In a quaint café nestled within the heart of an ancient village, I found myself eagerly awaiting a conversation with Eleanor White, a renowned heritage consultant. With Historic England recently unveiling their guidance on low-carbon interventions for heritage buildings, I was keen to understand the acceptable methods for upgrading these historic treasures. My anticipation grew as I prepared to delve into the nuances of insulation, double glazing, and energy supply systems in the context of heritage conservation.
Successful low-energy building design hinges on careful planning. Focus360 Energy can help.
Eleanor, with her extensive experience and fervent passion for preserving historical edifices while embracing contemporary advancements, was the ideal individual to provide insights on this topic. Her expertise promised a harmonious blend of technical knowledge and a heartfelt appreciation for heritage structures.
“Thank you for meeting with me, Eleanor,” I began as we settled into our seats. “Historic England’s new guidance has certainly stirred a lot of interest. Could you walk me through the key points?”
“Of course, Tobiasz,” she responded warmly. “The guidance, formally titled ‘Adapting Historic Buildings for Energy and Carbon Efficiency: Historic England Advice Note 18’, offers a comprehensive overview of interventions likely to receive approval through the planning process. It targets local planning authorities, heritage consultants like myself, and anyone involved in planning for listed or unlisted buildings, excluding places of worship.”
Eleanor elaborated that the guidance primarily focuses on energy efficiency and solar energy generation, but each case must be individually evaluated, ideally with specialist advice. Turning her attention to windows, she explained, “Draught-proofing is almost always acceptable and can be achieved with minimal impact on a building’s special interest. However, exceptions exist, such as windows of exceptional delicacy, where draught-proofing might be detrimental.”
“And what about double glazing?” I inquired.
“Secondary glazing or slim-profile/vacuum double-glazing within historic frames is generally acceptable,” Eleanor replied. “The key is to retain original glazing bars and refurbish the windows simultaneously to maximise the benefits. Sash windows may require heavier weights to balance the increased glass weight. Additionally, double-glazed windows of appropriate material and pattern can replace those that don’t contribute to the architectural or historic interest of a building.”
As our discussion progressed, Eleanor delved into the critical aspect of insulation in heritage buildings. “Loft insulation is usually acceptable and unlikely to affect the building’s special interest,” she noted. “However, spraying adhesive foam insulation to the underside of the roof covering is strongly discouraged. It can damage the building’s fabric and is difficult to remove.”
“And insulation within the roof plane?” I queried further.
“That’s acceptable in some cases,” Eleanor responded, “often above, between, or below the rafters. However, it is not suitable if it necessitates the loss of historic plasterwork or obscures significant elements of the roof structure. Listed building consent is typically required for such interventions.”
Eleanor’s passion for her work was evident as she discussed floor insulation. “Insulation between or under floors is generally acceptable with specific considerations. For instance, insulation within the floor void shouldn’t alter floor levels or damage any historic floor surfaces. Underfloor insulation should be avoided if it impacts significant underfloor layers or finishes. Insulating under solid floors might not be suitable where historic floor surfaces or archaeological remains exist just below the current floor, or where shallow foundations could be compromised.”
We then turned our attention to wall insulation, a more nuanced and complex subject. “Internal wall insulation is only acceptable in some cases,” Eleanor explained. “It generally disrupts the character of historic interiors, including finishes like plaster, joinery, cornices, and chimneypieces. However, previously unplastered internal walls could be lined with insulation as part of a conversion, provided listed building consent is obtained.”
“And external wall insulation?” I asked.
“That’s even trickier,” she admitted. “The external appearance of listed buildings is a key concern, so external wall insulation is unlikely to be acceptable due to its potential harmful impact. However, insulation within external walls can be acceptable in certain scenarios, such as where the historic infill has been replaced with modern materials. It may be appropriate to renew the infill with insulation. Similarly, insulation could be inserted between the outer cladding and internal plaster of weather-boarded houses, provided an air gap is maintained to mitigate moisture risk.”
Eleanor also emphasised the importance of reinstating historic render finishes where there is clear evidence that a building was originally intended to be rendered. This can enhance thermal performance and is almost always desirable. “Cavity walls in post-Second World War buildings,” she added, “present an excellent opportunity for invisible, cost-effective, and quick-to-install insulation, without reducing room sizes.”
As our conversation drew to a close, I couldn’t help but feel a profound appreciation for the delicate balance between preserving the past and embracing the future. Eleanor’s insights illuminated the careful considerations and expert knowledge required to navigate the complexities of upgrading heritage buildings in a low-carbon world. Historic England’s guidance, as expertly unpacked by Eleanor White, serves as an invaluable resource for those dedicated to preserving our past while forging a sustainable future. Leaving the café, I felt a renewed respect for the intricate dance between heritage conservation and modern sustainability.
Be the first to comment