The concept of Circular Economy has gained momentum during the last decade. Yet unsustainable circular systems can also create unintended social, economic and environmental damage. Sustainability is highly dependent on a system’s geographical context, such as location of resources, cultural acceptance, economic, environmental and transport geography. While in some cases an impact of the proposed change may be considered equally significant under all circumstances (e.g. increase of carbon emissions as a main contributor to the global climate change), many impacts may change both their direction and the extent of significance dependent on their context (e.g. land consumption may be positively evaluated if applied to abandoned territories or negatively if a forest needs to be sacrificed). The geographical context, (i.e. its sensitivity, vulnerability or potential) is commonly assessed by Spatial Decision Support Systems. However, currently those systems typically do not perform an actual impact assessment as impact characteristics stay constant regardless of location. Likewise, relevant Impact Assessment methods, although gradually becoming more spatial, assume their context as invariable. As a consequence, impact significance so far is also a spatially unvarying concept. However, current technological developments allow to rapidly record, analyse and visualise spatial data. This article introduces the concept of spatially varying impact significance assessment, by reviewing its current definitions in literature, and analysing to what extent the concept is applied in existing assessment methods. It concludes with a formulation of spatially varying impact significance assessment for innovation in the field of impact assessment.

Urban metabolism is a multi-disciplinary approach to qualitatively and quantitatively evaluate resource flows in urban systems, which aims to provide important insights into the dynamics of cities to make them more ecologically responsible. It has been also introduced into the urban design domain, however most of the attempts concern only tracking of energy and/or material flows to reduce environmental impacts by redesigning closed loops in a specific area. The hypothesis of this paper is that the concept of urban metabolism, and its indicators, could play an important role in advancing the science and practice related to sustainability in urban design and development. At the moment, however we lack indicators to support evaluation of urban design related decisions from the perspective of urban metabolism. The aim of this paper is to explore the application of urban metabolism indicators in urban design based on their characteristics. It reviews development periods of the concept and analytical models of urban metabolism, in order to identify crucial urban metabolism indicators for urban design. Next, these urban metabolism indicators are classified regarding type of analytical model, accounting method, indicator type, and indicator level. Finally, several suggestions are offered on how to integrate urban metabolism indicators into urban design. In addition, directions for future research on the topic are discussed.

It has been argued that different urban configurations-planned vs. organic, treelike vs. grid like-perform differently when it comes to the intensity and distribution of pedestrian flows, built density and land uses. However, definitions of urban configurations are often rather abstract, ill-defined and at worse end in fixed stereotypes hiding underlying spatial complexity. Recent publications define morphological typologies based on quantitative variables (e.g. Barthelemy, 2015; Serra, 2013a; Gil et al., 2012; Berghauser Pont and Haupt, 2010) and solve some of these shortcomings. These approaches contribute to the discussion of types in two ways: firstly, they allow for the definition of types based on multiple variables in a precise and repeattable manner, enabling the study of large samples and the comparison between both cities and regions; secondly, they frame design choices in terms of types without being fixed and so open up for design explorations where the relation between the variables can be challenged to propose new types. This paper explores the typologies defined by Serra (2013a) and Berghauser Pont and Haupt (2010) further, as these target two of the most important morphological entities of urban form, namely the street network and the building structure. The purpose is to gain a better understanding of how types are composed and distributed within and across different cities. The method is based on GIS and statistical modeling of four cities to allow for a comparative analysis of four cities: Amsterdam, London, Stockholm and Gothenburg. For the street network, we process the Road-Centre-line maps to obtain a clean network model, then run segment angular analysis to calculate the space syntax measures of betweenness at different metric radii, defining the "centrality palimpsest" (Serra, 2013a). For the building structure, we process elevation data to obtain building height, then run accessible density analysis for all building density metrics (FSI, GSI, OSR, L) using the Place Syntax Tool (Berghauser Pont and Marcus, 2014). The street and building types are defined using cluster analysis (unsupervised classification), following a similar approach to Serra (2013a). The result is a typology of street ('paths') and building types ('places'), with different profiles of centrality and density across scales. The spatial distribution and frequency of these types across the four cities gives an objective summary of their spatial structure, identifying common as well as unique traits.

This paper reviews an idea of vital local high-street places with their walking spaces and economies founded in interfaces between neighbourhood and city (between walking and public transport/bicycle movement infrastructures). It then extends this idea to higher scales, considering interfaces between city and region, which have already been theorised as ‘mobility environments’ (Bertolini & Dijst 2003) focusing on places and modal transfer points in new regional cities of high mobility. High-streets and mobility environments are both central places and our way of describing them suggests a new definition of central places as interfaces between normative (but also technically-infrastructually supported) political spaces (neighbourhood, city and region). It also clarifies the role of scale in place theory and we will deal with this in a following paper. Here we introduce ideas of ‘modality places’ and ‘modality environments’. The ‘modality environment’ is concerned with areal and network transportation forms in whole fabrics and resulting conditions of sustainability and urbanity. Modality environments are understood in terms of transportation networks and the social and functional factors (like sustainability and urbanity) they produce. Modality environments are seen as lived environments built around movement infrastructure grids that distribute everyday urban functions. Ideally modality environments would be simple clear grids that distribute all or close to all the functions of everyday life so that a walking grid or a bicycle grid that gets adults to work, their children to school and includes shopping and recreation would be walking or bicycle modality environments. They would be expected to have high levels of direct visibility-legibility in the way urban elements present themselves to a mobile community. Modality environments would also include the central places (like high-streets or mobility environments like stations) at which people would transfer to other modality environments. We will use a notion of ‘movement culture’ to indicate the convergence of land uses and mobile communities mediated in information-rich networks. We are concerned first with how modality environments (for cycling or walking for example) may afford more sustainable lifestyles. We are concerned in addition with the ways they can be designed to include central places as zones of urbanity and vitality and as socially and culturally mixed centres. We start not with a principle of accessibility of/from nodes in an extensive space but with the idea that particular social and political territories (communities and polities) are already articulations of distinct modality environments. We demonstrate using the case of the Amsterdam metropolitan area.