R value of soft wood

In cold 30℉ weather, condensation is seen at the top vent and cloake board entrance. Warm moist air exiting from these locations are 11℉ warmer than the outside air and this resulted in a large drops of condensation and a wet cloake board landing area.  Foam board insulation above the inner cover and R8 Bee Cozy hive wrap enhances condensation outside of the hive - not inside the hive. Compared to home building codes, R8 insulation does not seem large, but this hive wrap is a wind break and equivalent to 6 inches (15cm) of soft wood. This equivalent hive wall thickness is more like a natural tree cavity wall thickness.

insulated hive wrap and cloake board stack

 

In Atlanta, cold 20°F temperatures arrived on Christmas Day and the ensemble of 11 arctic oscillation forecast a large negative downturn. I used these metrics as significant evidence that winter temperatures are here to stay.  Since 2010, I have reused my NOD Bee Cozy R8 insulated hive wraps  and believe hive wraps improved the chance of overwintered bee hive survival. As a lazy (aka stubborn) beekeeper and despite warm winter fluctuations, I'll leave the Bee Cozy on till spring 2021.

Photo shows joined hives - overwintered hive below and a March 23rd spring swarm capture above an open Cloake Board. The bee cozy is designed for 10-frame equipment, so it easily slipped over the Bloake Board without removing 8-frame boxes. 

I'm encouraged to see warm moist air (bee respiration) condense outside the hive at the top vent and Cloake Board Entrance. 

Here are current the hive elements:

• screen bottom board with no counting board insert
• NOD Bee Cozy R8 insulated hive wraps surrounding the May 25 hive reorganization
• inner cover with top notch up ventilation
• two 3/4 inch sheets of XPS foam board insulation between inner cover and telescoping cover
• white corrugated plastic sheet overhang
• concrete pavers on top

2019 Bee Cozy

Ants create tunnels and nest in the extruded polystyrene foam boards in warmer weather, so I postponed insulating the hives until now. In Atlanta, first frost arrived on November 12th which is just on the early side of historical average.  November 12 also marked the first subtle Arctic Oscillation downturn this winter.

Here are current the hive elements:

• screen bottom board with no counting board insert
• bee cozy hive wrap surrounding the August hive down-sizing
• inner cover with notch up ventilation
• two 3/4 inch sheets of XPS foam board insulation between inner cover and telescoping cover
• white corrugated plastic sheet overhang
• concrete bricks on top

bee respiration with and without Bee Cozy

Here I'll compare winter bee respiration with and without the Bee Cozy hive wrap for two hives.  On the graph, think of the horizontal axis as outdoor temperature and vertical axis as the bee respiration temperature.  See previous posts for the measurement method.  All graph points have top vent temperatures greater than paver temperatures which is consistent with an active and alive hive. Red circles without fill are measurements with no Bee Cozy.

In the graph notice:

• all points are consistently closer to the upper left corner with the Bee Cozy
• hive #1 has top vent temperatures as large as 80 ℉ and consistently warmer than hive #2
• the last measurement (blue circle with fill) is consistently closer to the upper left corner than other graph points.  

Hive #1 has more flight activity than hive #2 and the last measurement (blue circle with fill) is most likely attributed to a larger bee population in response to spring forage and warmer spring temperatures.

with and without Bee Cozy hive wrap

There's no ideal way to compare winter bee respiration with and without the Bee Cozy, but I'll do my best here.

IR temperature measurements started on 12-Nov-2017 without the Bee Cozy.  See a previous post, bee respiration, for measurement method.  On 2-Jan-2018, the 17.0°F outdoor temperature convinced me to add the Bee Cozy to two vertically stacked hives.  Only the queen excluder portion of a cloake board separate these hives.  1 Bee Cozy is added to the bottom hive (4 boxes) and 2 overlapping Bee Cozys are added to the top hive (5 boxes). The Bee Cozy is designed for 10 frame equipment.  So, the Bee Cozy easily slips over my 8 frame boxes and cloake board with no effort.  This 2-Jan-2018 measurement point appears as a blue dot in the lower left corner of dots - Paver temperature equals 17.0°F and Top Vent temperature equals 31.0°F.  On the graph, think of the horizontal axis as outdoor temperature and vertical axis as the bee respiration temperature.

All graph points lie above the green line (x= y) which is consistent with an active and alive hive. Blue dots are measurements without the Bee Cozy and trend beneath orange dots which are measurements with the Bee Cozy.  Excluding a few points, the Bee Cozy consistently increases bee respiration (Top Vent) temperature.

Wondering why I went into winter with such a tall stack of boxes which requires step ladder beekeeping - there's no good reason other than lazy beekeeping.

Arctic Oscillation Jan '17

Here's my go-to metric, Arctic Oscillation, for anticipating history making low winter temperatures in Atlanta.  I can hold-off no longer, today I added the bee cozy for the first time this winter.

Listed from the bottom upwards, here are the hive elements at this time.

• screen bottom board with no counting board insert
• bee cozy hive wrap surrounding the late August hive re-sizing
• inner cover with top notch ventilation
• two 3/4 inch sheets of XPS insulation
• telescoping cover
• white over-hanging corrugated plastic sheet
• concrete pavers

Arctic Oscillation & Bee Cozy Hive Wrap

This might not be the optimal time to add the bee cozy hive wrap, but I'm itching to acknowledge winter.   As you can see from the Arctic Oscillation forecast, this is the first significant negative downturn this winter.  Atlanta December temperatures have been mild and I held off adding the bee cozy. My concerns include limited winter forage and a larger than seasonally appropriate bee population. Here are the hive elements at this time.

• screen bottom board with no counting board insert
• bee cozy hive wrap surrounding the June-July hive re-sizing
• inner cover with top notch ventilation
• two 3/4 inch sheets of XPS insulation between inner cover and telescoping cover
• white corrugated plastic sheet overhang with concrete pavers on top

La Niña pattern

Cold surface water in the equatorial pacific may result in a warmer and dryer Atlanta winter. See the links to the official forecast: 

• David Emory Stooksbury "It is too early to tell exactly how the La Niña pattern will impact Georgia" 
• NOAA Wet Season 2010/2011 Outlook
• NOAA Upper SE La Niña precipitation probabilities October-December
• NOAA Upper SE La Niña precipitation probabilities January-March

The harsh winter encouraged me to purchase Bee Cozy hive wraps.  The hive wraps have just arrived.  Regardless of whether a mild winter materializes, my high shade apiary will probably benefit from the hive wraps.