Modeling the effects of daylight scattering by window glass: The case of sixth century Hagia Sophia in Istanbul

The utilization of daylight in Hagia Sophia is discussed as one of the key elements of its architectural design. But little attention has been paid to the impact of window glass on the lighting of its late antique interior. Production processes leading to air inclusions in the glass volume, uneven thickness and undulated surfaces of Roman window glass cause scattering of transmitted and reflected light. In a preceding study, the scattering properties of four exemplary finds of Roman glass were quantitatively ascertained. A transmission model fit to these measured optical properties is applied with a geometric model of Hagia Sophia in daylight simulations. Two reference cases of ideally clear and perfectly diffuse glass are defined. The effects of the three modeled glazing types on the light distribution in the building interior under different sky conditions are compared. The study shall initiate a discussion on the glazing’s impact on the visual perception of the interior of Hagia Sophia.