Improving Daylight Availability in Heritage Buildings: A Case Study of Below-grade Classrooms in Tehran

Refurbished heritage buildings usually lack in meeting the required standards defined for the new function especially when reused as educational buildings. Therefore, they are usually equipped with different post-occupancy retrofit strategies to achieve an acceptable level of environmental quality and energy demand. Daylight quality and the distribution of natural light is a critical issue in educational spaces, given that the low level of illuminance in classrooms can decrease students' performance and disrupt visual tasks. In this study, daylight performance of below-grade south-facing classrooms in a heritage building in Tehran, Iran is investigated by implementing 57 different daylighting retrofit strategies using climate-based daylight simulations, in relation to the metric Useful Daylight Illuminance 300-3000lux (UDI-Autonomous). The research proposes the use of reflectors on the interior ceiling and exterior side of the windows (on the ground) to achieve the highest result possible. Although, applying these two systems individually, can boost the spatial distribution of daylight to 75 % and 71%, respectively, the combination of them provide users with UDI-Autonomous in 99% of the classroom space for more than half of the occupancy time. © 2021 The Author(s). Published by solarlits.com. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/).