When Signify installed 31 air purifiers as coronavirus fighters at a German supermarket this month, LEDs Magazine wondered whether the company had partnered with an HVAC group to boost the chances that the store’s air would circulate up to the fixtures, which are mounted roughly 11 ft high pointing outwards parallel to the ground rather than down at it.
Signify responded that it had worked on its own, and that it did not boost the existing circulation in the Hamburg outlet of the national Edeka chain.
That came as a mild surprise to us.
Sure, the technology that Signify deployed — UV-C radiation emitted at 254 nm from conventional mercury vapor tubes — has been proven to kill in seconds the virus that causes COVID-19. But the effectiveness of an air purifier is limited by how much air passes through the radiation zone at any one time, especially considering that the virus, SARS-CoV-2, is believed to survive in an airborne state for up to three hours. With the UV-C radiators mounted high up for safety reasons, it would seem that a circulatory kick of some sort would be in order. Signify CEO Eric Rondolat himself has suggested as much during the course of presentations on UV-C coronavirus disinfection over the last few months.
Signify did not take that course of action at Edeka.
“No additional air circulation equipment [was] needed,” a Signify spokesperson told us. The deployment fit a general scheme in wall-mounted and ceiling-mounted UV-C in which “as air flows through the room and with natural convection eventually all air gets in the radiation zone at the ceiling and gets disinfected,” he said.
Then again, it was certainly not a total surprise. Some amount of air disinfection is better than none. Upper air disinfection, if nothing else, provides an extra layer of defense against the coronavirus. Combined with other measures, such as a UV-C disinfection chamber that Edeka is using to sanitize objects including handheld scanners, it can be a useful weapon in the war on the pandemic.
In tandem with enhanced circulation, it could be even more useful. So LEDs went looking for an example of where such pairings might be happening.
It didn’t take us long to find an initiative coming from the HVAC side. Lexington, KY’s Big Ass Fans earlier this year started offering a couple of ceiling fans that include UV-C lamps embedded in the suspension stem, above the blades and pointing outwards. The idea is that the fans draw air up where it passes through the UV-C radiation before the whirring fan helps the air return its journey to lower levels.
Big Ass Fans has at least two products with UV-C. One, called the Clean Air System and aimed at industrial spaces, also includes an ionization technology that Big Ass Fans says is effective at killing the coronavirus. A smaller model, which is part of Big Ass Fans’ residential line called Haiku, does not have the ionization feature.
We don’t know who is supplying the UV-C lamps to Big Ass Fans, but we will update you if we find out.
Notably, whereas Signify was not able to provide us with any quantification of air disinfection rates at Edeka, Big Ass Fans has issued some general test numbers for its UV-C/fan combination, as measured by California testing lab Innovative Bioanalysis. The company shared the results two months ago with technology website CNET, in the form of a cover letter that that the lab’s chief operating officer Kevin Noble sent to Big Ass Fans along with the test report.
The report appears to have examined the effectiveness of the Haiku model — the version without the extra ionization feature.
“With regards to the aerosol testing we saw approximately a 48% reduction [of airborne SARS-CoV-2] above the fan at 5 minutes and approximately an 86% reduction above the fan at 10 minutes,” Noble’s letter to Big Ass Fans read. “It can be concluded that between 10 and 20 minutes there was an overall reduction of 99.99% or greater… With regards to whether your technology works on denaturing SARS-CoV-2, I would say that you could clearly state that pathogens in the air passing over the fan and through the UVC are in fact negatively impacted by the UV light.”
Big Ass Fans is testing the unit in different settings including school classrooms.
“One test, which measured the efficacy of two fans spinning in a classroom environment contaminated by the SARS virus, found that the UVC lights would reduce a student’s risk of exposure during a 60 minute class from 39% to 5%,” CNET reported. “ For a teacher spending seven hours in the room over the course of the day, the risk of exposure fell from 97% to 30%.”
Pittsburgh’s Carnegie Mellon University is among the schools to be using the technology, according to the article.
Big Ass Fans’ chief financial officer Eric Evans is a 2001 MBA graduate of CMU’s Tepper School of Business.
The company is selling its Haiku home UV-C fan online for between $1744 and $2244.
This is not the first time that Big Ass Fans has worked with the lighting industry. Back in 2017, we noted that the company was an early advocate of the Thread protocol for Internet of Things (IoT) schemes, which was then picking up interest among lighting companies.
MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).
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