hive ventilation - sauna or chimney?

[admanga]

[Warre discussion alert - for those that are allergic - please leave now]

1. Ventilation

There seems to be strongly conflicting views on ventilation. Do the bees need a hive with sauna-like conditions or chimney-like conditions?

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card” and “don’t remove the plank below the varroa board until temperatures reach 30 degC”. He and other users therefore are aiming for sauna conditions for the bees.

Next, I’ll turn the rest of this discussion towards the Warre hive, as I’ve started studying that design, and thanks to David Heaf, there is a good collection of links to books and articles about it (https://warre.biobees.com/index.html). I’ve studied that site and I’ve read some of the original texts in French by developers of various more recent versions of that hive.

Strict Warre hives use a cloth topbar cover and a “cushion” which is typically a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Delon and others say that it is beneficial for the bees if the top of the brood chamber is closed to retain heat (except for winter when some airflow is needed to prevent mold). This could be likened to a nest in a tree, which would typically be closed at the top and open below. Delon recommended a well-insulated crown board (30 mm of wood-fibre insulation) so that humid air descends and condenses down below by the entrance. Delon criticises crown boards with a hole in them. If a crown board contains a bee escape then the bees seal it up indicating that their priority is to retain heat. Concerning varroa, apparently they do not thrive so well in hot and humid conditions. So Delon was in favour of sauna-like conditions.

Guillaume and Freres on the other hand preferred a ventilated roof but criticised the original Warre design for its sealed by propolis top cloth and lack of airflow above the cushion. G&F used a mosquito net over the top bars and a ventilated roof volume above the cushion. (They recommend that this could be retrofitted to Dadant type hives for improvement of their ventilation). The bees fill the mosquito net with propolis and can adjust hive airflow themselves by adding or removing propolis. Above the ventilated part, they also used a thick layer of proper insulation like Delon. G&F also recommended a solid wooden floor, only replacing it with a screen to check varroa in spring for a few days. They are strongly critical of ventilated floors because the bees have no control over airflow and have to use more energy to keep warm.

2. Whole hive insulation
Warre wrote that external insulation was not needed for his hive and was even detrimental to the chances of the bees surviving winter. His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

Delon liked to add external insulation for winter and also his hives were built of 30 mm thick wood instead of 24 mm as per Warre. He criticised Warre by noting that cushion insulation which absorbs moisture is not insulating. I get his point. He also waxed the inside of hives to prevent the walls absorbing moisture. Again, this seems logical if there is a means to evacuate condensed water. I do imagine that his hives stood in a puddle of condensation, while Warre’s probably got rid of some moisture as water vapour.

By the way, Delon’s 45 degree sloping entrance that is minutely adjustable by moving the brood box backwards/forwards seemed like a good idea that went nowhere.

I’m still none the wiser because of these experts' conflicting views. Warre is credible, he spent his whole life studying bees (read his book before writing him off as a mad monk). Delon is credible, having managed hundreds of commercial hives, while Guillaume and Freres are much more recent and write in a highly-opinionated style but without data to back up anything they say (in all I’ve read so far). But possibly because G was the scribe while F was the beek.

The purpose of the “cushion” with moisture absorbing wood shavings would appear to be to wick away moisture. I agree with Delon that if it becomes damp, then its not going to be much of an insulator. I'm not using the cushion for now.

I have put a layer of insulation between the crown boards and flat galvanised roofs to protect the hives from excess summer heat. And I've left the crown board bee escape partially unblocked, so there is a slight chimney effect. But the bees have definitely slowed down this month in their building.

And I’m a bit dismayed that Guillaume and Freres reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature rather than any other for both Dadant and Warre. For now, the removable ventilation board is left in place. Guillaume and Freres were of the opinion that bees in a Warre are so healthy that they did not need the anti-varroa floor (or any chemical treatment). But no numbers for colony survival were given - impossible to judge their credibility.

 

[Antipodes]

[Warre discussion alert - for those that are allergic - please leave now]

1. Ventilation

There seems to be strongly conflicting views on ventilation. Do the bees need a hive with sauna-like conditions or chimney-like conditions?

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card” and “don’t remove the plank below the varroa board until temperatures reach 30 degC”. He and other users therefore are aiming for sauna conditions for the bees.

Next, I’ll turn the rest of this discussion towards the Warre hive, as I’ve started studying that design, and thanks to David Heaf, there is a good collection of links to books and articles about it (https://warre.biobees.com/index.html). I’ve studied that site and I’ve read some of the original texts in French by developers of various more recent versions of that hive.

Strict Warre hives use a cloth topbar cover and a “cushion” which is typically a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Delon and others say that it is beneficial for the bees if the top of the brood chamber is closed to retain heat (except for winter when some airflow is needed to prevent mold). This could be likened to a nest in a tree, which would typically be closed at the top and open below. Delon recommended a well-insulated crown board (30 mm of wood-fibre insulation) so that humid air descends and condenses down below by the entrance. Delon criticises crown boards with a hole in them. If a crown board contains a bee escape then the bees seal it up indicating that their priority is to retain heat. Concerning varroa, apparently they do not thrive so well in hot and humid conditions. So Delon was in favour of sauna-like conditions.

Guillaume and Freres on the other hand preferred a ventilated roof but criticised the original Warre design for its sealed by propolis top cloth and lack of airflow above the cushion. G&F used a mosquito net over the top bars and a ventilated roof volume above the cushion. (They recommend that this could be retrofitted to Dadant type hives for improvement of their ventilation). The bees fill the mosquito net with propolis and can adjust hive airflow themselves by adding or removing propolis. Above the ventilated part, they also used a thick layer of proper insulation like Delon. G&F also recommended a solid wooden floor, only replacing it with a screen to check varroa in spring for a few days. They are strongly critical of ventilated floors because the bees have no control over airflow and have to use more energy to keep warm.

2. Whole hive insulation
Warre wrote that external insulation was not needed for his hive and was even detrimental to the chances of the bees surviving winter. His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

Delon liked to add external insulation for winter and also his hives were built of 30 mm thick wood instead of 24 mm as per Warre. He criticised Warre by noting that cushion insulation which absorbs moisture is not insulating. I get his point. He also waxed the inside of hives to prevent the walls absorbing moisture. Again, this seems logical if there is a means to evacuate condensed water. I do imagine that his hives stood in a puddle of condensation, while Warre’s probably got rid of some moisture as water vapour.

By the way, Delon’s 45 degree sloping entrance that is minutely adjustable by moving the brood box backwards/forwards seemed like a good idea that went nowhere.

I’m still none the wiser because of these experts' conflicting views. Warre is credible, he spent his whole life studying bees (read his book before writing him off as a mad monk). Delon is credible, having managed hundreds of commercial hives, while Guillaume and Freres are much more recent and write in a highly-opinionated style but without data to back up anything they say (in all I’ve read so far). But possibly because G was the scribe while F was the beek.

The purpose of the “cushion” with moisture absorbing wood shavings would appear to be to wick away moisture. I agree with Delon that if it becomes damp, then its not going to be much of an insulator. I'm not using the cushion for now.

I have put a layer of insulation between the crown boards and flat galvanised roofs to protect the hives from excess summer heat. And I've left the crown board bee escape partially unblocked, so there is a slight chimney effect. But the bees have definitely slowed down this month in their building.

And I’m a bit dismayed that Guillaume and Freres reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature rather than any other for both Dadant and Warre. For now, the removable ventilation board is left in place. Guillaume and Freres were of the opinion that bees in a Warre are so healthy that they did not need the anti-varroa floor (or any chemical treatment). But no numbers for colony survival were given - impossible to judge their credibility.

Great post Admanga. Ventilation has been argued about by beekeepers for a very, very long time. I was looking in an old American Beekeeping Journal a few years ago (perhaps from the 1870's) and there was a report there where the matter had been discussed at a meeting of some sort and the vote was split about half way, for and against. Presumably that wasn't when the difference of opinion first emerged.
Research has been done down here to indicate that the decision to ventilate should be based primarily on external humidity.

 

[jenkinsbrynmair]

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card”

It seems like you encountered a pretty wise beekeeper. Forget this rubbish about 'sauna conditions' the bees will sort out ventilation/air circulation and humidity themselves without us unnecessarily interfering

His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

a theory which has now been proven to be absolute rubbish

 

[Wilco]

Where's our resident expert on insulation and hive thermodynamics?

 

[Erichalfbee]

Where's our resident expert on insulation and hive thermodynamics?

Don't !

 

[Mint Bee]

Wow, not sure where to start with this. Most, if not all, of your discussion points are not exclusive to Warre hives. If you want to expand to review experience with other hive types, search the forum for some very inciteful discussions on others experiences of how to work with the bees rather than against them.

 

[madasafish]

I overwinter hives in insulated boxes with minimal ventilation. (Slowly discarding OMF floors).
Poly nucs? I use as supplied.
Last Winter losses in a cold windy and damp place were MUCH lower than my beekeeping colleagues on OMFs. - (150- 250meters above sea level, edge of Staffordshire Moorlands)

 

[admanga]

@jenkinsbrynmair absolutely not forgetting the sauna aspect. Guillaume and Freres even though that an antiseptic shower is created with a heavily propolised mosquito net above the top bars or frames and condensation containing propolis raining down on the bees.

@madasafish, Since writing the post, I've read earlier discussions here about OMF floors and insulation. Very good comments, and I will look to insulating below the mesh in time for winter. Already at the hive top, I put 40 mm of cork under the galvanised roof and the hive gets partial shade mid afternoon. I have to to plan for -12 to +40 degC. Humidity is unlikely to be a problem, though months of drought can happen.

 

[jenkinsbrynmair]

absolutely not forgetting the sauna aspect.

lost me now - no such thing, it's just a supposition generated after reading some of the rubbish pumped out by these self appointed experts.

 

[Antipodes]

@jenkinsbrynmair absolutely not forgetting the sauna aspect. Guillaume and Freres even though that an antiseptic shower is created with a heavily propolised mosquito net above the top bars or frames and condensation containing propolis raining down on the bees.

@madasafish, Since writing the post, I've read earlier discussions here about OMF floors and insulation. Very good comments, and I will look to insulating below the mesh in time for winter. Already at the hive top, I put 40 mm of cork under the galvanised roof and the hive gets partial shade mid afternoon. I have to to plan for -12 to +40 degC. Humidity is unlikely to be a problem, though months of drought can happen.

PM me if you like.
There are a few unscientific myths bandied about.

 

[Gilberdyke John]

[Warre discussion alert - for those that are allergic - please leave now]

1. Ventilation

There seems to be strongly conflicting views on ventilation. Do the bees need a hive with sauna-like conditions or chimney-like conditions?

On helping me to set up a hive for new bees, a longtime Dadant user advised “cover the ventilation hole/porter bee escape in the crown board with a square of card” and “don’t remove the plank below the varroa board until temperatures reach 30 degC”. He and other users therefore are aiming for sauna conditions for the bees.

Next, I’ll turn the rest of this discussion towards the Warre hive, as I’ve started studying that design, and thanks to David Heaf, there is a good collection of links to books and articles about it (https://warre.biobees.com/index.html). I’ve studied that site and I’ve read some of the original texts in French by developers of various more recent versions of that hive.

Strict Warre hives use a cloth topbar cover and a “cushion” which is typically a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Delon and others say that it is beneficial for the bees if the top of the brood chamber is closed to retain heat (except for winter when some airflow is needed to prevent mold). This could be likened to a nest in a tree, which would typically be closed at the top and open below. Delon recommended a well-insulated crown board (30 mm of wood-fibre insulation) so that humid air descends and condenses down below by the entrance. Delon criticises crown boards with a hole in them. If a crown board contains a bee escape then the bees seal it up indicating that their priority is to retain heat. Concerning varroa, apparently they do not thrive so well in hot and humid conditions. So Delon was in favour of sauna-like conditions.

Guillaume and Freres on the other hand preferred a ventilated roof but criticised the original Warre design for its sealed by propolis top cloth and lack of airflow above the cushion. G&F used a mosquito net over the top bars and a ventilated roof volume above the cushion. (They recommend that this could be retrofitted to Dadant type hives for improvement of their ventilation). The bees fill the mosquito net with propolis and can adjust hive airflow themselves by adding or removing propolis. Above the ventilated part, they also used a thick layer of proper insulation like Delon. G&F also recommended a solid wooden floor, only replacing it with a screen to check varroa in spring for a few days. They are strongly critical of ventilated floors because the bees have no control over airflow and have to use more energy to keep warm.

2. Whole hive insulation
Warre wrote that external insulation was not needed for his hive and was even detrimental to the chances of the bees surviving winter. His logic was that bees in a lightly insulated hive enter their “hibernating” state, while those in well-insulated hive continue to work and use up honey stores unnecessarily.

Delon liked to add external insulation for winter and also his hives were built of 30 mm thick wood instead of 24 mm as per Warre. He criticised Warre by noting that cushion insulation which absorbs moisture is not insulating. I get his point. He also waxed the inside of hives to prevent the walls absorbing moisture. Again, this seems logical if there is a means to evacuate condensed water. I do imagine that his hives stood in a puddle of condensation, while Warre’s probably got rid of some moisture as water vapour.

By the way, Delon’s 45 degree sloping entrance that is minutely adjustable by moving the brood box backwards/forwards seemed like a good idea that went nowhere.

I’m still none the wiser because of these experts' conflicting views. Warre is credible, he spent his whole life studying bees (read his book before writing him off as a mad monk). Delon is credible, having managed hundreds of commercial hives, while Guillaume and Freres are much more recent and write in a highly-opinionated style but without data to back up anything they say (in all I’ve read so far). But possibly because G was the scribe while F was the beek.

The purpose of the “cushion” with moisture absorbing wood shavings would appear to be to wick away moisture. I agree with Delon that if it becomes damp, then its not going to be much of an insulator. I'm not using the cushion for now.

I have put a layer of insulation between the crown boards and flat galvanised roofs to protect the hives from excess summer heat. And I've left the crown board bee escape partially unblocked, so there is a slight chimney effect. But the bees have definitely slowed down this month in their building.

And I’m a bit dismayed that Guillaume and Freres reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature rather than any other for both Dadant and Warre. For now, the removable ventilation board is left in place. Guillaume and Freres were of the opinion that bees in a Warre are so healthy that they did not need the anti-varroa floor (or any chemical treatment). But no numbers for colony survival were given - impossible to judge their credibility.

PM me if you like.
There are a few unscientific myths bandied about.

There are a LOT of unscientific myths bandied about much of beekeeping can be infested with them. Personally I use Abelo 11 frame National polyhives which by definition are insulated. NO holes in the crownboard except when I open them for feeding in autumn/winter and then they are covered by syrup feeders or inverted sandwich boxes of fondant so there's no loss of warm air. The open mesh floors remain open except when the inspection board is briefly fitted for varroa counting.
I use 9" x 18" x 6" building blocks as hive stands. Two parallel supporting the sides of the hive and one blocking the gap to minimize eddying in windy conditions. It works for me. Note before using polyhives I used wooden hives and made up loosely fitted hive cosys with insulation board over sides and tops. In all cases the bees live just fine.

 

[ericbeaumont]

a box of wood shavings as insulation. In theory, this setup works as a chimney that the bees regulate by propolising the topbar cover cloth.

Fanciful interpretation: just as likely that bees are saying 'sod that, we don't want top ventilation!'

cover the ventilation hole/porter bee escape in the crown board with a square of card

No insulation gain, apart from in the beekeeper's imagination: do the job properly and give 50mm PIR.

reject the ventilated floor for Varroa management, as my hive purchases were motivated by that feature

Marketing trick; where is the evidence that supports the use of the OMF principle?

hives were built of 30 mm thick wood instead of 24 mm as per Warre

That's bold: how thick is a hollow tree trunk, and which insulates better?

likened to a nest in a tree, which would typically be closed at the top and open below

Cooler below, but why would a hollow trunk have an open base?

still none the wiser because of these experts' conflicting views

We're all in the same boat, but beware of over-processed human interpretations that will always lead astray. Think instead like a bee, because I doubt that the colony collective made an error when it evolved to use a thick hollow tree with no ventilation, a humid environment and a small entrance.

 

[admanga]

Read this week Treatment Free Beekeeping, David Heaf. Excellent book. Points out that those successful in going treatment free in North Wales typically had insulated hives, and there is a photo of an externally cork clad hive. This led me to a web search and I came across a paper by researchers in Sardinia that shows the benefit of insulation for a stable temperature inside the hive: The use of cork in the thermoregulation of the hive: an innovation attempt to enhance non-wood products and beekeeping in Mediterranean forests, Ignazio Floris: https://journals-crea.4science.it/index.php/asr/article/view/2116/pdf
That convinced me, insulation is good as it helps the bees stabilise the hive temperature, using less energy, so more honey is produced. Warre was wrong on that point.

 

[BugsInABox]

Read this week Treatment Free Beekeeping, David Heaf. Excellent book. Points out that those successful in going treatment free in North Wales typically had insulated hives, and there is a photo of an externally cork clad hive. This led me to a web search and I came across a paper by researchers in Sardinia that shows the benefit of insulation for a stable temperature inside the hive: The use of cork in the thermoregulation of the hive: an innovation attempt to enhance non-wood products and beekeeping in Mediterranean forests, Ignazio Floris: https://journals-crea.4science.it/index.php/asr/article/view/2116/pdf
That convinced me, insulation is good as it helps the bees stabilise the hive temperature, using less energy, so more honey is produced. Warre was wrong on that point.

Correlation is not causation.
A stable thermal environment could represent a higher thermal mass caused by increased stores.
So maybe the hives survive because they have more stores (as revealed by the stable temperature) rather than the stable temperature itself being advantageous.

 

[ericbeaumont]

insulation is good as it helps the bees stabilise the hive temperature, using less energy, so more honey is produced

Yes.

 

[Erichalfbee]

Like poly hives.

 

[jenkinsbrynmair]

why would a hollow trunk have an open base?

many do - i can point out quite a few just around here - trees often develop a cavity at the base (think of the stylised 'fairy door' drawings seen in books over the decades) that can expand to meet a trunk cavity

 

[Gilberdyke John]

many do - i can point out quite a few just around here - trees often develop a cavity at the base (think of the stylised 'fairy door' drawings seen in books over the decades) that can expand to meet a trunk cavity

As a boy living near the Yorkshire Howden, there was an old elm tree on the roadside near a junction. The main trunk was quite hollow up to the first branches at about 20 feet where it opened out and us kids would clamber up inside to peer out from the elevated space. At ground level it was possible to walk in to a large opening at one side and crawl out of a lower opening at the other. It was massive and of great age. Eventually bits started breaking off in the wind and it was cut down. End of a landmark although the location is still known as Elm Tree Corner.

 

[admanga]

Just in case useful for others, Randy Oliver gave a great presentation about overwintering bees. Dispels the chimney idea. Bees need insulation and sealed upper chambers, and the ventilated floor would be better off closed in winter, and the entrance reduced to a minumum.



Well that truly buries the breathable Warre hive cushion idea! And I would like to swap out ventilated floors for solid for winter.

 

[Garry R]

Just in case useful for others, Randy Oliver gave a great presentation about overwintering bees. Dispels the chimney idea. Bees need insulation and sealed upper chambers, and the ventilated floor would be better off closed in winter, and the entrance reduced to a minumum.



Well that truly buries the breathable Warre hive cushion idea! And I would like to swap out ventilated floors for solid for winter.

I have always wondered why anyone would insulate a hive all around but have ventilation which would chimney away the heat which you have tried so hard to preserve. Harking back to the 1970s and 1980s Bernard Mobus introduced me to poly hives with polystyrene lined roofs on top of crown boards which, because they were warm there is no or little condensation. In those days there were no open mesh floors as there was no varroa. I have continued with this arrangement using small entrances winter and summer. I think temperature regulation is a big feature in beekeeping and poly hives give you that. But there are loads of opinions about this and perhaps the wooden hive afficionados have adapted their methods to suit those hives. I would point out that poly nucs are all the rage now but this is not matched by full poly brood boxes.