Millions of micromirrors inside building glazing are envisaged to guide and control light by electrostatic actuation, enabling energy saving and tailored personalized lighting in smart buildings. The amount, direction and degree of steering of the guided light are tailored to winter, summer, variable daytime requirements and presence and position of persons. Micromirror arrays have been designed, fabricated, characterized and finally placed in a modern quadruple insulation glazing inside a miniature room. Experimental data on actuation voltages, lifetime, power consumption and heat impact regulation are presented.