# 4: Building Systems

This component returns the environmental impact values for a specific building system based on the values in KBOB.

**INPUTS:**

The building system can be selected by the [Item Selector](https://bombyx.gitbook.io/docs/components/0-database/item-selector) from the [System Groups](https://bombyx.gitbook.io/docs/components/0-database/3-systems-groups) list.

Additionally, the system sizing should also be provided. This value will be multiplied by the impact factors.

> **NOTE:** In the case of services which have other units than ERA (Gerät, Stk., Kollektorfläche, or Max. Leistung), the units for the services can be seen in the [KBOB Database](https://bombyx.gitbook.io/docs/databases/kbob).

**OUTPUTS:**

System properties (Text) provides the impact headers and values together for better readability, and System properties (Values) is the output that should be used through the workflow.