The article deals with the issue of the influence of selected material and construction solutions for a floor in a historic wooden building on heat exchange with the ground. The scope of the work included continuous measurements of selected parameters of internal and external microclimate, which were later used for numerical analysis of selected calculation variants. The research was carried out in a historic wooden church located in southern Poland. The research period covered 2019, while all measurements were performed every 1 h. For the variant analysis, a building with a wooden and stone floor was adopted. The influence of the heating system on the heat exchange with the ground for wooden and stone floors was also analysed. As a result of a detailed analysis, it was found that the material and construction solutions, as well as the heating system, have a significant impact on the formation of heat exchange with the ground. The building with a wooden floor was characterised by significantly higher values of energy losses to the ground in relation to heat gains. During the year, the total energy losses to land amounted to 1005 kWh, while the gain was 47 kWh. The energy flow from inside the building to the ground in August was 2.4 times higher in variant 2 than in variant 1. In February, heat losses to the ground were 1.6 times higher in variant 2 compared to variant 1.