Anyone have IAQ monitors they like? Reviews online are so mixed and I think it’s because people don’t know what they’re looking for.
I want temp/humidity/VOC/1/2.5
And I want the ability to trend
Homeowners typically don’t know how any of this affects them, so reviews online and such are diminished in my mind.
This is for my house btw, I’m gonna test out some gimmicks in my house and see if they work
You touch a pet project of mine that has been evolving for the last 5 years.
Before I ramble here's my view on the parameters you mentioned:
Temp/RH
For temp/ humidity there are, of course, and number of inexpensive devices that will deliver accuracy to <+~5%. More expensive devices are more responsive (quicker).
As far as interfaces go wifi, bluetooth, memory storage in the hardware - there are many options. I usually buy low cost units from Amazon with an LCD display. The smart controller on my Bryant provides temp/humidity via wifi so I can read from anywhere with a smart phone. Unfortunately the temp readings are not as accurate or as responsive as some the units I've bought from Amazon.
In any case fairly accurate temp/humidity are easily available to any home owner.
Particulate Matter Pollution:
When you hear a news story about the dangers of air pollution and the 4 - 6 million deaths a year - the reference is to Particulate Pollution especially the really small stuff below 2.5um (2.5 millionths of a meter).
Over the decades was has been considered acceptable levels of PM 2.5 have fallen precipitously.
In fact, the latest data shows about 200,000 deaths a year in the US at PM2.5 levels below current EPA standards (12um). In fact many scientist believe there is not acceptable level of PM2.5.
I'm incredulous but anytime we breath pm2.5 it can be adsorbed into the blood stream. Keep in mind this has been going one for the last couple of billion years on earth long before the industrial revolution.
Two good pieces of good news:
1. Accurate measurement of PM levels are accessible to the home owner for about $200 -$300. Laser based PM level detectors with a pump provide surprisingly accurate, high resolution, and responsive readings. I use one of the Dylos products myself, but there are others. Beware of non- lasers based systems.
2. Hepa filters and even Merv 11+ AC return filters do an amazing job of keeping PM2.5 levels down.
VOCs
VOCs are where the issues become murky with all sorts of unjustified claims.
What's not appreciated about VOCs is that the boiling points range between 50 - 250 C (122 - 482 F)
That means the VOCs that get to our nose are just off gassing from liquids and solids in our home. Until the source is eliminated or exhausted we will have a VOC problem.
There are VOCs that are known to be dangerous at fairly low levels - benzene, formaldehyde, acrolein, acetaldehyde, ect, but many VOC have limits that are much higher than I ever expected. For instance OSHA allows levels of 500PPM of acetone (think nail polish) - that's huge!
My most immediate problem with VOC, even at low levels, is that well being and cognitive processing are effected. A group at Harvard studied office workers exposed to an extremely low levels of multiple VOC in an office environment where levels were manipulated. And even when levels were only very, very moderatlely increased, cognitive capabilities decreased. And these levels were much lower than what many of us are exposed to continuously in our home and work environments. This was a double blind study so neither the office workers or researches knew when levels are increased.
Unfortunately measuring VOCs, contrary to all the companies pedaling VOC meters is not easy for the home user, but it can be done - kinda sorta.
Here's three methods:
GC/MS lab testing.
I know of at least 2 companies (Home Air Check) is one that will provide a real test kit calibrated to lab standards provide a sample to be return to the company for a fairly accurate result. Cost is about 150 - 225 per room. Takes about a week for results. If you have a VOC issue or think you do this test can be invaluable. Unfortunately is not inexpensive and takes a week to get results.
Photo Ionization Meters:
This device provides and immediate real time readout of VOC levels. These devices cost about 8K but can be rented for about 120 - 175/day. Not cheap but really useful when you want immediate readings or desire data on some gizmo or mitigation strategy. These devices make assumptions and cannot be used to determine the true TVOC level, but are invaluable in determining if a problems exist.
Consumer based MOS sensors:
In the last few years a low cost semiconductor technology has been promoted for measuring VOC levels. About 4 different companies actually manufacture the silicon chips and provide an "application note" so any one with moderate electronic experience can build these devices. The absolute readings of these device can vary widely even when comparing the multiple units of the same model setting right next to each other.
I've been using the Temtop M10 to measure TVOC levels. I've got 3 units right next to each other one reads - 240ug/m3. another reads 380 ug/me and yet another reads at 600. I've seem many similar reports.
What i have found though is that the relative readings of these device can be very valuable for determining if a given mitigation strategy is working or not.
I've seen heavy carbon canisters reduce TVOC levels 40 - 90 % with these devices. At the same time i've measured No change when using a number of different PCO hydroxyl or bipolar devices.
On the other hand bringing in fresh air and exhausting stale air can bring levels to almost zero in short order.
I'm very interested in your investigations, please let me (us) know what you find when testing various "gizmos". The only thing, so far, that I've found effective for VOCs are ventilation and heavy carbon canisters.
The important issue is fresh, filtered air change when the home occupied. This will purge indoor pollutants and renew oxygen. Fresh air change occurs when the wind blows and stack effect occurs. Most home get adequate fresh air change during winter weather. Rather than attempt to monitor indoor pollutants (some unknown), I suggest tacking CO2 to determine occupancy and fresh air change rates. Outdoor air is +-450 PPM CO2. One person in a home generating typical CO2 amounts that will raise indoor CO2 levels to +650 PPM. This a good starting point to activate mechanical filtered fresh air ventilation. I suggest using make-up in an effort to provide make-up air for the various exhaust device in a home, like the kitchen hood, clothes drier, and bath fans. Depending on your needs, a fresh air change in 3-5 hours will handle purging the indoor pollutants and renewing oxygen needed by the occupants.
When the wind blows enough, this avoids over-ventilating. Also avoids ventilating when unoccupied during extended hours.
The are many inexpensive monitoring devices that track CO2 and will activate mechanical ventilate and blend filtered fresh air throughout the home. A common device is the Netatmo WiFi internet device that will monitor outside temp/%RH/rain, indoor temp/%RH/CO2 PPM/Db noise and atmo pressure for <$200 Amazon. This includes memory on the web of all the measurement available on the web.
CO2 controllers are available for +-$200 to activate ventilating, filtering ventilation.
Ventilation in green grass climates also increases the need for supplemental dehumidification during the mild seasons +55^F outdoor dew points to maintain the ideal indoor %RH of <50%RH during low/no sensible cooling loads. Thus companies like Therma-Stor supply ULtra-Aire whole house dehumidifiers with a filtered fresh air option.
The story goes on.
Regards Teddy Bear
A screen shot of Netatmo
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
Thanks for the replies guys. Fresh air would suck to duct in to my place, that’s one reason I’m looking at all the gimmicks to see if any actually help. I’m in Texas with a 1985 home so plenty for air infiltration in lieu of fresh air currently.
I understand the goal of diluting pollutants but really I’m just trying to perform an at-home test of market products. That being said, looking for something to monitor the products I try out.
I too am in Texas where currently dew points this time of year vary between the mid 60s to the low 70's. No change insight until mid Sept at the earliest.
I've got a confirmed VOC problem - measured by lab testing and PID meters. I've tested all sort of devices with little to no luck except ventilation and heavy carbon canisters.
But carbon saturates much faster than most realize and ventilation is temporary. It's the VOCs in and on surfaces in liquid/solid that's the source.
I take pains to keep my summer time RH < 50%. Don't know if an UltraAir device would resolve my issues or not. It would definitely keep my CO2 levels down but not sure about the VOCs. On top of that my Condo HOA does not make it easy to make modifications.
I'll be very interested in what you find from your testing. Feel free to PM me as your research develops.
I know this is a little old but i did some extensive research on this a little while ago.
I would look at the airthings line of products. The view plus will have everything in it you want but it looks like itÂ’s back ordered right now. I have been using the wave plus and a mini to do everything except pm 2.5. So if you want pm 2.5 i would recommend iqair for that. If you can wait a month or two then just get the view plus as it can do voc and pm 1/2.5
Here is a review i did of the airthings line a few months back.
Without measuring the accuracy of the TVoc and PM sensors your review is, for me, useless.
I've got about 6 consumer monitors (including an Air Things model) and these devices are close to worthless for accurate TVoc measurements and many are useless for PM 2.5 levels.
I have found some of these devices useful measuring trends - increasing or decreasing levels, but the absolute readings cannot be trusted..
Without measuring the accuracy of the TVoc and PM sensors your review is, for me, useless.
I've got about 6 consumer monitors (including an Air Things model) and these devices are close to worthless for accurate TVoc measurements and many are useless for PM 2.5 levels.
I have found some of these devices useful measuring trends - increasing or decreasing levels, but the absolute readings cannot be trusted..
I brought up some issues with TVoc measurement in the review. You have a few things you need to think about. One, the TVoc level is not specific. So the numbers they use as "safe" vs "unsafe" are arbitrary. I could have low levels of a "bad" VOC like benzene for example, but since the detector cant distinguish between that and the VOC's in an orange peal it would count them as equal. This would show a "safe" level even though we know the VOCs from benzene are much worse then an orange peal. So this is a problem.
The second problem is the issue is with the way TVoc sensors work. They take a few days to calibrate. They take the lowest VOC rating as 0 or in most cases 50 is the floor for Airthings. If the device never sees true fresh air, the floor can actually have a pretty high VOC level that does not show up on the detector. The only way I have been able to some what mitigate that is to take the unit outside every 5 days or so for 30 minutes to get it a fresh air reading.
So I think there is only so much we can do right now at a consumer cost level. Like you mentioned the data is useful for trends but people need to be careful and informed on what/how these devices read VOC levels .
The next step is how to ventilate correctly to make sure we can dilute the air when we have a spike in VOC's and to reduce the baseline VOC levels. This is where an ERV/HRV comes into play. Especially with newer houses since they are built so tight. You want 3 or so air changes per hour. Its important to make sure the air thats coming in is not just return air from the rest of the house. An ERV/HRV will make sure there is a constant stream of fresh air coming into your house.
I brought u You have a few things you need to think about. One, the TVoc level is not specific. So the numbers they use as "safe" vs "unsafe" are arbitrary.
No. TVoc levels are not arbitrary.
TVoc specifically means the weight of all Vocs in a cubic meter of air. In other words grab a cubic meter of indoor, separate all the Vocs and weigh them.
Organization in both the US and Europe have set standards.
Generally levels <400ug/m^3 are considered "OK", under 200 even better.
Levels >500 are problematic
I could have low levels of a "bad" VOC like benzene for example, but since the detector cant distinguish between that and the VOC's in an orange peal it would count them as equal. This would show a "safe" level even though we know the VOCs from benzene are much worse then an orange peal. So this is a problem.
Agreed fully. And to make that determination GC/MS testing is needed, not a consumer MOS Voc sensor.
The second problem is the issue is with the way TVoc sensors work. They take a few days to calibrate.
it's seems you are not aware of the different between a PID Voc sensor and a MOS Voc sensor.
PID meters have a UVC generator at a specific frequency. Hundreds of Vocs have been characterized by the intensity of ionization to this specific frequency. Most PID meters use a pump to sample air and give reliable readouts in real time.
It's true that PID meters do not differentiate between different Vocs, but if certain assumptions are made a good estimate is obtained. Unlike MOS sensors, readings will always be consistent and accurate in a given environment.
When academic or government investigators need to take live readings they will use a PID sensor, never a MOS sensor.
MOS sensors, on the other hand, are is a totally different technology that's become available in low cost consumer devices. A small handful of silicon chip companies manufacture these "chips" and provide an "application note" on how to add some simple circuitry to make a so called functioning "Voc sensor". Companies like "Air Things" purchase these chips and with the add of the "application note" produce a a product. I believe Air Things use the MOS chip manufactured by Bosch.
The calibration process you described is only applicable to some, not all, MOS Voc sensor chip.
Just the variability in these chips, even from the same manufacturer, are so far out of bounds to make any judgement of TVocs readings impossible. In addition the MOS film on these chip changes characteristics over time to add another element of unreliability.
So I think there is only so much we can do right now at a consumer cost level. Like you mentioned the data is useful for trends but people need to be careful and informed on what/how these devices read VOC levels .
Agreed! I just wished you would have done more "informing" in your review
The next step is how to ventilate correctly to make sure we can dilute the air when we have a spike in VOC's and to reduce the baseline VOC levels. This is where an ERV/HRV comes into play. Especially with newer houses since they are built so tight. You want 3 or so air changes per hour. Its important to make sure the air thats coming in is not just return air from the rest of the house. An ERV/HRV will make sure there is a constant stream of fresh air coming into your house.
No doubt ventilation, ERVs, or devices that only bring in fresh air with humidification will make things much better.
BUT - VOCs boil between 120 - 450 F. That means the Vocs that are in the air are just off gassing from liquids/solids on surfaces. Until these Vocs are removed from surfaces there will always be a problem.
I like 'view plus' by airthings. It has 7 sensors:
radon
PM2.5
CO2
VOC
Humidity
Temperature
Pressure
- all in one device. works on batteries - but i wish it had bigger screen - it shows only 2 sensor readings at the same time (though you can always look into details through their app).
Cant compare with any, since that was the only one i bought - but it seemed to have good reviews on amazon
I brought up some issues with TVoc measurement in the review. You have a few things you need to think about. One, the TVoc level is not specific. So the numbers they use as "safe" vs "unsafe" are arbitrary. I could have low levels of a "bad" VOC like benzene for example, but since the detector cant distinguish between that and the VOC's in an orange peal it would count them as equal. This would show a "safe" level even though we know the VOCs from benzene are much worse then an orange peal. So this is a problem.
The second problem is the issue is with the way TVoc sensors work. They take a few days to calibrate. They take the lowest VOC rating as 0 or in most cases 50 is the floor for Airthings. If the device never sees true fresh air, the floor can actually have a pretty high VOC level that does not show up on the detector. The only way I have been able to some what mitigate that is to take the unit outside every 5 days or so for 30 minutes to get it a fresh air reading.
So I think there is only so much we can do right now at a consumer cost level. Like you mentioned the data is useful for trends but people need to be careful and informed on what/how these devices read VOC levels .
The next step is how to ventilate correctly to make sure we can dilute the air when we have a spike in VOC's and to reduce the baseline VOC levels. This is where an ERV/HRV comes into play. Especially with newer houses since they are built so tight. You want 3 or so air changes per hour. Its important to make sure the air thats coming in is not just return air from the rest of the house. An ERV/HRV will make sure there is a constant stream of fresh air coming into your house.
You want an 3 air changes in an hour????? ASHRAE suggest a fresh air change in 3 hours in occupied space. What does an ERV or HRV have to do with it. You have exhaust devices in most home like the kitchen hood, clothes drier, and bath fans. These devices need make-up air. When the wind blows and you have a strong stack effect, natural infiltration is about a fresh air change in 3 hours. So no fresh air ventilation required. When the home is not occupied, no fresh air required. Also keep the indoor %RH +40%RH and <50%RH during the mild season makes the home more comfortable and free of mold and dust mites.
Tell us about 3 fresh air changes in an hour.
Regards Teddy Bear
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
ReplyOriginally Posted by Iamwildbill
