The sustainable city model requires analysis method’s with quantitative indicators and models, for making short and medium term decisions. Environmental assessment systems for urban environment and buildings are based in measured actions qualitatively, and they do not show real environmental impact's urban panorama. Given these characteristics this work development an environmental assessment and diagnosis system for the built city, that is based on the analysis of the life cycle (LCA), for made a impact model and making decisions in the urban intervention, linked in the urban intervention, and ecosystem’s ecological conditions. The methodology implemented shows the relationship between building volume and environmental impact, for environment reinterpretation of city.