CAVE systems are an immersive environment that surrounds one or more viewers with multiple large screens, which portray a virtual 3D environment. CAVEs use generally between three and six sides and are thus effectively permanent installations, due to the required floor and room space. We describe TIVS, the Temporary Immersive Virtual environment at Simon Fraser University, a system whose defining feature is that it does not consume any permanent floor space. Yet, TIVS can be in operation in less than a minute. Viewers sit on swivel chairs in the center of an 8' × 6' space, where TIVS's frame is mounted onto the ceiling. The bottom of said frame is 7' above the ground, making it easy for people to walk below it. The screens mounted on the frame are rolled down whenever the system is being used and are otherwise stowed away. That frees the floor space for other uses when the system is not in use. The projection geometry ensures that people sitting in the center area of the space do not cast shadows onto the screens. A tracking system attached to the frame provides for head tracking. Overall, the non-permanent nature of the system makes it surprisingly easy to integrate Virtual Reality into everyday environments.