Buildings and infrastructure are responsible for over 30% of the UK's carbon emissions, produce over 60% of the UK's waste, and consume approximately 50% of all extracted materials globally. Radical change is urgently required to achieve a sustainable construction sector. The circular economy (CE) is a well-recognised opportunity to turn waste into resources while reducing carbon emissions. CE aims to keep materials at the highest value possible, via a hierarchy of strategies, e.g. first prioritising extending the lifetime of buildings, then reusing building elements directly in-situ or on another site, then remanufacturing elements, and finally recycling material to conserve resources and avoid disposal. However, CE is still far from typical construction practice. Action to date has largely focused on one-off case studies of individual buildings, or recycling targets leading to wasteful downcycling, and lacks the national-scale, systems-level impact that is so desperately needed. BuildZero's vision is one of a building stock that delivers the UK's space requirements but no longer relies on extraction of new resources, by leveraging the CE to meet materials needs, and eliminating both waste and carbon emissions from material extraction and production. Using this highly ambitious end goal as a springboard, we will explore CE solutions across multiple scales, identified, co-created and co-delivered with our highly engaged industrial consortium, assess the extent to which this vision is achievable nationally, regionally and in relation to individual buildings, and determine the conditions in which the BuildZero vision leads to favourable social, environmental, and economic outcomes. This new knowledge base will provide a platform to enable these solutions to be translated into practice at scale, catalysing regional and national policy to stimulate real change. To achieve this, we will develop an interdisciplinary, multi-scale systems model of buildings and resources flows, focused around four themes: Theme 1: How does the baseline state of the system, including the interplay between societal attitudes, current materials/buildings and legislation constrain moves towards a co-created vision? Theme 2: How far can solutions that make the best use of space take us towards this vision? Theme 3: How far can making the best use of materials, including waste resources, take us? Theme 4: How can our future needs & potential solutions combine to achieve a BuildZero future? To tackle these research challenges we will use methods from industrial ecology, to understand material stocks and flows; from architecture, structural engineering, and materials science, to understand the technical potential of CE solutions; from social sciences, to understand social attitudes and trade-offs; and from economics, to understand potential CE business models. As well as conducting novel research in each underpinning area, we will commit significant resources to working with stakeholders to synthesise findings on what a CE for buildings looks like, by creating interactive foresight/backcasting tools, co-creating future scenarios and identifying the actions needed to catalyse change. Demonstrator projects will apply research to specific contexts, generating early impact. We will build a fundamental understanding of how and when to implement CE strategies, investigating economic viability, social inclusivity, and zero-carbon compatibility, considering these across multiple geographical and policy scales. Our programme of research will culminate in the identification of pathways to achieve the BuildZero vision over different time frames, and a co-created 10 year research roadmap that outlines the remaining work required to deliver a BuildZero future.

The first phase of the SUE Programme has focused necessarily on the present, assessing current solutions and their application in the near future, thus providing a strong empirical base on which to build. There now exist both the need and a sufficient body of work to extrapolate the findings to establish and test alternative urban futures: to create a variety of scenarios, building on prior and new work, and predicated on different fundamental assumptions and priorities; to assess those scenarios in terms of design, engineering implementation and measurement of performance; to refine them, in terms of mitigation and adaptation measures, incorporating novel solutions; and ultimately to provide alternative solutions with an associated evidence base and strategies for their implementation. This bid seeks to integrate the outputs of three current SUE consortia (Birmingham Eastside, VivaCity 2020 and WaND) and complementary research on the use of trees to mitigate the effects of atmospheric pollution. The team will work across disciplines to envision and establish alternative futures (using extensive literature on this subject and prior WaND consortium work) and construct scenarios that might flow from each alternative future. The various work packages will then focus on testing specific dimensions of each alternative future vis a vis their design, implementation and performance in the context of case history sites. Each project will engage an expert panel of influential stakeholders who will meet six-monthly to test and help shape new ideas, the chairs of each of the expert panels forming the higher level project steering committee. Panel consultation will be followed by interviews of stakeholders on motivations and the decision-making process, and specific empirical research and modelling. The following high level questions will be addressed via this process: - How does the ab initio conceptualization of sustainability influence design outcomes (e.g. form, density)? How would outcomes change if urban renewal were predicated on either environmental or social or economic overriding drivers? - How does development impact on its environs, and vice versa (e.g. is a 'sustainable' site good for the city / region / country and, if so, in what ways?) and is there an optimum development size to yield optimally sustainable outcomes? - Push versus pull to achieve sustainable outcomes. Much of what is done is thought good (for individuals, society, the environment), what might be wanted (push). Thus decisions are made and people must decide whether or not to take ownership. Might more sustainable outcomes follow if those who must take ownership dictate what is created (pull)? Birmingham Eastside will be used both to develop sustainability ideas and to test them on sites at various stages of planning and development (the research team has unparalleled access via its partnerships with key stakeholders involved in Eastside). Lancaster (with Morecambe, population 96k) and Worcester (94k) will be used to test the outcomes at the scale of smaller urban areas (e.g. market towns) but no attempt will be made to build comprehensive databases as at Eastside. Several other UK and international urban areas (including Sao Paulo, Singapore and an urban area in India) will be used to test a sub-set of the project's findings to assess the transferability of the scenarios to a variety of contexts and thus their general applicability.