ISO 24448:2023

Overview

ISO 24448:2023 defines laboratory light-source and radiometer requirements for evaluating semiconducting photocatalytic materials under indoor LED lighting. Developed by ISO/TC 206 (Fine ceramics), the standard ensures reproducible, comparable photocatalytic performance tests when white LED lamps are used in place of older fluorescent lamps. It explicitly covers LED characteristics, illuminance meter specifications, measurement conditions and required test-report information. Note: indoor lighting excludes sunlight passing through window glass.

Key topics and technical requirements

• LED light source
  • Phosphor-type white LEDs with a peak emission at 450 nm ± 10 nm.
  • CIE 1974 general colour rendering index (Ra): 80 ≤ Ra < 90.
  • Correlated colour temperature (CCT): national or regional testing-standard defined; otherwise 3 800 K–4 500 K (F4000).
  • Drive mode: LED lamps must be DC-driven (AC-driven not permitted).
  • Reflection plates (if used) shall be white.
  • For large irradiation areas, use the same lamp model (manufacturer/catalogue number) and preferably select lamps by peak-wavelength.
  • If manufacturer spectral data are unavailable, measure peak wavelength with a calibrated spectral irradiance or spectral illuminance meter traceable to national standards.
• Illuminance meters and radiometers
  • Use a conventional filter-type illuminance meter, not a spectral radiometer as the meter.
  • Spectral mismatch index f' ≤ 6% and directional (cosine) response index f ≤ 4%.
  • Meter calibration must be traceable to a national calibration laboratory or standard lamp.
• Measurement and use conditions
  • Set illuminance, ambient temperature and humidity to values specified in the applicable testing standard.
  • Maintain stable illuminance with drift ≤ 1.25%/h; measure illuminance at the start and end of irradiation.
  • Replace the light source when illuminance decreases to 70% of the initial value.
• Test report essentials
  • Reference ISO 24448:2023 and list lamp and meter details (manufacturer, catalogue numbers, Ra, peak wavelength, spectral data, illuminance at sample, test date).

Applications and users

ISO 24448:2023 is intended for:

• Laboratories and researchers testing semiconducting photocatalytic materials (including fine/advanced ceramics).
• Product developers and manufacturers of photocatalytic coatings, tiles, air/water purification surfaces and related materials used indoors under LED lighting.
• Certification bodies and standards committees seeking reproducible, comparable indoor-light photocatalysis test data.

Practical value: ensures consistent LED-based irradiation conditions, enabling reliable performance comparison and accelerating adoption of LED-appropriate test methods.

Related standards

• ISO 14605 (alternative for indoor testing using fluorescent lamps)
• ISO/CIE 19476 (photometer indices)
• CEN/TS 16599 (photocatalysis action-spectrum guidance)
• IEC terminology references (IEC 60050 series)

Keywords: ISO 24448:2023, LED light source, photocatalytic materials, indoor lighting, fine ceramics, illuminance meter, correlated colour temperature, CIE Ra.