Generally speaking, the virtualization technique allows to maximize the exploitation of available physical resources by abstracting from them a set of virtual resources that users independently own. This paper proposes to apply the virtualization technique to the built space. For this, we present a case study called on-demand room, where the same physical resources (space, furniture, appliances and networks) are dynamically and transparently reallocated to different apartments. Thanks to implicit interaction and automatic reconfigurations, inhabitants have the impression of owning a bigger surface than the physically available one. We present a demonstrator of on-demand room that was realized leveraging a large-scale immersive virtual reality platform and provide some perspectives for the generalization of the virtualization approach.