Publisher Summary This chapter describes the application of reflecting flat or convex parapet as well as reflecting louvres placed on roofs of high buildings in order to provide reflection of sunlight to northward oriented faces of neighboring buildings. The faces of buildings that are otherwise never illuminated by direct sunlight in winter days, obtain significant amount of solar radiation. A method of calculation is developed that enables determinations of the width of the illuminated belt at neighboring building, as dependent on the radius of curvature of the reflecting convex parapet and the position of its center of curvature. The theory presented in the chapter enables the calculation of the inclination and the radius of curvature of the parapet. In a sophisticated version of the parapet, it is possible to manipulate the illumination, both in terms of intensity and virtual position of the sun by electronic remote control.