CO2 measurement based in Government documents is a process to be followed if you prefer to get any type of Government recognition and be able to use all recognitions and benefits defined.
The best way to estimate your CO2 emissions is starting to be familiar with calculators and Calculators guide issued by your local government
See some examples
Spain: Page of Ecological transition Minister
Spain / Catalonia Government:
In both cases you will find as in other countries 2 documents
- Excel to create your GHG inventory
- Guide to use excel file and tables to support emission factors in your country.