Bored?..Let's Talk Inside Home Air Quality

Jim Rosenow

Jim Rosenow

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Jim Rosenow
A question posed to the amazing diversity of this forum....

About 10 years ago we built a super-tight ICF house (tight to the point we have to crack a window or the clothes dryer isn't able to suck enough air out of the house to dry). We have a HRV of course, and have been running it on low to ventilate all these years, like the experts in the field say we should. We're essentially blowing out our hot air and sucking in cold in the winter, reverse in the summer. I hate wasting those BTUs, even tho the HRV, admittedly, saves many of them.

The house is completely electric...no combustion gases or residue of any kind. The carpets, paints, and other volatile organic sources should (assumption on my part) have off-gassed by now.

I've been trying an experiment since it got cold this fall...I'm running the HRV only when my internal logic says it's warranted...i.e, when cooking, showering, when it feels 'stuffy' inside, etc. Of course we accumulate humidity constantly..my wife and the dogs insist on breathing regularly. The result has been that by running a stand-alone de-humidifier enough to maintain 50 percent relative humidity, we produce enough (all internal to the house, remember) heat by the process that until it gets down around freezing outside, the heat pump doesn't even run.

The furnace fan is on 'low' constantly, running thru a 16x25x4 MERV 13 filter. Of course the relevant question is....'How's the pollution level inside?' Our 2.5 Particulate Matter runs between 000 and 002, and the level actually increases when we ventilate heavily. The VOC's vary between .6 and 1.3, and stay the same when we ventilate. Based on the oximeter we use in the airplane, our oxygen levels are good in the house.

I have yet to find a government or 'authoritative' source that tells me if these levels are good, bad, or indifferent. Is it bad not to have fresh air if the inside air is good? Looking for different thoughts and views. Thanks!

Jim
 
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I thought the whole point of an HRV was to recover the heat before the stale air is vented outside? Otherwise, you might as well open a window.
 
Hi, Bob...haven't read the entirety of either of the websites, but been far in enough previously to see that nobody is saying 'This much VOC is too much', or "At 'This much 2.5 PM' it becomes a health problem''. Hoping someone who deals with this stuff every day will have an idea of what is 'normal'. I understand the 'more is bad' that EPA and others spend pages and pages on...<sigh> Thanks!

Jim
 
Chip Sylverne said:
I thought the whole point of an HRV was to recover the heat before the stale air is vented outside? Otherwise, you might as well open a window.
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Agreed, Chip! 90% give or take on the specific unit....but if the air is cleaner inside?...why leave the window 10 percent open? :) I don't pretend to know the answer...thus the question.

Jim
 
I don't think you're going to see a number on voc's, because it all depends on what those compounds are. A natural Christmas tree, that probably puts out enough VOC's to peg your meter? Probably harmless. A non-stick frying pan, heated up just a little bit too high? Has the potential to kill pets at the PPM range, from what I understand.

As someone that used to work with a lot of environmental engineers, and occasionally chemists, I'd say you're looking at the problem backwards. I'd suggest finding the recommended number of air changes per hour, based on what you have in the house, and make sure you're on the high side of whatever that number is. For me, I'd take whatever the recommended number is and multiply it by about 10. I say that because I suspect the numbers are based on short term comfort, rather than long term chronic exposure to toxins.

Up here in the northeast, sick building syndrome was a real thing. Mostly just people not feeling great, but I think the problem was larger than that. I don't think it's a peer reviewed article, but here's an example: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796751/

That lists cfm/person, and I think more appropriate would be either cfm/person or air changes/hour, whichever is a higher rate.
 
Hi Tom..thanks for the article. Many of your comments square with the research I've done. As a philosophical discussion at this point, all agree that VOCs is a 'group' of chemicals from benign to nasty, most likely a mixed grouping in any environment. Logic tends to indicate then, that the devices that measure 'VOC' are pretty much useless, as there's no way to tell which specific component you're measuring, and thus, the related risk factor (your christmas tree, for example, or formaldehyde).

In my case, the level of 'indicated' VOC in the house remains pretty much constant whether static or highly ventilated. There's no way to determine relative changes in the components of the VOC reading using the monitor I have, so it's a crap shoot if I'm making the 'nasty' VOC exposure better or worse by ventilating. (This can be mitigated by aggressive use of ventilation during peak periods of known VOC production (using your frying pan)).

The 2.5 particulate matter in the air increases by multiples when pulling inside air in so that'a a minus in the whole equation. My long term chronic exposure to toxins will probably be limited actuarily...I'm 73. That also gives me the option to be a bit nutty...option taken! :)

I started the 'shut down constant outside air' test at the peak of pollen season, and it helped my allergies. To this point, neither my wife nor I have noticed any negative health effects. To compare using current conditions, I fired up the HRV this morning and will run it hard for a few days. We'll see if we have any perceivable changes. Thanks!

Jim
 
:) Reducing the air exchange to keep the pollen down does make sense. And in some areas particulates are a big thing. Have you considered putting a HEPA filter on the air exchange unit? Or perhaps the fan doesn't create enough pressure for that to work properly. HEPA is great, but the filters I've seen have quite a bit of pressure drop.

When I was in school, I'd sometimes visit a friend of mine at his work study lab, which was an organic chemistry lab. Even though they took all of the appropriate and official precautions at the time - this was in the mid 80's - the fumes in the air, to me that smelled like benzene, made my eyes burn. I asked him if he thought that this was healthy, and why he was pursuing that career. He said that he knew it was dangerous, that the companies just flip a molecule around one way or another to make a new solvent to replace the old one that's been proven to be carcinogenic. That it was a game they played. He said he estimated his life expectancy would be about 10 years shorter than average, but he was OK with that, as he loved the field. Smart guy overall, but I'll never forget that conversation.

Anyway, over the years I've lost a number of friends, too soon, to cancer. Sometimes they suspect why, sometimes not. I try not to be a nut about it, I use solvents from time to time, I'm not anti-plastic overall, but I do have a bit of caution around things that might be harmful that way. It's a lousy way to go.

Jim, glad you're good and being sensible from the sound of it as well. Hope I didn't sound too negative before.
 
I didn't take your reply so much negative, as concerned for a fellow aviator's safety, which I appreciate, Tom!

I've thought about engineering a HEPA filter for the HRV. It already has an internal MERV8 inside...marginal at best, but abetted somewhat by the MERV13 in the heat pump. The internal HRV fan certainly wouldn't be up to the task, so I'd have to custom engineer something remote with a booster fan. Then there's the effect on the balanced flow of the HRV. Doable probably...and on the list.

Interesting story about your friend's career choice. We all made lifestyle choices back then...some inadvertently. My first career was LE, which I started in the early 70s...which meant at least once a month I was on the shooting range without ear protection, killing paper targets. Then I'd go home and hop in my Champ for a couple of hours, without a headset. Didn't affect me at all...I SAID IT DIDN"T AFFECT ME AT ALL! :)

The early 70's was my first bout with being thought strange about housing. I hand-built my first new house with 6" stud walls full of fiberglass, and 12" inches of 'glass in the ceiling...all wrapped in plastic. Who would do such a thing?..gas is so cheap! (but then again, so was fiberglass) But I digress...

You sound as paranoid as we are about carcinogens....no solvents in the house as much a practicable, and 'plastic' is for the most part a dirty word.

Jim
 
I spent more than 40 years as an engineer in he HVAC industry. I am now a California green building special inspector. VOC limits for materials are specified by the Green Building Standards Code. The code does not specify VOC limits in the building itself.

In all my years in the field I came across one instance where an office employee claimed he had reaction to the air quality in a high rise office building in San Francisco. He was apparently a valued employee as the company wrote us a blank check to figure out the problem and solve it. We investigated and tested the HVAC system. We hired and environmental health specialist that brought in equipment to measure air particle quantity and type. They took samples and analyzed. We added a separate, filtered, outside air supply to office. In the end, we found nothing and never "cured" his issue.

There is no data on acceptable VOC limits in the air as there is no hard evidence that certain levels of VOCs from building materials will adversely affect the average persons health. Likewise, there is no hard evidence that certain levels of outside air in a building actually have health benefits.

However, the California Building Code officials obviously feel there is some basis for concern and continue to require reduced levels of VOC's in building materials, and greater volumes of outside air to be provided thru the HVAC system.

Certainly some people can have an allergic reaction to VOCs and some people have problems when building air is "stuffy" or stagnant from lack of outside air.

Personally, I always feel a little headachy when I go into a big box store. I don't know if it's VOC's or CO levels but I can't take it for very long. I don't know if I am imagining this, or if I'm really having a reaction to something. Therein lies the problem. Even someone who has spent a lifetime dealing with building air systems can't be sure if there is a real problem or a perceived one.

Maybe one day there will be some empirical evidence to support those of us who sense, sometimes, there is something wrong with the air we're breathing in a modern building. Right now, it doesn't exist.
 
Albany Tom said:
:) Reducing the air exchange to keep the pollen down does make sense. And in some areas particulates are a big thing. Have you considered putting a HEPA filter on the air exchange unit? Or perhaps the fan doesn't create enough pressure for that to work properly. HEPA is great, but the filters I've seen have quite a bit of pressure drop.
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Few, if any, home HVAC systems have the ability to handle the static pressure drop of a full airflow true HEPA filter (and not the fake ones that are claimed to be in your vacuum cleaner), even when its clean. The closest you can get is a high quality electronic air cleaner. However, that won't approach the efficiency of a true HEPA filter. Also, if you put a true HEPA filter, you need a pre-filter ahead of it to keep from clogging the HEPA up too quickly. So the HVAC system needs to handle the static pressure loss of the pre-filter as well. Increases in static pressure require a larger motor to overcome. HEPA filter systems use significantly more electrical energy for this reason.

With current, available, HVAC technology for homes there is no practical way to add a HEPA filter system. Could one be designed if money, and energy efficiency was not a concern? Sure. Is it practical for the average home? Not at this time.
 
Clip4 said:
I’d be worried about mold somewhere.
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We monitor constantly, and keep the humidity level between 45 and 50 percent (using the dehumidifier, if not the HRV). So far, things have been ok. Thanks!

Jim
 
Great information, Gary!...thank you!

Honeywell was the vendor for our heat pump, and they actually make an electronic air cleaner that looks to be a slide-in replacement for our filter (with comparable back pressure). Comes with it's own pre-filter for $550-ish. Sounds like that may be just what the HVAC Dr. ordered, then just use the HRV to purge. Thoughts? Am I correct that this would only require a 110v connection? Thanks!

Jim
 
Lndwarrior said:
I spent more than 40 years as an engineer in he HVAC industry. I am now a California green building special inspector. VOC limits for materials are specified by the Green Building Standards Code. The code does not specify VOC limits in the building itself.
...
Maybe one day there will be some empirical evidence to support those of us who sense, sometimes, there is something wrong with the air we're breathing in a modern building. Right now, it doesn't exist.
Click to expand...

Yep, I believe that there isn't anything empirical yet. I'm in the testing program for exposure from 9-11 at wtc. So far, knock on wood, I'm fine. But have friends who aren't. Now that was a clear particulate problem, but there's still a large gap between the effects and what should be the known causes. At the time, the exposure was not predicted to be all that bad. I don't mean to be a sky is falling guy, but I try to lean toward caution, too. I'm not the only one...some buildings around here were torn down because publicity around them being "sick" was enough to cause people to just refuse to work in them. I want to say that was mid-90's? Not sure.

One of the things I've wondered about is as you mentioned, allergic reactions or perhaps exposure to something where a combination of a couple of different of things is a problem, or even if the exposure needs to be long term to make a difference. The example that comes to mind there is around epoxies. I've worked with them as part of different hobbies for years, and don't have any symptoms, but some people - maybe everyone - develops a sensitivity to some of the amines, and it affects them a lot. So I wear an organic vapor respirator when I work with epoxy now.
 
rpadula said:
Don't worry, the radon will get you.
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Well THAT certainly took longer than I expected :)

I've done a LOT of reading on that subject, Rich. The perception of risk all boils down to who you believe, I guess. Figures don't lie, but liars figure :) We have a radon detector in the house, and as lifetime non-smokers, we're both comfortable with the levels that are indicated by it. As I said above, the extent of our 'long-term' exposure will be significantly less than the average.

Hell...something's gonna kill you eventually!!

Jim

PS--I'd love a response to the radon discussion from Tom and Gary....
 
:) I'm not as funny as the cat, but I sometimes operate at the same level of judgement.

Just me, if I had kids I'd be cautious of radon. At my age I don't worry about it. Jim, you have a bit over a decade on me, but we're probably both from a generation when we were surrounded with things that these days would likely be considered nuts.

Probably my choices seem random or even contradictory. I try to be aware of the risks, consider the remediation cost or hassle, and balance that against the risk. I think everyone should do that, and except for exposing things to kids I think it should be an individual choice. My only complaint is when the risks are hidden.
 
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