Buildings are a big sustainability challenge. And yet, as a value, sustainability is not central to how architects' work is evaluated by their peers and society at large. They are mainly recognised and rewarded for their aesthetic achievements, the benchmarks for which can be traced to the exemplars of unsustainable modernism, including Le Corbusier's Chandigarh. Over the last forty years, however, a broad current of architectural practice has developed many sustainability critiques of the hallowed mainstream and also established new exemplars and principles of building sustainably in India. The social, technical, and aesthetic achievements of the practitioners that form this current are important and have opened exciting new paths for sustainability explorations. But I argue that this current of practice urges us to consider something more fundamental: aesthetic or cultural achievement is a relatively narrow value to center architectural practice on. What matters is the criticality of practice, that forms the basis of creativity. Through a discussion of pioneers of sustainable architecture in contemporary India, then I will present some thoughts on the orienting ideal of 'critical practice' that hopefully has relevance beyond the field of architecture, building on and departing from Rendell's (2007) and Schon (1992).