This part of ISO 15663 specifies requirements for undertaking life-cycle costing for the development and operation of facilities for drilling, production and pipeline transportation within the petroleum and natural gas industries. The life-cycle costing methodology described in this part of ISO 15663 can be applied when making decisions on any option which has cost implications for more than one cost element or asset phase, in order to estimate the cost difference between competing options. The process is applicable to a wide range of options, particularly when decisions are being considered on the following: the process concept; equipment location, e.g template-based solutions vs. satellite-based solutions; project execution strategies; health, safety and environment; system concept and sizing; equipment type; equipment configuration; layout; maintenance and operation strategies; manning strategy; manning levels; logistic support strategy; facility modifications; spares and support strategy; reuse and/or disposal