26 Jul 2019
Much of the focus of the revised Planning Practice Guidance (PPG) has been on green belt, housing and the effective use of land yet there has also been a raft of updates which have implications for the historic environment.
Non-Designated Heritage Assets
PPG previously recognised that there was no requirement for LPAs to prepare a list of non-designated heritage assets, though encouraged them to do so. The revised wording is much stronger. Plan-making bodies, it says:
“should make clear and up to date information on non-designated heritage assets accessible to the public to provide greater clarity and certainty for developers and decision-makers. This includes information on the criteria used to select non-designated heritage assets and information about the location of existing assets”.
LPAs can still also identify non-designated heritage assets through the decision-making process, though rather being encouraged (as it was previously), this should now only be done “in some cases”. The focus instead is now on LPA’s identifying their non-designated heritage assets in advance, rather than at application stage.
PPG also now confirms that “only a minority [of buildings] have enough heritage significance to merit identification as non-designated heritage assets”. This is much stronger than the wording in the previous version and indicates a shift away from non-designated heritage assets sweeping up everything that is old and traditional to a much more selective category.
Realistically it will not be possible for LPAs to capture all non-designated heritage assets within a list. There will always be buildings or structures which, on detailed consideration, appear to be more significant than previously thought. LPA resources are also stretched and lists of assets will require both time and resource. That said, a list of non-designated heritage assets within each authority would help land owners, developers and decision-makers to identify at an early stage whether there are heritage assets which need to be considered as proposals for development and change progress.
Optimum Viable Use
The National Planning Policy Framework (NPPF) says that harm to a heritage asset which is categorised as “less than substantial” should be weighed against the public benefits of the proposal, including securing its optimum viable use.
Demonstrating that a proposal represents the optimum viable use of a heritage asset is tricky, but the Government has provided some clarification on the issue through its amendments to PPG.
The revised version clarifies that, where there are a range of alternatives uses, the optimum viable use is the use which is both “economically viable” and likely to cause the least harm to the significance of the asset.
We now have clarity though that this option must stack up financially and not simply be an option which is physically capable of being achieved, which is useful. That said, while the wording has shifted, it still confirms that the optimum viable use may not be the use that brings the greatest financial return.
The evidence required to demonstrate that a heritage asset has no viable use has also been updated, though PPG still doesn’t explain how this should then be dealt with in the planning balance. There is no longer a need to demonstrate that the heritage asset is redundant, it no longer needs to be marketed to “all” potential buyers and the prospective purchaser must also now be willing to find a “viable” use for the site, rather than simply finding a new use.
Inspectors are often concerned that insufficient evidence has been provided that the use proposed is in fact the optimum viable use. Often, they feel that alternative uses exist which would represent the optimum viable use of the building but have not been identified or considered by the applicant. Unfortunately, there is still no clarification on how to demonstrate that alternative uses have been considered.
Decision-makers have grappled with the concepts of “substantial harm” and “less than substantial harm” since they were first introduced.
Lichfields draws on a methodology for environmental impact assessment to quantify the effect of proposals on the significance of heritage assets. Consideration is given to the nature (e.g. adverse) and degree (e.g. minor) of the effect. Once this has been established, the harm is then given a category (e.g. less than substantial harm).
Where this intermediate step to quantify harm is not undertaken in the decision-making process, and harm is simply categorised as ‘substantial’ or ‘less than substantial’, it is difficult for a decision-maker to weigh this in the planning balance or carry out their statutory duty. How can a decision-maker know if the benefits outweigh the harm if they don’t know whether that the effect is so slight that its almost neutral or so harmful that its almost substantial?
Much-needed clarification on this has now been provided by government. The revised PPG is clear that ‘less than substantial harm’ and ‘substantial harm’ are simply categories of harm. It confirms that it is no longer enough to simply identify the category of harm; further articulation about where the proposal sits within that category will now also be required.
Some other notable changes
Where relevant, applicants must now explain how understanding significance and setting has informed the development of the proposals
Reflecting and enhancing local character and distinctiveness (with regard given to the prevailing styles of design and use of materials in a local area) is now identified as a means of conserving/enhancing heritage assets
Works to a private dwelling which secure its future are recognised as a public benefit
Detailed definitions of archaeological, architectural, artistic and historic interest are provided, drawing on those set out in the draft Conservation Principles document published for consultation by Historic England in 2017, though this has not yet been re-issued following consultation and could be subject to change.
The section on the setting of heritage assets has been updated to reflect case law which has emerged over the last few years
Sir Owen Williams was one of 20th-Century Britain’s most influential engineering architects who left behind a rich legacy of innovative modernist buildings. On the 50th anniversary of his death in May 1969, we celebrate two of the iconic buildings he designed and which we have been privileged to advise on, helping to secure their future.
1912: Enterprise House, Hillingdon (Grade II listed)
Enterprise House is an early and innovative example of a reinforced concrete framed industrial building. Built for the Gramophone Company at its Hayes headquarters in 1912, the building was designed by Owen Williams in conjunction with Arthur Blomfield and A. Henderson, who – unusually, for this date – used the Kahn system of reinforcement and expressed the structure of the building externally. It is the earliest known work of Owen Williams, and it joined a growing collection of Gramophone Company buildings at the beginning and middle of the 20th Century designed to meet the needs of the records factory. Enterprise House is thought to be the first complete building by Truscon (the “Trussed Concrete Steel Company”).
The Kahn system utilised ribbed reinforcement, a Kahn bar, with a square section featuring two projecting strips on opposite corners, bent upwards at angles to provide additional reinforcement to counteract shear stresses. This was a revolutionary new system used initially in the United States for factory buildings built around “daylight factory” principles to provide large expanses of natural light for factory workers. Enterprise House utilised the Kahn system in a very successful way, with form following function: the structure was externally expressed in a striking design aesthetic, not concealed behind brick or render. The result was a building which is highly evocative of the early 20th Century.
The experimental nature of the construction materials and methods meant that, by the beginning of the 21st Century, rusting reinforcement and serious concrete deterioration required urgent and radical steps to conserve the building. Together with the then owners and an experienced team of architects and engineers including FSP Architects & Engineers, Furness Partnership and Furness Green Partnership, we worked to develop proposals for the complete refurbishment of the Grade II-listed building for mixed uses, including a factory producing vinyl records, a business centre, a café and residential units. Enterprise House is listed as a ‘Priority D’ structure on Historic England’s 2018 Heritage At Risk Register, recognising that a solution has been agreed but not yet implemented. It is hoped that once implemented the works will allow it to be removed from the Heritage At Risk register.
Enterprise House is situated opposite The Old Vinyl Factory (formerly known as the EMI/HMV site), which is being redeveloped as part of a project to reinvigorate the former industrial area. As Planning Project Manager for The Old Vinyl Factory development site, we devised a planning strategy for the site. We successfully secured outline permission for a mixed-used redevelopment scheme including restoration of former factory buildings and conversion to accommodate over 600 residential units with additional workspace, helping to preserve and enhance the setting of Owen Williams’s earliest structure. In 2013 the masterplan and mixed-use redevelopment scheme for The Old Vinyl Factory was granted outline planning permission. The majority of the masterplan has now been approved in detail and some of the buildings have been completed and are now occupied, resulting in the Hayes Botwell: Thorn EMI Conservation Area being removed from Historic England’s Heritage at Risk register.
Figure 1: Enterprise House is the earliest known work of Owen Williams; it is hoped that once implemented, the works will allow the building to be removed from the Heritage At Risk Register.
Figure 2: The Record Store by Wallis Gilbert and Partners (1927) forms part of the Botwell: Thorn EMI Conservation Area in which Owen Williams’ Enterprise House is situated. The conservation area has successfully been removed from the Heritage At Risk Register.
1951-55: British Overseas Airway Corporation Technical Block A (Grade II listed)
Technical Block A (TBA) is a Grade II-listed hangar at Heathrow Airport, designed by Owen Williams and built between 1951 and 1955. TBA involved an innovative application of concrete engineering to aircraft hangar design: four hangars were centred on a triple-height engineering hall with offices for the former British Overseas Airway Company. The central spine features a stunning series of long-span reinforced concrete arches which provide an unusually wide and long—867 feet—space, formerly used for engineering workshops. The colossal structure was designed to house the entire corporation under a single roof, providing both cellular office accommodation and large, well-lit spaces in one building – a serious engineering challenge for its day.
Originally designed for a 30-year lifespan, the building still continues to be an integral part of British Airways’ operations, though changes to the building have been necessary as the design and maintenance requirements for aircraft has changed during the 20th and 21st We carried out extensive historical research into the original design, which confirmed Owen Williams’s vision for a flexible building capable of evolving to meet the needs of the aviation industry. As part of the building’s evolution, we secured planning permission and listed building consent for the British Airways Global Learning Academy, incorporating flight simulators in the central engineering hall to train British Airways pilots. The result has been the reuse of a partially disused building, transforming it into a valued training centre as well as an operational aircraft maintenance depot, and ensuring the continued use of Owen William’s innovative aircraft hangar structure.
Extensive discussion took place with Historic England and Hillingdon Borough Council to agree the acceptability of the works to the listed building. These included removal of a later 1960s set of offices which although not of special interest themselves, did illustrate the evolving functioning of the building in line with Owen William’s vision of creating a flexible space. The sixteen flight simulators together with their operational requirements such as operating offices, electrical requirements and maintenance rooms also had to be carefully incorporated within the building. The aim was to insert the pods along the length of the triple-height central engineering hall while still retaining views of the impressive concrete frame that spans the hangar.
Lichfields’ heritage team, who are dual qualified members of the Royal Town Planning Institute and Institute of Historic Building Conservation, can provide assistance on listed buildings of all ages to assist with securing a sustainable future for an asset. Please contact the Heritage team on 0207 8374477.