GENIUS: A tool for multi-disciplinary and multi-scalar databases
Résumé
Cities are responsible for the majority of energy consumption on the planet. As a consequence, researches regarding energy use in urban context have been increasing for the last decades. Recently the interrelationship between city, energy consumption and urban microclimate appeared as a key component of urban sustainability.
To be accurate, those studies must take into account a multidisciplinary urban context and modelling tools need high definition data. Nevertheless, at the city scale, input data is either imprecise or only available for small areas. In particular, there is a lack of information about buildings footprints, roofs sloping, envelope materials, etc. Moreover, the existing data do not allow researchers to explore prospective issues such as climate change or future urban development.
In this sense, we developed a new tool called GENIUS (GENerator of Interactive Urban blockS) to build high definition and evolutionary maps from available databases. GENIUS creates maps composed of archetypical neighbourhood coming as shape-files of polygons with additional information (height, age, use, thermal insulation, etc.). Those archetypical neighbourhoods come to seven types of urban blocks that can be found in most European cities. Those types can be compared with Stewart and Oke Local Climate Zones (LCZ). The first step of our method is to transform an existing map into an “archetypical map”. To do this, the urban database of the IGN (French Geographical Institute) was used. The maps were divided into cells of 250 meters resolution. For each cell, about 40 morphological indicators were calculated. Seven groups of blocks were then identified by means of Principal Component Analysis.
GENIUS databases are also able to evolve through time. As a matter of fact, the initial map is transformed, year after year, by taking into account changes in density and urban history. In that sense, GENIUS communicates with NEDUM, a model developed by the CIRED (International Centre for Environment and Development), that simulates the spread of the city and provides information on build density. Under the influence of those density evolutions and of different urban planning scenarios, GENIUS changes the type of urban blocks and their parameters (height, plot ratio, thermal properties, etc.).
The paper will present the validation of GENIUS and its application on the French city of Toulouse. Six scenarios have been designed taking into account demographic evolutions, economic contexts and urban planning policies. For each of those scenarios, we generated maps of the city and its surroundings from 2010 to 2100.
The obtained maps enabled us to come up with simulations of Toulouse energy consumptions and microclimate both present and future.
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