Ground properties

The dialog for an object of the type Ground conditions, is displayed by clicking on the button with the same name in the building form. Here the calculation model, ground layers and temperature conditions under and around the building can be described.

Field description:

Ground model

Use ISO 13370 (default) or method from IDA ICE 3

Ground layers under basement slab

Ground layers under slab down to virtual (ISO 13370) or constant (ICE 3) temperature.

Ground layer outside basement walls

Ground layers outside wall to virtual (ISO 13370) or ambient (ICE 3) temperature.

Ground temperature when no whole-year climate file has been selected 

Temperature used in situations when no climate file is known, e.g. when synthetic design day is selected. For it to be used you also have to set the “Climate description” in the Location to <value not set>.

ISO 13370 model

When multiple ground layers have been specified in the Ground properties dialog, only the outermost layer is regarded as "ground" in the ISO sense. Only the material properties of this layer are used, not the specified thickness. Other described layers are regarded as part of the building (in the ISO sense) and are added to layers that have been described elsewhere for building walls and floors.

The ISO model has been implemented for slab on ground and for heated basement (slab below ground) situations. ISO methods for suspended floors (ventilated crawl spaces) and edge insulation are not supported.

The calculated heat resistance of the ground is expressed in two layers; one 0.5 m thick layer of the outermost layer material and below that, a 0.1 m virtual layer with a neglectable heat capacity and a heat conductivity calculated to represent the rest of the heat resistance. The ground temperature is calculated according to the standard as a weighted average value of the annual and the monthly mean air temperatures, including a calculated time lag. From IDA ICE 5.2, different ground temperatures are used for “edge” zones with external walls and “internal” zones without external walls, but giving the same area weighted mean value as before.

A more detailed description of the ISO 13370 model is given here.

ICE 3 model

The ground layer under the basement floor is connected to a constant temperature, which is computed as the mean air temperature of the selected climate file. The layers around the basement walls are coupled to a facade object for crawl space, which is kept at ground surface temperature. Note that no 2D or 3D effects are modeled for either of these couplings.