Thermoregulation

[max2]

With winter approaching here I would like to revisit  the issue of Thermoregulation in bees.
I'm very interested to learn more about how/if Thermoregulation has an influence on condensation of hives.
We know that adult bees are poikilothermic and endothermic creatures.
We know that they can tolerate a wide range of temperatures.
The bee's body temperature varies over a wide range -  etymologically, it is irregular.
The body temperature of bees have been measured and the nest temperature is surprisingly consistent, whatever the outside temperature.
My own measurements in a subtropical environment showed that at an outside temperature of about 18C bees start to be quite active.
The first bees will fly before this temperature is reached.
Below 7C  the bees fall into some sort of " coma'. We rarely experience such temperatures but bees are sluggish above this temperature  if caught outside the hive.
We know that workers are deliberately endothermic but drones too  are contributing to the maintenance of the brood nest.
Seeley goes into some detail about heat loss.

What I question is:
- at which point  ( hive temperature being assumed to be fairly constant)  will condensation occur? e.g. what outside temperature is critical?
- Humidity must make a contribution here?
- The jury seems to be out regarding ventilation or not?
- In our warm winters insulation of a hive is definitely over the top ( but in cold climates seems to be a good option)

[The15thMember]

- Humidity must make a contribution here?

Humidity is THE question here.  At every given temperature, air can hold only so much water before condensation occurs; generally, the colder the air, the less water vapor the air can hold.  So the relative humidity, like you see on a weather app or broadcast, is the percentage of saturation of the current air temperature (and pressure).  For example, right now where I live it's 21C (70F) and 34% humidity (quite low for us).  So the air is holding about one third as much water vapor as it could, in the current conditions.  Now, the dew point is the temperature at a given pressure and humidity level, where condensation will form.  The dew point for my current conditions is 5C (42F), so if it suddenly plummeted to that temperature, there would be condensation.  So to find out at what temperature condensation would form in a hive, you'd need to know the relative humidity and the temperature, and plug that into a dew point calculator.  Td = T - ((100 - RH)/5), where Td is the dew point, T is the temperature in C, and RH is the relative humidity, will give you a reasonable estimate at humidities above 50%, but the real equation is too involved to do by hand unless you are some sort of genius. 

- The jury seems to be out regarding ventilation or not?

This is why ventilation is so tricky.  In conditions with high humidity, excessive ventilation increases the likelihood of condensation, because the humidity outside the hive is very high.  But conversely under low humidity conditions and without much ventilation, the bees will be unable to vent the water vapor they are producing, creating condensation. 

[BeeMaster2]

Max,
Keep in mind that, during the winter, the bees are depending on condensation on the walls to use to dilute the honey so that they can digest it. What we don?t want is condensation above the brood/cluster. This is where a good insulation in the cover is really important.

Jim Altmiller

[NigelP]

Also worth remembering that a winter in Queensland is like a decent summer in the UK.
 

[Michael Bush]

>Also worth remembering that a winter in Queensland is like a decent summer in the UK.

Yes, it is.  It is like summer in the UK and it is worth remembering.

[max2]

Max,
Keep in mind that, during the winter, the bees are depending on condensation on the walls to use to dilute the honey so that they can digest it. What we don?t want is condensation above the brood/cluster. This is where a good insulation in the cover is really important.

Jim Altmiller

Thanks Jim and 15th.
It would be a rare day when bees could not fly to find water in our winters - water is not an issue as far as bee needs is concerned.
Too much condensation is ( in some winters) a problem.
I have experimented with ventilation and no ventilation but I don't get uniform results.
The calculation is doable...if i can get the data. It is an ever chaging situation - day to day, hour to hour.

[max2]

Also worth remembering that a winter in Queensland is like a decent summer in the UK.
 

Depends on the location in Qld
I'm in the subtropical part.
I would guess that we receive less rain in winter then the UK.
4 hrs from here is apple growing country - very cold.

Up north - tropical.
It is a big state