Listed buildings and historic land are given high regard in many types of planning Consents. As a part of the nation’s history, they are and should always be treated with respect. This respect extends to intended changes to the property/land. In just England alone, there are over 300,000 listed buildings recorded as of 2024, making them the largest category of heritage assets.
That said, such protected buildings require upkeep and, over time, may need significant alterations to remain functional. However, due to their status, any planned changes are analysed in much greater detail than for more modern buildings.
These are guided by a Heritage Impact Assessment (HIA) throughout their development and conclusion. But what exactly is a HIA, and what circumstances require them? We explain all here.
What Is a Heritage Impact Assessment?
A Heritage Impact Assessment is a document used to determine how a planned development or alteration will affect protected buildings or other types of heritage assets.
In an assessment, applicants should provide a detailed description of their intended plans, including any potential negative impacts. In England, the National Planning Policy Framework (NPPF) must be followed. This states that the level of detail included should be proportionate to the asset’s significance, meaning that the more significant a building or piece of land is, the greater the scrutiny it receives.
However, impact is just one part of the assessment – HIAs must also include sufficient detail on the building’s context, including its cultural and national significance, which is derived from a significance analysis.
Why Are Heritage Impact Assessments Needed?
Whilst the development of HIA’s is a most sensible element in determining appropriate changes, the laws in Wales make them a specific requirement, but less so in other UK nations. However, in England, they can be used to comply with the rules set out in the NPPF, which require applicants to “describe the significance of any heritage assets affected, including any contribution made by their setting”.
Often, a series of Impact assessments is combined into a single document. However, they are sometimes bundled together with other required documents, such as a heritage statement. Regardless, many pieces of historical land or heritage buildings will need an appropriate assessment before work can be carried out.
How Are Heritage Impact Assessments Made?
According to the NPPF, applicants should, as a minimum, consult the “relevant historic environment record”. However, there are additional details to include, such as:
- Significance report: Details around what makes the site relevant from a heritage perspective.
- Related documentation: Any documentation that would signify the target building or piece of land as a heritage site.
- Images of the site: Recent, high-quality images of the building/land. These can also be mixed with older images to demonstrate how the structure has changed (if any are available).
- Geographical information: Combined with land registry details, maps help outline the surrounding area and the property/land’s boundaries.
- Impact assessment: Used to describe how planned work will affect the site and its surrounding area.
- Remediation measures: Planned methods of mitigating any negative impacts.
HIAs are essentially composed of two elements. The first is a neutral, unbiased account of the asset. Applicants should use this to recognise why a building is recognised as a heritage asset and provide relevant supplementary information.
The second is when your intentions can start to come into play. Here, applicants will describe their plans, why they consider them necessary with relevant evidence, their anticipated impact, and how they aim to navigate any adverse effects. It is also necessary to detail alternative proposals considered that might achieve the overall objectives, and detail why they were rejected in favour of the proposal.
Dealing With Damp in Heritage Buildings
The Environment Study Centre offers a variety of engaging courses to help you with issues such as damp and condensation in buildings, including those of heritage significance.
Book a course today to learn key principles in retrofitting, damp investigation, and even project management. Within these courses, the Environment Study Centre go beyond the NPPF and includes working to robust British Standards such as BS 7913.
When Is a Heritage Impact Assessment Required?
As with many planning-type applications, no two heritage impact assessments are the same. This means that every assessment is handled individually, and that different circumstances can affect one building but not the other.
Any changes proposed to a building with special protection that require consent should be developed through HIAs. These are some examples:
Change of Use
If you plan on changing the use, involving altering the heritage building, it makes perfect sense to develop HIA’s to outline the extent of your changes and what you plan to do to negate any negative impacts. This could include converting a Grade II-listed building into an HMO, for example, which might require several changes to the building and its surroundings.
Adding An Extension
Extending an existing building can not only affect its structure but also the aesthetics of its surroundings. As such, HIAs should be developed.
Developing Close To Heritage Sites
While it is possible to develop near an old or listed building, doing so should require HIAs due to potential disruption to the building’s setting.
Can You Make Your Own Heritage Impact Assessment?
The National Planning Policy Framework mentions that heritage assessments should consult “appropriate expertise where necessary”.
This technically means that not all applications will require third-party insight. However, to increase their validity and for credibility’s sake, it’s often recommended to consult an expert when producing one or to have an expert handle the entire assessment for you.
Heritage Impact Assessment Training
As the above describes, there will be many occasions when HIAs will be necessary. Therefore, in many of the Environment Study Centre courses, either reference to them is made, or they are described in detail. For example, within the Level 3 Award in Energy Efficiency for Older and Traditional Buildings – 2 Day Retrofit Course, these are described in detail, with further information available within the ESC HUB on retrofitting traditional buildings.
Book this course today to be taught by Professor John Edwards – an expert with decades of experience.
