Reference

ICOMOS 2022 HIA Guidance: Summary for UK Practitioners

Reviewed by

Oliver Wakefield-Smith

Founder, Digital Signet

Last reviewed 22 June 2026 · Refreshed quarterly

Direct answer

What does the ICOMOS 2022 guidance say?

The ICOMOS 2022 Guidance and Toolkit for Impact Assessments in a World Heritage Context is the current international methodology for HIAs on UNESCO World Heritage Sites. It supersedes the 2011 ICOMOS HIA guidance and the 2011 IUCN guidance for natural sites, introducing an integrated framework that applies to cultural, natural and mixed sites.

Six stages of the ICOMOS 2022 method

Screening, does the project require an HIA?
Scoping, what attributes of OUV are in scope?
Baseline, current condition of the attributes.
Impact identification and evaluation, direct, indirect, cumulative.
Mitigation, avoid, reduce, compensate, hierarchy.
Reporting and decision-making, including independent peer review for major projects.

Differences from the 2011 ICOMOS guidance

Integrated cultural-and-natural framework (one document for mixed sites).
Explicit climate-resilience considerations.
Strengthened expectation of independent peer review.
More granular OUV attribute-by-attribute assessment.
Greater emphasis on cumulative effects across multiple projects.

How it interacts with NPPF in the UK

For a UK WHS, both frameworks apply. The NPPF (paras 200, 207, 208) governs the domestic planning decision; the ICOMOS 2022 guidance governs the OUV-impact methodology that informs the heritage component of the application. In practice, UK WHS HIAs are structured to satisfy both, with explicit cross-referencing.