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Global and regional estimation and evaluation of suitable roof area for solar and green roof applications
No full textBuildings contribute to 40% of energy consumption and 30% of CO2 emissions in 2019 globally, therefore it is necessary to exploit different solutions to decrease the corresponding energy demand, including green and cool roofs as well as on-site energy generation. To evaluate the potential of such technologies, one major input data for models and calculations is the available roof area, yet the literature shows a huge knowledge gap in this regard. Therefore, this paper contributes to filling this gap by estimating the roof availability over the period 2022–2060, using the detailed regional projections of the BISE (Building Integrated Solar Energy) model. Our results show that the roof area is likely to increase globally and in most of the analysed regions over the forthcoming decades, driven primarily by newly built tertiary buildings. In European context, the future increase of commercial/public rooftops is projected to be more pronounced for the western countries, although the overall growth is predicted to be slightly offset by shrinking residential rooftops both in the western and eastern regions. This study also demonstrates that despite the shading-related uncertainties of the estimation, the dimension of the available rooftop area could ensure significant potential for energy production and thermal regulation
Homophilic organization of egocentric communities in ICT services
No full textMembers of a society can be characterized by a large number of features, such as gender, age, ethnicity, religion, social status, and shared activities. One of the main tie-forming factors between individuals in human societies is homophily, the tendency of being attracted to similar others. Homophily has been studied mainly in the context of link formation and social dynamics. However, less is known about the role of the multidimensional homophily in forming egocentric communities on Information and Communications Technology (ICT) services. To close this gap, we analyze three ICT datasets, namely, two online social networks and one network deduced from mobile phone calls, in all of which data about individual features are available. We identify communities within egocentric networks and surprisingly find that the larger the community, the more overlap is found between features of its members and the ego. We interpret this finding in terms of the effort needed to manage the communities; the larger diversity requires more effort such that maintaining a large diverse group may exceed the capacity of the members. As the ego reaches out to their alters on an ICT service, we observe that the first alter in each community tends to have a higher feature overlap with the ego than the rest. Moreover, the feature overlap of the ego with all their alters displays a non-monotonic behavior as a function of the ego’s degree. We propose a simple mechanism of how people add links in their egocentric networks of alters that reproduces the empirical observations and shows the reason behind non-monotonic tendency of the egocentric feature overlap as a function of the ego’s degree
