<I doubt it will be of much value in working out the thermal conductivity of
a beehive

No need to calculate it, those are known values and very well documented.
The relationship (Primary Cold Defense Mechanism - Cluster vs Enclosure Properties). Still holds from my initial calculation with 349 data points per enclosure type. I now have 2516 point per enclosure type (x 2 for the double deep).

What I have learnt so far from my data:
-Enclosure is thermally stable (driven by R-Value), energy balance seems to favour -2 to 10C range (90% of temperature values below cluster and above slatted rack), this is the metabolic rate sweet spot. (95% between -6C and 12C).
-Enclosure is the colony's primary mode of cold defense - even at -40C enclosure outside Temperature correlates with heat loss calculation R2>0.9 and internal Tmin shows minor relationship with outside temperature which was clearly shown in my analysis of a wooden hive
-Starvation is low risk if keeper ensures adequate honey stores. It is easily accessible throughout winter, consumption is predictable at all temperatures
-Bees can quickly heat up interior of hive (volume dependent) due to various known (disturbance, brood rearing) and unknown as described in an earlier post reasons at a minimal energy cost. Therefore increasing heat output to maintain brood nest will have minimal impact on honey consumption.
-Enclosure effectively reduces cold stress on bees, only lower surface area of hemispherical cluster gets exposed to colder temperatures but much warmer than external temperatures due to heat buoyancy effect and mixing of incoming and outgoing air (only one lower entrance). Energy saving process (like HRVs - Heat Recovery Ventilation systems)  
-Based on my CDH (cluster Degree Hours 8C), winter equivalent intensity is reduced by 50-60% of what the bees would have to endure without the insulated enclosure.




             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html