Overview
ISO 13837:2021 - "Road vehicles - Safety glazing materials - Method for the determination of solar transmittance" specifies standardized test methods to measure how glazing for road vehicles transmits and modifies solar radiation. The standard covers luminous transmittance, solar (UV and direct) transmittance, direct reflectance/absorbance, total solar transmittance, and colorimetry (CIE Lab)* for monolithic or laminated, clear or tinted safety glazing. It applies to essentially flat sections of parts or flat samples and replaces the 2008 edition with updated calculation tables and procedures.
Key topics and technical requirements
- Scope and sample types: Applies to monolithic and laminated safety glazing materials (clear or tinted); allows use of flat sections from curved parts.
- Instrumentation: Requires spectral transmittance data obtained with a scanning spectrophotometer, preferably with an integrating sphere, over the spectral range relevant to solar energy.
- Sample preparation & measurement: Cleaning and orientation reporting (film/coating side, curvature) prior to standardized spectral measurement.
- Calculation methods:
- Luminous transmittance (T_L) using CIE weighting for visible radiation (e.g., 380–780 nm).
- Solar UV transmittance (T_UV) using solar weight tables for specified upper limits (e.g., 380 nm and 400 nm).
- Solar direct transmittance/reflectance (T_e, R_e) and absorbance (a_e) using solar spectral weighting (300–2 500 nm in the direct solar calculation).
- Total solar transmittance (T_TS) which adds transmitted energy plus secondary heat flux (q_i) calculated using convective and radiative heat transfer conventions (standardized h-values and emissivity assumptions).
- Colorimetry: Tristimulus X,Y,Z and conversion to CIE 1976 Lab* per ISO/CIE 11664-4:2019.
- Reporting: Record specimen description, measurement temperature, heat flux assumptions, and all calculated properties.
Applications and who uses it
ISO 13837:2021 is used to:
- Verify optical and thermal performance of vehicle glazing (windscreens, side windows, sunroofs)
- Support regulatory compliance and safety certification for automotive glazing
- Guide material selection and R&D for glazing manufacturers and automotive OEMs
- Provide test laboratory methods for suppliers, third‑party test houses, and certification bodies
Typical users: automotive engineers, glazing manufacturers, test laboratories, compliance officers, and materials researchers focused on vehicle visibility, occupant comfort, and solar heat gain control.
Related standards
- ISO/CIE 11664-4:2019 (Colorimetry - CIE 1976 Lab* colour space) - referenced for color calculations.
- ISO 9050 and ISO 10292 - referenced for extended thermal/infrared and emissivity considerations when needed.
Keywords: ISO 13837:2021, safety glazing, solar transmittance, luminous transmittance, vehicle glazing, colorimetry, spectrophotometer, automotive standards.
