From sink to stock : the potential for recycling materials from the existing built environment

The urban built environment maintains the alluring prospect of being a source for our future resource needs. This work imagines new local recycling paradigms for concrete and masonry waste within an existing urban environment. Using Lisbon, Portugal as a case study, we proposed three context-specific material recycling scenarios to make use of mineral construction waste generated as the city’s aging residential building stock is replaced over the next 30 years. We compared four scenarios – three recycling proposals and standard landfill disposal – in terms of production potential, land use, greenhouse gas emissions, and cost. The results show that from both an environmental and economic standpoint, recycling is not always the optimal solution. The impacts depend not only on the recycling processes and end uses, but also the avoided and added burdens consequent to changes in the existing system. Through this analysis, we identified the limiting factors and potential opportunities for improvement in the current processes of construction material reuse and recycling, in Lisbon and beyond.