TiO2-P25 Enhanced Thermochromic Coatings for Energy Efficient Roofing: Evaluating Long-Term Performance through Accelerated Aging Tests

Autor(es)

Hidalgo-Araujo, Ana Carolina ; Salomao, Rafael ; Berardi, Umberto ; Dornelles, Kelen Almeida

• Tipo de documento: Artigo Científico
• Fonte: BUILDING AND ENVIRONMENT; v. 281, p. 13-pg., 2025-08-01.

Resumo

As global warming intensifies, passive cooling strategies are critical in reducing energy consumption, mitigating the urban heat island effect, and reducing greenhouse gas emissions. This study investigates the energy performance and durability of thermochromic coatings applied to ceramic and fiber cement roof tiles in two climatically different Brazilian cities: Manaus (humid equatorial) and Curitiba (subtropical). The coatings of microencapsulated organic pigments combined with rutile TiO2 were enhanced with colloidal silica (SiO2) and anatase TiO2-P25 nanoparticles to improve long-term stability. Accelerated aging tests were performed according to ASTM D7897, and solar reflectance was measured according to ASTM E903 and G173. This data was incorporated into EnergyPlus simulations under projected climate conditions for 2050. Simulation results showed that lowering the pigment's transition temperature (TT) to 20 degrees C significantly improved energy performance in subtropical climates. In Curitiba, thermochromic roof coatings reduced energy consumption by up to 7.3% in unaged and 5.2% in aged samples compared to the ceramic roof reference. However, savings could reach 11.3% with improved optical contrast between the two-color states of the pigment. Adding a TiO2-P25 protective layer effectively reduced pigment degradation, as evidenced by solar reflectance losses that were approximately 50.4% lower below the TT and 33.3% lower above the TT, compared to unprotected samples. These results highlight the potential of thermochromic coatings to improve the energy efficiency of buildings in climates with significant temperature variations and underscore the need for tailored formulations. The study also calls for region-specific accelerated aging protocols, natural weathering testing, and further research to enhance color contrast and reduce photodegradation to improve the durability and reliability of thermochromic pigments. (AU)

• Processo FAPESP: 24/00850-9 - Caracterização e simulação termoenergética de telhas multifuncionais
• Beneficiário: Ana Carolina Hidalgo Araujo
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 22/03655-7 - Redução de perdas energéticas em processos industriais com isolamento térmico de alta eficiência usando revestimentos moldáveis de silicato de cálcio microporoso produzido a partir de elementos de biomassa: cascas de ovos e cinzas de cascas de arroz
• Beneficiário: Rafael Salomão
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular
• Processo FAPESP: 24/10060-5 - REVESTIMENTOS PARA O ENVELOPE CONSTRUTIVO E A AVALIAÇÃO DA DEGRADAÇÃO DA ABSORTÂNCIA À RADIAÇÃO SOLAR: proposta de um método nacional de ensaio acelerado
• Beneficiário: Kelen Almeida Dornelles
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 22/14074-5 - Telhas termocrômicas e autolimpantes: uma cobertura adaptativa e resiliente
• Beneficiário: Ana Carolina Hidalgo Araujo
• Modalidade de apoio: Bolsas no Brasil - Doutorado