Abstract: The energy-efficient sun room of this invention includes a generally rectangular or box-like frame assembly including a front wall, opposing side walls with a curved transition section between a flat, major roof portion and the front wall. The flat, major roof portion includes a plurality of roof frame members which mount insulated roof panels to provide insulation against the sun. The curved transition section mounts curved glass panel members to enhance the overall open appearance of the insulated sun room of this invention. The insulated roof panels and the curved sections of the glass panels are mounted in a continuum to provide an attractive, insulated but open appearing sun room.