Smart glass or switchable glass (also smart windows or switchable windows in those applications) is glass or glazing whose light transmission properties are altered when voltage, light or heat is applied. Generally, the glass changes from translucent to transparent, changing from blocking some (or all) wavelengths of light to letting light pass through.

Smart glass technologies include electrochromic, photochromic, thermochromic, suspended particle, micro-blind and liquid crystal devices.^[1]

When installed in the envelope of buildings, smart glass creates climate adaptive building shells, with the ability to save costs for heating, air-conditioningand lighting^[2][3] and avoid the cost of installing and maintaining motorized light screens or blinds or curtains. Most smart glass blocks ultraviolet light, reducing fabric fading; for SPD-type smart glass, this is achieved in conjunction with low emissivity coatings.

Critical aspects of smart glass include material costs, installation costs, electricity costs and durability, as well as functional features such as the speed of control, possibilities for dimming, and the degree of transparency.-From Wikipeida.

More details: https://en.wikipedia.org/wiki/Smart_glass