The activities of the AEC sector contribute greatly to what is considered to be the biggest problem facing the world today, climate change. Buildings consume enormous amounts of energy during their entire life-cycle (from construction, through operation, to dismantle) depleting non-renewable resources and releasing greenhouse gases in the atmosphere, the very causes of climate change. Research has shown sustainability to be the way to curbing this problem. The pace towards addressing more sustainable outcomes in the AEC sector will depend on knowledge and consciousness of individual actions and roles. Research has shown that there is a disparity between construction professionals’ understanding of sustainability and how their perceptions of it are translated into practice. This presentation presents the state of the art of sustainability issues in the AEC sector, and what it is for the case of Ireland. Findings from engagements with sustainability experts into what sort of sustainability expertise/competencies practitioners in the AEC sector need will be presented as well.