Table 1.

Research process development.

Steps	Research Process
Scope	How does CE meet the complexity of the policy and be coherent to achieve circularity in respect of sustainable buildings?
Question definition	Is there a need for a comprehensive definition of a CE in the built sector?
Objective(s)	a. Identify the current state of research. b. Establish the gaps and barriers to the adoption of the CE and its future development within the building sector.
Selection criteria	Identification of papers relating to the CE concept and its application in the building sector.
Strategy	Data basis and grey literature.
Screening	Not matching the selection criteria.
Eligibility	Selected papers studied by authors.
Results	Findings from the selected papers.