most high yield measure to improve indoor air quality

jimmyenz17

Hi there,

I'd like to improve my indoor air quality, IAQ, but not sure where to start. I have searched the forum, it seems like HRV is better than ERV for improving air quality; is that better than air purifer (whole-house)?

If I have to pick one, what is the single most effective way to improve indoor air quality?

Subjectively, the air feels very stale in my house (my Airthings sensor does occasionally show increased CO2 when the room is occupied for a while, and also low humidity during winter time). The indoor air feels stale both during summer (normal humidity 40-60%, with AC turned on) and winter (my humidity plummets to high 20s, low 30s, heating is via Steam).

Other info:

I'm in Zone 7a. Single family house, 5000 sqf, 3 stories.

AC with 2 handlers (one for 1st floor, other for 2nd/3rd floor)

Heating is mainly Steam (single pipe)

Radon mitigation installed

Whole house humidifier (installed but I don't use as it uses a lot of water and does not raise the humidity much).

Please advise (I tried looking for contractors but it seems like the list is mostly for heating/plubming/steam not so much for HVAC-related). Thanks in advance

delcrossv

Best thing I did for IAQ was install an electrostatic air cleaner. And not one of those little guys with a 4 inch collector. But a real one, with integral wash. My system is 2 tons so my CFM is lower (which makes it work better)

Universal set me up: Stainless steel case, programmed an eprom so the anodes would de-energize on the wash cycle and system blower would shut off, 7 day clock control for wash etc. Still working after 20 years.

https://compression-systems.uapc.com/viewitems/precipitators/ial-deluxe-precipitators-4-ton-through-5-ton-units

delcrossv

Also, those Aprilaire drip humidifiers are pretty useless. Went with Dri-Steem, (but they do use a good deal of electricity, and require annual descaling.

https://www.dristeem.com/products/steam-generation/vapormist-electric-humidifier/

Larry Weingarten

Hi, I'd start with testing to see if there is anything off about the indoor air. I'd then do a blower door test to see how tight the shell of the house is. If leaky, fix the big, easy leaks. After that, look at an HRV (maybe ERV) assuming you have good outdoor air to pull from. This might be useful also. https://www.haywardscore.com/

Yours, Larry

DCContrarian

"Subjectively, the air feels very stale in my house (my Airthings sensor does occasionally show increased CO2 when the room is occupied for a while, and also low humidity during winter time)."

Before doing anything you need to find out what is going on. What's making the air feel stale?

Low winter humidity is associated with high levels of air leakage.

Jamie Hall

There really are two aspects to this kind of problem.

The first — and by far the most important in my view — is to ask what the outdoor air quality is like. This view of mine stems, perhaps, from being able to remember the reactions to the first "we have to save energy" panic of the '70s. Everyone and their uncle went around tightening up the envelope of their houses/schools/offices/whatever and, to no one's surprise, indoor air quality plummeted.

So my first thought is this: if the outdoor air quality is better, and acceptable (it may not be in some locations), bring as much of it in as you can while maintaining some energy efficiency. This means HRVs, as ERVs sometimes — not always — return contaminants to the house along with heat. The recommended air changes per hour can be found here:

Air Change Rates in typical Rooms and Buildings

Residences are listed as 1 to 2 air changes per hour. So that's the place to start. A blower door test can give you a very rough estimate.

Now the next thing is to consider what is needed to feel comfortable, and their really are only two parameters to consider — the air temperature and the relative humidity. Both are somewhat affected by the individual; some folks don't mind relatively low temperatures in the winter (or high in the summer) and some do. Similarly, some folks don't mind drier air in the winter and moister in the summer, but some do. Any time air is warmed the relative humidity will decrease (it doesn't matter what kind of heating system is used), and so, particularly in colder weather and colder climates adding humidity may be needed. This can be spot humidifiers — for instance, in a bedroom — or whole house units. The one caution is to make sure that it doesn't get so high that condensation occurs on walls and windows — not uncommon in colder climates.

The last point is what else is in the air to reduce the air quality? In a way, this goes back to the first point — if you have enough air changes per hour, and the outdoor air quality is reasonable, you won't have a problem. But what about if you don't have enough air changes, or the air quality outside is bad? Then you have to figure out what is in the air that is reducing quality, and attack that. Some things are easy enough — dust, for instance, and some bacteria can be reduced to acceptable levels with high quality filtration. Other bacteria and virus, and some airborne moulds, can be reduced with ultraviolet sterilization after high quality filtration. Some other problems, however, cannot: objectionable gasses. This would include carbon dioxide, of course, but also includes most odours. There are ways to handle these — submarines and space stations do work, after all — but the best possible way to handle them is… outside air.