For the life cycle assessment of an economic good, all the related energy inputs have to be considered for the entire life cycle. A tool for this is the cumulative energy demand (CED) according to VDI guideline 4600:
The cumulative energy demand states the entire demand, valued as primary energy, which arises in connection with the production, use and disposal of an economic good.
This includes on the one hand the energy demand for the production, use and disposal, and but on the other hand also all upstream chains of the different production stages.
Examples for the method of life cycle assessment:
CO2-balance of renewable energies
Energetic comparison of electric and conventional vehicles
Assessment of power-heat cogeneration regarding primary energy
Life cycle assessment of processes and products