## 3 Results
### Tool Review  
For each of the selected tools, tables such as Table 4 have been filled, showing CE-relevant criteria and the adopted metrics and targets. \begin{table}
\begin{tabular}{c c} \hline \hline
**Approaches** & **Refs.** \\ \hline
**Industrial symbiosis**: Several studies mention multiple co-benefits of Industrial Symbiosis (IS) approach for CE & [33; 34; 35; 36] \\ \hline
**Renovation**: CE is deemed relevant for renovation projects to reduce constructions’ environmental impact & [37; 38; 39; 40; 41; 42] \\ \hline
**Adaptive reuse of cultural heritage**: Concept that has diversified applicability for CE & [43; 44; 45; 40; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55] \\ \hline
**Replace as an additional R principle**: Additional mainstream approach in CE principles & [46] \\ \hline
**Design for disassembly**: Environmental benefits from the design of components designed for disassembly to facilitate better applicability of life cycle assessment & [37; 40; 47] \\ \hline
**Zero waste**: Educational practices designed to promote changes in user behavior to support CE & [48] \\ \hline
**Practices** & \\ \hline
**Construction and Demolition waste**: CE applied to CDW represents an important strategy with social and economic benefits & [41; 49; 50; 51; 52; 53; 54; 55] \\ \hline
**Urban mining**: As powerful means to help CE in constructions & [56; 57; 58; 59; 60; 61; 62; 63] \\ \hline
**Upcycling**: As novel and positive way to reach a high-quality reuse in buildings & [63] \\ \hline
**Material bank**: Key to facilitate CE spread & [64] \\ \hline
**By-products/secondary materials market**: Useful practice to integrate the policy on the efficiency of materials during production and consumption & [40; 52; 59; 63; 65] \\ \hline
**Deconstruction practices and hub**: A key optimization in CE to limit the resource demand and structural waste & [66; 67] \\ \hline
**Tools** & \\ \hline
**Green Public Procurement**: GPP as strategic tool to achieve CE objectives & [11] \\ \hline
**Material passport**: (MP) as a useful tool for CE & [59; 68] \\ \hline
**Digitalization (including BIM, GIS)**: Digitalization as a support to CE; including BIM or GIS with info about building component lifespan and recycling potential & [50; 65; 69; 70; 71] \\ \hline
**Carbon footprint**: Carbon footprint indicator among the most recurrent metric for CE & [34] \\ \hline
**Material circularity indicator**: Among the most used indicators in the circular economy, complementary to LCA & [72] \\ \hline
**Materials** & \\ \hline
**Water reuse in constructions**: Towards a circular model in the water sector, the configuration of future water & [73] \\ infrastructure changes through the integration of grey and green infrastructure & \\ \hline
**Nature-based solutions**: Nature-based solutions for CE to contrast the negative urbanization impact & [73; 74] \\ \hline
**Wood up-cycling**: Need to improve the applicability of life cycle assessment in a normative context & [75] \\ \hline
**Circular concrete**: Circular concrete is mainstream & [50; 76; 77] \\ \hline
**Urban vertical farms**: Urban vertical farms and CE benefits for dwellings & [78] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cluster of records per homogeneous classes. \begin{table}
\begin{tabular}{c c} \hline \hline
**Group** & **Refs.** \\ \hline Papers highly relevant to CE policies & [11; 34; 66; 69; 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81] \\ \hline Papers highly relevant to CE tools and indicators & [39; 49; 59; 72; 82; 83; 84; 85] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Selection of highly relevant papers to the scope of the study. Thereafter, critically analyzing the protocols, eight major common themes (Table 5) are identified with reference to resource circularity, as follows:  
* Recycled materials, including credits that award the reuse of existing materials or the use of high levels of recycled content. This can be accomplished mainly during the design and construction stages, but also includes waste collection during the in-use stage.