Circularity is finding its feet in construction. Several Building Circularity Indicators (BCIs) have been developed to measure buildings' Circular Economy (CE) potential, but none of them has been standardized. Currently, the BCIs methodologies lack consensus on CE definition and scope, Key Performance Indicators (KPIs), and various other technical aspects. New research is hardly building upon the existing works and this lack of incrementalism hinders the standardization process. The current research addresses these limitations by developing a comprehensive and innovative Whole-Building Circularity Indicator (WBCI). WBCI consolidates the existing advancements by including the best features of various methodologies (like VBCI, MCI, Flex 4.0, etc.) and covering a wide range of KPIs. It has been developed from a life cycle perspective, taking into account all material flows from the point of origin to disposal or waste treatment. The adopted methodology complements popular sustainability tools like Life Cycle Assessment (LCA). The validation is done through a case study of a typical Italian residential building. WBCI along with an existing popular tool is applied to the case study using the actual building data to validate and highlight the improvements made in the developed framework. The building performed poorly in terms of circularity, scoring 0.243 on a scale of 0 (fully linear) to 1 (fully circular). It is found that resource-intensive construction processes and longer service life can substantially affect CE performance. Recommendations for improving the building circularity are given. From the methodological point of view, results emphasize that WBCI is a multilevel framework capable of identifying the best-performing CE solution at the material, element, system, and whole-building levels. Contractors, consultants, and policymakers may leverage WBCI's features to assess the circular performance of buildings at early stages. Researchers can also use the findings to further expand and standardize the BCIs.@en

The circular economy (CE) paradigm can eradicate the problems caused by the traditional linear economic approach adopted by the building industry. But the efforts to implement CE in the building and construction industry are fragmented and lack consensus. If improved, the ability to measure and report on progress can help in effectively transiting to CE. In this regard, wide-ranging building circularity indicators (C-indicators) have been proposed. However, the extant literature highlights that the comprehensive research on existing CE assessment tools in the building industry is still lacking, while policymakers (e.g., European Commission) and standards (e.g., ISO) have emphasized the need for a universally recognized circularity framework for buildings. To help this cause, this review inventories and critically analyzes 35 existing tools through an extended systematic literature review of 51 carefully selected documents from both academic and grey literature. It is found that there is a sharp increase in publications in recent years, with Europe leading the way. Along with the academic community, government agencies and consulting companies have also developed several C-indicators. The content analysis suggests that most indicators are quantitative and can vary in terms of the scale of application, the adopted CE scope and definition, and the underlying key performance indicators (KPIs). The descriptive analysis reveals that most indicators are in the developing stage and substantially stress recycling and reuse, overlooking some important aspects like energy, emission, and water. Innovative technical solutions like the design for adaptability and disassembly are excessively used to measure the circular potential of structures. The existing sustainability and circularity tools are seen as a good starting point for developing new frameworks. This extensive review and critical analysis provide a synthesis and explanation of the developing research theme of building C-indicators and highlight the remaining key challenges. The findings can drive the standardization of a universally accepted framework.@en

Several recent studies have highlighted the potential of Actively Heated Fiber Optics (AHFO) for high resolution soil moisture mapping. In AHFO, the soil moisture can be calculated from the cumulative temperature (T_cum), the maximum temperature (T_max), or the soil thermal conductivity determined from the cooling phase after heating (λ). This study investigates the performance of the T_cum, T_max and λ methods for different heating strategies, i.e., differences in the duration and input power of the applied heat pulse. The aim is to compare the three approaches and to determine which is best suited to field applications where the power supply is limited. Results show that increasing the input power of the heat pulses makes it easier to differentiate between dry and wet soil conditions, which leads to an improved accuracy. Results suggest that if the power supply is limited, the heating strength is insufficient for the λ method to yield accurate estimates. Generally, the T_cum and T_max methods have similar accuracy. If the input power is limited, increasing the heat pulse duration can improve the accuracy of the AHFO method for both of these techniques. In particular, extending the heating duration can significantly increase the sensitivity of T_cum to soil moisture. Hence, the T_cum method is recommended when the input power is limited. Finally, results also show that up to 50% of the cable temperature change during the heat pulse can be attributed to soil background temperature, i.e., soil temperature changed by the net solar radiation. A method is proposed to correct this background temperature change. Without correction, soil moisture information can be completely masked by the background temperature error.

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