An Innovative Daylighting System Incorporating Active Light Collection

Speaker: Sepideh Khosravi, PhD, Department of Physics and Astronomy SBSP (Sustainable Building Science Program) Trainee, The University of British Columbia

Location: Policy Labs, CIRS building, 2260 West Mall

Date: Thursday, February 12th, 1-2PM


The building industry recognizes the importance of incorporating daylighting into the illumination of buildings to improve both the energy performance of the building and the overall lighting quality. There are several well-known methods to increase the daylighting level in buildings, including windows and skylights. However, they are usually not capable of illuminating the core of the building, and may increase the energy usage of the building due to poor insulation.

A daylighting system investigated in this project offers a novel approach to illuminating the core of buildings. This system, so called the Two-Stage Core Sun lighting System, consists of active and passive optical elements that capture sunlight outside the building and transfer it to the dark core. Active sunlight redirectors, mounted at the rooftop level edge of the building, track the sun throughout the day and redirect the sunlight towards building façades at a certain angle. Passive concentrator elements mounted on the façades of the building capture and concentrate the light and direct it into light guides. The sunlight is then distributed within the building via interior light guides that illuminate the building.

The performance of the Two-Stage Core Sun lighting System was evaluated for five different cities. The energy savings calculations and the cost estimation show that the Two-Stage Core Sun lighting System can provide a practical approach to daylighting of a building without negatively impacting its overall energy performance.



Sepideh is a PhD graduate from department of Physics and Astronomy at the University of British Columbia. She holds Master’s degree in Gravitational Physics and Cosmology from University of Tehran in Iran.

She is a specialist in Applied Science and Industrial Physics. Her PhD research focused on design and development of a Core Sun lighting System and implementation of the system in the commercial building to enhance the daylighting inside the building core.