Overview
ISO 9050:2026 – Glass in building - Determination of luminous and solar characteristics of glazing is an international standard developed by ISO for the building and construction sector. This standard provides precise methods for determining the luminous (light-transmitting and reflecting) and solar (heat and energy transfer) properties of glazing materials used in buildings. By establishing these metrics, ISO 9050:2026 supports architects, engineers, and energy performance specialists in evaluating, comparing, and optimizing glazing for enhanced daylighting, energy efficiency, and occupant comfort.
Applicable to conventional, absorbing, and solar-control glazing, as well as building-integrated photovoltaic (BIPV) glazing, this standard is essential for the design and assessment of vertical and horizontal glazed apertures. ISO 9050:2026 covers transparent materials with the exception of those with significant transmission in the 5 µm to 50 µm wavelength region (such as certain plastics) and excludes vacuum insulating glass (VIG), which falls under ISO 19916-1.
Key Topics
- Luminous Transmittance and Reflectance: Methods for measuring and calculating the fraction of visible light transmitted and reflected by different glazing types.
- Solar Direct Transmittance, Reflectance, and Absorptance: Determination of how solar energy is transferred, reflected, or absorbed by glazing, vital for accurate heating and cooling load calculations.
- Total Solar Energy Transmittance (g value): Precise calculation methods for assessing the overall solar energy transmitted, including secondary heat transfer-fundamental for evaluating energy performance.
- Shading Coefficient: Provides a comparative metric for the solar heat gain through specific glazing versus standard clear float glass.
- Ultraviolet (UV) Transmittance: Evaluation of glazing's capability to filter UV radiation, important for occupant health and interior material preservation.
- Colour Rendering Index: Method for determining the impact of glazing on the color appearance of transmitted light.
- Matrix Method for Multi-pane Glazing: An alternative calculation approach for complex, multi-layered systems.
- Spectral Properties of Advanced Glazings: Includes guidelines for laminated, screen printed, and BIPV glazing solutions.
- Explicit Exclusions: Materials with substantial infrared transmission (5 µm–50 µm), optically scattered materials under certain conditions, and VIG.
Applications
- Building Energy Modeling: Provides standardized input values for simulation software, enabling accurate predictions of lighting, heating, and cooling loads based on glazing selection.
- Glazing Selection and Specification: Enables professionals to compare glazing products objectively, facilitating optimal choices for energy savings, daylighting, and thermal comfort.
- Sustainable Building Certifications: Supports compliance with green building rating systems (e.g., LEED, BREEAM) that require performance demonstration for envelope materials.
- Solar Control and Comfort: Helps manufacturers and designers ensure selected glazings limit unwanted solar gain or loss, improving occupant comfort and energy costs.
- Integration of Photovoltaic Glazing: Facilitates the adoption of BIPV systems by providing standardized methods for assessing their dual role in daylighting and energy generation.
- Protection of Interiors: Assists facility managers and architects in selecting glass that reduces UV transmission, thereby protecting occupants and interior finishes.
Related Standards
- ISO 10291, ISO 10292, ISO 10293: Thermal transmittance (U-value) determination for multiple glazing - critical for a holistic assessment of building envelope performance.
- ISO 20589: Procedures for determining the emissivity of glass surfaces - necessary for calculating heat transfer coefficients.
- ISO 19916-1: Specifies the determination of the g value for vacuum insulating glass units.
- IEC TS 61836: Photovoltaic module terminology and definitions, referenced for consistency in PV and BIPV glazing applications.
ISO 9050:2026 is a key reference for professionals concerned with daylight, solar energy management, and energy efficiency in modern architecture and sustainable building design.
For additional resources and the latest information about international glass standards, visit www.iso.org.