does not reduce as much during the day.

btw 34C  the average brood temp according to my sources. 36C is the maximum.

So finski can you tell me what are my bees going to do this winter in their 0.4W/C hive with an 150mm deep open grid floor and  sloping tunnel  entrance?

[windfall]

I had not noticed that you were comparing 3/4 to 2" until bluebee pointed it out...that way the numbers make more sense.

I actually have built my long hive from 2" thick white cedar in an effort to mimic the thermal mass and insulating value of a hollow log...I also happened to have a whole bunch of thick scrap lying around, and for the long hive weight is not an issue. Time will tell how that experiment fares.

Don't get me wrong derek, I am very interested in the use of insulation, just not ready to throw overboard the experience of those more knowledgeable in bees than I. The principles of insulation and air infiltration/ventilation are not new. Running the numbers is one thing, testing (which it sounds like you are doing) is another, and having years of use in varying conditions yet another still.

I appreciate you sharing your experience with us.

[Finski]

So finski can you tell me what are my bees going to do this winter in their 0.4W/C hive with an 150mm deep open grid floor and  sloping tunnel  entrance?

hah hah. Many guys are mad with their grid floors.
I cannot say nothing about your values.

I just say that I tried mesh floor in 6 hives. 3 2 boxes and 3 one box.

In one box hives food consumption was 100 % more than with solid bottom. One starved and 2 was nearby to starve. Nohing good to say.

In 2 box hives I did not notice anything special.

I have seen how harmfull is windy places to bees in summer, in winter and in spring.
Open floor adds the harms of wind.
In human houses it is easy to notice how heat escapes from rooms.

[T Beek]

If only humans had wings :-D  I mean as long as we're comparing ;) bees and humans.

thomas

[Finski]

If only humans had wings :-D  I mean as long as we're comparing ;) bees and humans.

thomas

my experience is that if a human has wings, he/she is an angel.

[derekm]

So finski can you tell me what are my bees going to do this winter in their 0.4W/C hive with an 150mm deep open grid floor and  sloping tunnel  entrance?

hah hah. Many guys are mad with their grid floors.
I cannot say nothing about your values.

I just say that I tried mesh floor in 6 hives. 3 2 boxes and 3 one box.

In one box hives food consumption was 100 % more than with solid bottom. One starved and 2 was nearby to starve. Nohing good to say.

In 2 box hives I did not notice anything special.

I have seen how harmfull is windy places to bees in summer, in winter and in spring.
Open floor adds the harms of wind.
In human houses it is easy to notice how heat escapes from rooms.

so now i'm mad? well may i suggest your answers show you may need to learn someting about air movement and how air movement is achieved and controlled