What is a Heritage Impact Assessment?
A Heritage Impact Assessment is a planning-submission document that identifies the significance of a heritage asset affected by a proposal, describes the proposed works, evaluates the resulting harm against NPPF ¶200 and NPPF ¶208, and sets out mitigation. It is the proportionate evidence base that allows the LPA to discharge its duty under LBCAA 1990 s.16 ors.66 (and s.72 in conservation areas) without requiring further information.
The four GPA 2 sections every HIA contains
Historic England Good Practice Advice 2 (Managing Significance in Decision-Taking, 2nd edition) is the structural template every UK heritage consultant works from. The four sections, in sequence, are:
- Understanding significance. Identify what makes the asset important , architectural, historic, archaeological, artistic , and describe its setting per GPA 3.
- Describing the proposal. What is changing, where, in what materials and with what reversibility.
- Evaluating impact. Where on the substantial / less-than- substantial spectrum the harm sits, with reasons.
- Mitigation and public benefit. What design changes, recording or enhancement offset the harm, and what public benefit (perNPPF ¶208) is offered.
When HIA became a validation requirement
Heritage Statements have been an implicit validation requirement for listed- building consent since the 2010 NPPF first articulated the significance test. The SI 2023/1024 amendment to the Listed Buildings Regulations made the requirement explicit: every LBC application must include a description of the significance of the parts affected, proportionate to the asset's importance. Validation officers now return applications lacking any heritage submission rather than logging a request for further information.
Who is qualified to write one
There is no single statutory qualification. In practice LPAs expect the author to be one of:
- RIBA Conservation-Accredited Architect (SCA or CA grades)
- IHBC full member
- CIfA Member or Affiliate (for archaeology-leaning HIA)
- RICS Building Conservation Accredited surveyor
For Grade I and Grade II* cases, named accreditation is effectively required; submissions by uncredentialled authors are routinely returned for further information, costing two to six weeks of planning-clock time.
How an HIA differs from a Heritage Statement
A Statement of Heritage Significance (per HEAN 12) is the shorter, proportionate document for Grade II minor and conservation-area works. It still follows the GPA 2 structure but at lower depth, typically two to six pages. A Heritage Impact Assessment is the fuller document, ten to forty pages, used for higher-grade or higher-impact cases.