Reorienting Smart Window Innovation: From Material-Centric Metrics to Grid-Interactive Flexibility

Smart windows are heralded as a pivotal technology for building energy efficiency and carbon neutrality. By dynamically regulating solar heat gain, they fundamentally alter building thermal loads. However, the field is currently constrained by a unidirectional loss system spanning the entire innovation chain. While academic breakthroughs propel laboratory devices to new performance peaks, the transition to commercial products is consistently plagued by severe performance degradation. This Perspective dissects the full technical chain to identify the critical bottlenecks responsible for this cascading degradation. We highlight that the most consequential gap lies not merely in the disconnect between laboratory metrics and real-world application scenarios, but more critically in the prevailing paradigm that treats smart windows solely as passive energy-saving barriers. This narrow focus entirely overlooks their potential as active, demand-side flexibility nodes interacting with the emerging new power system. To bridge these gaps, this paper proposes shifting from a linear, material-centric pipeline to a circular, application-driven ecosystem that redefines smart windows as grid-interactive flexible assets.