Fundamentals
Grid mix
The combination of generation sources supplying an electricity system, which sets the emissions intensity of consumption.
Grid mix changes hourly as demand shifts and renewables fluctuate. Annual averages smooth this away, and using them can misstate the impact of a project that shifts load to specific hours.
Marginal rather than average intensity is the correct basis for asking what a new consumer or generator changes, since it is the plant that responds to the additional demand that determines the emission effect.
Frequently asked questions
Why do grid factors update?
Because the generation fleet changes, and stale factors misstate every calculation that uses them.
Which factor should a project use?
The programme's prescribed factor, applied consistently and disclosed.