Obstacles and opportunities for the reuse of structural elements

The revised Waste Framework Directive (WFD) obliges Member States to improve material recycling. The EU's objective is to achieve a recycling rate of 70% for construction waste by the year 2020. Direct re-use of building elements is one way to support the objective.

In a national ReUSE project jointly funded by the Ministry of the Environment, VTT Technical Research Centre of Finland, Tampere University of Technology, Ekokem and Finnish Wood Research, the obstacles to and opportunities for re-use of structural elements were evaluated. The project addressed the potential and challenges currently facing the re-use of elements from existing buildings and design for re-use in new buildings. Number of case studies in which elements have been used in new buildings has also been mapped in the project.

Returning the structural components back to service in the built environment is a rather complex process affecting all the parties involved in the life cycle. Designers have to consider the new source of materials and carefully plan for deconstruction, increased demand for coordination and flexibility in decision making will be needed during construction, and finally new business areas can be opened up to provide services for the phase between deconstruction and new building. The process also depends strongly on the size and complexity of the element or structure that is being re-used.

Re-use of building elements without re-processing saves almost all of their embodied impacts and preserves their economic and cultural value. This has been always seen as the biggest opportunity to increase environmental efficiency of the built environment. In most of the cases the presented concept competes with other recovery strategies, and therefore its feasibility has to be always evaluated. Moreover, it is possible to extend the service life of such composite elements in existing building stock that cannot be easily recycled because of difficult material separation. Re- use creates many business opportunities in the local communities especially for re-distribution of salvaged material. In many cases is also cheaper to dismantle building part-by-part and sell the components than traditional demolition and waste processing. In that sense we can conclude that re-use concept is contributing to all aspects of sustainability of the built environment.

Unfortunately, there are many practical barriers to the building components re-use that should be addressed. One is the lack of strength grading rules for materials in re-used elements. This means that re-usable load-bearing components are forced to be applied for non-structural purpose unless they are thoroughly tested. Another barrier is the difficult deconstruction of existing buildings. The extended time and high demands on manual labour is usually increasing the cost of the whole process. This can be partly improved by applying standardized deconstruction practices, proper staff training and using selected technologies for deconstruction. However, the greatest impact on the building re-usability is in its design stage. Therefore we recommend addressing this issue in the planning of future steps towards resource efficiency.