[Bldg-sim] Filter options for residential retrofit (chemically sensitive occupant)

[Nick Caton]

Hi Adam,

This posting is reaching an audience which includes many mechanical designers of varying experience, and there are no rules restricting the subject matter over the mailing lists, but I think you may crossing a line of comfort for many professionals by presenting a series of questions which are essentially seeking to arrive at medical/healthcare advice.

Any responsible response on this forum would absolutely include the direction to consult your physician first.  For professional liability reasons, it may also be correct to say there is no other responsible way to respond to this query.  Anything along the lines of "what I would do..." invites the possibility for someone (maybe not you) to "lawyer up" down the road.

That said, I am comfortable sharing a few general and succinct points which cannot be construed as medical advice:

*         Consider particulate filtration (dust/pollen/mold/smoke) and gas phase filtration (ozone, off-gassing of materials) as two separate problems.  There are 'hybrid' products intended to address both categories, but a really fancy particulate filter should not be expected to pick up gaseous contaminants and vice versa.

*         Gas phase filtration media (i.e. activated carbon) DOES require a replacement schedule to maintain a continued effect, and the only way to determine that frequency for a specific environment is with testing.

*         If outdoor gas (ozone)  and particulate (smoke) contaminants are bad enough, a leaky envelope (and windows/doors left open) can overwhelm even extensive efforts to improve indoor air quality.  Practical and affordable measures to minimize infiltration should be considered as part of your filtration strategy.

*         Here is a solid link for further reading on the topic of IAQ, with many published research and resources specific to the topics you're bringing to the table: http://www.epa.gov/iaq/pubs/residair.html

I hope this helps answer some of the non-medical facets of your query!  Definitely consult a healthcare professional for recommendations to arrive at a strategy that fits your needs.

Regards,

~Nick
[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Adam Jackaway
Sent: Tuesday, September 03, 2013 1:14 PM
To: Building Sim Listserve
Subject: [Bldg-sim] Filter options for residential retrofit (chemically sensitive occupant)

Apologies if off-topic, but perhaps someone with HVAC experience in this arena can provide some insights off-line.

-------------

I recently vacated my house due to mold contamination. Problems were extensive in subfloor and crawlspace. Kitchen and several bathrooms had to be gutted. Remediation is now complete, and remodeling nearing completion. House has an  American Standard AUD100R9V5K4  Ser #8235NSX1G forced air furnace, and no cooling system (located in Colorado). The system is 100% recirc, with no humidifier. We have kept the furnace, but replaced all ducts to eliminate concern of mold spore contamination. All interior surfaces of building have been 'treated', and all personal belongings removed. Unfortunately, we have learned that sometimes even dead mold spores can linger (clinging to surfaces, etc), and if inhaled by a sensitive occupant (that's me), can then induce recurrence of health problems.

Question: What would be the best way to introduce high quality filtration to this system? (At this point, targets include spores, pollen, and even chemicals off-gassing from new materials).
Obvious options would seem to include:

- high Merv-rating filters in existing furnace
- 'sidecar' HEPA / Activated charcoal unit on the CAR (a good option, but doesn't treat 100% of the air)
- UV has fallen out of favor since we don't have a cooling coil to point it at, and not sure what other surface would be appropriate
- Electric / ionizing systems have fallen out of favor due to ozone conerns
- Could fabricate a deck in the CAR just upstream of furnace to receive a HEPA filter, and suffer the fan energy penalty in exchange for additional filtration confidence.
- Not sure what to make of stand-alone Activated Charcoal filters -- seems like they need to be discharged frequently. True?
- Another option would be to go with just the MERV filter in the furnace, then purchase mobile stand-alone HEPA / Charcoal units for main rooms of each floor. More local control, but more noise.
- Are there other options we're missing?

Note:
- We are well aware of benefits of OA in such situations, but there are complications with high smoke and ozone days in this region, so 100% will actually be desirable at times -- and night flushing is a common strategy when conditions allow. Also, the house is 115yrs old, so infiltration is significant anyway.
- HRV would obviously come into play if we pursue an OA configuration, but when filtration requirements are added, we're concerned about complexity of system.

Has anyone gone through this type of exercise? Comments / suggestions welcome.

Regards,

Adam



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