The impact of the urban form on energy consumption and solar access, case of individual housing subdivisions in Constantine

Abstract

Climate change and energy are more topical than ever. Many governments around the world are striving to meet these challenges, especially for the future, which would see severe climate change if the environmental problems caused persist. To address these two issues, it is needed to promote the use of renewable energy and the introduction of energy efficiency measures particularly in urban areas. Buildings are indeed among the world's largest consumers of primary energy, principally of fossil origin. The increase or decrease of this consumption is due to the regime of several factors, citing; climate change; typo-morphological factors on the three scales; urban, architectural and envelope; occupant behaviour as well as the energy potential brought by the integration of on-site renewable energy solutions. However, to overcome this situation, a lot of work has been done on the issue of energy in buildings, but without considering the assessment of the future climate. In this respect, seeking a present and future projection related to the energy and climate change issue, this research project aims to examine energy demand, local solar energy production and the impact of urban typo-morphological factors on cooling and heating needs as well as on solar access, in present and future climate scenarios. The focus of the study is on the case of individual housing subdivisions in Algeria, in the metropolis of Constantine. To this end, the study method starts with the selection of four different urban residential forms in the city through an analysis of subdivision housing in the city's commune. Through a closer examination of the selected cases, the geometric and typo-morphological factors of the buildings were identified. In addition, the actual energy consumption data estimated for the four urban forms were obtained. Then, the urban energy model of the urban forms was carried out using the urban building energy modelling tool CitySim. This model goes through three tools, starting by AutoCAD and SketchUp with an identified 3D geometric urban form modelling, then the 3D model is imported into the CitySim software, where the latter requires the addition of the climatic data of the location and building input data. Using test simulations, at this stage, the calibration method of the building energy model and the modelling of the future climate of 2050 have been carried out. In the analysis of the impact of urban form factors on the energy behaviour, solar irradiation and the evolution of the latter two components on the future projection, a mathematical linear regression model was used. For the evaluation of solar techniques in urban forms, the method developed by Professor Raphael Compagnon is used. Finally, an approach to model photovoltaics on buildings and how rooftop photovoltaic production can reduce energy needs in current and future scenarios was discussed. The results obtained showed that the variation of typo-morphological factors leads to a wide range of heating and cooling requirements, per unit of building volume, which differ by a factor of 2 and 6, respectively, between the urban forms. The solar energy assessment shows that there is significant solar potential on roofs. A relatively small photovoltaic area can eliminate most of the electricity demand for all urban forms. The results tend to improve the energy efficiency of housing and further enhance its environmental quality. They can also contribute to a strategy of reducing energy consumption and moving towards clean energy in the residential sector.