An electro-optic window assembly is provided that includes a first substantially transparent substrate comprising: a first surface, a second surface, and a first peripheral edge; and a second substantially transparent substrate comprising: a third surface, a fourth surface, and a second peripheral edge. The first and second substrates define a cavity. The assembly further includes an electro-optic medium at least partially filling the cavity and configured to reduce the transmission of light viewed through the electro-optic window assembly. Further, the electro-optic window assembly is configured such that the substrates each have a theoretical maximum thermal stress of less than approximately 25 MPa upon exposure of the window assembly to an application environment.