ABSTRACT
The ongoing climate and nature crises force humanity to re-think, re-imagine and re-design its use of resources. One of the main strategies to reduce the use of virgin materials is the introduction of circular economy, which in the context of buildings means extending the lifespans of existing buildings, re-using materials from existing buildings and drastically reducing the need to extract and harvest new building materials. It has become essential to document and understand the existing building stock at a high granularity and spatially explicitly as it will hopefully replace natural resources as the main source of building materials in the future. In this article, we detail the lessons learned from the past 2 years of data gathering, structuring and analysis of Trondheim’s building stock. In the framework of the Circular City project that aims to build a research infrastructure, a digital twin and a material flow analysis of the current ~77,000 buildings in the municipality, we examine the overarching concepts that govern the identification of data sources, data gathering and structuring as well as the quantified variables, qualitative descriptions, architectural drawings and building information models that serve as data variables. We document that this multi-source/multi-variable approach enables a discussion on trust, data conflict and usability that is essential to develop building stock models and assumptions, as well as develop efficient strategies to fill the gaps in the data.
