Watch the AT webinar, in partnership with Selectaglaze and Velux, exploring strategies for balancing architectural heritage with modern performance demands.

How can architects retrofit historic buildings to meet contemporary standards of sustainability, accessibility, and efficiency without compromising their character? What role do glazing solutions, urban design, and strategic interventions play in ensuring longevity and usability? And how can the built environment be adapted to meet ambitious net-zero targets while respecting its past? These questions and more were explored in this AT webinar, supported by Selectaglaze and Velux.

Speakers (from left to right): Daisy Narayanan, Richard Williams, James Manning, Colin Bignell, Julia Feix, and Jonathan Flint.

Chaired by Architecture Today’s Jason Sayer, the event included presentations by Julia Feix, founding Partner at Feix&Merlin Architects with Jonathan Flint, structural engineer at Heyne Tillett Steel; Colin Bignell, Sales Director at Selectaglaze; Daisy Narayanan, Public Realm Director at The Crown Estate; Richard Williams, Senior Architectural Development Manager at Velux; and James Manning, London Estate Strategy and Performance Lead at Grosvenor and Deputy Chair of the Building Better Partnership.

Feix&Merlin’s skilful reworking of Walworth Town Hall in south London, has breathed new life into a Grade-II listed landmark that was damaged by fire more than a decade ago (photo: Chris Wharton).

Julia Feix opened the session by detailing the restoration of London’s Walworth Town Hall, a Grade II listed building that suffered extensive fire damage in 2013. The winning competition scheme, led by Feix&Merlin Architects, carefully balanced heritage preservation with modern interventions, incorporating CLT and glulam timber to differentiate old from new.

The project provides a series of dedicated public spaces, including a community centre, public café and restaurant located within the central lobby (photo: Chris Wharton).

A key move was the repositioning of the main entrance to enhance accessibility, alongside the addition of two new lifts, increasing accessibility from 24 per cent to 60 per cent. Feix highlighted the decision to preserve visible traces of fire damage as a storytelling device, remarking, “We wanted to keep a visual record of the destruction that was caused by the fire, letting the building tell its own story.” The project’s success in blending conservation, sustainability, and usability ultimately led to its removal from the Heritage at Risk Register.

Selectaglaze can provide sustainable energy efficiency upgrades for outdated double glazing (photo: Kate Lindeman).

Colin Bignell followed with an overview of the benefits of secondary glazing in improving energy efficiency, comfort, and security in heritage buildings. “Secondary glazing is probably more relevant today than it’s ever been in its history,” he stated, highlighting its importance in contemporary retrofit strategies. He explained how modern secondary glazing – installed on the room-side of existing windows – enhances insulation, reduces drafts, and contributes to net-zero goals, while maintaining historical integrity.

Sympathetic secondary glazing from Selectaglaze was installed in The OWO Residences by Raffles, which forms part of the retrofitted Old War Office in London’s Whitehall (photo: James Attree).

Using the case study of the Old War Office in London, where more than 600 windows were fitted with secondary glazing, Bignell demonstrated its adaptability for large-scale conservation projects. He also emphasised secondary glazing’s reversibility, low maintenance, and compliance with conservation bodies, such as Historic England and the National Trust.

The Crown Estate and Westminster City Council have been working together to develop a long-term vision for the design of Regent Street’s public realm (photo: Jason Hawkes).

Daisy Narayanan spoke about the broader challenges of integrating sustainability, placemaking, and accessibility within London’s public spaces. She outlined initiatives across Regent Street, Haymarket, and Piccadilly Circus aimed at prioritising pedestrian movement, introducing urban greening, and enhancing heritage preservation. Acknowledging the complexity of making historic spaces more accessible, Narayanan highlighted the Crown Estate’s Inclusive Spaces and Places report, which advocates for lived-experience engagement, rigorous accessibility assessments, and exceeding regulatory requirements.

Launched by The Crown Estate and Westminster City Council, ‘The future of Regent Street, Haymarket and Piccadilly Circus public realm’ project seeks to create a more sustainable, inclusive and accessible West End, through greener and more welcoming public space.

She concluded with a call for collaboration, citing Jane Jacobs’ belief that “Cities have the capability of providing something for everybody only because, and only when, they’re created by everybody.”

VELUX Heritage conservation roof windows are designed to blend seamlessly into the building.

Richard Williams presented Velux’s development of a heritage roof window that blends traditional aesthetics with modern performance. After six years of consultation with architects, conservation officers, and planners, the company introduced a slim-profile, flush-fitting window that meets conservation requirements while significantly improving daylighting and ventilation.

The addition of a roof window has transformed this bathroom, which was previously a ‘box room’ with no natural light at all.

Williams noted the importance of preserving visual continuity, sharing homeowner Andrew’s testimonial: “Because they are so low profile, they just look like they’ve always been there.” A case study of an Edwardian home renovation in Tynemouth was also used to demonstrate how the product enhances both usability and historical authenticity.

Thermal image of a Victorian building on Elizabeth Street near Victoria Station in London, showing reduced heat loss following a retrofit scheme implemented by Grosvenor (image: Grey Hutton).

The final speaker, James Manning, outlined Grosvenor’s retrofit strategy, which is structured into three tiers: optimisation, light retrofit, and deep retrofit, with each catering to different levels of intervention. With a £90m fund dedicated to retrofitting historic buildings, Grosvenor has reduced emissions by 32 per cent since 2019 and aims for a 90 per cent reduction by 2040. Manning discussed challenges, including planning constraints, energy modelling inaccuracies, and the urgent need to address the skills gap, noting that 200,000 retrofit specialists will be required by 2050.

Grosvenor has undertaken significant retrofit works to reduce the carbon impact of 126-136 Buckingham Palace Road, which is located within a conversation area in London’s Belgravia (photo: Belinda Lawley).

He advocated for data-driven approaches and tenant-led retrofits to enhance efficiency, while maintaining heritage integrity. Summarising Grosvenor’s ethos, Manning remarked, “One size does not fit all – retrofitting historic buildings presents unique challenges, and we need to think holistically, considering each building’s unique characteristics, history, and constraints.”