Everyone has ever met this situation for an urban walk. A pedestrian along the walkway crosses quiet places and suddenly is blown after the corner of the building. Venturi effects, wake effects, swirl effects or wise effects are scientific words to describe the complexity of the urban flow.
Numerous studies in the world try to predict the urban flow in order to avoid such shear flows generating strong transition and could affect the pedestrian equilibrium and his comfort. Despite these behaviors are well known, they may appear in any new urban designs. Urban planners need to qualify an outdoor spaces according to the wind aspects.
A multi-criteria approach to improve the pedestrian comfort
Such wind behaviors should impact the perception of the comfort. Obviously build dense urban city in windy area lead to meet such uncomfortable situations. On the other hand, windy places may remain “comfortable places” as soon as sun irradiates the urban pedestrian area.
The climatic comfort depends also on the pedestrian activity (seated, moving slow or quick walking) and on the pedestrian clothing. Comfort appears at this stage complex and depending on lots of criteria. The multi-criteria approach of outdoor comfort consists in characterizing the pedestrian comfort with various physical criteria. Among others, thermal ambiance, lighting, acoustical ambiance are crucial as soon as the quality of outdoor spaces is concerned. Urban planners need a synthesis approach based of multi-criteria tool in order to improve their project. Such a tool was developed throw a partnership named Envie. Four teams, Meteodyn, Siradel, Cerma, MGDIS joined their skills to build a tool based on 3D buildings modeling. Technical inputs such as frequency of discomfort, wind energy, solar energy, feed the visualization interface. Viewers move in the 3D virtual space and extract useful information devoted to qualify the urban.