Visual impact of BIPV in building retrofits

The public defense of the doctoral thesis presented by Ran XU took place on October 31 2016 at the Ecole polytechnique fédérale de Lausanne (EPFL). Conducted under the supervision of Prof. Jean-Louis Scartezzini (EPFL) and Prof. Stephen Wittkopf (HSLU), this research has investigated the issues related to the visual assessment of building-integrated photovoltaics (BIPV) in building retrofits using saliency models. It was realized in the framework of the ACTIVE INTERFACES interdisciplinary research project, which aims to develop new strategies for the implementation of BIPV in urban renewal processes.

 

Limited fossil energy resources and the potential danger of nuclear power plants led to growing popularity of solar energy. In Switzerland, PV (BIPV and BAPV) was expected to be responsible for up to quarter of the energy production from renewable resources by the time of 2030. In order to protect the existing natural landscape, PV must be concentrated in urban spaces, which means that certain amount of existing building envelopes have to be turned into energy generators. There is a growing concern about BIPV retrofits because they may change the visual appearance of the existing city images to a large extend and/or in a negative way.

 

In order to manage the potential visual impact resulting from PV expansion in urban spaces, in particular on buildings with a clear historical value, evaluation methods should be able to measure it appropriately. This research proposes an objective evaluation method is proposed that is capable of measuring the BIPV visual impact in building retrofits in a quantified approach based on neuroscience knowledge. 

 

The proposed evaluation method integrates saliency model, which imitates the mechanism of human visual attention, into assessment procedures. It is applied on a realistic case study: BIPV designs for a church roof. 

 

It is believed that the synergy between architecture and neuroscience can contribute to a growing understanding of human responses to the built environment. Hopefully the findings from this thesis can help in minimizing the negative visual impact induced by BIPV expansion in urban spaces, and also aid architects in gaining new understandings for visual aspects in architecture design.