Reshaping the City: Containing the Urban Sprawl and Reducing Solar Access on the Streets in a Hot Desert Climate City

Abstract

Most of the studies on world demographic evolution point to a population growth foresight of almost double by 2050. Also, the proportion of the urban population is expected to grow, from the current 55% to 68% of the total. This perspective generates the need to think about the present and future cities, especially those located in mid – latitudes, where most of that populations accumulates. Many of these cities have a hot desert climate and follow, until now, a dispersed city model (a large extension of the urban area and low densities). These characteristics move them away from the sustainability objectives, so work must be done to reverse the situation. One of the objectives of this work is to demonstrate that urban densification, through the reshaping and stacking of the city, represents an intelligent way to contain the urban sprawl. At the same time, and given that the climate plays a decisive role in these types of cities, in this study is intended to improve the quality of life in the urban public space while answering the growing housing demand. To carry out this work, a hot desert climate city was selected, Hermosillo. The city is located in the state of Sonora in Mexico. It currently has a population of approximately 900,000 inhabitants, it is expected that by the year 2030 it will have increased to around 1,100,000 inhabitants. Therefore, its urban area will go from 17, 500 hectares to almost 23,000 hectares, all of this will create a great housing demand to meet. The methodology in this work is applied to an area of Hermosillo. In this area, the dominant type of land use is commercial, but it also presents other uses to a lesser extent: urban equipment and housing. This type of configuration, together with low-rise buildings, results in an area with low density. The methodology of this study is divided into three stages. The first is the collection of statistical, urban and climatological data. Second, the processing of this data and the creation of GIS-based maps using the ArcMap software. The third stage is the assessment of the solar access at street level, for this, 3D models were elaborated for simulation and evaluation using the Heliodon2 calculation tool. The results have shown that carrying out urban densification through these approaches, and taking into account the planning regulations of Hermosillo favors the increase, favors the increase of housing in the study area, as well as an improvement in the use of public space. A 6.5 times higher density than the actual is achieved by maintaining the current average ratio of square meters of living space per person. At the same time, a considerable reduction of direct solar access at street level is produced. This favors the pedestrian’s thermal comfort, resulting in an improvement in the quality of urban life. This paper concludes that urban densification through these types of approaches generates the possibility to provide quality housing (in terms of habitable space of each dwelling). At the same time, it makes possible the contention of the urban sprawl. As for the improvement of the public spaces conditions, the generation of shade upon the urban space is achieved by using the form of the city itself.