Business Green: The sheer scale of the challenge facing the government as it tries to meet its own targets to cut carbon emissions from public buildings was underlined today after it was revealed that many of the UK’s most iconic buildings are dogged by extremely poor energy efficiency. Under new legislation taking effect from today, around 18,000 public buildings larger than 1,000 square metres will have to exhibit Display Energy Certificates (DEC) detailing how energy efficient the building is on …