My only moan about dynomight emails/posts is that I don't have time to read them all. But this Wirecutter post is a stonecold gem. Re-read. Cross-checked. It all adds up. Classic. Thank you.
One thing that I've never understood about the graphs of particle size vs filtration efficiency: small gas molecules (e.g., oxygen, carbon dioxide, etc.) apparently pass thru the filter easily. So, does the filtration efficiency drop off in the sub-nanometer range (and if so, why)? Or are these gas molecules chemically different from particulate air pollution in some relevant way?
Great post, thanks! I wanted to comment that while I agree with you on almost all of your points, and in particular I agree that the IKEA filter is a great choice for small rooms (like the 70 sqft bedroom you used as an example), I think it's important to mention that there are better, more cost-effective air purifiers for bigger rooms. I think the IKEA filter is the most cost-effective filter I've seen for small rooms while the Coway Mighty is the most cost-effective for medium and large rooms (it's also my overall favorite).
I did a fair amount of research on different models and ran the numbers on filtration rate and cost: my post is https://firstsigma.github.io/air-filtration and numbers are in my spreadsheet https://firstsigma.github.io/air-filtration-sheet. I agree that the IKEA filter is cheaper than the Wirecutter's small-room recommendations. However, for anything other than very small rooms, I recommend the Coway Mighty instead (also Wirecutter's top overall pick) - it's very cheap in the long run and offers far more filtration capacity (CADR), and more CADR per dollar (i.e. more cost-effectiveness for medium and large rooms).
The Coway also has all of the advantages you mentioned for the IKEA filter (pretty, cleanable pre-filter, cheap replaceable filters, minimal electricity, cheap overall). It's a bit more expensive - which is worth it for bigger rooms because it filters much more. If you want to get a target amount of filtration (CADR) with least cost, by my calculations the Coway is cheapest for everything but small rooms.
One important difference in my figures is you ran the numbers for high speed, but I recommend using medium speed in general. The Coway Mighty consumes shockingly less electricity on medium: 8W on medium and 70W on high (I was very surprised so I tested it myself with a wattmeter; the Wirecutter also had approximately the same measurements). And medium speed is much much quieter - I wouldn't want to constantly have the noise of high speed in the background.
I calculated the total annualized cost over 5 years including the air purifier, filter replacements, and electricity to run 24/7 on medium. The Coway Mighty costs around $75/year and the IKEA Förnuftig around $40/year. If we look at CADR per dollar, which is appropriate if you are choosing whether to filter a larger room with one Coway or two IKEAs, the Coway is far cheaper than any other air purifier I've looked at (and even roughly on par with a cheap DIY Corsi-Rosenthal box)
One of my friends just bought the IKEA filter after reading your blog post, but when I asked them about how big their living space was it turned out they hadn't considered sizing for the air purifier, and it was not a small room. Though having a small filter is still a lot better than nothing (and there are diminishing marginal returns on CADR), so it's still good that your post got them to invest in air filtration! Thanks again for the post!
Beautifully done. A polemic, but not a rant.
My only moan about dynomight emails/posts is that I don't have time to read them all. But this Wirecutter post is a stonecold gem. Re-read. Cross-checked. It all adds up. Classic. Thank you.
I came, read the post, ended up learning new things, and to top it off I had a couple good laughs.
Wonderful post, bravo!
Indignant bullshit detecting is the BEST.
The degree of ongoing outrage caused by IKEA making decent & attractive products available at a recent price is unbelievable.
One thing that I've never understood about the graphs of particle size vs filtration efficiency: small gas molecules (e.g., oxygen, carbon dioxide, etc.) apparently pass thru the filter easily. So, does the filtration efficiency drop off in the sub-nanometer range (and if so, why)? Or are these gas molecules chemically different from particulate air pollution in some relevant way?
Great post, thanks! I wanted to comment that while I agree with you on almost all of your points, and in particular I agree that the IKEA filter is a great choice for small rooms (like the 70 sqft bedroom you used as an example), I think it's important to mention that there are better, more cost-effective air purifiers for bigger rooms. I think the IKEA filter is the most cost-effective filter I've seen for small rooms while the Coway Mighty is the most cost-effective for medium and large rooms (it's also my overall favorite).
I did a fair amount of research on different models and ran the numbers on filtration rate and cost: my post is https://firstsigma.github.io/air-filtration and numbers are in my spreadsheet https://firstsigma.github.io/air-filtration-sheet. I agree that the IKEA filter is cheaper than the Wirecutter's small-room recommendations. However, for anything other than very small rooms, I recommend the Coway Mighty instead (also Wirecutter's top overall pick) - it's very cheap in the long run and offers far more filtration capacity (CADR), and more CADR per dollar (i.e. more cost-effectiveness for medium and large rooms).
The Coway also has all of the advantages you mentioned for the IKEA filter (pretty, cleanable pre-filter, cheap replaceable filters, minimal electricity, cheap overall). It's a bit more expensive - which is worth it for bigger rooms because it filters much more. If you want to get a target amount of filtration (CADR) with least cost, by my calculations the Coway is cheapest for everything but small rooms.
One important difference in my figures is you ran the numbers for high speed, but I recommend using medium speed in general. The Coway Mighty consumes shockingly less electricity on medium: 8W on medium and 70W on high (I was very surprised so I tested it myself with a wattmeter; the Wirecutter also had approximately the same measurements). And medium speed is much much quieter - I wouldn't want to constantly have the noise of high speed in the background.
I calculated the total annualized cost over 5 years including the air purifier, filter replacements, and electricity to run 24/7 on medium. The Coway Mighty costs around $75/year and the IKEA Förnuftig around $40/year. If we look at CADR per dollar, which is appropriate if you are choosing whether to filter a larger room with one Coway or two IKEAs, the Coway is far cheaper than any other air purifier I've looked at (and even roughly on par with a cheap DIY Corsi-Rosenthal box)
One of my friends just bought the IKEA filter after reading your blog post, but when I asked them about how big their living space was it turned out they hadn't considered sizing for the air purifier, and it was not a small room. Though having a small filter is still a lot better than nothing (and there are diminishing marginal returns on CADR), so it's still good that your post got them to invest in air filtration! Thanks again for the post!