Understanding the past, building our future

By Vasiliki Savvilotidou

Cities as urban mines

One of CIRCuIT’s aims is to extend the idea of urban mining to construction and demolition activities, reimagining cities as rich sources of reusable building materials.

The construction industry is widely acknowledged as one of the most important sources of waste. But what if new buildings had to be adapted and reused or built only with materials already available?

Urban mining is the process of reclaiming materials from any kind of manmade stock. This involves the process of reclaiming materials from the building stock and other build infrastructure 1,2.

How CIRCuIT aims to bridge the past and the future

CIRCuIT and other projects are building collaborative tools to create and centralise communication with stakeholders, allowing for knowledge transfer among case studies, cities and contexts. To increase the reuse and recycling, it is very urgent first to understand the actual quantity of material stocks in buildings, which will allow us to utilise resources more efficiently.

However, there are still two major challenges; the first one is the difficulty of harvesting building data taking into account the time spent, financial backing, accessibility, interoperability, and data quality. The second one is the heterogeneity of buildings in terms of construction types, materials and morphologies which renders their systematic description difficult. This reflects the diversity among the case studies for material stocks accounting, involving different measures, different materials, or the same materials measured in a different way.

Additionally, accounting for building materials in a city is only the start for a systemic understanding of material flows. Measuring the entering and exiting flows is also not enough; a lot more information about how materials are used when building a property and removed once it is demolished is needed. We need to understand the systems used in cities in much more depth, raising the following questions:

Who is consuming? Where we are consuming? Why we are consuming? What drives our consumption; and when material stocks will become available?

CIRCuIT aims to develop a knowledge platform where data and tools will be gathered, centralised and built upon, aiming to support urban mining strategies towards a circular economy and cities regenerative capacity.

How to produce more with less

The circular economy is restorative and regenerative by design, involving a ‘design out’ waste principle, where waste does not exist, and products are designed/optimised for reuse.3 Following this principle, we aim to encourage the production of more buildings that use less new materials, which requires a clear understanding of the possibilities for recovery and material quality. For this to happen, city managers and practitioners must be equipped with tools and the know-how to build a transition towards sustainable and resource-efficient cities using integrated systemic approaches. Integration of efficient automated processes, such as a pre-demolition audits, and advanced recycling technologies will also accelerate circularity in decision-making, improving customer service and reducing costs.

Pre-demolition audit and selective demolition

Knowledge on the quality of a material and its properties is needed to justify their use in buildings. The quality of a material is essential to determine the potential and value of recycling it and ensures the customers confidence in the product. If the end users do not fully understand and trust the processing of recycled material, they will choose to use new materials instead of used ones. In order to create a profitable marketplace for circular construction materials, it is crucial that all actors in the value chain are confident about the quality of reusable materials.

Maximizing urban mining possibilities through 12 demonstrations in Hamburg, Helsinki, Copenhagen and London

A quality assessment system based on recycling technologies or tools that are accurate, cost-effective and environmentally friendly will assure confidence in the quality of recycled materials. Advanced recycling technology is needed to support selective demolition, as selective demolition alone does not guarantee a high-value, quality material. We cannot recover materials from demolition waste if we do not first identify the materials in the buildings, and if we do not separate the waste on site.

We need to create a system where data from pre-demolition audits can be put in and an assessment can be made of the quantities that can be reused. To do this we need information on the material quality, function, past uses, maintenance, recycling, and reuse possibilities. This harmonised database that contains information on materials that are used at present in buildings, will be used as an urban mine. As a result, recyclers will have access to information on the type of materials and expected quantities that they currently lack when considering the possibilities of what can be recycled. One of the major outputs of the CIRCuIT project will be the development of a digital pre-demolition audit which will be applicable across EU.

Thoughts on the potential of urban mining

Innovation is key in order to move beyond the current linear economic system and practices. To get the level of critical mass that can drive innovative thinking, we need to raise awareness and communication about why it is so important to reduce consumption and move towards a more circular economy in our cities. Furthermore, we need;

· to change the people’s attitude towards “used” materials from a negative to a more positive one,

· to reduce the environmental footprint and

· to address the question of consumption correctly so that we have a huge impact on our quality of life and the values that we have for our society.


1 Koutamanis, A., van Reijn, B., & van Bueren, E. (2018). Urban mining and buildings: A review of possibilities and limitations. Resources, Conservation and Recycling, 138, 32-39. https://doi.org/10.1016/j.resconrec.2018.06.024.

2 Cossu, R. & Williams, I.D. (2015). Urban mining: Concepts, terminology, challenges, Waste Management, 45, 2015, 1-3. ISSN 0956-053X, https://doi.org/10.1016/j.wasman.2015.09.040.

3 Ellen MacArthur Foundation (2013). Cities in the Circular Economy: An initial Exploration, URL: https://www.ellenmacarthurfoundation.org/assets/downloads/publications/Cities-in-the-CE_An-Initial-Exploration.pdf (viewed 28.10.2020)

LWARB manages this website and is the data controller. Personal data is managed in accordance with the LWARB privacy policy available here: https://www.lwarb.gov.uk/privacy-policy/