We present a new immersive system which allows initial conceptual design of simple architectural models, including lighting. Our system allows the manipulation of simple elements such as windows, doors and rooms while the overall model is automatically adjusted to the manipulation. The system runs on a four-sided stereoscopic, head-tracked immersive display. We also provide simple lighting design capabilities, with an abstract representation of sunlight and its effects when shining through a window. Our system provides three different modes of interaction, a miniature-model table mode, a fullscale immersive mode and a combination of table and immersive which we call mixed mode. We performed an initial pilot user test to evaluate the relative merits of each mode for a set of basic tasks such as resizing and moving windows or walls, and a basic light-matching task. The study indicates that users appreciated the immersive nature of the system, and found interaction to be natural and pleasant. In addition, the results indicate that the mean performance times seem quite similar in the different modes, opening up the possibility for their combined usage for effective immersive modeling systems for novice users.Read less <