Buildings are an important part of society's environmental impacts, both in the construction and in the use phase. As the energy performance of buildings improve, construction materials become more important as a cause of environmental impact.Less attention has been given to those materials. We explore, as an alternative for conventional buildings, the use of biobased materials and circular building practices.In addition to building design, we analyze the effect of urbanization. We assess the potential to close material cycles together with the material related impact, between 2018 and 2050 in the Netherlands. Our results show a limited potential to close material cycles until 2050, as a result of slow stock turnover and growth of the building stock. At present, end-of-life recycling rates are low, further limiting circularity.Primary material demand can be lowered when shifting toward biobased or circular construction. This shift also reduces material related carbon emissions. Large-scale implementation of biobased construction, however, drastically increases land area required for wood production. Material demand differs strongly spatially and depends on the degree of urbanization. Urbanization results in higher building replacement rates, but constructed dwellings are generally small compared to scenarios with more rural developments. The approach presented in this work can be used to analyze strategies aimed at closing material cycles in the building sector and lowering buildings' embodied environmental impact, at different spatial scales.

We are particularly excited to welcome you in Mondorf-Les-Bains in Luxembourg and continue the great series of biannual ECTQG meetings. For over 40 years now, the ECTQG has gathered young and leading scientists interested in advancing quantitative methods and theories with a strong geographical dimension.

In cities around the world, housing demand is increasing rapidly. Since housing supply is inelastic, house prices are rising as well, which causes affordability problems. Although there is consensus about the need to raise production, there is debate about its location: within the existing city, on underused or derelict buildings and sites, or on greenfield land outside existing city boundaries? The question we address is how researchers on the science–policy interface can support these debates and facilitate evidence-based decision-making. We address two major problems while doing this: (1) the complexity of the object at hand, that is, of the development of urban systems and (2) the politicised nature of science-for-policy. The contribution of this paper is that it links complexity theory to the literature about science-for-policy, two usually unconnected literatures. An additional contribution is that it shows how the role of the scientist as ‘honest broker’, as developed by Roger Pielke, can be operationalised and applied to existing policy debates. We do that for the Dutch debate about housing development in existing urban areas.

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