Hive Ventilation & Configuration
At the start of Autumn, the disagreements start about how warm to make the house. We compromise at 19.5C which means I’m wandering around in shorts whilst Heidi wears 3 layers of clothes. She sometimes pulls up her hoody but I think that’s just her trying to make a point. When the mother-in-law is down, she’s “freezing” (I think she has been scarred by Scottish winters), it’s 2 against 1, the thermostat goes up, the problem is exacerbated and I have to protest by wandering around naked. My protest does not go unnoticed (my daughter says “daddy pants on”) but it is ignored.
So whilst there is some disagreement in our local eco-system there is also disagreement between beekeepers when it comes to hive ventilation.
Preparing Bee Colony For Winter
Before we talk about hive ventilation, there are a number of elements that most beekeeping literature seems to agree on when preparing a hive to successfully over-winter:
- A strong colony
- Queen-right
- Disease free
- 20Kg of stores (read: feeding bees for more information)
- Low varroa count
- Insulation in the roof
My bees are in 14x12s with a super below.
Hive Ventilation
The reason the colony needs good ventilation is to make sure that condensation is not dripping on the bees during the cold, winter months.
There seems to be two schools of thought on hive ventilation and how to configure your hive between autumn and spring. In 2014 in separate issues of the BBKA magazine there were articles by beekeepers advocating both methods. These are described below.
Note: if you have solid floors then top ventilation is required.
Insulation
In all cases insulation in the roof is deemed a positive, though some beekeepers say it is unnecessary. The rationale for roof insulation is that with no insulation the warm moist air which rises will condense on the cold roof or crown board and drip on to the bees. Roof insulation reduces this process.
I say insulate the roof (and the walls if you can).
Option A: Top & Bottom Ventilation
Configuration:
- Open mesh floor (allows the air in)
- Holes open in the crown board (allow air to flow through)
- Insulated roof (means the warm air rising does not condense and drip down due to a cold roof)
- Side vents in the roof (allows the warm, moist air out)
Argument for: A chimney effect allows warm moist air to rise and escape.
Arguments against: Some/quite a lot of beekeepers say that this chills the bees too much and works against the nature of bees who try to propolise top vents.
Based on my experience I would advise against this chimney effect, the bees need to be cosy in winter. Go for bottom ventilation only.
Option B: Bottom Ventilation Only
Configuration:
- Open mesh floor
- Solid crown board
- Insulated roof
Argument for:
- This is more similar to how wild bees manage condensation
- This method establishes a convection current, warm air rises in the middle and then falls at the sides, when it reaches the bottom some of the moist air is exchanged for dryer air
Argument against: I couldn’t find arguments against.
National Bee Unit (NBU) Advice On Hive Ventilation
The NBU does not go into much detail but does say the following on hive ventilation: “Damp rather than cold kills bees so check hives, especially roofs, to ensure rain is shed away. It is best to ensure that your hives are off the ground on suitable stands. If your apiary site is not vulnerable to windy conditions, and you are using open mesh floors, they can be left with the floor inserts out. If not, or your hives are on solid floors, then you can lift the crown board on two-millimetre laths. Used matchsticks are excellent for this purpose.”
They have also produced a guide on “Preparing your hives for winter” – this link opens the PDF and is worth a read.
Conclusions
- Some ventilation is required but not too much
- Open mesh floor is enough
- I think open mesh floor with top ventilation is too much
- If you have solid floors then top ventilation is required
I welcome your thoughts on the above article.
Read More
Postscript: I had a disastrous Winter 2014 (see My Colony Losses). In Autumn 2015, I added roof insulation plus a Bee Cosy. I kept the Open Mesh Floor. Read Top Tips For Preparing To Winter Bees.
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Only just started this year, so this will be my first winter with bees. I had a poor start being infected with chalkbrood. They swarmed, but I captured the swarm making 2 hives. I replaced the queens in August with Buckfast queens and both colonies look quit strong now. Not having any experience of going through a winter, I am worried about their survival. Which brings me to this question. Insulating the roof is obvious, but what about insulating the sides? A thought I had was to build insulated dummy boards to replace the first/last frames within the hive and set insulation on the outside of my National hives within the recess’s front and back of the hive. Or is this un-necessary?
Insulated dummy boards – If you had a double brood box then there would be enough room left after the insulated dummy boards for the bees to store food for the winter, but not enough room if you had a single brood.
I don’t have any side insulation. I figure after they have consumed the stores in the most external frames then this provides some sort of insulation.
There are products you can buy that provide insulation on the hive exterior. If I had spare cash, which I don’t, I might invest in these.
Good luck for the winter. Seems that you are being very proactive and you stand as good a chance of any of us of successful over-wintering (presume you have fed them and treated for varroa).
I found similar stories, and also about a special super on top of the hive with wood chips and ventilation holes to combat humidity, an somewhere else about plastic foil to catch condensation and provide the bees with water to drink.
You’re conclusion is adout the same as the one I came to; screen bottom and insulation under the hive cover.
Mouse guards on? Fondant on? Oxalic acid coming up…?
I’ve just done fondant and no sugar syrup. Later breeding. No mouse guards. Good luck to any mouse that tries to get into my angry bees hives!
Risk taker! No woodpecker defences I guess?
No. I found my beesuit was no defence earlier in the season….! Good crop though!
We have overwintered an average of 6 hives for the last three years using open mesh floors, solid crown boards with no intentional ventilation and not lost a colony overwinter as yet. I work on the theory above, with an open floor and matches under the roof the bees are not able to build up any warmth as they are in a constant draught. The other thing we do on most hives is to wrap them with heavy duty bubble wrap to keep the hive sides dry, some bits we have are black so hopefully grabs some solar effect on sunny days.
Don’t feel too optimistic about survival rates this winter as we lost a couple of swarms in September, not sure what happened there: anyone else have late swarms this year?
I do research into the thermal propoerties of honeybee habitats, inculding measurements of thermal conductivity on hives of all types and models of trees. My researches show that the conventional wood hive loses heat several times the rate of their native habitat, and (counter intuitively) keeps the bees in a lower humidity than they have been shown to need.
Cold and damp increases the heat loss of the colony.
Interesting and thanks for commenting. Is it a problem? What is the solution? Do we just need to make sure we feed the bees (i.e. so they have an energy/heat source)? Or do we need to buy insulation for our hives? Or buy different type/material of hive? Look forward to hearing from you.
UK bee farmers report higher yields and survival in polystyrene hives.
However, top venting with insulation obviates its effect. Adding insulation needs attention to detail to make it work efficiently. Although it can be quite simple as those who attended my talk at the BBKA spring convention found.
Thanks Derek, Have you got some slides you could email me that I could upload to this page?
Hello Derek,
I was enthralled by your talk at the SBA Convention last weekend, thank you. Afterwards I had a look at your hive made from Recticel and chatted briefly with Elaine.
Just last week I had bought some 25mm insulation to make a “jacket” and to insert inside the roofs of my national hives. With my background in building and being a diy-er, I had been thinking of making some hives to combat the chilly Scottish weather where I live in the Borders, so your talk and what you have been doing was very interesting to me and many steps ahead.
I’d like to make a hive from insulation. Can you tell me was it 50mm you used to match a “tree” and what type of Recticel you have found best?
Have you published any research or other articles on what you presented that are available to read?
I hope you don’t mind my asking and all success with your continued bee research.
Dear David,
I’m glad you enjoyed the talk, it was a shame there wasn’t time for more questions, I was hoping someone would ask about bees not needing to cluster in tree nests just because its cold outside.
My research was published recently in the International Journal of Biometeorolgy
Int J Biometeorol. 2015 Sep 3. [Epub ahead of print]
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.
Dear Derek,
Thank you for your prompt reply. I’ll look up your research as I’m very interested to read it. Could you tell me, what thickness of Recticel insulation you use to make your hives?
Best regards,
David
50mm recticel
Hi Derek,
Interested on your thoughts on the Bee Cosy posts:
– Hive Insulation & Bee Cosy
– Top Tips For Preparing To Winter Bees
I’ve copied the abstract here for others that are interested:
In the absence of human intervention, the honeybee (Apis mellifera L.) usually constructs its nest in a tree within a tall, narrow, thick-walled cavity high above the ground (the enclosure); however, most research and apiculture is conducted in the thin-walled, squat wooden enclosures we know as hives. This experimental research, using various hives and thermal models of trees, has found that the heat transfer rate is approximately four to seven times greater in the hives in common use, compared to a typical tree enclosure in winter configuration. This gives a ratio of colony mass to lumped enclosure thermal conductance (MCR) of less than 0.8 kgW−1 K for wooden hives and greater than 5 kgW−1 K for tree enclosures. This result for tree enclosures implies higher levels of humidity in the nest, increased survival of smaller colonies and lower Varroa destructor breeding success. Many honeybee behaviours previously thought to be intrinsic may only be a coping mechanism for human intervention; for example, at an MCR of above 2 kgW−1 K, clustering in a tree enclosure may be an optional, rare, heat conservation behaviour for established colonies, rather than the compulsory, frequent, life-saving behaviour that is in the hives in common use. The implied improved survival in hives with thermal properties of tree nests may help to solve some of the problems honeybees are currently facing in apiculture.
The full article can be found here but you’ll need to pay.
Many thanks
Hi Derek Mitchell, I would like to meet you in person for a chat. I am interested on find out more about your research as would like to promote bees welfare on a social movement and your work seems to be on that direction. Would you please get in touch at hand . in . hand . with . nature @ gmail . com
Kind Regards,
Luisa
This is my first bee Winter with one colony in 14 x 12 box with super on top, with no queen excluded I have insulated the roof and fashioned polystyrene panels to fit three sides and the roof top. The roof has vents. I have just made a roof with 6 inch drop with no vents to use next Winter. I feel the vents are more use on the hot Summer days when the hive is in direct sunlight. Interestingly my ball of bees is located right against the front of the box where there is no poly insulation. Food for thought.
Is the uninsulated wall South facing? If so, it’s the warmest wall on a sunny day! I doubt that that bees would cluster against the coldest wall. You might get a bit of condensation on the coldest wall, especially where the joins between boxes allows cold air in…. None overhead though!
Derek Mitchell, would you be able to give a talk to Bridgend Beekeepers Association (south Wales) sometime in winter 2016? Thank you
Greg Nuttgens, Education Officer, Bridgend Beekeepers Association
This winter I am experimenting with three top venting systems. All hives have open wire mesh bottom and after half winter I found a big difference. During the cold snap the hive that had the most insulated roof had less dead bees on the bottom screen. Immediately I increased the top insulation of the other hives and the result was a drop in dead bees to a quarter of daily number. As the temperature went lower other hives increased the number of daily deceased bees. As protection I increased the insulation on those hives also. Next day the number of deceased bees was drastic reduced.
Hi John, Thanks for comment. Some beekeeper writers say best to let the hive be cold and the bees consume less stores, others say better to offer some insulation. Both sides of the argument have been written about in the BBKA magazine and offer graphs and evidence of success. Polyhives are also much lauded for their insulation properties. I am sticking with Bee Cosies on my hives for the time being.
Hi Roger, Thanks for reply. The hives entrance is all open and just broke my heart to have a handful of dead bees every day on the screen. The improvement in venting combined with insulation brought number of dead bees to a fraction. My point is that a large number daily dead bees require some action. I like to remove the dead bees daily to see the number fluctuation related to temperature or rain. And man we get a lot of it in Pacific NW.
May I suggest you read the research that went into ventilated floors for Wintering. This was before Varroa arrived. Please see B. Mobus Wintering.