The OpenBuildings Energy Simulator Materials manager allows for the inclusion of clay, gravel and soil based layers to allow for modelling of slab-on-grade constructions. An extensive array of such materials is available as below.
However your Ground floor will be taken as being in contact with the earth so some additional inputs are required. To view these properties you should right-click on Site in the project tree, and select Properties.
Here you can specify a ground temperature for each month.
Soil Type can also be specified.This is used to specify the nature of the soil at the project site by selecting one of the soil types available on the drop-down list. Soil type contributes to the direct and reflected solar energy transmitted into the building. The available soils types are: