I have worked on such systems at Signify: There are numerous barriers to wider adoption except for very high risk situations. For instance: there have yet to be lawsuits to determine the risk of exposing people to UV. As you see in the comments below, any "UV" is considered dangerous by people not aware of the biological effects of various wavelenghts.
Besides this, excimer lamps have a low expected lifetime, of both the light source as well as the filter due to the high energy in the UV photons. This makes replacement (and maintenance cost) a real risk. This could be remedied by similar wavelength LEDs from companies like CrystalIS but these are expensive and very low power (only work germicidal on a short distance).
Prof. Brenner at Columbia University has first foreseen applications of 222nm in operating rooms, to prevent infection during surgery.
On the whole, it would need significant investment in both research, certification and risk analysis for this to become commercially viable, so while some of the technology is there, the market demand so far just is not -- post-pandemic.
Is there any reason why they can't just be installed inside air purifiers/ventilation?
Especially since you could probably get more mileage out of the same amount of light energy by forcing the air through a narrower passage, since only airborne particles are actually going to absorb any energy anyway, and air is mostly just empty air.
That solution is actually suggested in the article. However, that still leaves the cost issue mentioned by GP, and until that is solved, this will remain something for specialized applications (operating rooms) and maybe hypochondriac millionaires...
From a quick search, they are not millionaire-level expensive. Here for example is a 20W 222nm lamp that costs $436, with a lifetime of several thousand hours.
Sure, I'm not saying it's cheap. I'm just saying there are lots of software developers and whatnot who could keep themselves in UV air filters if they really wanted to.
Yeah I saw a lamp for this and it had a proximity sensor to prevent overexposure. There's no way I'm buying a lamp that needs that to be safe. Especially if it's expensive and only lasts a year or two.
Mostly used to eliminate or reduce mould growth on the inverter? If HVAC is taking air in or blowing air out, there really wouldn't be a point disinfecting the air.
If it's re-circulating, it could reduce the spread of germs room to room as has been shown during the pandemic in elderly care facilities. That would be the only use-case I see.
they claim it would reduce growths on the coils but also eliminate mold and bacteria spores. Our system is a re-circulating system. One large intake in the center of the house and out flows in individual rooms.
The mould reduction is real, and could lenghten the maintenance intervals for cleaning. Not fully eliminate it though, it really only eliminates the parts the UV light reaches (so not the back, or any other part not exposed).
Depends on your HVAC system and the maintenance cost in your area. For me at 150€ per intervention it wouldn't make any sense, but I have heard some HVAC develop a smell and in that case, UV is likely to prevent it.
After years of being a fly on the wall I signed up just to say: most of those things are closer to Radithor than snake oil.
There are only a few companies that sell those things at that price point (installed, $600-$800 for the unit), and they’re all so egregiously fraudulent that I strongly considered doing the leg work for a class action lawsuit.
I got the same pitch a few years ago, but as their bad luck would have it I actually worked on a UV-C LED based germicidal system for years with the same goal in mind, albeit as a hobbyist. My focus was on the LED based variants, which dominates new residential products, so I can’t speak to other systems. That said, regardless of the technology a $1,500 UV-C germicidal HVAC system is a $1,500 MRI machine - no it isn’t.
I was extremely interested in how they managed to accomplish what I had deemed unreasonable with current technology, while also being about 1/4 the cost and 1/15th the power requirements. The latter magic claim is their biggest tell, since the power requirements are slapped on the box and the power supply itself. In this case it was ~17 watts. I’d estimated ~300w for a barely reasonable reduction of common pathogens, and that was based on trying to out-clever systems that used 700w+.
Long story short, I disassembled one of them and they’re regular blue-violet LEDs @ ~405nm, a ceramic fragrance diffuser (popular’ish air freshener in the 90’s) that they marketed as some kind of alien tech UV enhancer, and a high voltage ionizer buried deep in the housing. The last item was going to be my cause for action since they proudly claim zero ozone generation while including a device that is solely intended to produce it. Hilariously I actually had a box of the same ionizers and I think I paid $20 for two scoops of them. I believe they include it so they can technically say the device does indeed have some level of potentially measurable germicidal properties, whereas their purple LEDs would have zero. They never claimed the lights were what did it!
They try bank on a technicality and consumer confusion regarding the LEDs by being very careful to say “UV” on the box, not “UV-C”, and due to inefficiencies of not being a laser the spectral wings of ~405nm purple lights would accidentally qualify as emitting UV. I also think there’s probably a legal loophole that allows the minuscule amount of ozone being generated by the literal ozone generator to qualify as “zero” due to dilution, while still being “germicidal” (if they brush up against the electrodes), so they may be skirting the law there as well. I don’t think the totality of their attempt at legal shenanigans would hold up, but I can’t find any other rational explanation for their very specific design and marketing decisions.
That’s as far as I got with it, since I only had a couple hours to inspect the device, but that was more than enough to make up my mind. Final thought: even if they used enchanted technology that fell from space you may only need to consider the 6-8” wide device being installed directly in the ~18” airflow, and restricting it accordingly, to decide if you’d be happier with an external HEPA filter in a couple rooms instead.
there are much simpler and more reliable ways to significantly reduce indoor air contaminents.
one is a building method that produces a "floating" slab floor, that has a small gap around most of the walls, and the underfloor space is vented upwards with a chimney, this creates a small but continious air current that removes most dust and other things in the air.
And then the simple expedient of useing radiant heat sources, that while not as lethal as UV, are
in fact quite deadly to bacteria and anything tiny with a high water content, but completly harmless to humans and ,animals,plants. Couple this with hard, smooth ,surfaces that are designed so that there no crevices or areas filth can acumulate, useing hard woods,glass,tile,metal,leather/vinyl l,high gloss paint,for surfaces. No cloth, no carpet.While not exactly cosy or friendly, it makes getting home that much nicer.
Cheap, reliable, low maintenence, implimentable at scale, now.
Your first paragraph is advocating for ventilation, which is great but there's been so much incentive to reduce building energy consumption (heating/cooling) that recirculating, filtration and other technologies have resulted in offices becoming almost sealed off. We are now moving towards more balanced models as people don't feel comfortable in such offices e.g. sick building syndrome.
my description is a bare outline, actusl instalation could easily include a heat exchanger, and by going to radiant heat, it's surfaces that provide the heat,ie: floors (warm/cool feet) and walls, cielings, with humidity controll bieng done in air
HCAC is decidedly unsexy engineering, but it can effect, all of every day so worth a bit of attention
Since you seem to have a bit of knowledge here, are there any terms or links you would recommend for a novice to learn more about this floating concept? Really liking everything about this post
The whole idea, along with complete construction techniques was given to me verbaly, and would be stumpted as to where to send you, as my local , venerable {c:1980} passive solar organisation has gone darth, and is somewhat captured by industry, though if prompted still might publish there off grid solar design manual ,which had been adopted by many other organisations worldwide.
https://solarns.ca/
The whole idea is based on thermal loops, which is powered, as everything is, by the fact that heat rises, and that internal cavitys/rooms tend to be cooler at the walls, causing a down draft there,and that energy can be put to work.
I know of other instalations in service for decades useing similar methods, but theses ideas and the floating slab are just physics.
People are building houses here with double exterior walls acting as thermal breaks, which have no home heating installed, or ever needed, just air/heat exchange,normal domestic activity providing excess heat even @-25°c.
Straw bale houses have proven to be the same.
Luckily we have a long tradition of challenging building codes and getting engineers behind different ideas, but the full stack of passive technologies is still not bieng implimented at scale.
Besides this, excimer lamps have a low expected lifetime, of both the light source as well as the filter due to the high energy in the UV photons. This makes replacement (and maintenance cost) a real risk. This could be remedied by similar wavelength LEDs from companies like CrystalIS but these are expensive and very low power (only work germicidal on a short distance).
Prof. Brenner at Columbia University has first foreseen applications of 222nm in operating rooms, to prevent infection during surgery.
On the whole, it would need significant investment in both research, certification and risk analysis for this to become commercially viable, so while some of the technology is there, the market demand so far just is not -- post-pandemic.