You can perform sustainability analysis with a custom material by linking your custom material to a material with similar characteristics in 
the default SOLIDWORKS Materials database. The analysis is then performed using the Sustainability characteristics of the SOLIDWORKS material.
    
     If  a SOLIDWORKS material does not have Sustainability defined, you can copy the material to the Custom Materials folder to link it to a material in the SOLIDWORKS Materials database.
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In the FeatureManager design tree, right-click Material 
 and click Edit Material. and click Edit Material.
- In the Material dialog box, in the left panel, select the custom material.
- On the Properties tab, beside  Sustainability, click Select.
- In the Match Sustainability Information dialog box, select the material that is most similar to your custom material. Only materials with a link to the Sustainability database are listed. 
- Click OK.The linked material appears in Sustainability. 
- Click Apply, then Close.