Holistic Innovative Solutions for an Efficient Recycling and Recovery of Valuable Raw Materials from Complex Construction and Demolition Waste (HISER)


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HISER interactive workshop on integrated environmental and economic assessment

On July 2nd 2015 VITO, CML and D’Appolonia hosted a workshop in Brussels with internal and external experts in environmental and economic assessment from a life cycle perspective. The main goal of the workshop was to discuss specific methodological issues of the development of an integrated environmental and economic assessment framework. This framework will be used within the HISER project to assess and compare different business-as-usual (BAU) and new innovative solutions for the demolition of buildings, and sorting and recycling of complex construction and demolition waste consisting of stony fractions (concrete or bricks), gypsum and wood. The common assessment framework for the HISER case studies will be reported in a document that will be ready by the end of September of this year.

A total of six experts, who are not involved in the execution of the HISER project, attended the event:

- Karen Allacker (Assistant Professor at KU Leuven) gave her input as an expert in life cycle assessment (LCA) and Life Cycle Costing (LCC), the integration of both on building and building element level, and End-of-Life modelling.
- Harpa Birgisdóttir (sr. researcher at the Danish Building Research Institute within Aalborg University) assisted as an LCA expert within the built environment.
- Harry van Ewijk (sr. researcher and co-director at IVAM) proved his expertise in environmental LCA of the built environment from a construction and waste management point of view.
- Reinhout Heijungs (Associate Professor at the Free University of Amsterdam) is an overall LCA and LCC expert with a background in mathematics and statistics.
- Valentina Prado (researcher at CML) contributed with her input on the integration of life LCA and LCC, especially on weighting, normalisation and decision analysis.
- Carolin Spirinckx (project manager and sr. researcher at VITO) contributed to the workshop thanks to her LCA expertise on the built environment.

Five topics were discussed during the workshop. The interactive sessions, chaired by CML and VITO, started with the topic on the complexity of defining a sound functional unit (FU) for each HISER case study. Within each case multiple perspectives may be addressed, i.e. a waste management perspective (option A), a material production/recycling perspective (option B) and a dual-function perspective (option C). At the workshop, all experts agreed that a definition of the FU has to be looked at for each waste fraction separately. Even if option C is preferred, stakeholders may opt for option A or B due to different concerns. In addition, it was suggested to explicitly include possible effects of upstream and downstream processes of HISER technological and non-technological options. During the discussions, it became clear that a distinction has to be made between system boundaries and functional units. The importance of making a glossary was underlined to avoid semantic differences, if possible in connection to existing standards.

The second topic treated several approaches on normalisation and weighting of different environmental impact category results. Normalisation and weighting are used to facilitate decision-making in a comparative LCA. There was a consensus that it is not the aim within the HISER project to develop new normalization and weighting methods, but to select existing ones with some small development steps if necessary. Therefore, sensitivity analysis will be applied on the normalisation step – alternating the normalisation approach used within the Product Environmental Footprint (PEF) method and outranking method), and weighting step within LCA – alternating monetisation, PEF (equal) weighting and stochastic modelling – and on the life cycle impact assessment (LCIA) method for the category on depletion of resources. All experts agreed that the method of equal weighting (as currently used within PEF pilots) is not recommended. However, it will be included in the project to feed the Commission with practical results and possible consequences. Further internal discussions are needed to investigate if outranking and stochastic modelling are feasible within the HISER project.

For the third topic, a hybrid approach to integrate LCIA and LCC results was discussed. All experts concluded that the involved stakeholders should decide if they want to aggregate environmental and economic results in relation to their own objectives. For transparency reasons, aggregated scores should always be detailed by underlying environmental and economic results. For LCA, the modular approach of the EN 15804 standard remains an option, but for LCC it is better to (sub)divide the results for each stakeholder involved.

The fourth topic dealt with End-of-Life (EoL) and co-product allocation issues regarding the integration of LCC and LCIA results. This led to the conclusion that it is important to define the FU related to the technology system (i.e. all technology involved in demolition, sorting and recycling) that leads to specific products. This has to be investigated case-by-case. Furthermore, it was advised not to stick to the EN 15804 framework for LCC EoL modelling.

The last topic handled the question how to avoid contradictory results using different LCA software and generic LCI databases. As the three WP5 partners use three different LCA software packages, there is an opportunity to further exploring this topic, although this is out of the initial scope of the HISER project. CML will explore this issue and map the magnitude of the problem by means of a small exercise, with data input from D’Appolonia and VITO.

VITO, CML and D'Appolonia want to thank the external experts for their helpful input in co-developing the methodological assessment framework.



The project has received funding from the European Union's  Horizon 2020 research and innovation program under grant agreement No 642085.


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