Social housing as a source for urban mining in The Hague by 2050

Abstract

SummaryThe municipality of The Hague and the Social housing associations are researching on how to cope with the population growth in The Hague. Every year approximately 5,000 new persons arrive at The Hague, meaning that in 10 years The Hague will increase their population by 8%. The main problem is that currently, the city has a shortage of social housing, which is the most vulnerable sector in the city. The municipality has a variety of new governmental strategies that provide answers for these upcoming changes. The main challenge is that the municipality of The Hague’s strategies in the construction sector will result in significant volumes of waste. These waste streams need to be quantified to find opportunities for urban mining. Typically, the materials extracted from the construction and demolition (C&D) sector are downcycled into less valuable materials, incinerated or sent to the landfill, backfiring in economic loss and increase in CO₂ emissions. Nowadays, there are companies that recover the material form the C&D site and recycle it into new construction material. However, even if it has been proved that circular demolition is between 10-15% cheaper and decreases emissions up to 44%, it is not a common practice. This develops the questions about ‘why urban mining is not a common practice?’, and ‘how can it be encouraged?’The purpose of this research is to explore the topic of urban mining by assessing the possibilities of implementing urban mining in the social housing sector in the upcoming years.Methodology: For this research, three methods have been selected; A) Interviews, B) Stakeholder analysis and C) Mass Flow Analysis (MFA). A) Interviews: Ten interviews were conducted with the main stakeholders related to urban mining of social housing in The Hague. These include the municipality of The Hague, Social housing associations and C&D companies.B)Stakeholder Analysis: The stakeholder analysis was performed to analyse the relation and communication between the various parties involved. The goal of this analysis was to understand the communications barriers that stand in the way of urban mining becoming a common practice. C)Mass Flow Analysis: Using four different criteria (construction year, land use, energy label and the 20-80 rule) two estimations were created to quantify the projected number of social housing buildings that might be demolished by 2050. The result of the two estimates was the monetising of the material – brick and glass- that can be extracted from the social housing buildings.Results: Two main findings were established from the methodologies. On the one hand, the interviews and stakeholder analysis led to the finding that there is a lack of proper communication between social housing associations, municipalities, and C&D companies. The various parties are interested in collaborating in the area of urban mining. However, the lack of direct communication channels resulted in the slowing down of the process of upscaling to larger urban mining projects. On the other hand, after doing the MFA, the results showed that urban mining practices could be between 15-20% more profitable than standard practices. Construction companies can save up to 20% by buying recycled material from a C&D site. The results also showed that urban mining of materials, such as brick and glass, can reduce the CO₂ emissions by 44%.Conclusion: Urban mining in The Hague is an environmentally friendly and profitable option if the different parties agree to collaborate. After the municipality of The Hague creates a framework on how to apply urban mining techniques for the buildings owned by the municipality itself, the process can be more easily replicated by other companies. Scientific relevance: This research quantifies the competitiveness of urban mining of social housing in The Hague, opening the path for new research about urban mining implementation and development.