Preparation And Overall Energy Performance Assessment Of Nanoscale Transparent Thermal Insulation Coatings

Transparent thermal insulation coating,which can strongly shield the near infrared?NIR?lights and UV lights,have been widely studied and used in energy conservation of buildings.Antimony doped tin oxide?ATO?are the most widely reported materials used for thermal insulation coatings.However,ATO shows poor NIR shielding performance in wavelength range from 780 nm to 1300 nm.To enhance the NIR shielding property and retain high visible transparency,we herein proposed a wide waveband two-component transparent NIR shielding?WTNS?coatings combined with ATO and Cs_0.33WO₃ which has excellent heat insulation performance.The main innovation points and research results are as follows:1.ATO nanoparticles were synthesized by controllable solvothermal method and dispersed in water with silane coupling agents.The effects of doping content,reaction time and reaction temperature on the morphology and optical properties of ATO were investigated,by which the optimum reaction conditions were obtained:The doping content was 10%,the reaction temperature was 160?and the reaction time was 12 h.The effects of the kind and concentration of dispersant,pH value and dispersion methods were also analyzed.Using silane coupling agent SIM6942.72 with 5%,adjusting pH value to 9and ball milling with 0.3 mm zirconia beads by 6 h could obtain stable ATO aqueous dispersion.2.Cs_0.33WO₃ nanoparticles were synthesized by controllable solvothermal method and dispersed in water with surfactant.The effects of the concentration of acetic acid,reaction time and reaction temperature on the morphology and optical properties of ATO were investigated.The results show that Cs_0.33WO₃ nanoparticles which have the best optical property and morphology can be obtained when the concentration of acetic acid was 20 vol.%,the reaction temperature was 220?and the reaction time was 12 h.The effects of the kind and concentration of dispersant and dispersion methods were also studied,by which the optimum dispersion conditions were obtained:Using dispersant SN5040 with 5%,ball milling with 0.3 mm zirconia beads by 6 h.3.A wide waveband two-component transparent NIR shielding?WTNS?coatings combined with ATO and Cs_0.33WO₃ were synthesized using waterborne polyurethane?WPU?as matrix resin,which shows good NIR shielding performance and high visible transparency.By using WPU as matrix resin,the pencil hardness of coatings was 2 H,the adhesion force was grade 1,and the water resistance was good.The optimum concentrations of ATO and Cs_0.33WO₃ were adjusted to 20 wt.%and the optimum weight ratio was 1:1.The WTNS coated glass samples whose visible lights transmittance of70.6%and NIR lights transmittance of 9.1%,shows the best thermal insulation properties,and therefore could be used for the energy conservation of buildings.4.The overall energy performance assessment of this NIR shielding coatings was obtained,which includes thermal chamber test and software simulation in EnergyPlus.The chamber tests reveal the superior thermal insulation ability of WTNS coatings that the temperature difference between WTNS coated glass and normal glass could reach as much as 8.9?.The EnergyPlus simulations indicate that for the area like Hong Kong which is cooling dominated areas,WTNS coated glass has the best energy performance which can significantly save up to 15.22%and 9.15%electricity per year in comparison with the normal glass and low-e glass,respectively.