> For the complete documentation index, see [llms.txt](https://kb.bravegen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kb.bravegen.com/carbon/core-concepts/emission-factors/emission-factor-libraries.md).

# Emission Factor Libraries

### Activity Based Libraries

### Spend Based Libraries

#### BraveGen maintains copies of these spend based Emission Factor Libraries:

* EXIOBASE (Jan–Dec base year, updated annually)
* ThinkStep (Jan–Dec base year, updated annually)
* Footprint Lab (Dec–Jan base year, updated annually)
* Auckland Council (Apr–Mar base year; unlikely to add new factors)