What is the typical thermal conductivity of thermal insulation aluminum foil materials?

2026-03-20 14:04:36

Thermal conductivity is a core thermal performance indicator of insulation materials, which determines their ability to block heat transfer and directly affects the insulation effect in various application scenarios. As a widely used thermal insulation material, thermal insulation aluminum foil is favored in construction, industrial pipelines, aerospace, and automotive fields due to its lightweight, easy installation, and excellent heat reflection performance. However, many industry practitioners and users have questions about the typical thermal conductivity of thermal insulation aluminum foil materials, as it is not a fixed value and is affected by multiple factors such as material structure, thickness, temperature, and humidity. This article focuses on the typical thermal conductivity range of thermal insulation aluminum foil, analyzes the key factors affecting its thermal conductivity, details the differences in thermal conductivity under different application scenarios, and combines industry standards and practical cases to provide a comprehensive and accurate reference for readers, while meeting SEO optimization requirements.

First, it is necessary to clarify the definition of thermal conductivity and its significance for thermal insulation aluminum foil. Thermal conductivity, denoted as λ (lambda), refers to the amount of heat transferred through a 1-meter-thick material per square meter in 1 second when the temperature difference between the two surfaces of the material is 1 degree (either Celsius or Kelvin) under stable heat transfer conditions. Its unit is watts per meter per Kelvin (W/(m·K)), and this parameter directly reflects the heat transfer efficiency of the material — lower thermal conductivity means better thermal insulation performance. For thermal insulation aluminum foil, its thermal conductivity is closely related to its insulation mechanism, which mainly relies on reflecting thermal radiation and reducing heat conduction and convection, rather than relying solely on the material’s own heat-blocking ability like traditional porous insulation materials.

The typical thermal conductivity of thermal insulation aluminum foil materials is not a single fixed value but ranges within a certain interval, which is mainly determined by the material’s composition, structure, and processing technology. According to industry practice and test data, the typical thermal conductivity of common thermal insulation aluminum foil is between 0.03 W/(m·K) and 0.06 W/(m·K) under normal temperature conditions (20-25℃). This range is significantly lower than the thermal conductivity of pure aluminum (about 230 W/(m·K) at 300℃), which is due to the special processing technology and composite structure of thermal insulation aluminum foil — it is usually not pure aluminum foil but a composite material composed of aluminum foil, porous insulation base material (such as glass fiber, rock wool), and adhesive layer, which greatly reduces the overall thermal conductivity.

It should be emphasized that the thermal conductivity of thermal insulation aluminum foil is often referred to as effective thermal conductivity, which comprehensively considers the combined effect of heat conduction, convection, and radiation, rather than the pure thermal conductivity of the aluminum foil itself. Pure aluminum has high thermal conductivity, but when processed into thin foil and combined with porous insulation materials, the porous structure of the base material traps air (whose thermal conductivity is only about 0.024 W/(m·K) at 0℃), reducing heat conduction and convection, while the aluminum foil layer reflects thermal radiation, thereby achieving efficient thermal insulation. For example, composite thermal insulation aluminum foil with a 6μm aluminum layer and a glass fiber base has a typical thermal conductivity of 0.035-0.045 W/(m·K), which meets the basic requirements of most thermal insulation projects.

Different types of thermal insulation aluminum foil have slight differences in their typical thermal conductivity due to structural differences. Single-layer thermal insulation aluminum foil, which is mainly used for simple heat reflection scenarios, has a relatively higher thermal conductivity, usually between 0.045 W/(m·K) and 0.06 W/(m·K). This is because single-layer aluminum foil lacks the auxiliary insulation effect of a porous base material, and its thermal insulation mainly relies on radiation reflection, so its effective thermal conductivity is slightly higher. In contrast, double-layer or multi-layer composite thermal insulation aluminum foil, which combines aluminum foil with materials such as glass wool, rock wool, or polyester foam, has a lower thermal conductivity, usually between 0.03 W/(m·K) and 0.045 W/(m·K). The multi-layer structure further enhances the blocking effect on heat conduction and convection, making it more suitable for high-demand insulation scenarios such as industrial pipelines and building exterior walls.

In addition to material structure, temperature is one of the key factors affecting the thermal conductivity of thermal insulation aluminum foil. According to thermal conductivity principles, the thermal conductivity of most insulation materials increases with the increase of temperature, and thermal insulation aluminum foil is no exception. Under low-temperature conditions (below 0℃), the thermal conductivity of thermal insulation aluminum foil is usually between 0.028 W/(m·K) and 0.04 W/(m·K), because the molecular thermal movement is slowed down, and the heat conduction and convection effects in the porous structure are weakened. Under high-temperature conditions (above 100℃), the thermal conductivity will increase to 0.04 W/(m·K) to 0.07 W/(m·K), as the molecular thermal movement accelerates, and the radiation heat transfer between the aluminum foil layers is enhanced. For example, thermal insulation aluminum foil used in high-temperature steam pipelines (operating temperature 150-200℃) has a thermal conductivity of about 0.05-0.07 W/(m·K), which is higher than that under normal temperature but still meets the insulation requirements of industrial scenarios.

Humidity is another important factor affecting the thermal conductivity of thermal insulation aluminum foil. Most thermal insulation aluminum foil has a porous composite structure, which is prone to absorbing moisture in humid environments. Since the thermal conductivity of water (about 0.62 W/(m·K) at 30℃) is much higher than that of air and the Aluminum Foil Composite material itself, the absorption of moisture will significantly increase the thermal conductivity of the material. When the humidity is high (relative humidity above 80%), the thermal conductivity of thermal insulation aluminum foil may increase by 10-30%, from the typical 0.03-0.06 W/(m·K) to 0.033-0.078 W/(m·K). If the moisture freezes in low-temperature environments, the thermal conductivity will increase more significantly, as the thermal conductivity of ice (2.2 W/(m·K)) is much higher than that of water, which will seriously affect the insulation effect. Therefore, in humid or outdoor environments, thermal insulation aluminum foil with waterproof treatment is usually selected to avoid moisture absorption.

The thickness of thermal insulation aluminum foil also has a certain impact on its thermal conductivity, but this impact is not linear. Generally speaking, within a certain thickness range (0.03mm-0.2mm), increasing the thickness of the aluminum foil layer or the composite base material can slightly reduce the thermal conductivity, but when the thickness exceeds a certain value (usually 0.15mm), the reduction effect of thermal conductivity becomes very weak. This is because the thermal insulation effect of thermal insulation aluminum foil mainly depends on the reflection of thermal radiation and the blocking effect of the porous structure, and excessive thickness will not significantly improve these two effects but will increase the material weight and cost. For example, thermal insulation aluminum foil with a total thickness of 0.05mm has a thermal conductivity of about 0.045 W/(m·K), while that with a thickness of 0.1mm has a thermal conductivity of about 0.038 W/(m·K), and when the thickness increases to 0.2mm, the thermal conductivity only decreases to about 0.035 W/(m·K).

Industry standards also have clear regulations on the typical thermal conductivity of thermal insulation aluminum foil, which provides a basis for product production and project application. In China, the national standard GB/T 22648-2023 “Aluminium foils used for aluminium-plastic composite tube and packaging pouch of battery” specifies that the thermal conductivity of thermal insulation aluminum foil used in industrial pipelines should be between 0.03 W/(m·K) and 0.06 W/(m·K) under normal temperature conditions. The European Union’s EN 13163:2018 standard for thermal insulation materials also stipulates that the thermal conductivity of aluminum foil composite insulation materials should not exceed 0.06 W/(m·K) at 23℃, which is consistent with the typical range of thermal conductivity of thermal insulation aluminum foil. These standards ensure that thermal insulation aluminum foil can meet the basic insulation needs of various application scenarios and guide manufacturers to optimize product performance.

The typical thermal conductivity of thermal insulation aluminum foil also varies according to different application scenarios, which is determined by the specific insulation requirements of the scenario. In the construction industry, thermal insulation aluminum foil used for building exterior walls and roofs needs to have good thermal insulation performance to reduce indoor and outdoor heat exchange, so its typical thermal conductivity is between 0.03 W/(m·K) and 0.045 W/(m·K). For example, composite thermal insulation aluminum foil used in building roofs, which combines aluminum foil with glass wool, has a thermal conductivity of 0.035-0.04 W/(m·K), which can reduce the roof surface temperature by 10-15℃ in summer and reduce indoor energy consumption of air conditioning.

In the industrial field, thermal insulation aluminum foil used for pipeline insulation has different thermal conductivity requirements according to the pipeline temperature. For medium and low-temperature pipelines (0-100℃) such as air conditioning chilled water pipelines, the typical thermal conductivity of thermal insulation aluminum foil is between 0.035 W/(m·K) and 0.05 W/(m·K). For high-temperature pipelines (100-300℃) such as steam pipelines, the thermal conductivity can be as high as 0.05-0.07 W/(m·K), but it still needs to meet the requirement of reducing heat loss by more than 30% compared with uninsulated pipelines. In the aerospace field, thermal insulation aluminum foil used in spacecraft needs extremely low thermal conductivity, usually between 0.03 W/(m·K) and 0.04 W/(m·K), to withstand extreme temperature differences in space (-100℃ to 120℃) and ensure the normal operation of internal equipment.

In the automotive field, thermal insulation aluminum foil used in engine compartments and car roofs focuses on lightweight and heat insulation, so its typical thermal conductivity is between 0.04 W/(m·K) and 0.055 W/(m·K). This range can effectively block the heat of the engine and solar radiation, reduce the indoor temperature of the car, and improve driving comfort without increasing the vehicle weight significantly. In daily life, household thermal insulation aluminum foil (such as insulation film and aluminum foil blankets) has a relatively higher thermal conductivity, usually between 0.045 W/(m·K) and 0.06 W/(m·K), which is sufficient for simple insulation scenarios such as window insulation and emergency heat preservation.

With the continuous development of the thermal insulation material industry and the promotion of energy conservation and environmental protection policies, the thermal conductivity of thermal insulation aluminum foil is constantly optimized. Manufacturers are improving the composite structure of materials, such as using high-performance porous base materials (such as aerogel, whose thermal conductivity is as low as 0.01 W/(m·K)) and optimizing the surface treatment of aluminum foil to further reduce thermal conductivity. For example, aerogel composite thermal insulation aluminum foil developed in recent years has a typical thermal conductivity of 0.03-0.035 W/(m·K), which has better insulation performance and is widely used in high-demand scenarios such as aerospace and high-temperature industrial pipelines.

Industry data shows that the global thermal insulation material market is growing steadily, and the demand for thermal insulation aluminum foil, as an important type of insulation material, is also increasing. China’s aluminum foil output reached 5.4 million tons in 2024, of which a considerable proportion is used in thermal insulation fields. With the continuous improvement of energy conservation standards in various industries, the requirement for low thermal conductivity of thermal insulation aluminum foil is becoming more and more strict, which promotes the technological upgrading of the industry. It is expected that in the next few years, the typical thermal conductivity of high-performance thermal insulation aluminum foil will be further reduced to 0.025-0.04 W/(m·K), providing more efficient insulation solutions for various fields.

It should be noted that the thermal conductivity of thermal insulation aluminum foil needs to be tested according to standard methods to ensure accuracy. The common test methods include the guarded hot plate method and the heat flow meter method, which are specified in GB/T 10294-2008 “Thermal insulation materials — Determination of steady-state thermal resistance and related properties — Guarded hot plate method” and ISO 8301:1991 “Thermal insulation — Determination of steady-state thermal resistance and related properties — Heat flow meter method”. During the test, factors such as temperature, humidity, and material thickness need to be strictly controlled to ensure that the test results can truly reflect the thermal conductivity of the material in actual use.

In conclusion, the typical thermal conductivity of thermal insulation aluminum foil materials is between 0.03 W/(m·K) and 0.06 W/(m·K) under normal temperature conditions, which varies slightly according to material structure, thickness, temperature, humidity, and application scenarios. Single-layer thermal insulation aluminum foil has a relatively higher thermal conductivity (0.045-0.06 W/(m·K)), while multi-layer composite thermal insulation aluminum foil has a lower thermal conductivity (0.03-0.045 W/(m·K)). Temperature and humidity are important factors affecting thermal conductivity — high temperature and high humidity will increase thermal conductivity, while low temperature will reduce it. Understanding the typical thermal conductivity of thermal insulation aluminum foil and its influencing factors is crucial for selecting appropriate materials in engineering applications, ensuring insulation effect, and reducing energy consumption.

Whether in construction, industry, aerospace, or daily life, thermal insulation aluminum foil, with its appropriate thermal conductivity and excellent comprehensive performance, plays an important role in energy conservation and temperature control. With the continuous advancement of technology, the thermal conductivity of thermal insulation aluminum foil will be further optimized, providing more reliable and efficient thermal insulation solutions for various industries, and making greater contributions to global energy conservation and environmental protection.