EXPLORING METRICS ON THE EVALUATION OF THE BIOCLIMATIC POTENTIAL AT EARLY STAGES OF URBAN PROJECT

Understanding and limiting the impact of buildings on their environment while seeking for optimal comfort became a matter of prime concern in urban planning. This important issue brings us to a reflection on the definition of a “bioclimatic urban planning”: aiming at minimizing the energy needs while optimizing the luminous comfort on an urban project. In this paper, we explore different metrics of luminous comfort and daylighting of the literature [1, 2] in an attempt to define an indicator appropriated to the early stages of an urban project. We choose as a case-study an office building regarding its daily occupancy and strong lighti ng consumptions. Regarding urban planners practices in France, we can identify three key stages in the design of an urban project: the “guide plan”, the “mass plan” and the “block plan”. In the guide plan, an approximate 2D distribution of the different elements of the urban program is configured. The volumes are represented in the mass plan, as mass blocks corresponding to the level of detail LOD1 of the CityGML norm [3]. Finally, architectural details such as openings at windows positions, roof tilts or solar protections are defined in the block plan. The mass plan strikes us as a key stage of an urban project regarding its “bioclimatic potential”. Works on the search of an optimal geometrical configuration of the urban layout have pointed out the impact of parameters such as glazing ratios and performances or walls characteristics on the final solution [4]. Those parameters are still unknown at this stage of the project. Meanwhile, based on expert opinions, it is possible to emit consistent hypothesis for given cli matic zone, use and targeted thermal performances of the building. The architectural details remain unknown but it is possible to have a precise idea of the building envelope and an indication on its interior through those three parameters. Window positioning, solar protections or balcony are defined by the architects. Meanwhile, the urban planner may explore their impact on the performance of his project to set his architectural guidelines. Using procedural modeling to configure levels of detail may allow a refined ana lysis of the geometry at the early stages of the project [5].