Evaluating solar irradiance over facades in high building cities, based on LiDAR technology

Resumen

Arranging a solar irradiation map of the buildings of a city is a valuable tool for sustainable urban planning in regard to non-carbonized criteria in important applications. Such applications may include: selection of materials for the building envelope and insulation according to the irradiation received at each point; monitoring the installation of photovoltaic systems to ensure that they are located in the optimal irradiance zones; or building restoration to improve the energy efficiency and electric generation. The proposed method enables to estimate the incidence of the solar irradiance as well as to visualize the effect it produces in every region of the buildings that compose the urban area of a city. The process includes the use of Laser Imaging Detection and Ranging (LiDAR) information along with 5-min horizontal irradiance data. This developed algorithm has been verified through being applied to different building envelopes distributed in different geographical areas. The results demonstrate a satisfied performance which makes that the methodology can be extrapolated to any city where the LiDAR Data and irradiance information are available, permitting an accurate analysis of the solar irradiance over the building envelopes. The algorithm succeeds in obtaining a map of solar radiation captured by the envelope of any urban building that estimates the photovoltaic power generation depending on the geographic location and on the influence of shading caused by adjacent buildings. The provided results show clear evidence of the influence of the shade effect produced by both, the building itself and other nearby buildings. Even if the shading effect is a factor that determines the irradiation gradient, the orientation of the facades has been proven to be the most important parameter in seeking a higher value of irradiation. As a result, south facing walls present wider regions with greater irradiance values, which are of interest for photovoltaic implementation. In addition, monthly analyses have shown that the best-oriented facades have produce their maximum solar power during equinox months, March and September. This method is considered as a useful tool for sustainable urban planning and for building integrated photovoltaics development. Although the entire envelope of a building can be studied, this paper is limited to the analysis of the facades. © 2016 Elsevier Ltd