The Australian Federal Government has recently legislated to make it compulsory for all commercial offices to disclose their energy efficiency rating when the property is being disposed of, either by lease or freehold sale. The legislation is part of the governmentís sustainability and carbon reduction initiative. This paper investigates the implications of these changes for property managers. It will critically analyse the process which brought about the legislation and report on the implementation of the scheme, its early operation and issues faced by owners, managers and occupiers in complying with the legislation. Energy disclosure mandates the use of the New South Wales Governmentís NABERS rating tools. The paper critiques the operation of this tool and the impacts of mandatory application of a former voluntary tool. In order to meet these legislative requirements asset managers will need to continually monitor their energy consumption and maintain accurate records of tenant movements within their portfolio. The paper investigates the industry level of engagement with the scheme, the preparedness of the key stakeholders to meet the requirements and the likely effects the scheme will have on property transactions.