This article investigates the potential of selected urban typologies in Vienna to reach the state of Positive Energy Districts (PED) by achieving a positive annual energy balance. It follows the EU initiative for implementing at least 100 PED in Europe by 2025. Four urban typologies have been assessed using the bottom-up energy modelling tool MAPED that enables a simplified energy demand-supply analysis at the district scale. Considering relevant urban typologies in different construction periods, the analysis focused on converting the allocated building stocks into PED by employing comprehensive thermal refurbishment and energy efficiency measures, electrification of end-uses and fuel switching, exploitation of local renewable energy potential, and flexible interaction with the regional energy system. The results reveal that a detached housing district can achieve a positive annual energy balance (for heat and power) of 110% due to the fact that there are sufficient surfaces (roofs, facades, open land) available for the production of local renewable energy, whereas the remaining typologies fail to achieve the criteria with an annual balance ranking between 61% and 97%, showing additional margins for improvement to meet the PED conditions. The presented concept offers a practical approach to investigate the PED suitability of urban typologies. It will help the Austrian Ministry for Climate Action and Environment to identify appropriate strategies for the refurbishment of existing urban areas towards the PED standard.

Urban agglomerations show different development patterns and stages. Here, we describe, discuss and compare urban agglomerations in different continents. The introduction section gives a general overview of specific issues of urban agglomerations. Different characteristics in Europe, Asia and America are discussed as experienced by the article’s co-authors, living in or working for urban agglomerations in these continents. First, the history of urbanization and agglomeration evolvement is described, then patterns, functional structures and relations, drivers as well as social and demographic characteristics are discussed (e.g. migration, aging, household structure, housing patterns, workplaces, etc.). Transportation infrastructure (roads, public transport systems) is also addressed as trigger for spatial dynamics causing certain effects (floor space, office and apartment rents releasing urban sprawl or hyper-densification), as well as gentrification. Further topics are urban governance and its impact on agglomeration development. Recent state and future trends will be debated, if important. A conclusion section summarizes the comparison of state, dynamics, drivers and trends.

The Smarter Together project implemented in the three lighthouse cities (LHCs) of Lyon, Munich, and Vienna a set of co-created and integrated smart solutions for a better life in urban districts. The implemented solutions have been monitored using a novel integrated monitoring methodology (IMM) following a co-creation process involving key stakeholders of the LHCs. With focus on holistic building refurbishment and the integration of onsite renewable energy supply (RES), the three LHCs refurbished around 117,497 m² of floor area and constructed 12,446 m² of new floor area. They implemented around 833 kWp of PV, 35 kW of solar thermal and 13,122 kW of geothermal heating systems. Altogether, the realized solutions for low-energy districts in the three LHCs will annually save around 4000 MWh/a, generate 1145 MWh/a of RES and reduce around 1496 tCO₂/a of CO₂ emissions, corresponding to specific values of 37.6 kWh/m².a and 11.9 kg-CO₂/m².a for final energy saving and CO₂ emission reductions, respectively. KPI-based monitoring and evaluation of the implemented solutions provides qualitative and quantitative insight, experience and lessons learned to optimize the process of implementation and deployment of integrated solutions for holistic building refurbishment, and thus contribute to advancing sustainable urban transformation at the district level for both LHCs and FCs.