Building physics of bee hives and tree caves

Effect of high humidity in the beehive on the water content of honey

November 23, 2018August 20, 2018 by Roland Sachs

A balance is established between the water content of the honey and the surrounding air humidity. The balancing moisture content of honey at a relative humidity of 55% is about 17.5%. At a relative humidity of 80%, honey has a water content of over 30% (source: The hygroscopic properties of different dilutions of Honey, Doull & Mew 1977).

The wax capping of the honey cells slows down the speed of these water transports, but does not prevent diffusion. The wax layer is so thin that the resistance of this cap to water vapour diffusion is just as high as that of a 3.3 cm thick layer of air. The experimental setup for determining the diffusion density is explained below.

Thermal insulation of honeycombs

August 6, 2018April 5, 2018 by Roland Sachs

When considering the thermal insulation of bee hives, we also have to consider the honeycomb construction with its air layers in between. These layers themselves act as thermal insulation. The more honeycombs between the bee cluster and the side wall, the higher the insulation. I.e. with regard to the side thermal insulation, the broad constructions of the modern hives are quite helpful.

Straw bee hive with frames

June 13, 2018March 21, 2018 by Roland Sachs

Almost 100 years ago, straw hives with frames were already used for beekeeping. The hive has a wooden bottom, the entrance hole is only a small slit, the side walls are made of straw and the lid is a double-walled wooden construction with straw filling. In these hives there were no problems with mould and … Read moreStraw bee hive with frames

Physical properties of propolis

November 17, 2018December 18, 2017 by Roland Sachs

The antiseptic function of propolis is generally known. This property slows down the development and spread of pathogenic germs in hives and tree hollows. However, propolis also fights condensation and mold in a different way, which is probably unknown to beekeepers. It is a simple physical effect: In the propolis layer there is no capillary condensation, propolis is not hygroscopic.

Thermal images of bee hives

June 13, 2018December 3, 2017 by Roland Sachs

In a joint project with Sabine Bergmann (Sa Bienen Imkerei Schloß Hamborn) we made thermal images of different bee hives. Finally, the pictures do not provide any new insights. But they illustrate building physics properties very nicely.

News on the Diffusion Lid, October 2017

March 21, 2019October 16, 2017 by Roland Sachs

The Diffusion lid works, but not as well as calculated:
The calculations for the diffusion lid are basing on approved calculation methods of building physics. The difference in the temperature, the thickness and the type of the material are decisive for the amount of water vapor diffusion.

News on the diffusion lid, September 2017

February 17, 2018September 20, 2017 by Roland Sachs

Unfortunately, sheep’s wool in the form of insulation mats is usually treated with moth repellents. Please do not use this for the Diffusion lid! It is also best to buy untreated sheep’s wool directly from the shepherd or farm. Hemp insulation wool is also permeable and can be used as an alternative. The insulation properties are, however, slightly worse.

Water formation by the metabolism of the bees

February 17, 2018June 12, 2017 by Roland Sachs

In our calculations we have only considered the water contained in the honey so far (200ml water per Kg Honey). This is a customary assumption, but that’s only a part of the truth. The water formation caused by the metabolism of the bees is much bigger. Oxidative water is produced during the aerobic metabolism of … Read moreWater formation by the metabolism of the bees

Diffusion lid: Elimination of humidity and mould in beehives

February 17, 2018May 23, 2017 by Roland Sachs

We have designed a lid for conventional beehives that eliminates humidity and mould in beehives. This way we generate a relative humidity of about 50% in the upper part of the beehive. With this drought, most parasites can hardly reproduce. Not even the little hive beetle!