r/singapore • u/afiq980 • 1d ago
I Made This Home haze experiment results
I’ve always wondered how effective air conditioning is vs air purifier. So I did a simple experiment at home, see below for the results!
I’m not revealing the purifier brand to avoid discussions on brands.
EDITED: Added a test where I off both aircon and purifier after opening windows (and closing them). It went from 86 to 72 in 23 minutes. Then stagnated 69-72 for the next ten minutes.
<below results part summarized and graph made by AI>
Setup
- Master bedroom in Jurong West, near Jurong Point
- Room empty throughout
- Ceiling fan on max throughout
- Indoor PM2.5 read from the purifier's sensor
Outdoor (data.gov.sg, West)
- 5:59pm: 1-hr PM2.5 at 147, 24-hr PSI at 205
- 6:30pm: 1-hr PM2.5 at 134
Log (indoor PM2.5, µg/m³)
- 5:45 to 6:00pm, ventilator on, outside air coming in: 99 at 5:59
- 6:00 to 6:20pm, aircon on full blast: 73 at 6:12, 69 at 6:16, 66 at 6:19, 66 at 6:20
- Switched to the purifier because readings stayed at about 66 to 69 for about 5 minutes
- 6:20pm onwards, aircon off and purifier on at speed 10 with 25° oscillation: 46 at 6:23, 37 at 6:25, 31 at 6:26, 20 at 6:32, 17 at 6:38, 16 at 6:41
Summary
- Aircon phase: 99 down to 66 in 20 minutes, then it stayed at around 66 for the last 5 minutes.
- Purifier phase: 66 down to 16 in 21 minutes.
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u/IllustratorWitty5104 1d ago
In other words, air purifier did its job as expected
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u/afiq980 1d ago
Actually my main objective was to answer this: “how effective is aircon”, because people think that being indoors and/or aircon is enough. (It might not be)
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u/SG_wormsblink 🌈 I just like rainbows 1d ago edited 1d ago
It really depends on what filters you have installed on your AC.
Most ACs optimize to remove large dust particles since that’s what humans generate. They don’t really target PM2.5 but you can still get some minor reduction (like your data)
But if you install the high-end H13 filters onto your aircon they will be almost as effective as an equivalent air purifier (though your electricity cost will go up too since it’s forcing the air through the filters).
In the end, it depends on what filters you have. The pore size of the filter paper is what blocks Pm2.5 while letting clean air through. So as long as air is passing through the air filter paper by whatever means, it’s being cleaned.
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u/afiq980 1d ago
yeah, my quick google search says most homes dont have 2.5 filters, hope people aren't wasting energy switching on air-con the entire day (vs just closing windows).
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u/Equal-Purple-4247 1d ago
Can you do a test for just shut window, no aircon, no purifier, for about 20 minutes?
In theory, just shutting the window will reduce pm2.5 over time since those particles will settle. In theory also, normal aircon shouldn't reduce pm2.5 substantially since they don't have the right filter for that particulate size. They do reduce larger particles like dust.
For your findings, it is possible that the drop from 99 to 66 is partly due to pm2.5 particles just settling, not entirely due to aircon filter.
I'm curious because if aircon filter can reduce pm2.5 substantially, then maybe I should get someone to clean / service the aircon at my old people house for added protection.
Edit:
If too troublesome then don't need. Already appreciate your data.6
u/afiq980 1d ago
Yeap I did it! See my edited post :)
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u/Equal-Purple-4247 1d ago
Oh wah, either I missed it or you did it immediately for me. I'm gonna assume it's the latter, thaaanks!
Interesting that it naturally settles at around 70, similar to just aircon. Hard to say aircon is statistically effective in reducing pm2.5 with just this datapoint. But I guess it does make being in a closed environment much more pleasant.
I think I'll get the aircon serviced / cleaned after the haze situation subsides. No point doing it now then accumulate a lot of dust again.
Thanks again!
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u/SkyEclipse 🌈 I just like rainbows 14h ago
My mother refused to close the windows because she said if we do that the house will be ‘too stuffy’ lmao. I would rather she on aircon than leave the windows open. (But we don’t have aircon in living room either…)
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u/DuePomegranate 22h ago
Not necessarily. OP didn’t do a test run with aircon off.
Particles in the air will slowly clump together and sink down as dust. So even without the aircon’s mesh filter, the reading should go down by itself. Just not sure the relative contribution of time vs aircon.
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u/New_Basket_277 1d ago
You only get a partial understanding of the aircon, to make aircon effective, user need to close the door and window, it forced the user to make their room isolate from the outdoors haze, so when the haze outside goes bad, the room stays constant, it's never about filtering the air... your data do show
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u/RepulsiveWorker5739 1d ago
Would you mind summarising your results because I’m dum haha. Did just aircon make any meaningful difference? Thanks!
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u/darain2 1d ago edited 1d ago
It did but much less effective than an air purifier. He even puts it in the summary at the bottom of the text. From 100 to 66 (aircon), versus 66 to 16 (purifier), in the same timeframe. Honestly I don't even think it's the aircon doing the bulk of the work, should compare aircon versus simply shutting the windows. Because not allowing outside air containing FRESH particulate matter to blow in is IMO the biggest factor.
For people sensitive to PM2.5 + PM10, even 66 is a threshold that can cause physical discomfort. Easily can irritate skin, eyes, nose, throat.
Minor edit: I claim that closing window is biggest factor because I believe (don't know how true but it's based on observation of how dirty my surfaces in the room have been) that the PM2.5 eventually settles down in an enclosed area. So the limited PM2.5 that entered your room prior to windows closing will be (a) breathed in and sucked into your bloodstream; (b) settle down on surfaces and not circulate anymore if there's no agitation to the particles. Obviously most peoples rooms won't be hermetically sealed so any new PM2.5 that enters through the gaps will lead to higher reading in your room, but I assume it will be negligible as long as you do your best to keep windows + doors shut tight.
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u/afiq980 1d ago
I wanted to try simply shutting windows but my wife really wanted to use the room by then hahahaha
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u/darain2 1d ago edited 1d ago
No complaints from me sir, I love home-brewed "science experiments" lol. Just idea for anyone else reading this and want to reproduce the experiment. I haven't opened my windows in weeks now, even stepping outside for 15min I'll pay the price with my eyes. Nose+throat OK as long as protected by N95, it's really effective. But prolonged wearing and my skin around the edges of the mask peeling because of friction
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u/shroodlepoodle 1d ago
they serve two different purposes no? aircon brings new air into your home and pushes old air out in the process through pressure. you get “new air” albeit dirtier. air purifier recycles and clean the air alr in the home. just because aircon alr filters a bunch of the pollutant doesnt mean it’s its main function
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u/hatboyslim 1d ago
The AC doesn't bring in fresh air into your home. It just makes the stale air in your home cooler.
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u/Maleficent_Jaguar837 1d ago
Pretty interesting! I have new ACs and they have PM2.5 filters on them. Running AC made a notable difference compared to outside the last few weeks (I also live in the west). But the last few days I have had burning eyes and headache inside with AC and have had to go and buy an air purifier. Big difference in feeling!
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u/Skellig_Michael 11h ago
Maybe the PM2.5 filter on the new AC is clogged already thats why not so effective after prolonged usage.
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u/Sorry_Astronaut6040 22h ago
You forgot to take baseline measurements for 20 minutes of nothing running, and also 20 minutes of a person breathing would be interesting.
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1d ago
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u/Electronic-Sir-8854 1d ago
Wait huh weird your Aircon blow bring more haze? Is it a portable Aircon because those create neg pressure it will suck in outside air as a side effect of it venting hot air out
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u/NoBicDeal 1d ago
Rich guy. He live in landed with centralize air con system that's sucks in fresh air to mix with circulated air.
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1d ago
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u/hayashikin 1d ago
Normal A/C does not bring in any air from outside, it only circulates air in the room
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u/Jimmiiyy 1d ago
Most probably aircon needs cleaning. Too much dust and haze.
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1d ago
[deleted]
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u/Jimmiiyy 1d ago
I used those 3m filtrete type non woven cloth and I am changing it much more frequently than previously. Just saying, no offense.
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u/honey_102b 1d ago
you can put the data points to LLM and get the decay rates for the individual devices. exponential decay would be fine. rough eyeball Aircon alone takes 2-3x as long as purifier alone. happily surprised to see that either device is so effective. probably more than 90% reduction for 1hr of purifier alone or 2-3 hours of Aircon alone.
that means there's no need to run these things all day as long as doors and windows are closed of course. good for wallet, good for planet, good for health.
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u/hatboyslim 1d ago
Doors and windows are not airtight. There will be some outdoor air leaking into the house through diffusion and after a whole day, the indoor PM2.5 level will creep up to the outdoor level.
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u/Electronic-Sir-8854 1d ago
yeah will have outside air leak in that's why air purifier can adjust to low speed once it drop majority of the pm2.5
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u/afiq980 1d ago
too financially painful to switch on aircon the entire day haha
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u/stackontop 17h ago
Actually the aircon doesn’t use much electricity to maintain temperature and humidity after you hit your target setting.
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u/sonastyinc 19h ago
But you have to open the windows to let the Co2 out a couple of times a day, right?
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u/AltruisticRip7582 12h ago
Not really. I run a 400m3/h intake supply fan with G4 and H13 filter installed. All doors and windows except the toilet windows are closed. The toilet windows are opened as the exhaust path. The whole house is under positive pressure with approximately. 1 air change per hour with this set up. I did some CO2 measurements previously with a Fluke Airmeter. So far, i did not have any issue with the CO2 concentration.
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u/shuijikou 1d ago
I did a test myself few days back, indeed closed window and air-con only have the same data ≈ 70,
With purifier it goes down below 30 pretty quickly
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u/shuijikou 1d ago
Also, i assume brand of purifier didn't matter, as it ultimately depends on the filter used, as long as the filter suitable for PM2.5 the results more or less will be the same?
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u/Skellig_Michael 11h ago
it matters because every air purifier relies on its CADR which stands for Clean Air Delivery Rate - a standardized metric that measures how quickly an air purifier removes airborne particles from a room. In general a higher rate is required for bigger room, small one will struggle and require longer time to clean the air.
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u/New_Basket_277 1d ago
Well, if you were to open the evaporator side of the aircon and look, you probably only see dust mesh inside, never aircon for consumers have any form of filter in it.
Probably the only coincidence that remove particles is the wet dew vapor condensate on the evaporator fins, that's why your split drains can sometimes clog and need vacuum to clean it