Wind flows impact on pedestrian comfort study in a Joint Development Zone project

Abstract: Passive gains are becoming essentials with the introduction of new buildings thermal regulations. To optimize such gains, districts ground plan have to be based not only on urban consideration, but on bioclimatic considerations as well. Bioclimatism first purpose is to take advantage of the local climate and modify it if needed to obtain as much passive gains as possible for the building performance and interior comfort to be improved. The second one is to create a good exterior climate and pedestrian comfort. In fact, the first total factor of energy savings is the density of buildings. It is then of the greatest importance to attract population downtown by offering comfortable exterior spaces that can compete with more rural areas. This thesis will then focus on the wind flows impact on the outdoor and pedestrian comfort. To conduct this research, some points need to be clarified. First, what is the optimum scale to study and adapt the climate to our needs? The scale of the district had several advantages compared to a city or a dwelling scale: it is a representative city sample, its scale is reduced enough for limited data quantity to allow the evaluation of the development decisions impact on the building performance, it has a reduced number of decision makers diminishing the decision complexity and a certain amount of freedom remains allowing to adapt at best the local climate to the project needs. Second, who will be the actors of the bioclimatic conception during the project? The planner and the conception team are ubiquitous during a district conception phase and have a central position in the decision making. Hence, it is with them that the integration of the bioclimatic approach will be the more effective. Third, the success of the thesis is based on the capacity to make the heat engineers and the conception team exchange on the subject of bioclimatism. As a result, it had to be realized in a company possessing at least heat engineers and one of the conception team professions. The French company SCE, part of the Keran group, offered such environment with urban planning and energy and building activities. The process of the study was the following. A benchmark was made on the existing software that could be use by the company to realize pedestrian and outdoor comfort analysis. Then, an outdoor comfort study was made on a district construction project in the French town of Cancale. The project buildings impact on one another was analyzed. For each high frequency wind incidences, simulations were run first in 2D dimension and second in 3D dimensions. Based on the wind speed values inside the district zone calculated by the software, discomfort zone had be highlight. According to the level of discomfort, the installation of different wind breakers type was recommended.