The building sector’s contribution to climate change and the need for decarbonizing the sector necessitate a transition to sustainability and a Circular Economy (CE). To accelerate this transition, demonstration projects are considered valuable tools for facilitating upscaling and replication. Demonstration projects introduce new materials, technologies and concepts to the regular market and provide evidence of technical and commercial feasibility, reducing risks for the wider construction industry. However, there is limited evidence of how demonstration projects disseminate knowledge and lessons learned and influence the wider industry. Hence, in order to identify the most commonly adopted CE features in exemplar and demonstration projects, upscaling opportunities, and knowledge sharing strategies, a desktop study of exemplar and demonstration sustainable building projects was conducted through reviewing case study repositories from Green Building Councils and sustainability rating systems, industry reports, websites and academic publications. The identified cases included 43 international and 35 Australian residential and commercial building projects adopting CE principles or obtaining sustainability certifications indicating sustainability best practices and leadership. The results from the study highlighted the current most adopted circularity features include regenerating and reducing the energy and natural resources consumption through the use of renewable energy and closed-loop water systems. Furthermore, utilizing reused and recycled materials were identified as other common CE strategies. In terms of upscaling demonstration projects, economic viability, technical and technological readiness, and regulatory and policy implications were identified as potential factors influencing the upscaling and replication of sustainability initiatives. The study further identified that there is a lack of standardized process and framework for knowledge transfer from demonstration and exemplar projects to the wider industry stakeholders. Therefore, this paper helps address these gaps and provide researchers, policy makers and industry practitioners with insights on factors facilitating the demonstrative upscaling of CE and transition to sustainability within the sector.