Ecological comparison of hygrothermally safe floor constructions based on renewable raw materials for multi-storey buildings

The major goal of the European Green Deal states that Europe will be climate neutral by 2050. Hence, massive changes have to happen in the construction industry. One way to reduce the environmental impact caused by the building sector is the use of building materials consisting of renewable raw materials. In order to enable a wider application of bio-based building products, the hygrothermal safety of all building components has to be guaranteed. In this paper, three floor constructions based on renewable raw materials, each representing a type of construction and foundation, were examined for their hygrothermal safety. In addition, these were compared with a conventional floor structure in terms of their environmental characteristics. The ecological evaluation was carried out by the analysis of the global warming potential, Oekoindex OI3, disposal indicator and on the basis of corresponding environmental product declarations (EPDs). The software WUFI 2D was used for the hygrothermal evaluation. The results prove the constructions' hygrothermal safety in the simulated climate. The ecological calculation shows the possible reduction of the global warming potential of the floor constructions of up to 82% per m2, depending on the choice of construction type and materials. Applying the other three methods mentioned above, the analysis results in a reduction potential of the environmental load of approx. 53-55% per m2. Depending on the chosen assessment method the results differ. This states clearly how sensitive the selection of suitable indicators is. Fact is, that the data situation around the ecological indicators of building products is a key issue which has a major effect on the results of the evaluations. All results of the ecological assessment presented in this study were strongly influenced by the foundation type. Consequently, the material efficiency and type of foundation used have a significant effect on the ecology and the environmental performance of the simulated floor constructions.