A winter cluster is a living thermostat: bees on the outside form a tightly packed mantle that insulates a warm core, which they heat by shivering their flight muscles. How well the colony holds that core near 34–35°C — and whether condensation or isolation starvation threatens it — depends on which fast emergency protections are in place.
lossMult = 1
× 0.55 if wrap × 0.82 if reducer
topLoss = 0.4 if quilt else 1.0
deltaOut = 34 - outTemp
targetCore = clamp(34 - deltaOut·0.05·lossMult, outTemp+3, 34.5)
targetMantle = clamp(outTemp + (targetCore-outTemp)·(0.34/lossMult)·0.55, outTemp, 18)
humidityGap = clamp((targetCore-outTemp)/45, 0, 1)
condRisk = clamp(humidityGap·topLoss·(quilt? 0.35 : 1.15), 0, 1)
starveHours = candy ? 240
: clamp(96 - coldSeverity·80·lossMult, 4, 96)
- Emergency wrap — insulation around the outer hive body; cuts heat loss the most (×0.55).
- Entrance reducer — blocks wind-driven convective loss through the entrance (×0.82).
- Moisture quilt — absorbs the moist air rising off the cluster before it condenses on the cold inner cover; without it, condensation risk more than triples.
- Candy board — solid sugar placed in direct contact with the cluster; removes isolation-starvation risk almost entirely, since the bees never have to break formation to reach food.