A gate to gate system boundary in Life Cycle Assessment defines the scope of analysis to include only the processes and activities occurring within a specific production facility or site. The assessment begins where materials and energy enter the facility (the input "gate") and ends where products, by-products, or materials for treatment leave the facility (the output "gate").
This approach focuses exclusively on the internal operations of a single production unit, excluding upstream activities such as raw material extraction and transportation to the facility, as well as downstream activities including distribution, use, and end-of-life treatment. Gate to gate assessments are particularly useful for process optimisation, facility-specific environmental performance evaluation, and comparing alternative production technologies or configurations within a single site.
The gate to gate boundary represents one of several system boundary options defined in the context of ISO 14040 and ISO 14044 standards. Other common boundary definitions include cradle to gate (from raw material extraction to the facility output), cradle to grave (complete life cycle from extraction through disposal), and gate to grave (from facility output through end-of-life). The choice of system boundary should align with the goal and scope definition of the Life Cycle Assessment study and must be clearly stated and justified.
When conducting gate to gate assessments, practitioners must carefully account for all exchanges crossing the system boundary, including material inputs, energy consumption, emissions to air and water, and waste outputs. This boundary definition is often employed in Environmental Product Declarations for intermediate products or in industrial ecology studies focusing on manufacturing efficiency improvements.
