Nano Thermal Insulation and Self-Cleaning: The "Passive" Breakthrough for Building Energy Efficiency

Buildings are a critical front in the battle for "dual carbon" goals, and the performance limits of exterior walls and door/window materials directly determine the depth of urban energy conservation and emission reduction. In March 2026, a team from Dalian University of Technology reported a "three-film coupled" exterior wall composite functional material, which uses a piezocatalytic layer to decompose gaseous pollutants, a hydrophobic aerogel layer for thermal insulation and self-cleaning, and a ZIF-8/SPES composite membrane for adsorption-catalytic degradation, achieving an 86% pollutant degradation rate. As the GB30981.2—2025 low-VOC new regulation takes effect in June 2026, building energy-saving coating is evolving from "applying a layer of paint" to functional materials that "breathe, self-clean, and save energy."

I. The "Glass and Exterior Wall" Pain Points of Building Energy Consumption

In building operational energy consumption, the heat lost through glass and exterior walls accounts for a very high proportion. Traditional exterior wall insulation materials have single functions, lack self-cleaning, and weak pollutant degradation capacity; glass faces the contradiction of "wanting daylighting makes insulation difficult, wanting insulation sacrifices light transmission." Public buildings have high heating and cooling energy consumption and poor long-term insulation; exterior walls easily accumulate dirt, driving up O&M costs—this is precisely the gap where nano technology intervenes. According to industry estimates, the energy consumption during the building operation phase accounts for a considerable share of national total energy consumption, and exterior walls and doors/windows are the areas with the most concentrated thermal bridges. Any material that can improve per-unit-thickness insulation efficiency by an order of magnitude has a leverage effect on emission reduction.

II. Nano Transparent Thermal Insulation: "Applying" an Invisible Film to Glass

Glass transparent thermal-insulation coatings centered on nano metal oxides allow visible light to pass through while blocking part of infrared and ultraviolet. Mature market products (such as Jiajiali nano energy-saving sunblock liquid) performance metrics: UV shielding rate 75–95%, IR blocking rate 80–100%, visible light transmittance 67–77%, shading coefficient 0.68–0.70; on the environmental side, VOC value about 17.8 g/L (national standard requires ≤200), free formaldehyde 0.02 g/L, pencil hardness 3H, artificial weathering resistance 1000h. It upgrades ordinary glass to energy-saving glass, blocking heat ingress in summer and reducing indoor far-infrared loss in winter, lowering air-conditioning and heating loads. In retrofitting existing buildings, such transparent thermal-insulation liquids are especially practical—no need to replace glass, spraying a few microns of film upgrades the energy-saving grade, with short construction cycles and minimal disruption to normal use, making it a cost-effective entry point for low-carbon retrofits of old communities and public buildings. Combined with building-integrated photovoltaics (BIPV), nano anti-reflection and self-cleaning layers can also reduce dust occlusion and maintain module power generation efficiency. For southern hot-summer warm-winter regions, the payback period of such transparent thermal-insulation products is often shorter than one cooling season, with outstanding economy. It should be noted that the effect of transparent thermal-insulation liquid highly depends on construction quality; uneven film can cause optical distortion and local discoloration, so it should be applied by trained personnel per specifications, with post-construction random inspections of adhesion and weathering resistance.

III. Nano Aerogel Thin Coating: 2mm Equals 40mm

Nano aerogel coating uses aerogel as the core raw material; only a 2–3mm thin spray layer achieves the insulation effect of traditional insulation materials of 30–50mm—"thin coating, high efficiency," saving space and load. It has excellent solar thermal radiation reflection, with measured large temperature-difference cooling of 20–30℃, serving as both an "insulation layer" and an "active cooling layer"; the system is fully inorganic, Class A non-combustible, not burning in fire and producing no toxic smoke; after liquid spraying and curing it forms a continuous seamless protective layer, eliminating the "thermal bridges" and joint leakage of traditional boards, while also providing anti-corrosion, waterproofing, and anti-penetration. On metal tanks, roofs, and industrial equipment surfaces, it is both an insulation layer and an active cooling layer, significantly meaningful for reducing building air-conditioning loads and industrial equipment heat-dissipation costs, and is one of the options with shorter payback in existing plant energy-saving retrofits.

IV. Self-Cleaning Superhydrophobic: Let Rain "Wash" the Exterior Wall

The core of nano self-cleaning is the superhydrophobic structure: the coating surface forms nano-scale roughness, making dust and dirt less likely to adhere and easily washed away by rain. Such "smart functional coatings" do not merely passively protect, but actively maintain facade cleanliness, greatly reducing cleaning costs and extending aesthetic durability, with significant meaning for high-rise curtain walls and public building O&M. In climate zones with strong heating demand in the north and cooling demand in the south, facade self-cleaning also indirectly reduces water and labor consumed by frequent washing to maintain appearance, aligning with low-carbon O&M goals.

V. Multifunctional Integration: From Thermal Insulation to "Air Purification"

A more frontier direction is integrating multiple functions into the same coating. In the Dalian University of Technology "three-film coupled" material, the piezocatalytic layer converts environmental energy into electricity, driving strongly oxidative free radicals to rapidly decompose gaseous pollutants; the hydrophobic aerogel layer relies on nano pores for insulation and hydrophobic modification to achieve long-term insulation and active self-cleaning; the ZIF-8/SPES composite membrane builds adsorption-catalysis synergistic purification with self-regeneration, achieving 86% pollutant degradation, solving the industry problem of hard-to-combine insulation and decontamination. Another type, nano negative-ion inorganic multifunctional coating, contains no formaldehyde/VOC itself, with formaldehyde purification rate above 95%, and persistently releases negative oxygen ions, preventing mold and inhibiting bacteria. Such coatings generate active oxygen via water electrolysis to decompose harmful gases, and combine ten functions including releasing negative oxygen ions, regulating humidity, and mold/bacteria inhibition, suitable for concrete, brick walls, gypsum boards and other substrates, representing the direction of interior wall decoration evolving from "color coverage" to "healthy functional carrier."

VI. Data Comparison: Traditional Insulation vs Nano Solution

VII. Green Compliance and Low Carbon

Whether it is eco-friendly is no longer a choice. GB30981.2—2025 significantly tightens the VOC limits for industrial coating; water-based, high-solid, powder and radiation-curing have become the main trends; bio-based raw material substitution further reduces the carbon footprint, and companies have begun to disclose the carbon emissions per unit coating in product specifications. For coating companies, writing "lower VOC, longer service life, less material consumption" into every formulation is the real competitiveness to survive the cycle. More cutting-edge is to incorporate the carbon emissions per unit coating into formulation review and disclose carbon footprint data in product specifications; leading downstream real estate and infrastructure companies have already included suppliers' green qualifications and carbon data into access criteria, and the ability to provide traceable low-VOC and carbon footprint measured reports is becoming a hard threshold for order screening.

Kexin New Materials (Guangdong) Co., Ltd. uses water-based industrial coating to meet the "oil-to-water" demand for building energy efficiency and industrial protection, and continues to build reserves in nano thermal insulation and self-cleaning directions, matching downstream green procurement standards, see 2026 Industrial Coating Green Transition. Aligning nano functions with the water-based and low-VOC main line is the path to build real competitiveness in the policy-driven track of building energy efficiency.

VIII. Practical Thresholds of Construction, Testing and Scale-up

For the effect of nano functional coating, 70% lies in the material and 30% in the construction. The substrate must be cleaned and leveled, with moisture content and alkalinity up to standard; glass-type transparent thermal insulation liquid needs to be coated in a dust-free environment and ensure uniform film layer without bubbling or discoloration; aerogel thin coating relies on liquid spraying to form a continuous seamless layer, and is sensitive to substrate flatness and spraying parameters. On the testing side, in addition to conventional adhesion, weather resistance and aging resistance, self-cleaning needs contact angle and rinsing tests, thermal insulation needs infrared thermal imaging comparison, and purification coatings need third-party degradation rate verification. The bottleneck of scale-up lies in the dispersion stability and batch consistency of nano slurry—the film-forming performance of the same formulation may drift under different temperature and humidity, which is exactly the engineering threshold that small and medium coating companies must cross from "able to make samples" to "able to supply projects". For owners and designers, when selecting, they should not only look at a single indicator, but should require suppliers to provide measured reports for corresponding working conditions and existing project cases, turning "functional claims" into "verifiable data".

FAQ

Does nano transparent thermal insulation block light? High-quality products can maintain visible light transmittance of 67–77%, basically not affecting daylighting while blocking infrared and ultraviolet, with shading coefficient about 0.68–0.70.

Is aerogel thin coating safe? The fully inorganic system has A-class non-combustible characteristics, does not burn in fire and produces no toxic smoke, suitable for public buildings, energy storage and petrochemical scenarios with strict fire protection requirements.

How much maintenance can self-cleaning save? The superhydrophobic structure allows dust to be carried away by rainwater and not easily adhere, which can significantly reduce the cleaning frequency and cost of high-rise facades, but extreme dust environments still require regular maintenance.

Further reading: 2026 Industrial Coating Green Transition: Triple Challenges of Water-based, Low VOC and Carbon Footprint · Nano Coating Technology: Principles, Preparation and Multi-field Applications · Industrial Coating System Product Center