The energy crisis has arisen as the most pressing concern and top priority for policymakers, with buildings accounting for over 40% of global energy consumption. Currently, single‐function envelopes cannot satisfy energy efficiency for next‐generation buildings. Designing buildings with high mechanical robustness, thermal insulation properties, and more functionalities has attracted worldwide attention. Further optimization based on bioinspired design and material efficiency improvement has been adopted as effective approaches to achieve satisfactory performance. Herein, inspired by the strong and porous cuttlefish bone, a cement aerogel through self‐assembly of calcium aluminum silicate hydrate nanoparticles (C‐A‐S‐H, a major component in cement) in a polymeric solution as a building envelop is developed. The as‐synthesized cement aerogel demonstrates ultrahigh mechanical performance in terms of stiffness (315.65 MPa) and toughness (14.68 MJ m⁻³). Specifically, the highly porous microstructure with multiscale pores inside the cement aerogel greatly inhibits heat transfer, therefore achieving ultralow thermal conductivity (0.025 W m⁻¹ K⁻¹). Additionally, the inorganic C‐A‐S‐H nanoparticles in cement aerogel form a barrier against fire for good fire retardancy (limit oxygen index, LOI ≈ 46.26%, UL94‐V0). The versatile cement aerogel featuring high mechanical robustness, remarkable thermal insulation, light weight, and fire retardancy is a promising candidate for practical building applications.

Structural materials with the capability for passive daytime radiative cooling (PDRC) show promise for the sustainable cooling of buildings. However, developing durable PDRC structural materials with optical robustness, ease of deployment, and scalability remain a challenge for civil engineering applications. We synthesized a metasurface-enhanced cooling cement using a universal, scalable pressure-driven fabrication strategy during a low-carbon production process. The self-assembly of multiple-sized reflective ettringites as main hydration products toward the metasurface, coupled with hierarchical pores, guaranteed high solar reflectance (96.2%), whereas raw materials containing alumina- and sulfur-rich function groups leveraged inherent mid-infrared emissivity (96.0%). This photonic-architectured cement achieved a temperature drop of 5.4°C during midday conditions with a solar intensity of 850 watts per square meter. This supercool cement featured intrinsic high strength, armored abrasive resistance, and optical stability, even when exposed to harsh conditions, such as corrosive liquids, ultraviolet radiation, and freeze-thaw cycles. A machine learning–guided life-cycle assessment indicated its potential to achieve a net-negative carbon emission profile.

Smart windows that can passively regulate incident solar radiation by dynamically modulating optical transmittance have attracted increasing scientific interest due to their potential economic and environmental savings. However, challenges remain in the global adoption of such systems, given the extreme variability in climatic and economic conditions across different geographical locations. Aiming these issues, a methylcellulose (MC) salt system is synthesized with high tunability for intrinsic optical transmittance (89.3%), which can be applied globally to various locations. Specifically, the MC window exhibits superior heat shielding potential below transition temperatures, becoming opaque at temperatures above the Lower Critical Solution Temperature and reducing the solar heat gain by 55%. This optical tunability is attributable to the particle size change triggered by the temperature‐induced reversible coil‐to‐globular transition. This leads to effective refractive index and scattering modulation, making them prospective solutions for light management systems, an application ahead of intelligent fenestration systems. During the field tests, MC‐based windows demonstrated a 9 °C temperature decrease compared to double‐pane windows on sunny days and a 5 °C increase during winters, with simulations predicting an 11% energy savings. The ubiquitous availability of materials, low cost, and ease‐of‐manufacturing will provide technological equity and foster the ambition toward net‐zero buildings.