‘Zukunftsquartier’—On the Path to Plus Energy Neighbourhoods in Vienna

Abstract

This paper presents an approach to define and implement a ‘Zukunftsquartier’ (future neighbourhood) in the context of the densely populated city environment of Vienna, which is in line with the national energy targets 2050. The ‘Zukunftsquartier’ project explores the feasibility of plus energy neighbourhood concepts at four prospective project sites in Vienna. The case studies evaluate the potential of demand side management, innovative renewable energy systems including photovoltaic and near-surface geothermal energy by hourly energy balancing and are compared for the Austrian building code and ‘passive house’ construction standards. Due to the high floor space index of urban projects, all investigated concepts failed to achieve a positive energy balance, except theoretical variants with unfeasibly high PV utilization of virtually the entire roof and façade surfaces. To offset the unintended effect of plus energy being harder to achieve in a dense urban context, we propose a correction factor for the target energy balance of ‘plus energy’ buildings and neighbourhoods based on the floor space index. Together with a second energy balance adjustment, reflecting the prospective renewable energy system (RES) of Austria 2050, most ambitious variants (utilizing ground heat and moderate PV surfaces) achieved ‘plus energy’ standard for dense urban areas and life cycle costs compared to conventional realizations within 30 years.