Ian Bitterlin, professor emeritus at the University of Leeds – and retired chartered engineer – used his Eurobat presentation to challenge the way European data centres specify uninterruptible power supply (UPS) batteries. Invoking John Ruskin, Bitterlin reduced his purchasing philosophy to a simple rule: “You get what you pay for.” “If you start with a decent battery … it makes the lithium-ion battery still look really expensive,” he said. Referring to FM guidance, he advocated keeping lithium-ion batteries outside the building envelope in fire-rated, adequately separated enclosures. Bitterlin praised lead as a mature, extensively recycled material while dismissing claims that lithium-ion batteries could be recycled at rates approaching 97%.