Quantitative Evaluation of BIPV Visual Impact in Building Retrofits Using Saliency Models

Abstract

BIPV (Building Integrated Photovoltaics) integration in urban spaces requires, not only careful technical, but also aesthetic considerations as its visual impact is seen as a kind of environmental effect. To manage this effect, different methods were developed to measure it; however, most existing evaluation methods are either based on subjective speculations and have no continuous criteria standards, or they do not show much relevance to neuropsychological findings. This paper presents an alternative and complementary method for evaluating the BIPV visual impact using the saliency method with an objective, quantitative and neuropsychological-based approach. The application of the method was tested and is discussed in the context of an example case study in Switzerland. Several different BIPV designs were developed for the case study, purposely in ways that made it difficult to rank their visual impacts with one's subjective instinct. Using the proposed saliency method; however, the differences in BIPV visual impact across all designs could be identified, demonstrated and calculated sensitively. Potential applications of this proposed method include being a helping tool in deciding which BIPV design causes the least or most visual impact among others. Additionally, when combined with solar cadaster, the method enables a comprehensive estimation of BIPV potential in urban areas from both technical and societal aspects.

Aesthetic impact of solar energy systems

“…Additionally, fractality should be considered when analysing perception in a natural environment [18,19,23,67,69]. Recently, the adoption of the saliency from the computer vision to the aesthetic impact of SES has opened the door to new and interesting measures [55].…”

“…The saliency models extract information from colour contrast, light contrast and orientation of the image. Additionally, render images are generated with a software that is capable of following the physical behaviour of the light [55]. Note how this objective factor includes, at least partially, other significant objective factors mentioned above, such as colour and glare.…”

“…For the SES impact, the visibility and especially the integration degree are the most influential objective factors; however, colour and pattern can help to improve integration. The increasing use of computer tools for this type of study could facilitate the analysis of objective factors together in the future, as has being recently done in some research focused on colour and glare using the concept of visual salience [55].…”

Building-Integrated Photovoltaics (BIPV) in Historical Buildings: Opportunities and Constraints

“…The guidelines for improving energy efficiency in cultural heritage indicate that no solution can be considered in itself decisive and that the perspective, in which to move, can only be that which pragmatically proceeds on a case-by-case basis. The current approach is to reduce visual impact, using shields which obstruct the view of the modules to obtain a low magnitude of impact [21,42]. However, the approach cannot be simply one of concealment.…”

EU-Funded Projects with Actual Implementation of Renewable Energies in Cities. Analysis of Their Concern for Aesthetic Impact

“…For example, the social aesthetic perception of solar systems used in the solar house prototypes displayed during the Solar Decathlon Europe 2014 competition has been assessed [5]. We also found studies focusing on methods to evaluate the impact of PV applications [15][16][17]. Other researchers analyze the social acceptance of these installations [18,19].…”