On 22 April, Heads of State and Government will gather in New York to sign the historic Paris Climate Change Agreement that was secured last year in December. In preparation for the event, UNFCCC has launched a campaign, encouraging everyone across the world to become part of the change that is happening by posting a short video to show support. BRE Group Director, Guy Hammersley, talks about how BIM can make an impact on cutting waste and saving costs, helping the built environment industry come one step closer to a low-carbon future.