The early development stage of the National Australian Built Environment Rating System – NABERS was through a greenhouse gas emission rating, known as the Australian Building Greenhouse Rating (ABGR), developed through the Federal Government’s then Australian Greenhouse Office, and commercialised by the then NSW Sustainable Energy Development Authority (SEDA). The NSW Department of Environment and Climate Change now have responsibility for the management of the scheme and for the development of new tools. As of May 2008, the ABGR rating was incorporated into the NABERS scheme as the NABERS Office Energy rating.
NABERS Office Energy rates buildings for measured energy use, with emphasis on the amount of greenhouse gas emissions generated. Emissions are based on a per square metre of Net Lettable Area (NLA) measure to enable fair comparisons across different scales of buildings in different climate zones. Buildings are star rated, with 3 stars regarded as the peak of normal practice. Buildings with star ratings of 4-5 stars and more are regarded as high performance buildings exceeding normal practice.