Building-Tailored Hierarchical Electrochromism with Optimized Control Strategies.

Electrochromic smart windows struggle with a material-application disconnect. So, a building-centric paradigm is established to bridge this gap through dual breakthroughs: multi-band hierarchical material and control strategy. An electrochromic device (ECD) based on Prussian blue (PB) with multi-band hierarchical modulation is demonstrated, integrating Fe₄[Fe(CN)₆]₃ and Nb₁₈W₁₆O₉₃ film electrodes, where hierarchical regulation relies on potassium ion shuttling (rocking-chair mechanism) and cation-anion co-intercalation dynamics. It enables four spectral customization states: transparent heating (S1), zero-energy bright heating (S2), daylight-preserving bright cooling (S3), and maximum-blocking dark cooling (S4). An Electrochromic window (ECW) constructed with such ECD, when coupled with optional intelligent control strategies, transforms these capabilities into unprecedented energy savings. The load-responsive strategy focuses on building internal demands, leverages the zero-energy S2 state for >75% of summer operation, achieving 25.4% cooling energy reduction versus normal windows. The climate-adaptive strategy, centered on external environmental constraints and guided by "location-specific adjustment", reveals >50% performance disparities between control parameters, enabling location-optimized operation such as 56.9% summer energy savings even in cold Helsinki. By embedding tunable spectral control into the building energy management logic, material, and control strategy innovations have jointly paved a scalable path from laboratory innovation to building application.