Whole-life cost (WLC)
All significant and relevant initial and future costs and benefits of an asset across its life, including income, financing and externalities, which is a wider scope than life-cycle cost.
ISO 15686-5:2017 is the standard that settles this, and it defines two terms rather than one. A life-cycle cost is the cost of an asset or its parts throughout its life cycle while fulfilling the performance requirements. A whole-life cost is all significant and relevant initial and future costs and benefits of the asset across the same life. The second contains the first, and the word carrying the difference is benefits.
What sits in the gap is specific rather than vague. Life-cycle cost covers construction, maintenance, operation and end of life. Whole-life cost adds non-construction costs, income, environmental cost and externalities, where an externality is a quantifiable cost or benefit falling on people other than the parties to the transaction, and may include business staffing, productivity and user costs. The two also diverge at the front: the standard puts project costs incurred before design begins, such as feasibility studies, in whole-life cost and not in life-cycle cost. So a study can be excluded from one analysis and included in the other, on the same asset, correctly.
ISO 15686-5 defines the terms; it does not give a structure for reporting the numbers so that two assets can be compared. That is what the International Cost Management Standard does. ICMS 3 provides a classification and presentation structure for life cycle costs, and since its third edition for carbon alongside them, agreed by 49 professional bodies through the ICMS Coalition. It matters practically as well as technically: ISO 15686-5 is sold, and ICMS 3 and its Basis for Conclusions are both free, so an organisation without a standards budget can still adopt a defensible structure.
Neither figure means anything without its scope and its period. The standard leaves the period of analysis to be determined by the client and requires the scope of costs to be defined and agreed at the outset, which means there is no default and no such thing as the whole-life cost of an asset in the abstract. Two figures for the same building are comparable only if both state what was counted and over how many years, and whether the flows were discounted.
Sources
ISO 15686-5:2017, buildings and constructed assets, service life planning, part 5, life-cycle costing, second edition, July 2017, replacing the 2008 first edition. Clause 3.1.7 for life-cycle cost, 3.1.14 for whole-life cost, 3.1.15 note 1 for the external costs included in whole-life costing, 3.1.6 and 3.4.4 for external costs and externalities, 3.3.6 for the period of analysis being determined by the client, 4.1 for agreeing the scope of costs at the outset, 4.2.1 and Figure 2 for the boundary between the two and for feasibility costs sitting in whole-life cost.
Read the sources
- ISO 15686-5:2017, service life planning, life-cycle costing2017; read 2026-09-26.The link carries the abstract and publication details, not the requirement text.
- ICMS 3, International Cost Management Standard, life cycle costs and carbonthird edition, 2021; read 2026-08-29.Free. Agreed by 49 professional bodies through the ICMS Coalition, which RICS convenes.
- ICMS 3 Basis for ConclusionsDecember 2021; read 2026-08-29.Free. The coalition stating why the standard says what it says, which ISO does not publish.