Energy and Buildings 86 (2015) 340–348 Contents lists available at ScienceDirect Energy and Buildings j ourna l ho me pa g e: www.elsevier.com/locate/enbuild Using urban canyon geometries obtained from Google Street View for atmospheric studies: Potential applications in the calculation of street level total shortwave irradiances Roberto Carrasco-Hernandez ∗ , Andrew R.D. Smedley, Ann R. Webb Centre for Atmospheric Sciences, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Simon Building, Oxford Road, Manchester M13 9PL, UK a r t i c l e i n f o Article history: Received 24 February 2014 Received in revised form 30 September 2014 Accepted 4 October 2014 Keywords: Google Street View Street canyon irradiances Canyon fisheye images a b s t r a c t This paper presents an implementation of digital image processing tools, in order to reconstruct build- ing geometries and urban sky view factors for individual street canyons around the world. By using the Google Street View image database, it is possible to reconstruct canyon fisheye images at any point where a Google panorama is available. The Hugin software allows the geometrically correct merging of inde- pendent images in order to create a fisheye projection, covering the upper hemispheric view of the sky. Sky view factor calculations may then be performed by specialised software on the reconstructed fisheye image. In order to analyse the fitness of reconstructed panoramas, control images taken with a fisheye lens camera were used for comparison. The Rayman model was then used to calculate total shortwave global irradiances from the restricted canyon view and from a full hemispheric view. Finally, total shortwave global irradiances were measured for the same position in the street canyon and compared against obser- vatory measurements under a full sky view, this in order to evaluate the performance and usefulness of idealised calculations. The reconstructed urban geometries returned acceptable fine-scale descriptions, and their potential utility for scientific purposes in the atmospheric sciences was demonstrated with the examples provided. © 2014 Elsevier B.V. All rights reserved. 1. Introduction A growing proportion of the global population lives within urban canyons, i.e. city streets surrounded by buildings [1], in which the restricted sky view reduces solar energy access. Because of the unique microclimate conditions created by the specific geometry of each canyon, urban geometries affect the energy performance of buildings and, since main outdoor activities occur at these spaces, they also play a crucial role in human thermal comfort in streets [2,3]. Human exposure to sunlight within urban canyons is also a relevant health issue due to the diverse biological effects of ultra- violet light [4,5]. Some of the future aims of our study will include spectral irradiance calculations within urban canyons in order to determine urban solar UV patterns, as an aid for health studies. This paper presents the initial stages of reconstructing urban geometries for the calculation of total shortwave irradiances. ∗ Corresponding author. Present address: Simon Building, Oxford Road, Manches- ter M139PL, UK. Tel.: +44 7412852056. E-mail address: roberto.carrascohernandez@postgrad.manchester.ac.uk (R. Carrasco-Hernandez). The geometry of urban canyons, defined by the variations in height, length and spacing between buildings, has a significant effect on the energy budgets of urban areas [6]. Since the 1980s many urban meteorologists and climatologists have been using geometrical indices for describing urban canyons, particularly the Sky View Factor (SVF). According to the definition of [7] in [8], the Sky View Factor is “the ratio of the radiation received (or emitted) by a planar surface to the radiation emitted (or received) by the entire hemispheric environment”. However a more common way of understanding it is as the proportion of unobscured sky from the perspective of an observer. The SVF index has proven to be useful, not only for describing canyons, but also for modelling and predict- ing atmospheric conditions on urban micro-scales, affecting energy exchanges, temperature variations, and air movement phenomena [9–16]. The SVF has also been used to explain public health issues and create geographic models of disease risks, for example tuber- culosis [17]. It also has potential applications in building and city planning e.g. daylight in buildings, heat loading and energy conser- vation. In addition, it can provide with the exposure to sunlight of individuals within the canyons, for realistic assessment of people’s exposure to ultraviolet radiation, for example. Given its impor- tance, current and future research needs to focus on creating ways http://dx.doi.org/10.1016/j.enbuild.2014.10.001 0378-7788/© 2014 Elsevier B.V. All rights reserved.