The pandemic has changed the way we work and shop meaning a growing number of offices and retail outlets are empty. So, what do we do with them? Knock them down and start again or find a sustainable way to reuse them? The buzz word is ‘retrofit’: redesigning and refurbishing an existing building. Elsie Owusu is an architect and, in this episode of Costing the Earth, she explores this current and contentious issue. It’s usually cheaper to build new, so what can be done to encourage developers and architects to change their plans. She visits Selkirk House on Museum Street in London. Developers want to demolish this 1960s concrete tower-block and build something bigger in its place. Campaigners say that a vast amount of CO2 emissions would be saved it the building is retrofitted. Architect, Peter Fisher, takes Elsie to a 1950s, concrete, former print-works which is being refurbished. Just five years ago Peter says the decision would have been made to demolish but, times are changing, and by choosing retrofit CO2 emissions will be reduced by 50%. Smith Mordak takes a wider view of the debate, arguing that a cultural shift is needed across architecture and the associated disciplines. The automatic response to a design challenge of building new, or even building at all, should be rejected; there are more creative and greener ways of thinking to explore first. Contributors: Simon Alford of the Royal Institute of British Architects; Howard Crawshaw of the Knight Property Group; Jim Monahan of Save Museum Street; Simon Sturgis of Targeting Zero; Peter Fisher of Bennetts Associates; Smith Mordak of Buro Happold. Producer: Karen Gregor