Mandatory reporting of greenhouse gas (GHG) emissions, which is intended to help combat global warming, has been increasingly implemented across the world. For buildings in Hong Kong, however, GHG reporting remains entirely voluntary even though the government has issued a set of guidelines to facilitate building owners and managers to quantify GHG emissions from buildings. Aimed at understanding stakeholders' opinions on whether, and to what extent, the GHG reporting should be made mandatory, a study involving a questionnaire survey was carried out. Analysis of the opinions revealed that the majority supported making the reporting mandatory for office, hotel/hostel, and industrial buildings. Generally more support was received from those who were highly experienced, employees of non-government public organisations, academics/researchers, or qualified carbon/energy auditors. Their agreement on requiring reporting of activities under scopes I and 2 of the GHG Protocol was stronger than that for the scope 3 activities. Reporting of paper waste disposal attracted the weakest support. The reasons for not supporting the mandatory policy, including resource constraint and financial and knowledge barriers that confront the stakeholders, were identified. The findings of this study serve as reference for energy policy makers. (C) 2014 Elsevier Ltd. All rights reserved.