The thermographic images below show that the temperature distribution over the biofilter is not even (left photo), and that zones with an increased temperature profile can indicate preferential airflows (purple-red zones).
Analysis of the building structures showed that diffuse heat losses were very limited. At the height of one of the roofs and near a small zone of a pipe, heat loss could be detected along which diffuse emissions can be released (circled in red).
Important know-how for interpreting thermographic images is crucial here. For example, the light green warming zones in the building photos are due to solar radiation, and are therefore not a sign of diffuse heat loss. In order to map heat losses to the maximum, it is therefore opted to carry out thermal drone measurements with at least 80% cloud cover and in weather situations where the difference between ambient temperature and indoor temperature is at least 10 degrees Celsius.