The concept of sustainable development applied to built environment involves finding a long-term balance between environmental, socio-cultural and economic objectives. From an operational perspective, the challenge is to imagine concrete actions that foster the simultaneous emergence of positive effects in more than one of these dimensions. Regarding the architectural design, it is a question of implementing coherent strategies that are technically appropriate, environmentally friendly, economically viable and value adding on a socio-cultural level. Far from tabula rasa logic, the context of the European post-industrial city adds the extra issue of dealing with the complex transformation process of already built-up environment. In other words, urban and architectural designers are not designing a new “ideal city” in the open country anymore. They have to find adequate means to optimize existing cities and large conurbations.