A 1960s house in South London is staying 10C cooler than outside without air conditioning during extreme heat. It acts like an insulated flask maintaining a cooler temperature indoors by keeping heat outside

A 1960s ex-council house in south London stayed 10C cooler than outside during a 35C day without air conditioning. Architect Marion Baeli spent a decade upgrading the property with insulation, triple-glazed windows, airtight construction and ventilation, turning it into a Passivhaus-style home that uses far less energy.