> For the complete documentation index, see [llms.txt](https://docs.cscale.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs.

# Set Basis of Design Scenario

Set a scenario as the Basis of Design for each project phase in C.Scale. It becomes the reference for portfolio comparisons and AIA DDx carbon reports.

After [comparing scenarios](https://docs.cscale.io/users-guide/compare-scenarios.md), you can choose the one that best suits your desired emissions scenario and set it as your "Basis of Design".

Set a scenario as your Basis of Design by clicking the **3-dot menu** to the right of the scenario name in the left-hand panel.

![3-dot menu to the right of the scenario name.](https://docs.cscale.io/images/cscale-ui-scenario-row-menu-button.png)

Within the menu, click **Set as Basis of Design**. Each project phase has its own Basis of Design.

![Set Basis of Design scenario.](https://docs.cscale.io/images/cscale-ui-scenario-menu-set-as-target.png)

The **Basis of Design** scenario also becomes your reference scenario when [comparing different projects within your portfolio](https://docs.cscale.io/users-guide/benefits-of-an-organization-account/create-a-portfolio.md) and for [AIA DDx Reporting](https://docs.cscale.io/users-guide/benefits-of-an-organization-account/aia-ddx-reporting.md).