Improving energy efficiency is a fashionable policy that governments worldwide promote. On paper, it seems a no-brainer: improving energy efficiency is sold as cost-reducing, job-creating, and planet-saving. Win, win, win – and the media often help close the deal, focusing entirely on all the supposed upsides. But there is another side – a downside – to the story. After spending £240 million ($316 million), the United Kingdom ended government funding for its flagship energy-efficiency-loan program last year, after a scathing report from the National Audit Office showed...