The NPPF Just Made Heritage Significance Assessment a Formal Requirement

A barn in Suffolk, converted for use as a holiday let: new window and door openings, the interior subdivided, services run through it, the fabric altered room by room. Mid Suffolk District Council refused listed building consent. On appeal, a planning inspector agreed — the public benefit of the scheme was real but limited, and it did not outweigh the harm the works would do to a designated heritage asset. The barn is one of many. The reasoning is the one that comes up again and again in refused listed building consent cases: harm identified, but never properly weighed against what the works actually offer.

What Changed in the NPPF Published August 2026

For the first time, the NPPF makes assessing a heritage asset's significance a formal information requirement rather than something drawn only from guidance. Policy HE5 now requires an application to categorise the effect of proposed works on a heritage asset as one of four things: a positive effect, no effect, harm, or total loss — including whatever contribution the asset's setting makes to that significance. Policy HE4(2) goes further: the requirement to give clear and convincing justification for harm, previously reserved for designated heritage assets, now applies to non-designated ones too.

The Gap These Rules Are Closing

None of this is really new to conservation officers and heritage consultants — it is closer to a codification of what Historic England's own advice notes have said for years. What it changes is what an application has to show in writing. An applicant can no longer submit heritage input that gestures at significance without stating, plainly, which of the four categories the proposal falls into and why. That is precisely the gap in the Suffolk barn case: the works' effect on the building's fabric was real, but the application had not made the case for why the benefit justified it. Categorise, then justify — in that order — is now what the policy asks for on paper, not just in a conservation officer's head.

"A stronger policy requirement does not make a weak assessment stronger. It just makes the gap harder to miss."

Why Vision to Value Doesn't Need to Change for This

HeritageAI's Vision to Value process separates a Statement of Heritage Significance from the Heritage Impact Assessment that follows it, deliberately, because the significance assessment has to be independent and objective — it has to describe what a building is and why it matters before anyone weighs in on what should be done to it. An AI system is well suited to exactly that first read: it has no stake in the outcome the owner wants, so it has nothing to shade the assessment toward. What HE5 now asks every application to demonstrate on paper — a stated category of effect, reasoned against significance established beforehand — is the structure Vision to Value's Statement of Heritage Significance and Heritage Impact Assessment pillars were already built to produce. The policy caught up to the order the work should always have followed.

A stronger policy requirement does not make a weak assessment stronger. It just makes the gap harder to miss.