Agenda item

To be presented by Joanna Horton and Eliza Alqassar.

Joanna Horton (Heritage & Archaeology Team Leader) and Eliza Alqassar (Historic & Built Environment Manager) gave a presentation to the forum detailing the efforts that have been undertaken to ensure that listed buildings were adapted to cope with new energy efficiency measures and flood defences, and how archaeological sites were being impacted by tree planting projects and solar farm installations. The slides would be appended to the minutes of the meeting. The following key points were raised in their presentation:

Solar Farms

The traditional installation methods for solar farms (involving grounding panels by driving poles into the ground, and running underground cables to carry electricity) created various opportunities to disrupt and damage sites of potential archaeological interest. The Heritage and Archaeology team recommended t geophysical surveys at solar farm sites, followed by targeted trenching to identify the location of buried archaeological remains.

This had been undertaken at the Fox Covert Solar Farm near Adstock and Great Horwood, following the granting of planning permission in June 2021, where a geophysical survey and subsequent trenching found Iron Age roundhouses on site. The identified area was then removed from the solar farm scheme in order to preserve it.

Alternative solar farm installation methods mitigate the risk of damage to archaeological sites. These include grounding solar panels with concrete slabs and weights as opposed to driving poles into the ground and suspending the electric cables underneath the panels as opposed to running them underground.

Tree Planting

Buckinghamshire Council had committed to planting 543,000 trees by 2025. Much of this planting would take place in rural areas where the archaeological potential was less well known, including on some sites featuring medieval ridge and furrow.

One such site included an area designated for planting as part of the Wing Woods project, where archaeological features were identified. Those areas were removed from the tree planting scheme, with a ten-metre planting buffer zone around the archaeological remains in a manner that was suitable for both the planting project team and the heritage team. The remains would be left preserved in situ.

Built Heritage

The presentation also highlighted examples of listed buildings which had undergone retrofitting to ensure their resilience in the face of new natural threats related to climate change, such as flooding. This included The Queens Head in Chesham, which had had flood defences installed, as well as air source heat pumps.

The presentation also demonstrated how solar panels had been installed on a hidden area of the roof of a listed building in Brill, which allowed for easy maintenance without risk of damage to the building’s original fabric, thus protecting the fabric and character of the building. It was suggested that crown roofs were best suited to this.

It was explained that high profile cases of this retrofitting, often on well-known historic and listed buildings, acted as the catalyst for the wider effort elsewhere, as the public became aware of it. One such example being the installation of solar panels across the roof of Kings College Chapel in Cambridge.

Embodied and Operational Carbon

Much of the media coverage of newer development had focused on operational carbon emissions, produced over the lifetime of an older building as compared with a newer building. It was the view of the heritage team that a more holistic approach, which also assessed embodied carbon produced prior to and during the construction of newer buildings would offer a means by which existing buildings could contribute towards the effort to reduce carbon emissions through retrofitting as opposed to demolition and reconstruction.

The Energy Performance Certificate (EPC) calculations used to assess the energy efficiency of buildings assumed that a building was constructed with a cavity wall, and was therefore disproportionally inaccurate for many historic buildings, which did not have them, but when considering other factors would perform as well as those which did. The use of Lime in particular was identified as a reliable, and sustainable material to use on walls where existing plaster was crumbling.

When looking to retrofit or renovate older buildings, the advice was to avoid shying away from the ‘quick wins’ such as basic maintenance and repair work that would  compromise the physical appearance and character of the building. More involved improvements and upgrades included overhauling windows, replacing falling cement with lime render, and boiler upgrades.

Following questions, Joanna confirmed that historically, the Heritage team had not normally been asked to comment on sustainability factors relating to planning applications. Including them as a consultee, as well as the climate change team in future cases would facilitate the joined-up thinking required to preserve heritage sustainability moving forward.

Simon Peart (Conservation and Archaeology Team, Milton Keynes City Council) confirmed that embodied carbon policies would be included in the New City Plan.

Members thanked Joanna and Eliza for their presentation.