ISO 15686-5:2017

Overview

ISO 15686-5:2017 - Buildings and constructed assets - Service life planning - Part 5: Life‑cycle costing (LCC) provides requirements and guidance for performing life‑cycle cost analyses of buildings, constructed assets and their parts (new or existing). It defines what costs to include, how to set the period of analysis, and how to compare alternatives or estimate future costs at project, portfolio or component level. The standard supports transparent, consistent LCC practice by defining terminology, methodology and reporting expectations.

Key topics and technical requirements

• Scope and purpose: Clarifies whether LCC covers part of or the entire asset life cycle and establishes the agreed period of analysis.
• Cost variables: Identification and classification of costs to include, e.g. acquisition, operation, maintenance, replacement and disposal costs, residual valuations, taxes, subsidies and energy/utilities.
• Analysis methods: Use of real vs. nominal costs, discounting to present values, and measures such as Net Present Value (NPV) / Net Present Cost (NPC).
• Decision support: Guidance for LCC at different decision levels - strategic, system/design and service‑life planning - and for comparing alternatives.
• Uncertainty and risk: Procedures for identifying uncertainties, sensitivity analysis, and probabilistic approaches (e.g. Monte Carlo) to improve confidence in forecasts.
• Externalities and intangibles: Consideration of environmental impacts, social costs/benefits and future income streams where relevant.
• Data and reporting: Requirements for data quality at different project stages, reporting format, approvals, audit trails and worked examples (informative annexes).

Applications and who uses it

ISO 15686-5:2017 is used to inform cost‑based decision making across the building lifecycle. Typical users include:

• Asset owners and investors - to assess lifecycle affordability and return on investment.
• Design teams and architects - to compare design alternatives by whole‑life cost implications.
• Quantity surveyors and cost consultants - to structure LCC inputs and present robust NPV/NPC comparisons.
• Facility and maintenance managers - to plan maintenance, replacements and budgeting.
• Procurement and policy teams - to set evaluation criteria for tenders or sustainability targets.
  Practical uses include selecting materials/systems, budgeting for major repairs, portfolio-level forecasting, and linking service‑life planning to sustainability and performance targets.

Related standards

• Part of the ISO 15686 series on service life planning - complement with other parts of ISO 15686 for detailed definitions and techniques.
• Aligns with broader financial and sustainability assessment practices (e.g. whole‑life costing / WLC concepts) and ISO guidance on reporting and data handling.

Keywords: ISO 15686-5:2017, life‑cycle costing, LCC, buildings, constructed assets, service life planning, whole‑life costing, life‑cycle cost analysis, NPV, discount rate, sensitivity analysis.