Owners of large commercial buildings in Australia will have to disclose energy efficiency information when putting buildings up for sale or lease, under new laws introduced in parliament. Assistant Climate Change Minister Greg Combet said the laws were designed to promote energy efficiency in large commercial buildings, and will help Australia curb greenhouse gas emissions. "Energy efficiency represents one of the easiest and most cost-effective ways we can reduce our nation's greenhouse gas emissions, and the commercial building sector has the potential to deliver some of the lowest-cost abatement," Combet said as he introduced the laws. Energy used by Australian residential and commercial buildings accounts for around 20% of Australian greenhouse gas emissions. The new laws apply to buildings of 2,000 square meters or more. Building owners will need a building energy efficiency certificate when they put office space up for sale or lease. The certificates will spell out an energy efficiency rating, information about the efficiency of the lighting used and information about how energy efficiency could be improved.