In this paper we introduce a model for specifying fluid architectures of intelligent environments. A fluid architecture is one that is able to accommodate continuous structural changes without aversely affecting the system's behaviour. The model enables designers to specify structural modifications that may be performed by users as part of the normal interaction and which must be supported by the underlying environment infrastructure. The model is formulated as a generative architectural style: it defines component types, connector types and rules for their composition. This leads to a model that can describe an unlimited number of concrete architectures. To demonstrate the utility of our model, we discuss the design, architecture and change scenarios of an ambient display system