Enhancing Visual and Thermal Comfort Using a Hybrid Responsive Facade Implementing Additive Manufactured Photochromic Modules

Abstract

Building facades are critical mediators of indoor environmental quality, directlygoverning occupant visual and thermal comfort. Conventional facade systems, however, rely on static configurations or single-mode responsive strategies that are inherently limited in their capacity to adapt to dynamic environmental conditions. This dissertation addresses that limitation by developing and evaluating a hybrid responsive facade system that integrates passive photochromic materials with active mechanical control to achieve multi-dimensional performance improvements. Two control strategies are introduced and comparatively assessed: thePassive-Active Cluster (PAC) strategy, which employs centralized module rotation, and the Passive-Active Individual (PAI) strategy, which employs decentralized, localized control. A comprehensive evaluation methodology is established, combining experimental material characterization with simulation-based performance analysis. Optical and thermal properties of photochromic coatings are measured and incorporated into a climate-based daylight and thermal simulation framework, enabling systematic performance assessment across multiple orientations, seasons, and hours of the year. Visual performance is evaluated using Daylight Glare Probability (DGP) anduseful daylight illuminance, while thermal performance is assessed using operative temperature and Predicted Mean Vote (PMV). Results demonstrate that both strategies substantially improve indoor environmental conditions relative to a static baseline. PAC achieves greater reductions in glare and operative temperature, with DGP reductions of approximately 13-57% compared to 9-57% for PAI, and thermal improvements of approximately 67% in March compared to 55% for PAI during the same period. However, PAC's enhanced glare and thermal control is accompanied by a reduction in daylight availability, with useful illuminance decreasing by approximately 5% . PAI, by contrast, delivers a more balanced response, improving useful daylight illuminance by approximately 10-30% and enhancing thermal comfort consistency by up to 55% across seasonal conditions. Performance advantages are orientation and season-dependent: PAC is more effective in March and June and for North and East oriented buildings, while PAI performs better in September and December, during midday hours andSouth and West oriented buildings. A central contribution of this research is the integration of visual and thermalperformance evaluation within a unified temperature-illuminance assessment framework, demonstrating that optimal facade performance requires the simultaneous balancing of multiple comfort criteria. The findings establish that centralized control is more effective under extreme environmental conditions, while decentralized control is better suited to moderate and variable conditions, a distinction that motivates the development of an adaptive, hybrid control strategy. This research advances the field of responsive facade design by proposing a systemthat combines material-based and mechanically actuated responsiveness within a multi-objective evaluation framework. The findings highlight the potential of hybrid facade systems to meaningfully enhance occupant comfort while supporting climate-responsive building design.