Advanced BIPV Window System Design for a Better Overall Energy Performance and Human-centered Indoor Comfort

Abstract

With global economic growth and rising populations, energy demand is increasing. Renewable energy technologies have gained attention as a key solution. Buildings consume about one-third of total energy, with windows contributing nearly half of the energy loss in building envelopes, making window energy efficiency crucial. Building-Integrated Photovoltaic (BIPV) systems offer the potential for energy self-sufficiency and emission reduction. As a key category of BIPV, photovoltaic (PV) windows not only enhance building aesthetics and daylighting, but also significantly contribute to energy savings and emission reduction.

Previous research on PV windows has primarily focused on their thermal performance and electrical output, while holistic studies including the study of human-centered indoor comfort remain relatively limited. To bridge this research gap, this PhD study aims to systematically investigate the comprehensive impact of PV windows on overall energy performance and indoor comfort. By optimizing the design of PV window systems, this study explored how to enhance building energy efficiency while simultaneously creating a more comfortable indoor environment. First, through experiments and numerical simulations, this research compared electrical performance, thermal performance, and daylighting effects of different types of PV windows, including traditional windows. The first step results indicated that the innovative PV window not only significantly outperformed traditional PV windows in terms of energy-saving performance but also enhanced electricity generation. Second, by combining subjective evaluations with objective measurements, the performance of PV windows in the aspects of both visual and non-visual comfort was comprehensively assessed. The findings revealed that PV windows could significantly improve the indoor light environment and effectively meet the natural lighting requirements for circadian rhythms, thereby enhancing overall occupant comfort. Finally, to further improve the interior daylight performance in response to the dynamic outdoor weather. The third part of this study developed a dynamic PV integrated light shelf system and evaluated the performance of different types of shading systems in terms of indoor daylighting and energy-saving potential. The results indicated that the dynamic PV shading system could not only improve energy generation efficiency but also significantly optimize indoor lighting conditions, thereby further reducing the overall energy consumption of the building. In the final part, the research findings, academic contributions and future research directions are discussed and proposed.

Keywords: BIPV window system, energy performance, human-centric design, climate responsive, sustainable building

Date of Award	2025
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Changying XIANG (Supervisor) & Hongxing Yang (Supervisor)