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Evaluating tools for predicting and measuring radiometric performance of germicidal ultraviolet systems
Valeria Holland1, Belal Abboushi1, Eduardo Rodriguez-Feo Bermudez1
1Pacific Northwest National Laboratory, Richland, Washington, USA.
Photochemistry and Photobiology
|February 19, 2026
Summary
Germicidal ultraviolet (GUV) air treatment systems show promise for reducing disease transmission. Simulation software and measurement techniques were evaluated for accuracy, with tetrahedron approximations proving more reliable for fluence rate estimation.
Area of Science:
- Indoor air quality
- Photochemistry
- Public health
Background:
- Germicidal ultraviolet (GUV) technologies offer effective air treatment for reducing airborne pathogen transmission.
- Current design and evaluation of GUV systems rely on simulation and measurement tools needing accuracy validation.
- Accurate estimation of fluence rate and irradiance is critical for GUV system efficacy and safety.
Purpose of the Study:
- To assess the accuracy of two simulation software (Visual Lighting, Photopia) and two measurement approximations (tetrahedron, cubic) for GUV fluence rate.
- To compare simulated planar UV-C irradiance for eye and skin exposure against measurements.
- To provide data for improving GUV system design and validation methodologies.
Main Methods:
- Chemical actinometry was used as a benchmark for quantifying GUV fluence rate in a chamber.
- Two simulation software, Visual Lighting and Photopia, were employed for fluence rate estimation.
- Tetrahedron and cubic approximations were used for spatial fluence rate measurements.
- Planar UV-C irradiance was measured for eye and skin exposure comparisons.
Main Results:
- Simulation software (Visual Lighting, Photopia) showed similar mean fluence rates to actinometry for Wide-Room (WR) GUV systems.
- Photopia demonstrated similar mean fluence rates to actinometry for Upper-Room (UR) GUV systems.
- The tetrahedron approximation more accurately predicted mean fluence rate for both WR and UR GUV systems compared to the cubic approximation.
- Simulated eye and skin irradiance showed variability when compared to measurements, with higher variability for eye irradiance.
Conclusions:
- Validated simulation software can aid in GUV system design but requires supplementation with in situ measurements.
- Tetrahedron approximation is a more reliable method for fluence rate estimation in GUV applications.
- Accurate GUV system evaluation necessitates a combination of simulation and precise in situ measurements for reliable disease control.
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