Comparative analysis of energy-saving potential and solar modulation performance of thermochromic fiber-reinforced cementitious and polymeric building composites

Growing urbanization and rising energy demand necessitate smart construction materials that merge strength with energy efficiency. Developing multifunctional composites is crucial for reducing thermal loads, lowering building energy consumption, and mitigating greenhouse gas emissions. This study investigates cement and polymeric (epoxy and polyester) composites reinforced with thermochromic-functionalized fibers to enhance thermal regulation and mechanical performance. Thermochromic fibers passively control temperature by modulating solar radiation response according to real-time conditions. Mechanical and durability tests showed that polymeric composites had lower water absorption, higher compressive strength (113-124.44 MPa), and higher flexural strength (26.15-28.56 MPa) compared to cement composites (45.0-49.10 MPa and 8.89-10.89 MPa, respectively. Thermal evaluation indicated that epoxy and polyester composites exhibited lower thermal conductivity, reduced surface temperatures, and greater solar modulation at both 10 °C and 36 °C, improving indoor comfort. Energy simulations revealed that thermochromic fiber-based composite envelopes reduced annual heating and cooling demands by 12.02-17.52 kWh/m 2 and carbon emissions by 4.16-6.19% compared to composites with uncoated fibers. Microstructural analyses (XRD, FTIR, SEM) showed that thermochromic fibers slightly hindered cement hydration, weakening fiber-matrix bonding and increasing porosity, thereby reducing strength.. Conversely, polymeric composites formed denser matrices with stronger fiber adhesion and improved structural integrity. The acrylic binder shielded fibers from cement alkalinity, while the lower alkalinity of polymeric matrices preserved coating stability. Overall, polymeric thermochromic fiber composites present a promising approach for sustainable construction, offering superior thermal regulation, enhanced mechanical strength, reduced energy use, and lower environmental impact.