Projections of design implications on energy performance of future cities: A case study from Vienna

• Building performance simulations were used to evaluate alternative building designs.
• Assumed climate change trend suggest lower heating and higher cooling loads.
• Results show the importance of taking microclimatic conditions into account.
• Heating and cooling loads may vary (8–15%) depending on selected weather file.

This paper presents the results of a research project involving a new urban development project in the city of Vienna. Given the expected long life-cycle of this project, the developers requested scientifically-based information concerning the projected extent of the microclimatic changes in the development area and their potential ramifications for open urban spaces and the planned buildings’ energy and thermal performance. To address this inquiry, the first stage of the research involved capturing both the current state and future projections of the climatic conditions of the area. As a next step building performance simulation models were used to evaluate alternative building designs (specifically various surface and layout design options and degrees of vegetation) in view of their mitigation effectiveness vis-à-vis climate change projections. The simulated implications of the assumed climate change trend suggest that the future heating loads will be lower, whereas cooling loads will significantly increase. The results help providing qualified estimations of the extent to which certain surface and building design features influence future cooling and heating loads. Furthermore results show the importance of taking microclimatic conditions of the relevant area into account.