Overview
EN ISO 22969:2020 (identical to ISO 22969:2019) specifies a standardized method for determining the solar reflectance of coating systems (paints and varnishes). The method uses a spectrophotometer with a wide spectral range (300 nm to 2 500 nm) together with a defined reference global solar radiation spectrum to calculate total solar reflectance. This measurement helps quantify how much solar energy a coated surface reflects versus absorbs, supporting energy-efficiency and thermal performance assessments.
Key topics and technical requirements
- Scope: Applicable to coating systems (paints and varnishes) for measuring total solar reflectance (SR/TSR).
- Spectral range: Measurements from 300 nm to 2 500 nm; typical sampling interval 5 nm (1 nm alternative noted).
- Instrument: Use of a spectrophotometer with an integrating sphere and geometry 8°:di or di:8° so specular (regular) reflection can be included; measurement scale must be traceable to national metrology institutes.
- Reference solar spectrum: Uses the SMARTS 2.9.5 model reference global solar radiation at sea level with parameters: air mass 1.0; aerosol optical depth 0.10; water vapor 1.42 atm-cm; ozone 0.340 atm-cm. Annex A provides the irradiance table for 300–2 500 nm at 5 nm intervals.
- Calculation: Solar reflectance is obtained by weighting the specimen’s spectral reflectance ρ(λ) by the reference global irradiance E(λ) across the wavelength range and integrating (formula provided in Clause 5.3).
- Test conditions: Standard conditioning at (23 ± 2) °C and (50 ± 5) % RH (ISO 3270); deviations must be reported.
- Reporting: Test report must include method reference (ISO 22969:2019), specimen description, instrument type and geometry, wavelength range and increments, spectral reflectance data, calculated solar reflectance, deviations and test date.
Practical applications and users
- Who uses it: paint and varnish manufacturers, independent test labs, product certifiers, architects, façade engineers, roofing product developers, energy-efficiency consultants, regulators and labeling bodies.
- Applications:
- Developing and validating cool roof and high-reflectance façade coatings to reduce heat gain.
- Comparing coating formulations for energy savings, HVAC load reduction and urban heat island mitigation.
- Supporting product compliance, environmental declarations and marketing claims based on measured solar reflectance and solar reflectance index (SRI).
- Quality control in manufacturing and formulation optimization for reflective pigments and binders.
Related standards
- ISO 3270 - conditioning temperatures and humidities for testing
- ISO 4618 - paints and varnishes terms and definitions
- CIE 15 - recommended practices for reflectance measurement geometry and integrating spheres
Keywords: EN ISO 22969:2020, ISO 22969:2019, solar reflectance, paints and varnishes, spectrophotometer, SMARTS 2.9.5, coating systems, cool roofs, global solar radiation.
