DOE Publishes Second Round of Germicidal Ultraviolet Product Test Results
The U.S. Department of Energy (DOE) has published the second round of CALiPER test results for germicidal ultraviolet (GUV) products. These Round 2 results further demonstrate the importance of education and industry standards in the GUV product industry.
GUV air treatment is an effective and energy-efficient method to reduce airborne disease transmission in combination with ventilation and filtration. GUV can play a critical role in meeting advanced indoor air quality standards using less energy. To turn this potential into reality, specifiers and buyers of GUV technology need complete and accurate performance data for the safe, effective, and energy-efficient application of the technology. At the same time, product developers need industry-standard test methods and associated laboratory capabilities to provide this data.
The prior round of CALiPER GUV testing evaluated radiometric and electrical performance for a mix of GUV product types. Round 2 focused on a single product type: upper-room GUV luminaires for occupied rooms. Of the eight GUV luminaires tested, three used UV-emitting LEDs and five used low-pressure mercury (LPM) lamps.
Key Findings and Recommendations
CALiPER results compare measured performance against manufacturer or vendor claims. Differences between performance claims and test results in Round 2 were fewer and smaller than in Round 1, but the results continue to suggest that some product developers and sellers may not understand how to measure and accurately report GUV product performance. To address this issue, the industry could prioritize development of a standard set of recommended testing for each product type, with a standard set of associated performance data that should be reported for each product. In one such effort, the ANSI C137.12 working group has begun drafting a new standard that is partly aimed at presenting consistent and accurate information regarding GUV products. Once developed, product developers, sellers, specifiers, and buyers could be educated about its use.
The Round 2 results also demonstrate substantial variation in radiometric performance among different upper-room GUV luminaires. LPM luminaires that had parabolic reflectors aligned with inclined louvers exhibited substantially higher UV-C radiant efficiency than tested LPM luminaires with other designs, potentially cutting energy use by 75%. Results also showed that although UV LED emitters have much lower radiant efficiency than LPM lamps (at the source level), UV LED luminaires can offer UV-C radiant efficiency comparable to LPM luminaires in upper-room GUV applications that require a focused, directional beam.
Finally, the Round 2 results demonstrate there is more work needed to address testing limitations and improve test lab infrastructure and capabilities to support the accurate testing of GUV products. Mirrors typically used in goniophotometry can reflect little-to-no UV-C, so the test laboratory in Round 1 used their gonioradiometer without a mirror; in many cases, this yielded near-field radiant intensity data, which cannot be used to reliably predict irradiance at far-field distances when imported into GUV application design software. However, the test laboratory in Round 2 was able to produce far-field radiant intensity data using the mirror on its gonioradiometer. CALiPER is currently conducting intralaboratory and interlaboratory comparison (i.e., round-robin) testing to gauge any differences between gonio measurements with and without a mirror.
“GUV air treatment is an important technology to address current public health challenges and prepare the country for future pandemics while using less energy,” notes Dr. Diane Poster, Senior Advisor, Director’s Office, Material Measurement Laboratory at the National Institute of Standards and Technology (NIST). “NIST is very involved in the development of standards for this technology, where having standardized, accurate methods to test and report GUV performance are essential components to successful technology deployment. Pacific Northwest National Laboratory (PNNL) is serving an important role in this area through the CALiPER product testing program and their involvement with standards development committees. The CALiPER program is uncovering valuable insights not only about GUV products, but also new and emerging GUV test methods, standards, and laboratory capabilities.”
Download the Round 2 report for complete results and recommendations.
