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. The basic methodology of this part of ISO 15663 is applicable to all asset decisions, but the extent of planning and management of the process depends on the magnitude of the costs involved and the potential value that can be created. The methodology is of value when decisions are taken relating to new investments in projects. It also provides the means of identifying key cost drivers and provides a cost-control framework for these drivers, allowing effective cost control and optimization over the entire life of an asset. The scope of this part of ISO 15663 is limited to life-cycle costing. It is not concerned with determining the life-cycle cost of an item of equipment, since then it would be necessary to determine all costs associated with that equipment during the life of the asset.