Considering C&D waste has been identified by the European Union as a priority stream and that raw materials resources are limited, urban mining (i.e. considering the materials of the existing buildings as a source of materials for new constructions) has gained interest in the construction sector within the broader concept of circular economy.
C&D waste is about 650.000 tons in Brussels’ region. A part of this waste is related to refurbishment of office buildings. While office buildings cover just 12% of the total amount of built surfaces, each year the renovation of 41% of the office buildings area is authorized to be performed. Even “light” renovations (without modification of the building area) lead to the production of a large amount of waste, internal partition walls being a major source.
A fusion between several public organisations and the introduction of teleworking, brought the need to rethink a workplace (41.378 m²) in a more flexible way. This meant transforming the existing highly compartmentalized area into an open space by removing the internal partition walls. The objective was to address sustainability concerns and to demonstrate the exemplary role of public authorities.
The first step was to perform a pre-renovation audit in order to quantify the materials to be dismantled and to search for strategies for material flow management. The audit revealed the presence of 4 km of modular partition panels representing 817 m³ of mineral wool insulation (within the panels) and 187 tons of steel (external sheets of the panels).
The second step was to write the project specifications for the tender in terms of material flow management based on the strategies revealed by the pre-renovation audit. The contractor was asked to look for and to implement actions in order to recycle and to reuse a maximum of the partition wall panels.
On site, firstly, the contractor decided to carefully deconstruct the partition walls instead of demolishing them.
The first strategy was to reuse some materials and elements. The reuse of materials consists in dismantling the panels in order to separate the steel and the mineral wool insulation. A sample of insulation has been tested in laboratory in order to measure the thermal conductivity of the insulation that would be reused. This measurement was the key issue to convince another client of the contractor to reuse the entire amount of insulation within a residential retrofit project.
The second strategy consisted in the deconstruction of some partition panels and the recovery of doors or glazed partition modules for reuse them with the same purpose on other projects or to resale them on the local second hand market.
The third strategy was the treatment of mineral wool insulation in a closed loop recycling plant.
The project shows that, in renovation, innovative strategies for material flow management allow recovery of materials for new applications, even under a tight schedule and without a strong push for those strategies from the beginning of the project. The support from the authorities in the form of guidance and subsidies and the fact that both the project owner and the contractor have one person dedicated to reducing the environmental impact were two conditions for success.
Lessons learnt from practical projects , Proof of compliance - requirements and quality assurance , Processing possibilities and logistics
