Environment: Rome, ENEA turns building heritage in urban mine

ENEA and Rome University La Sapienza have developed an innovative analysis technique to identify and quantify materials hidden in old or disused buildings, to be repurposed in architectural redevelopment projects or new constructions from a circular economy perspective. The study, conducted as part of the ENEA ES-PA project and published in the journal Sustainable Chemistry and Pharmacy^[1], has shown that over 95% of demolition materials can be reused for renovating the structure itself (35% ) and for other uses (60%), without ending up in a landfill.

The technique^[2] was applied on one of the many industrial archaeology sites in Italy (which cover 3% of the territory, an area of 9 thousand square kilometers) specifically to a project for the recovery of a bus depot of 11 thousand square meters, built in Rome in the 1930s and disused since 2008.

 “The approach allows evaluation at different scales, from the national scale to estimate the extent of the materials recoverable from the Italian building stock to plan an efficient domestic use of resources, through the intermediate scale to plan strategic local areas or areas characterized by homogenous construction characteristics, up to the local scale to provide operational tools to plan urban areas, neighborhoods or single buildings", said Antonella Luciano, researcher at the ENEA Valorization of resources in Production and Territorial Systems Laboratory and co-author of the study with Laura Cutaia (ENEA), Paola Altamura and Serena Baiani at Rome University La Sapienza.

Preliminary analyses revealed that the deposit has around 18 thousand m3 of materials, mainly reinforced concrete, for a total weight of approximately 35 thousand tonnes and over 15 thousand tonnes of CO₂ embodied carbon. The architectural renovation project, one of the key aspects of the ENEA-Sapienza method, provides for the conservation of the reinforced concrete structure and almost total recovery of some materials and structural elements (windows with iron frames and wooden doors). “While demolition materials like plaster, tiles, bricks and systems - are sent to off-site for recycling in the respective value chains, in plants in the Rome area, or for regeneration for future reuses” , explained the ENEA researcher.

 “Out of a total of over one thousand cubic meters of demolition materials, only a minimal amount (4.7% by volume and 4.2% by weight) is destined for disposal in landfill because potentially dangerous - said Antonella Luciano -. It was thus possible to improve the minimum legal threshold for the recovery of demolition materials by 25%^[3] (70%). And this method can be applied to all construction types, including abandoned industrial buildings and residential and school buildings".

The widespread presence of abandoned sites represents an opportunity for urban regeneration and valorisation of the stocks of materials in buildings. The significant amount of materials and components, buildings and infrastructures 'at the end of their life' can be considered as an actual urban mine, a potential source of new resources which, however, need to be quantified and mapped to contribute to the development of new reuse and recycling strategies, an essential condition for a national plan for an efficient use of resources.

 “Concretely, a large-scale implementation of circularity in the construction sector requires an innovative design and construction process that integrates various activities such as the estimation of material stocks, selective demolition, local sourcing and waste recycling also from different industrial sectors, the so-called industrial symbiosis. To allow the reuse of materials, a new approach to the demolition of buildings (deconstruction) is needed, already being designed, which provides for selective dismantling of components and optimization of the recovery of all recyclable materials like clay bricks, stone slabs and blocks and steel elements with a high embodied energy and a low decline in performance over time”, pointed out Antonella Luciano at ENEA.

To promote this new approach, four factors are key: quantification of the environmental value of the stock of disused or end-of-life construction materials; material databases and georeferenced mapping to know the distribution areas of potentially reusable materials in a territory, which can be integrated into the BIM (Building Information Modeling) software for the optimization of planning, construction and construction management; platforms^[4] for exchanging components and materials from deconstructions.

Globally, the construction sector is responsible for 60% of raw material consumption, 23% of carbon dioxide emissions and 50% of waste produced by construction and demolition activities. Some regulatory constraints, the fragmentation of technical and environmental regulations and a sometimes non-univocal interpretation of the regulations have in fact seriously slowed down an effective recovery and reuse of such waste in recent years^[5]. “But something is moving as demonstrated by some recent regulatory updates that aim to reduce the disposal of construction and demolition waste and facilitate the creation of a market for recovered components,” concluded the ENEA researcher.

[1] A. Luciano, P. Altamura, S. Baiani, L. Cutaia, The building stock as an urban mine: The case of the circular regeneration of disused buildings, Sustainable Chemistry and Pharmacy, 33 (2023) 101104.

[2] The bottom-up approach used provides for a detailed data collection on materials for greater accuracy of results, in terms of composition, intensity and geographical distribution. It foresees five subsequent phases: 1. Technological analysis of the building; 2. Identification and quantitative estimate of the stock of materials present in the building; 3. Architectural and environmental renovation project of the building with the adoption of circular strategies; 4. Quantitative estimate of the removed materials and identification of their final destination, including the estimate of the project material and the final balance of incoming and outgoing materials; 5. Evaluation of the effectiveness of the intervention with circularity and decarbonisation indicators.

[3] The minimum environmental criteria for green public procurement for interventions on public buildings also provide for 15% content of recycled material and 50% of components that can be dismantled at the end of their life and that the use of materials extracted, collected, recovered or processed at distances of less than 150 km for at least 60% of the total materials used, shall be taken into account.

[4] We have developed the DECORUM platform as a support tool to the various actors involved in the life cycle of public works (clients/contracting authorities; designers, construction managers, testers, laboratories, construction and demolition companies, manufacturers of recycled materials for construction and operators of recycled aggregate treatment and production plants). Antonella Luciano, Laura Cutaia, Flavio Cioffi & Claudio Sinibaldi (2021). Demolition and construction recycling unified management: the DECORUM platform for improvement of resource efficiency in the construction sector. Environmental Science and Pollution Research. 28, 24558–24569. https://doi.org/10.1007/s11356-020-09513-6. https://doi.org/10.1007/s11356-020-09513-6

[5] Luciano, A. Cutaia, L. Altamura, P. Penalvo. Critical issues hindering a widespread construction and demolition waste (CDW) recycling practice in EU countries and actions to undertake: The stakeholder's perspective (2022). Sustainable Chemistry and Pharmacy. 29,100745. https://doi.org/10.1016/j.scp.2022.100745