In his recent article for Building.co.uk, When is demolition better than retention? Thomas Lane reports on the carbon impact of the retrofit of the façade of 1-4 Marble Arch. Its poor condition left the project team wondering whether it would, in fact, have been less carbon-intensive to knock it down and start again.
"To demolish or not demolish? That is the question currently exercising many within the construction industry. And this is a dilemma perhaps best exemplified by the row over Marks & Spencer's flagship store on Oxford Street.
Should this disparate collection of buildings be refurbished rather than demolished in order to save carbon? A public inquiry considering this question – the first to do so – closed last month with a decision on the store's fate expected imminently. Part of the argument hinges on the fact that the loss of the landmark, art deco building could potentially harm the historic character of Oxford Street."
Introba Associate and Building the Future Commissioner Clara Bagenal George was invited to weigh in on this question, with her featured perspective as a thought leader in whole life carbon analysis:
"There is a lot of debate around retrofit versus demolish, and many factors need to be considered, including cultural and historical significance, design quality, and of course, cost. But for me, it all boils down to energy and carbon—retrofit should be the starting point for projects as it is likely to be the most sustainable option.
What we then need more of is accurate, consistent methodologies and data to understand the whole-life carbon impact of a development. This will help guide conversations and allow us to deliver evidence-based decisions early on in the design.
Better collaboration across the industry is important to getting the right information and tools in place to prove what is the most carbon-effective option. Low Energy Transformation Initiative (LETI), working with CIBSE, has created a methodology for measuring the embodied carbon impact of MEP products, which can make up a substantial part of a refurbishment or retrofit project's embodied carbon. We have got to share this knowledge across the sector.
It is vital that assessments take a whole-life carbon approach, so considering both embodied and operational carbon for retrofit and rebuild options; otherwise, you are only getting half the picture. Something I think we also need to increasingly ask ourselves is whether a building design allows for flexibility and different uses later down the line.
People's behaviors and what we want from our built environment are changing all the time, so what works for today's market won't necessarily be right in 20 or 30 years. Regulation on things like energy efficiency is evolving too. There is a risk that, in a decade or two, a building will have to be retrofitted again or demolished without that long-term perspective, negating any carbon savings that might have been made during a previous refurbishment.
It is about engineers and architects giving advice based on technically robust analysis so that we can be confident that we are making the best choice from a sustainability perspective over a building's lifetime.
Clara Bagenal George is an associate at Introba and won the Mayor of London’s Design Advocates for Good Growth.
Coming from an interdisciplinary background, she works seamlessly between environmental analysis, mechanical engineering, and sustainability fields.
Clara initiated the London Energy Transformation Initiative (LETI), which has engaged over 250 industry professionals to put together collaborative cross-sector policy recommendations for a zero-emissions London.
She has published articles for the CIBSE Journal and Modern Building Services advocating for positive change across the industry. Clara was recognized as the inaugural Engineer of the Year at the CIBSE Building Performance Awards as well as UKGBC’s Rising Star 2017 due to her work on energy policy and low-energy building design.
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