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. It is understood that the camera only detects energy losses that are removed by the components. It makes the surface temperature of the components visible. Energy losses due to ventilation cannot be made visible.
The temperature measurements of such thermal images must always be considered with care. Inaccuracies are caused by material-dependent properties. However, the difference between two points of the same material can be calculated very precisely. Therefore, in the following pictures a second point on the same material (Sp2) has been chosen next to the point of maximum surface heat (Sp1), which is unaffected by the beehive. This temperature difference provides information about the heat losses on the component.
The massive wooden walls hardly lose any heat through the walls. In the area of the inspection opening (simple board with cover of branches and leaves) and the entrance, however, we see heat losses as expected.
The wooden Langstroth hives lose a lot of heat through the walls in the area of the beehive. In the areas away from the bees, little energy is lost through the side walls, which is due to the open floors. The heat hardly reaches the side walls, it is already removed by ventilation.
In this wooden beehive lives a strong colony. The heat losses are similar to those in the magazine hives.
Beehives made of straw
Beehives made of straw seem to suffer similar losses as the Langstroth hives. However, there is one difference: the straw hives are closed and have only minor losses due to ventilation (just like the log hives). This results in higher temperatures on the inside of the hive walls. This means that a similar amount of energy is lost through the walls, even though the temperature inside the straw hives is higher.
The tree hives do not show any losses on the thermal images, not even at the entrance. The different surface temperatures are only due to the different materials. A third identical and uninhabited construction shows the same temperature distribution. The small losses are not surprising, the hives were designed with this purpose in mind. The upper part is well insulated and the entrance hole is located so far below that no heat is lost. The thermal images of the honeycombs show that there is life in the two hives.
The 4th pictured beehive is equipped with a diffusion lid. This component shows little heat losses.