Circular Construction Process: Method for Developing a Selective, Low CO2eq Disassembly and Demolition Plan

Abstract

With the increasing focus on the construction sector (e.g., following the European Green Deal initiative) with the aim to reduce emissions by 55% by 2030 (compared to 1990 levels), as well as achieve full decarbonisation by 2050, the built environment remains a strategic domain for the R&I (Research and Innovation) agenda. Indeed, the building and construction sector is the main contributor to greenhouse gas emissions (39% of global emissions as of 2018), highlighting the need to start a process of decarbonisation of this sector. The overall reduction in the environmental impact of building materials is achieved by establishing sustainable continuity between the end-of-life phase of the building and the production phase of individual building components. In particular, with reference to the end-of-life phase of the building (BS EN 15978: 2011), the Minimum Environmental Criteria foresee the preparation of a plan for the disassembly and selective demolition of the building, which allows the reuse or recycling of materials, building components and prefabricated elements used. According to the guidelines of a low-carbon construction design, which takes into account a circular economy, the following thesis deals with a methodological proposal to study “dry” construction systems (wood and steel). In particular, the study intends to reach the development of such an elaboration by carrying out an assessment of the environmental impact of a process of selective disassembly and demolition of steel building systems. The model is developed on the basis of a reading of the level of sustainability of emblematic case studies, appropriately identified, i.e., ‘quality’ architectures, built with ‘dry’ (steel) building systems.

End‐of‐life solution prioritization for pre‐cast concrete components aligning with circular economy targets

“…Using the existing literature and expert knowledge, all the important criteria and sub‐criteria have been identified while selecting the end‐of‐life solutions (i.e., goal), as given in Table 2. Existing experience (EE) is one of the criteria that addresses the knowledge of the level of dismantling of different connections, 8 past experience on the usage of different technical solutions, 36 standards/guidelines, and repair/reuse opportunities 41 . Moreover, different levels of dismantling of the pre‐cast concrete components are essential to all end‐of‐life solutions.…”

“…TC has been further divided into two sub‐criteria, including labor and equipment cost for dismantling (C1), transport cost (C2), and material cost (C3). Moreover, transport cost covers the cost associated with the transport of pre‐cast concrete components to a disposal site/recycling plant 36 and/or lifting of the components within the building premises. During the lifting of pre‐cast concrete components, O'Grady, Minunno 14 have discussed possible lifting methods for components/material (CM) such as if CM < 20 kg, then one person can lift or if CM < 42 kg, two people can lift, if CM < 50 kg, then hand trolleys can be used, while forklifts for components up to 2000 kg and components heavier than 2000 kg with cranes 14 .…”

“…The criteria of energy consumption (EC) address the use of energy for transport of the components and lifting of the components within the building premises. CO 2eq emissions (CO) during each end‐of‐life solution can be estimated by considering the rate of emissions produced by the dismantling activity, share of emissions from scrap resulting from demolition operations, share of emissions from transport off‐site (i.e., storage areas, recycling or waste disposal centers), and share of emissions from processing for reuse 36 . The emission level is dependent on the number of tools and machinery required to dismantle structural connections.…”

“…CO 2eq emissions (CO) during each end-of-life solution can be estimated by considering the rate of emissions produced by the dismantling activity, share of emissions from scrap resulting from demolition operations, share of emissions from transport off-site (i.e., storage areas, recycling or waste disposal centers), and share of emissions from processing for reuse. 36 The emission level is dependent on the number of tools and machinery required to dismantle structural connections. In addition, to address societal criteria during the selection of end-of-life solutions, safety (S) concerns have been considered.…”

“…A variety of qualitative and quantitative criteria have to be considered while selecting an end‐of‐life solution for a particular pre‐cast concrete component. This includes the dismantling time, 8 existing experiences on technical issues related to dismantling/repair methods/recycle options, economic issues (e.g., cost for transport, cost for dismantling, and cost for material), emissions, 36 and energy consumptions 37 for different solutions. However, it is quite challenging to prioritize the end‐of‐life solutions considering both the aforementioned qualitative and quantitative criteria.…”