Thursday, 26 January 2017: 4:00 PM
Conference Center: Tahoma 2 (Washington State Convention Center )
A fine description of the urban tissue is necessary in order to perform accurate urban climate simulations or analysis of risks in urban areas. However, global landuse land cover databases only describe the urban areas as 'urban'. The WUDAPT (World Urban Database and Acces Portal Tool; http://www.wudapt.org/) initiative offers a unified methodology to improve dramatically the description of the urban areas. WUDAPT uses the Local Climate zones (LCZ) classification, newly and widely adopted by the urban climate community. The WUDAPT methodology is to use landsat images in order to classify the LCZ with pixels at 100m of resolution. Each city would be processed and validated by a scientist with local knowledge. This is a very promising to acquire urban data for urban climate modeling anywhere in the world. However there is no description of the morphological or architectural parameters yet. Those parameters are still uniform for each class (so-called WUDAPT level '0'). The ambition of the present contribution is to propose a way to describe the specific architectural characteristics of each LCZ for a given city (Paris buildings are not built as New York or Niamey) or even the variability of these architectural characteristics inside each city. Our methodology is based on building architectural archetypes. These are used to define, in each region of the world (a region, a country, a part of a country), how the buildings and houses have been built in the past. This approach requires expertise from local architects, that will have to provide a description of the construction methods and materials of their geographical area of expertise. The methodology, presented on the picture below, is done in three steps, the 4th step being essentially a validation phase. Note that in the example below, the use of the TEB-BEM model can be replaced by other urban canopy models. The building archetypes are based on four inputs : urban types (LCZ, whose maps are provided by WUDAPT level 0 methodology), information on geographical location (the city or country under consideration), and two other inputs, that are variable within the city : date of construction of the building and building's use. These two are important because old buildings use different materials, architectural forms (e.g. glazing ratio) and insulation than newer ones; and commercial, offices or residential buildings are also different. for each possible combination of these 4 parameters, several material and physical properties of the buildings are defined (e.g. thickness of wall insulation layer, albedo and material of roof, use or not of air-conditioning, glazing ratio, etc...). Then, once these building archetypes are described this way, this description is used to map the urban characteristics for the urban canopy model. Mapping of buildings use and age would be the best, as it will allow to produce variability of the buidlings architectural characteristics between the different areas of the city (WUDAPT level 2 information). If such information is not available, one should have to assign building's use and age to LCZ classes, and this would still produce refined information (level 1) compared to level 0 WUDAPT, as the physical and architectural parameters will still be region dependant, and specific to the urban area of interest (Paris description will be different from New York or Niamey). This approach will be presented and evaluated on several cities.
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