A method is proposed to assess the natural ventilation potential (NVP) of the Basel Region, Switzerland, by taking into account the most comprehensive set of factors involved in natural ventilation. These factors are either driving forces, such as wind pressure and stack effect, or constraints, like noise pollution and atmospheric pollution. The process considers these factors in an ordinal qualitative scale and gives its result in this same scale. Climatic data are extracted from a mesoscale atmospheric simulation model referred to as FVM (Finite Volume Model), accounting for the effect of the urban tissue and taking as boundary conditions data coming from a model of the Swiss national weather service (MeteoSwiss). FVM provides an urban turbulence module which specifically simulates the effects of urban areas on the meteorology. Qualitative scales allow to bypass the problem of the inaccuracy of some parameters, which can be very high, especially in urban environment and in the pre-design phase of a construction project. Actually, the method is particularly suitable for designers intending to take early-stage decisions.