AbstractsPhysics

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. There are other systems designed for illuminating the core of buildings with daylighting, but they all have some limitations that have impeded widespread adoption. A daylighting system investigated in this PhD project offers a novel approach to illuminating the core of buildings. This system, so called the Two-Stage Core Sunlighting System, consists of active and passive optical elements that capture sunlight outside of 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 Sunlighting System was evaluated for five different cities. The energy savings calculations and the cost estimation showed that the Two-Stage Core Sunlighting System can provide a practical approach to daylighting a building without negatively impacting its overall energy performance. As a complement to the main research project, an analysis was carried out to determine whether performance improvements could be possible in the future. The analysis focused on modifications to the prismatic microstructured film, in particular the addition of reflective structures that may enhance the efficiency of the film by recapturing a portion of the energy that would otherwise be lost. Simulation results showed that such modifications do not substantially change the performance of the currently available microstructured films, but that they can improve the performance of a nanostructured film in future applications.