NASA found the 18 best plants for naturally filtering the air in your home | Hacker News Reader

NASA found the 18 best plants for naturally filtering the air in your home

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21 pointsmrafiee16 comments

Worth noting that you need hundreds of plants in a small room for any actually useful magnitude of effect.

Is there another tool that is more pragmatic? Like a hepa air filter device or something?

I just installed an ERV (Energy Recovery Vent) into my 1970-built bedroom — it has drastically increased the air quality (I have it set to exchange the entire house volume 8x per day). It is as quiet as the ceiling fan, nowhere near as loud as a dehumidifier (which pair well, together, for overall room/house comfort). I also leave the central HVAC fan `ON` 24/7.

There is a HVAC cost because the ERV is only ~60-75% efficient (at recovering heat/humidity with external supply air exchange), depending on the cfm/setting... but it gets rid of every stink, and you smell the morning dew and approaching thunderstorms. As is recommended, I leave mine on 24/7 — it has a boost mode which can be activated with switches wired anywhere else (e.g. bathroom, for during showers)... I plan to use a wallswitch timer for this temporary airflow increase, because the 24/7 setting I've set is 70% efficient, and at MAX it drops to only 60% energy recover.

The Panasonic unit I installed was ~$600, plus an additional $100 in venting. Took me about eight hours to DIY install (but I have decades of blue collar electric under my belt and am familiar with house). This would have probably been bid out ~$2500 if a company were doing it, on a simple install (i.e. <25ft ducting to non-roof penetration).

I think either DIY or Pro expense would be worth it, particularly if your air is stale / litter box / subtropical humidity. Modern building codes require HRVs/ERVs in most new construction, so if your building is even just a couple decades older, ERVs are worth looking in to (HRV if you live in desert climates).

[0] https://en.wikipedia.org/wiki/Heat_recovery_ventilation#Fixe...

[example] https://www.homedepot.com/p/Panasonic-WhisperComfort-60-20-5...

An ERV itself does nothing for air quality, yours is likely just a a fixed plate air-to-air heat exchanger, much easier for a homeowner to maintain than an enthalpy wheel that has a motor and needs additional air filters since the fixed plate ERV has no moving parts.

Setting your furnace fan to ON to increase the number of air exchanges in your house without the heat exchanger would do the same thing.

Your indoor air quality, assuming your HVAC is properly balanced to have positive pressure, is determined by your furnace filter type and age and how clean your ducts are.

There are other types of heat exchangers used to capture heat from exhaust air streams (enthalpy wheels are common in commercial HVAC) but none of them change air quality.

That being said, ERVs/HRVs are amazing and should be in every house, along with domestic hot water recirculating pumps[0] :)

There are also heat exchangers that capture latent heat from your shower water [1] to preheat the cold water line going into the hot water heater, though I am unsure if you’d ever capture enough latent heat back to pay for it. They’re made out of copper so they’re a bit pricey, and virtually everyone has a natural gas water heater where I live (MN), so it’s practically free to heat water.

[0] https://www.nachi.org/hot-water-recirculation-systems.htm

[1] https://www.energy.gov/energysaver/drain-water-heat-recovery

>An ERV itself does nothing for air quality

I disagree — it is literally exchanging outdoor air with indoor air; so perhaps if it was heavily polluted outdoors then it could certainly worsen indoor air quality.

>Setting your furnace fan to ON to increase the number of air exchanges in your house without the heat exchanger would do the same thing.

I think you are misunderstanding how an ERV is plumbed. Unlike furnace `ON` cycling indoor air indoors, the ERV is literally exchanging inside/outside air constantly & entirely, directly through the plate membrane.

>Your indoor air quality, assuming your HVAC is properly balanced to have positive pressure

In the ERV setup I described installing, earlier, it is the ERV which generates/maintains the positive pressure differential.

>There are also heat exchangers that capture latent heat from your shower water [1] to preheat the cold water line going into the hot water heater, though I am unsure if you’d ever capture enough latent heat back to pay for it.

This is why instead of drain heat capture (not economical at microscale) to save energy, I installed a heat pump water heater. I live in the US SE (technically a subtropical rainforest) so the heating of the water is essentially "free cooling / dehumidifying" for all the non-HVAC-heat days of the year (~9 months). During the brief winter, it switches over to standard dual 4500W heating elements.

  Is there another tool that is more pragmatic? Like a hepa air filter device or something?

Activated carbon. These NASA plants absorb VOCs. Same as activated carbon. But you need a lot of it. Like several KGs of it in one air filter. The mainstream air filters you buy usually have 100-200g of it only. Need 5 - 25kg ideally.

For particulates (smoke, dust, allergens, etc.) you can get a good HEPA filter. For odours and VOCs, filters with active carbon can work extremely well but you need one with a big mass of carbon. A carbon filter is easier to jerry-rig to a fan, air duct or existing HEPA air purifier because they often have a very low airflow impedance.

1. Dwarf Date Palm

2. Boston Fern

3. Kimberly Queen Fern

4. Spider Plant

5. Chinese Evergreen

6. Bamboo Palm

7. Weeping Fig

8. Devil's Ivy

9. Flamingo Lily

10. Lilyturf

11. Broadleaf Lady Palm

12. Barberton Daisy

13. Cornstalk Dracena

14. English Ivy

15. Varigated Snake Plant

16. Red-Edged Dracaena

17. Peace Lily

18. Florist's Chrysanthemum

Needs to be ordered by pet safe and hardest to kill.

Devils ivy, aka Pothos. I just got on a kick and bought 7 varieties. Not sure what attracted me to them but it’s nice to have some green in my life.

I'm unsure about the Weeping Figs' inclusion in the list, although I do expect NASA has considered this - but, don't Weeping Figs contain lactose, which becomes air born when dried into a dust, and isn't anaphylactic shock a potential consequence of lactose dust inhalation?

Or is it that the impact of Weeping Figs lactose content is minimal when compared to the benefits of the plant, overall - perhaps the lactose is why it is able to filter air so well, anyway?

https://pubmed.ncbi.nlm.nih.gov/8603279/

I've always found this more aspirational than helpful, as my back-of-the-napkin math puts the number of plants needed to make an impact on air quality at some ludicrous number.

please share the math... or the napkin.

Not sure about other chemicals, but carbon seems particularly hopeless. Plants produce CO2 as they respirate and consume it as they photosynthesize. So rather than think in terms of number of plants, think in terms of the weight of the plants (not the dirt). Carbon sequestration is going to have to add net weight to the plants. A human produces 2.3 pounds of CO2 per day. So, how many pounds per day will your crop of carbon scrubbing plants have to increase by in order to sequester that carbon? How much green material by weight do you need to achieve that rate of growth?

This represents a nuanced understanding of most plants' carbon fixation cycles — mass captures CO2 while simple existance does not — that is technically correct.

In the application of having just a few indoor plants, I do think the air quality is fresher (just beyond CO2 levels; which indoors the effect is nil).

The research: https://ntrs.nasa.gov/citations/19930073077

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