Hybrid roofscapes - architectural impacts of roof-integrated PV/T-collectors

Abstract

In the future, buildings must be operated free of CO2-emissions. To achieve this goal the chair of building systems at ETHZ has developed a system named Sol2ergie. In a Sol2ergie building large surfaces of PV/T-collectors (PV/T) are needed to regenerate the deep ground heat exchanger. The system covers up to 90% of all the thermal demand for heating and domestic hot water by locally stored heat and considerably decreases the maximum power requirement. Architecturally, the PV/T is the most sensible element of the system. For energetic and economic reasons it makes sense to integrate the PV/T into the building skin, but replacing the modular application with functional integration implies a complete new interpretation of historical and contemporary roof constructions. For that reason, this study is part of a research project based on an interdisciplinary cooperation between ETHZ and the institute for constructive design at the ZHAW. The aim of the presented study is to investigate how this new technology may change the roof on a typological and urban level. Seven scenarios in four different existing urban situations show future transformation strategies. In the conservative scenarios the roofs do not offer enough PV/T-surfaces, whereas in the more progressive and innovative ones the new roof typologies may cover the whole annual energy demand. Therefore we argue that the design of roofs is going to be one of the key aspects on the way towards a more sustainable built environment. In addition this study is also a contribution to the discussion about the vertical densification of central urban districts.