Thermal insulation of bee hives & hollows

Energy losses

Poor insulation of the beehives means energy losses for the bee colonies.

The lid

The highest temperature is located on the inside of the lid. Here a good thermal insulation is most important. Conventional lids of bee hives usually consist of several thin layers. Usually they include a 2.0cm thick wooden fibreboard.

The thermal resistance of the illustrated construction is 0.832m²K/W. If we increase the layer thickness to 5cm wooden fibreboard, a thermal resistance of 1.499m²K/W would result.

With the following example, I would just like to illustrate how much energy savings would already be possible with little material input. For a rough calculation, we make the following assumptions:

  • average outdoor temperature in the 6 cold months 4°C
  • average temperature under the conventional lid 9°C
  • lid of the hive  with an inner surface of 48x48cm
  • 100g honey has approx. 1380kJ
  • efficiency of bees for heat production 80%

The 0.667m²K/W higher thermal resistance results in an energy saving of 27000 KJ during the 6 cold months. This saving means a 2.40kg reduction in honey consumption and 1.63l less water production.

The extra cost of material would pay off already in the first winter…

The sidewalls

The poor thermal insulation of the side walls is not as fatal for the heat management of the bees as one might think at first. At least not with the usual magazine hives, which are wider than high. The honeycombs and the air between function as thermal insulation. We have can take the air layers between the honeycombs as “slightly ventilated” when considering the thermal insulation and the ventilation situation, even if there is no bottom. This is due to the fact that there is an almost linear drop in temperature between the periphery of the bee cluster and the sidewalls of the hive. If there were air movements in this area, the temperature would be constant and the layers would have no thermal insulation effect.

Nevertheless, additional insulation of the side walls has a positive effect. On the one hand, of course, the overall thermal insulation is enhanced, and on the other, the dew point for condensation water is shifted outwards towards the sidewall. With the non-insulated thin-walled bee hives, this dew point is already in the middle of honeycomb construction.

Thermal insulation of tree caves

As already mentioned under tree caves, the wood surrounding the cave insulates very well. The tree caves are as well insulated as our houses. There are many advantages to this excellent insulation:

  • Lower energy losses result in lower honey consumption and less moisture in the tree cavity.
  • The higher temperature of the wood surfaces of the cave walls reduces the risk of condensation.
  • Valuable time remains for the bees to do important work, they are forced to take the winter formation at much lower temperatures.
cross-section
cross-section of tree and cave