Another Calculation Post:

Lots of interesting information (Remembers these are approximations)

This data could technically be generated with 2 sensors (in hive temperature) to measure T-nest and T-lowest and one data logging weather station (sensor) to measure Ta. My current sensors take a reading every hour. They are capable of doing 5 minute intervals but the battery wouldn't last the winter. I wasn't really able to calculate much for my 5 frame nuc as I only had one sensor installed - likely at ~12 lbs of 31 lbs of honey consumed.

One sensor should be placed dead center of your lowest box, the 2nd sensor should be place as far as possible away from the cluster to get a Low Temp (Ti Lowest). I believe this will give you a decent estimate. Accuracy will likely drop if you do not "wrap/insulated" your hives as Ti will be very close to Ta. I have noticed that during most of the winter so far the cluster has been just above the lower entrance to the right next to the shared wall (no top entrance). It would move up in very cold weather. Luckily I had one of my sensors at the far left back position.

I attached 3 pictures: 
1) This one is a new version of my bee math summary (I made a couple of small mistakes on my thermal mass stored calculation)

2) If you like charts, this set shows a few Ti to Ta relationships, Thermal buffer lag (either due actual thermal mass of honey and/or A/Rsi (Area/Insulation influence) in slowing down the heat transfer. The big chart shows the ambient temperature vs the calculated Meta rate WHr (cluster size included), cumulative honey consumption and Ti for both H2 - Double and H7 - Single.

The honey consumptions actually do line up with my records for the last couple of years. (H2 ~61lbs so far; H7~26lbs). September/early October numbers are likely skewed on H2 as hives really warm up when being moved or handled.

3) This table summarizes the chart data by year, month and week. I added the CDH 10 (Cluster degree hours) into the table. CDH 10 Wood proportional to the energy the hive would require at its very low R-Value. The CDH 10 H2 and H7 are calculated based on the lowest interior hive temperature. Earlier in the season when those honey frames were fully charged up with stored heat, the bees would be milling about on the bottom board at -15C. Now it occurs typically between -10C and -5C. Another thing you will notice in the charts and the table is the higher CDH for H7 vs H2 (also seen when comparing H2 Ti Lowest to H7 Ti lowest). The larger cluster in H2 seems more effective at reacting to large T swings or dealing with extreme lows.

I know this is a lot to take in (hopefully some of you can gain some insight)
I am currently running some trials with/without an artificial cluster (15W) hive to measure/ better understand the impact of thermal mass. I had some full honey frames to test with. A friend lent me his unused sensors.

Note: I didn't bother correcting my ambient Ts when as it was below -40C for about 65 hours. (lowest on my traditional thermometer was -47C)

             ***********************************************
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