Soft actuators are the compliant-material based devices capable of producing large deformation upon external stimuli. Dielectric elastomer actuators(DEA) are a type of soft actuators that operate on voltage stimuli. Apart from soft robotics, these actuators can serve many novel applications, for example, tunable optical gratings, lens, diffusers, smart windows and so on. This talk presents our current work on tunable smart windows which can regulate the light transmittance and the sound absorption. This smart window can promote daylighting while maintaining privacy by switching between transparent and opaque. As a tunable optical surface scatters, it turns transparent with smooth surfaces like a flat glass; but it turns ‘opaque’ (translucent) with the micro-rough surface. The surface roughness is varied by means of surface micro-wrinkling or unfolding using dielectric elastomer actuation. In addition, this smart window is equipped with another layer of transparent micro-perforated dielectric elastomer actuator (DEA), which acts like Helmholtz resonators serving as a tunable and broader sound absorber. It can electrically tune its absorption spectrum to match the noise frequency for maximum acoustic absorption. The membrane tension and perforation size are tuned using DEA activation to tune its acoustic resonant frequency. Such novel smart window can be made as cheap as glass due to its simple all-solid-state construction. They are used to green building and could potentially enhance the urban livability.