glass is glass or glazing whose light transmission properties are altered when voltage 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 works electro chromic manually When installed in the envelope of building , smart glass creates climate adaptive building shells , with the ability to save costs for heating, air condition lighting and avoid the cost of installing and maintaining motorized light screens or blinds or curtains . Blackout smart glass blocks 99.4% Barrak glass Factories provide this products according to the customers' needs and up to 2 m X 1.5 m