> For the complete documentation index, see [llms.txt](https://bombyx.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bombyx.gitbook.io/docs/components/1-bottom-up/3-element-impact.md).

# 3: Element Impact

This component calculates the environmental impact of a building element, connecting the Grasshopper definition with the Rhino model of the building.

**INPUT:**

* The "Component Properties" input will take the already-defined components from the [previous step](/docs/components/1-bottom-up/2-component-impact.md).
* The "Thermal Resistivity" model differentiates between the scenarios of U-value calculations:

\- In case of elements exposed to air, the value of 0.17 is added to the calculated U-value from the layers. this includes "Internal Walls", "External Walls", "Roofs", and "Ceilings".\
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\- In case of "Floors", the value of 0.13 is added to the calculated U-value from the layers.\
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\- In other cases, the U-value is calculated normally.

* The "Surface Area" input is where the parametric model can be connected to the plugin, either by using the take-off script (in the example file) or other possible methods.

**OUTPUT:**

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

Additionally, the U-value output provides the thermal transmittance of the element.

the UA-value output provides the multiplication of the U-value with the element's surface area.