When people think of making reductions in carbon dioxide emissions, it is customary to look at power generation, heavy industry and transport especially planes and cars. However, buildings contribute half the carbon dioxide emissions from the UK, and homes make up a significant part of that. It's been a real drive of people to get engaged with thinking about how buildings can contribute towards the UK's carbon targets. One of the most contentious issues has been to agree on the definition of a zero-carbon home. The quest to build zero-carbon homes is plagued by controversy but it is vital to a low-carbon future.