Replies

1. 
   CramerSilkworth | Jun 04, 2011 05:33pm | #1

   Marshall,

   This is an issue that I just heard about yesterday and have started digging into. The short answer is it that it seems like some contaminants can indeed be transferred into the fresh air: http://www.homeenergy.org/article_full.php?id=739

   I'm trying to find the published research Sherman refers to, but no luck yet. If I find it I'll post a link here.

2. GBA Editor
   Martin Holladay | Jun 05, 2011 05:36am | #2

   Marshall,
   We're all waiting for more data on this question. My own reaction to Max Sherman's concern:
   1. We should all be building homes with low-formaldehyde or no-formaldehyde cabinets. Federal regulations are already moving us in that direction, fortunately.

   2. A good mechanical ventilation system will greatly improve indoor air quality. If there isn't a lot of formaldehyde in your house, you don't have to worry that a very small amount might migrate through the permeable membranes in your ERV.

   3. There are some very good HRVs out there if this potential problem keeps you up at night worrying.

3. 
   4QgL3ti4A2 | Jun 05, 2011 06:54am | #3

   Thanks for the link. Also we do try to avoid mdf and other materials which we think maybe problematic. Im not only concerned about the materials that we build into the house. We also have to worry about what the purchasers buy in the way of furnishings and what "household chemicals" they bring into the house solvents, cleaners etc; The way i understand it and my knowledge is very limited the transfer of the water vapor is accomplished by adhering to the surface of the material in the kyoto wheel. What the wheel transfers is dependent on the size of the molecule since the geometric specifications of the surface of the wheel (micro) will determine what size molecules can adhere and be transferred. I believe dilution of contaminants (full range) is important if there is doubt about the erv performing this functions as to the full range of the contaminants i think i would choose to give up some of the energy savings and use an hrv until this is issue is clarified. We all need the specifics and we will need it as to each model of erv.
   We just dont know what is meant by "very small amount passing through the membrane" and what this small amount means, My concern is if there ends up being a concentration of the contaminants built up inside the house over time.

4. 
   user-659915 | Jun 05, 2011 09:48am | #4

   "My concern is if there ends up being a concentration of the contaminants built up inside the house over time."
   This might be a concern if the ERV were the only ventilation mechanism. Fortunately we do not live in space capsules and there are no climate zones in the US where radical whole house ventilation by means of opening windows and doors a few well-chosen times a year would not seem to preclude without energy penalty the possibility of this kind of long-term atmospheric contaminant buildup.

5. 
   bigrig | Jun 06, 2011 03:36pm | #5

   I would agree with Martin’s point #2. While there may be a small amount of transfer from the outgoing air to the incoming, it would be greatly diluted by the incoming fresh air stream. Unless there was a massive source of contaminants within the building the air exchanges should eventually bring the contaminants levels down to slightly above the outside levels. Unless, of course, the outside air is also contaminated. In an average neighborhood you may have small engine exhaust from lawnmowers and trimmers, lawn fertilizers/week killers being (over)used and many other sources of chemicals. Before the company I work for switched to a “green” lawn care chemical system I would feel physically nauseous several times a year when the lawn was treated.