Using a supplier-specific emissions factor is the best practice for scope 2 according to the GHG Protocol. The supplier-specific emissions factor is one that is reported by your utility as an emissions factor (e.g., kg CO2/kwh), and it should ideally be published publicly. This factor can be entered as a custom supplier-specific emissions factor on the utility emissions factors page. Note: The supplier-specific emissions factor is only used (and can only be edited) when you have selected the market-based method for scope 2.
Note: This is different from a custom fuel mix, which is calculated as a weighted average in SIMAP based on your fuel mix and is not a recommended best practice.
GHG Protcool Scope 2 Guidance for requesting a supplier-specific emission factor from your local utility
Here is the guidance on the types of questions that should be asked when a user contacts their local utility to request a supplier-specific emissions factor for the market-based scope 2approach. This text comres from section 6.11.3 (page 55) of the scope 2 guidance report:
" When using a supplier-specific emission factor, companies should seek to ensure that:
- The emission rate is disclosed, preferably publicly, according to best available information, and where possible using best practice methods such as The Climate Registry Electric Power Sector Protocol. Methods for calculating and disclosing the mix and related attributes may also be specified by regulation.
- That the utility or supplier discloses whether and how certificates are used in the emission factor calculation, unless there is third-party certification of the utility product. In particular, companies should seek to ensure that if the supplier has a differentiated product (e.g. a renewable energy product or tariff), the certificates or other contracts used for that product should be used only for that product and not counted in the standard product offer.
- That the supplier-specific emission factor includes emissions from all the energy delivered by the utility, not just the generation assets owned by the supplier (e.g. what is required by some fuel mix disclosure rules). Many suppliers purchase significant portions of their energy from other generators via contracts, or through the spot market. The emission factor should reflect the emissions from all of these purchases. A supplier-specific emission rate can also reflect certificates retired for compliance purposes (such as U.S. state RPS programs) which also convey attributes for public benefit and claims."