Hive Ventilation & Configuration

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
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.

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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