Overview
ISO 21239:2026 specifies the requirements for factory-made reflective insulating products designed for building thermal insulation applications. These products incorporate one or more reflective or low-emissivity surfaces and are intended to be used with an air space to enhance insulation performance. The standard covers products in the form of rolls, boards, and sheets, as well as those used in prefabricated insulation systems and composite panels (though such systems themselves are not within the scope). The products addressed are not intended for load-bearing applications. ISO 21239 provides requirements for product characteristics, testing methods, durability, and conformity assessment, ensuring reliability and consistency in insulation performance worldwide.
Key Topics
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Reflective and Low-Emissivity Surfaces
ISO 21239 sets criteria for thermal insulation materials that derive their performance from one or more reflective or low-emissivity surfaces. These surfaces are designed to minimize radiant heat transfer when combined with air spaces.
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Product Forms and Types
The standard applies to factory-made insulation in rolls, boards, and sheets, establishing classification based on physical characteristics and structure, including material thickness and surface configuration.
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Testing and Durability
It details methods for testing thermal resistance, emissivity, dimensional stability, combustibility, water vapor transmission, moisture content, and mildew resistance. Durability requirements address emissivity and insulation performance over time, as well as the integrity of reflective layers under various conditions.
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Conformity Assessment
ISO 21239 requires initial type testing (ITT), factory production control (FPC), and clear marking and labelling to demonstrate conformity and performance, supporting quality assurance in manufacturing and supply.
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Performance Declaration
The standard outlines the proper declaration of product characteristics such as thermal resistance (R-value), emissivity, thickness tolerances, water absorption, and vapor transmission resistance.
Applications
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Building Envelope Insulation
Reflective insulation products according to ISO 21239 are used within building envelopes to enhance thermal efficiency. They are suitable for walls, roofs, floors, and ceilings where radiant heat transfer needs to be minimized.
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Prefabricated Panels and Systems
While prefabricated insulation systems and composite panels themselves are outside the direct scope, the reflective insulating products they contain are covered, facilitating integration into modular and composite construction elements.
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Retrofit and New Construction
These products are applicable in both new building projects and retrofitting of existing structures, offering improved energy performance and compliance with modern building regulations.
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Sustainable Building
By reducing heat loss or gain, reflective insulation products contribute to sustainable building practices, lower energy consumption, and enhance indoor comfort.
Related Standards
- ISO 22097:2023 – Related standard for determination of the thermal performance of reflective insulation products.
- ISO 12576-1 – Guidance on factory-made insulating materials and products for conformity control systems.
- ISO 29465, ISO 29466, ISO 29467, and ISO 29472 – Measurement methods for length, width, thickness, squareness, and dimensional stability.
- ISO 9229 – Thermal insulation vocabulary.
- ISO 1182, ISO 1716, ISO 9772, ISO 11925-2 – Reaction to fire tests and combustibility.
- ISO 12570, ISO 12572, ISO 16535, ISO 16536 – Testing of moisture content, water vapour transmission, and water absorption.
- ISO 846 and ISO 4590 – Tests for mildew resistance and closed cell content.
These referenced standards provide validated methodologies and consistent terminology, supporting comprehensive testing and international comparability in the evaluation of building insulation products.
Keywords: ISO 21239:2026, reflective insulation, thermal insulation products, low-emissivity surfaces, building insulation, factory-made insulation, air space insulation, insulation specification, thermal resistance, sustainability, conformity assessment, international standards.
Open preview (PDF)Thermal insulation products for buildings — Reflective insulating products — Specification
