As often happens to container-concepts in this period of communication, the term sustainability is another that embraces a broad and vague semantic arc, dissolved into myriad streams affecting as many aspects of our sociosphere. The most obvious thing to be noted is that sustainability is evoked as a key issue in all discussions about climate change and transformations – in a pejorative sense – within the eco-environmental system. In these cases, the concept is used to express the norms and technical devices adopted by governments and institutions to attenuate our ecological footprint on the planet. A norm is the formal procedure that establishes order and governs habitual behaviour of a given community. In the interaction of these two poles, however, it is essential that habit be a substratum existing prior to the rule. In fact, if a community has no habitual culture capable of receiving and understanding it, the norm remains only an empty husk, a mere exercise in style. As for the ethic of sustainability, one’s suspicion is that exactly the opposite occurs: by a sort of inexplicable reversal of the logical nexus, the laying down and production of notions, options and sustainable projects today seems abstracted and disembodied from common behaviour as a whole. There is a detachment and an unbridgeable gap between these two dimensions. The main problem seems to be precisely how to find the right virtuous mechanism needed to co-opt the dimension of a collective ethos when approaching sustainable dynamics. As Yona Friedman writes in this month’s Intersections, it is not by governing from above, at a macroscopic level, that a mutation of our society can be thought of in a sustainable sense. The macroscopic result, if there is one, will be the effect of billions of daily micro-behaviours merged into networks. Two examples, recounted by Julie Sze and Simon Sadler, again in Intersections, significantly illustrate the importance of clearly recognising the role of habitual culture in the theoretical formalism of a norm. These are two attempts, each very different in their assumptions and outcome, to create eco-sustainable communities – in China and in South Africa. While the experience of the eco-village at Huangbaiyu, in the north of the People’s Republic, proved an utter failure, because the application of an abstract ecological norm ignored the social peculiarities of the local rural community, the second experience – Ivory Park in Johannesburg – has on the contrary been an incredible success, because here the process was sparked by requests from a grass-roots community which managed to create a norm out of a new need for a certain behaviour. The role of collective awareness in an eco-sustainable choice is decisive when sanctioning the outcome and sense of our redefined model for living. By reducing the scale of design from the urban to the individual, and working on the threshold where exterior macrospace and interior microspace come into contact, architecture may perhaps be able to contribute with better results than it has achieved so far, to a change of social behaviour in a sustainable sense. Naturally, the terms of architecture’s acceptance of the sustainability theorem will need to be reconsidered. And they won’t be those of a technocratic application of certified standards any more, but of a radicalised approach by design to space. Philippe Rahm, for example, at the latest Venice Architecture Biennale, admirably showed how this task is within architecture’s reach. In his Digestible Gulf Stream, Rahm develops concepts that are of a disarming simplicity, yet extremely effective in their capacity to prompt suggestions and connections. Design, by confronting the matter of thermal comfort, admits that a habitable environment is the result of a balance struck by different communicating dimensions: climate, but also clothing, food and physical activity. “Architecture,” Rahm claims, “is the thermodynamic mediation between the macroscopic and the microscopic, body and space, clothing and nakedness, movement and stillness, the individual and the group, meteorology and physiology.” Voilà. This oscillation between infinitely small and infinitely large, between the abstract space of concepts and the concrete place of habits, is the – decidedly very empirical and unspectacular – scenario within which, to my mind, an architecture can and must operate if it is to succeed in radically designing a hypothetically sustainable living.