Towards a Circular Built Environment: wasteful construction and demolition practices and how to overcome them

Buildings and materials are valuable, yet underutilized reserves of space and secondary resources embedded within the urban built environment. To reach global sustainability goals, the principles of circular economy (CE) are a promising countermodel to current linear waste practices by utilizing the resource potentials of the existing building and material stocks.

The main research subjects of this doctoral dissertation are the Finnish cities of Tampere and Vantaa. In the first part of this dissertation, the focus lies on the cities’ building stocks, construction, and demolition. The study’s methodological framework is Urban Metabolism (UM) which is defined as the in- and outflows of materials and energy, their respective stocks as well as the internal processes which generate and shape them (Baccini and Brunner, 2012). Due to the absence of material indicators for the Finnish building stock (Pesu et al., 2020), the research focus at this earlier stage lies on buildings as such. Despite this unconventional approach, the study method can be described as a Material Flow Analysis which is defined as the analysis of flows of materials (and products) as a balance of in- and outflows and their impact on a stock (Brunner and Rechberger, 2004). Through a statistical and spatiotemporal analysis of Tampere’s and Vantaa’s building stocks, in- and outflows in form of construction and demolition between 2000 and 2018 the aim is to get deeper insights into patterns and drivers within their UMs.

One notable contribution of this dissertation will be the creation of material indicators for parts of the Finnish building stock which will be combined with findings from the aforementioned study of building stocks and flows. The analysis of material contents links patterns in urban spatial and temporal development with their carbon, hence environmental consequences. The outcomes are expected to inform stakeholders from throughout the building industry and policy-making about the negative impacts of current business-as-usual practices and to redirect towards an approach that focuses on maintenance and transformation.

The final part of this dissertation investigates how the natural adaptation potential of the whole Finnish building stock could be utilized to extend building hence, material life cycles. The research method encompasses a statistical and geographical investigation of buildings throughout Finland that have changed their function between 2014 and 2018 in order to identify building types and properties that favour transformation over demolition. Evidence from buildings with a high transformation capacity will be compared with the preceding research on demolition patterns to identify the potential of building adaptation to mitigate material and waste streams. Furthermore, this research will show archetypes that lack the natural transformation capacity which will call for follow-up research that studies the architectural and other internal and external factors impacting the transformation capacity of buildings.

This dissertation sets out to create a foundation for understanding the dynamics within the Finnish building stock. The goals are to find environmentally harmful construction and demolition practices, to identify the natural transformation capacity of buildings, and – with this in mind – to define the most impactful application areas for the implementation of CE strategies.

This dissertation is largely funded by the collaborative Horizon 2020 project CIRCuIT (Circular Construction in Regenerative Cities). For its finalization, this dissertation was awarded a one-year grant by the Finnish foundation Kaute-säätiö.