Abstract: A solar radiation assembly forming a portion of an envelope of a building wherein sunlight entering the building is selectively regulated by exterior and interior variable radiation transmission assemblies positioned, respectively, on the outside and inside of a central unit of glazing. The exterior assembly includes adjustable reflective vanes and an outer protective glazing. The interior assembly comprises adjustable dark colored vanes and a retractable insulating cover positioned between the inner vanes and the central glazing. Additionally, where thermal insulating glazing is employed as a glazing unit, the integrity of sealed air chambers between layers of glazing are protected by an expandable bladder.