I have had many weatherization contractors who are being subsidized by the state for low income housing contact us for radon remediation based upon their testing of clients homes. It is nice to see that they are taking this step and consider the correlation between making a house more green or air tight with elevated radon levels.
Passive radon remediation or simply 'blocking out" radon has not seemed to be that effective and we have always recommended active radon remediation to ensure overall effectiveness.
Share the knowledge and lets get active radon systems into all homes

Hi- Attached is a study done in Ft. Collins, CO on RRNC. Chrys

I would like to contrast the two statements:

First Dick's: "My personal experience over 29 years of mitigating radon in homes is that passive measures by themselves do not have a significant effect on building radon levels unless the starting point is already close to 4.0 pCi/l, and I'm prepared to tell them that."

Then from the Ft. Collins study: "We found that RRNC reduces radon by an average of 49%, which confirms the findings of similar studies in other part of the nation. We further found that the number of homes above 4 pCi/l dropped from 83% with the radon system disabled [capped] to 40% with the radon system enabled [uncapped]."

It would be interesting to compare Dick's capped/uncapped data with the Ft. Collins dataset.

I will leave aside for purposes of this reply the question of how many of the passive systems Dick ran across were properly installed in the first place. But I do want to say that if we limit our discussion to properly installed RRNC systems, some distinction needs to clearly be made:

- It's one thing to define effectiveness as "getting radon levels down to below a threshold" such as the EPA Action Level of 4 pCi/L. And certainly, I think we all agree that RRNC is not expected to be uniformly "effective" in that respect. That kind of effectiveness is a proper metric to evaluate active systems, but isn't a standard that it's fair to hold passive systems to.

- But it's something else entirely if one of the metrics with which to look at passive systems is how effective it is at reducing radon levels, independent of whether the levels are reduced enough to be less than the Action Level. By this measure, the Ft. Collins reduction of 49% is a gratifying result, and the conditions under which it was achieved should be replicated elsewhere--so long as all parties understand that this kind of effectiveness is NOT the last word on radon reduction in a dwelling.

My point is to encourage Dick not to undersell the "average reduction fraction effectiveness" of properly done RRNC when discussing Rn with Wx people, even as he is clear with them that RRNC is not to be relied upon to achieve "mitigation effectiveness."

Thanks for the comments. However the context for my post was not new construction. It was Weatherization, which is exclusively existing houses, and my comment on my personal experiences was also in the context of existing houses.

(Apparently my email address in my original post didn't translate too clearly. I hope this is better:
rakornbl @ twcny . rr . com)

Your point is well taken. Sorry I was in a hurry and leapt to reply before appreciating that. Of course, your list of passive measures undertaken by Wx people is significantly deficient compared to RRNC.

Other than what the Wx folks may be doing within their means to address the problem, I would expect that currently there is little appetite among mitigators for encouraging doing radon mitigation via passive measures. I imagine most of the science on the inadequacy of those (e.g., not "sealing alone" for "mitigation effectiveness") is from the '80s and '90s, and that is now considered a settled issue. Maybe those studies can be dug up and "average reduction fraction effectiveness" can also be looked at.

I would certainly be interested in any studies that investigated the performance of passive measures only in existing buildings. If anyone has a link to any studies or documents from the studies, please let me know. I only have my personal experience to go by, which is limited, although not encouraging wrt passive measure effectiveness in reducing radon in existing buildings.

Dick,
I'd call this anecdotal evidence as opposed to a study, but I think it still has some value. In the 1980's we attempted to mitigate by sealing crawl spaces, sumps, cracks, block tops etc. It didn't seem too successful, so I tallied the results of perhaps 20 or 30 jobs where "step one" was sealing only. 50% of the time the radon went up, 50% of the time it went down. Most of the changes were small and were probably due to the weather, although there were a few significant increases and decreases.

Dick,

I agree 98% with you. I would though, consider explaining to the DOE / NREL / WX folks that ASD Systems also provide moisture reduction. We have seen this anecdotally in our experience (over 30,000 ASD Systems). While, some studies exist, a lot are not great.

Simple test:

 Put a portable dehumidifier in the basement of a house with an operating ASD system.
 Measure the water collected in the tray over a set period.
 Turn off the ASD System and wait a few days.
 Run the portable dehumidifier.
 Measure the water collected in the tray over a set period.
 Quantify the difference.

You point out: "Wx funding is targeted to energy saving" . Dehumidification reduces cooling costs and reduces mold conditions. So, Dehumidification, Radon and Mold, all can be addressed by an active ASD System. ASD should be incorporated into all WX homes.

My 2 cents
John Mallon

Good evening Dick,

My first thoughts went in the line of Kevin's remarks. While we will never know what the real numbers would have been without a passive RRNC system (designed to CCAH-2013) because the collection pipe and extensive sealing of the plenum beneath the slab can't be undone, neither can proper comparative with/without testing, I can site several examples of significant success if the protocol is followed very closely to the letter.

However, since we are speaking of Weatherization of existing homes, I would have to concur that a passive system will likely have little significant radon reduction. However, as you well know, a well designed and installed ADS system will do wonders. And as John pointed out moisture reduction is amazing. I can't tell you the number of customers I've had that tell me that their dehumidifiers that previously ran constantly, do not ever run since instillation of raw ADS. I'm sure you have heard the same thing.

Cost is a significant factor in this type of low income housing. I know that it is a ton of work from a coordination aspect, but there are numerous suppliers out there from Lowe's and Home Depot to Fan and equipment manufacturers and distributors who canned have helped to minimize the cost for truly needy families with elevated radon levels. Wx Program managers and administrators are probably accustomed to working with these type of donors, so it may not be a real problem for them - it is what they do.

Good luck!

David

I think there a few important distinctions to make whenever discussing these topics:

1) Can passive efforts reduce radon? The short answer is yes (with the caveat of sometimes, maybe and it depends);
2) Do passive efforts achieve safe levels (i.e., below the action level)? The short answer is not very often;
3) Can study data that averages effects of weatherization and passive efforts across various populations of homes be used for making decisions about the building(s) you are working on? No. This is because the ramifications from weatherization and passive efforts are both "sometimes, maybe and it depends."

To elaborate:

My item 1 and 2: From 1988-1994, "phased in" mitigation ruled. My stats on a few thousand homes indicated (when weather was similar both before and after the work) a rough average of 20% reductions from sealing efforts with an occasional > 50% reduction and ..... every so often an actual increase rather than reduction of indoor concentrations. So while we gain a health benefit with as little as 10-20% reduction, fat chance for reducing 8 pCi/L to > 4 pCi/L with passive efforts.

My item 3: A study in the early 1990s indicated virtually the same reductions from sealing the attic (to close air escape routes) as achieved by closing entry points at the slabs. Almost all such studies on passive efforts (e.g., sealing of slabs, attics and passive RRNC piping) have traditionally reported "as much as 50% reductions."

It's really pretty simple for radon as it would apply to smells or CO from combustion appliances: If too potent for natural ventilation to handle, the pollutant requires powered-venting (e.g., for radon, this means ASD or dilution).

The study is an admirable effort that reconfirms a lot of published data. The interpretations of the data are however less than comprehensive.
For instance: If weatherization reduces air-change-rate ventilation, do radon concentrations increase? The short answer is yes. However (like the mobile home is these studies that would be inherently leaky): if weatherization also reduces the amount of air that escapes the upper portion or topside of the building, stack effect has been impacted to reduce the flow (volume of radon entry) and the degree of negative indoor pressure (in terms of negative indoor air pressure compared to the air pressure under the building).
As these realities play out across a wide sampling of different structures and their customized extent of weatherization, it is no surprise that conclusions indicate a random relationship.

If I were asked about optimizing weatherization, I would say invert the current focus: seal air escape routes first rather than cold air entry-routes; continue sealing downward for any large openings; but also limit airtight sealing in lower lived-in areas to the extent that a desired air-change-rate for the building is still maintained for reducing airborne hazards from biological and chemical concerns.
2 cents

Thanks for the responses. They all either confirmed my experiences or added to my knowledge.

Randy, you have more data than I have, but it conforms with my more limited experience. Sealing alone does not do much to reduce radon levels.

John and David, I agree with you about the beneficial effect of ASD on basement humidity. We have seen this reported over and over from customers. It would be interesting to see a study comparing the costs of ASD as a dehumidifying strategy versus dehumidifiers. Unfortunately, for the low-income weatherization industry, capital costs and budget limitations rule.

Gary, totally agree that " fat chance for reducing 8 pCi/L to > 4 pCi/L with passive efforts." I'm glad you mentioned the importance of stack effect.. The good news from the Wx front is that attic air sealing is an absolute priority in weatherization, and, as far as I know, is always done.I also know that basement duct sealing is done routinely. If return duct leaks predominate over supply duct leaks, than duct sealing should reduce basement radon levels (we've actually done return duct sealing in our private sector radon work). However, the national IAQ study, which measured radon levels before and after Wx work couldn't definitively conclude that Wx, which always included attic air sealing, significantly reduces basement radon levels. Part of this may be due to the fact that the buildings were also tightened so that natural ventilation was reduced.

There is some interesting research from Paul Francisco of the University of Illinois that increasing whole house ventilation, even using exhaust only ventilation (e.g. bath fans on timers), tends to reduce radon in the living spaces of homes slated for weatherization services.

It's all very complicated, but I hate to see Wx dollars wasted on measures that don't work.

Thanks.

Dick Kornbluth

Thank you Chrystine for posting the Fort Collins study. It is important to note that just because the passive systems were inspected does not mean that they were properly designed. The most important part of these passive systems is often done incorrectly due to budget constraints and unqualified installers. I regularly observe new homes in the early stages of construction and witness these mistakes to this day.

Dick,
Just some informational bantering on it.... It's not really so complicated as many studies imply.

A building is a living and breathing animal that comes in wide variety of species. The anatomy of the these animals (boxes) are extremely rudimentary compared to the human anatomy. They breathe air in and out. But their primary purpose and requirement is human comfort.
These animals are simple enough that one can be confident that for every action, there will be a reciprocal reaction that is definable. For instance: If you suck air out of a box (building), the volume of air being expelled will come from somewhere. And it will come from somewhere that is usually quite predictable. For our purpose and example, we can confidently predict that indoor radon concentrations are significantly influenced only by pressure changes (that increase or decrease the volume of radon entry) or dilution after radon entry.

Studies are designed to look at a specific phenomena but the scope of most studies does not include getting definitive on why the phenomena witnessed is occurring. For instance, I recall reading a study that was commissioned by a manufacturer to prove whether or not this one gadget (product) that pulls a lot of air out of the basement would consistently lower radon readings and humidity. The study concluded success. But it did not elaborate on why. In this case, it would not be in the interest of the manufacturer to describe the energy penalties from massive increases in air exchange rates for the building.

It seems here (as an analogy): If we evaluate blood pumping relative to breathing functions for a large number and a wide range of mammal species, we will have very interesting data that is useful in some way. But whatever the data suggests, its conclusions are too broad-brushed for use in medical applications for a human body (i.e., specific species). Our building animals are rudimentary boxes by comparison, but the challenge? They come in a wide variety of species. I have yet to see a study conducted that segregates the more than a dozen similarly configured and common building styles (species) that exist out there.
2 cents of banter.
Gary

It's important to note also that the study referred to here is from old weatherization practices. Since this study was published, new requirements were implemented. Now, weatherized homes must meet ASHRAE 62.2.

DOE has the BARRIER study, which I believe is nearly complete, and it looks at effects of enhanced and standard practices on radon (and I believe moisture is included). But also, DOE is now into year two of the BEX study to look at if and how the new standard practices affect radon. This large study includes 200+ homes.

Essentially, the ventilation requirements are being met by exhaust-only ventilation, which as you can imagine, has it's own set of possibilities for what can happen. A pilot study was completed before the larger study that is occurring now (but it only looked at a handful of homes). The pilot study concluded that meeting ASHRAE 62.2 didn't raise radon.

In the meantime, any homes in this study that go from below the action level to above, will be mitigated (not at owner's expense).

One thing to be very clear about is the point of the measures done by weatherization, and potentially other programs. These are not radon mitigation programs and budgets are limited. They need to look at issues from a "do no harm" perspective, which is consistent with EPA's Healthy Indoor Environment Protocols. Would we like to be able to mitigate every home? Sure, and if there was a program that provided additional funds when homes were identified as high I am sure that weatherization programs would be fine being a vehicle. But internally the focus is to not worsen health in the process of saving energy. I think that is reasonable.

Dick, not that it adresses your question, but did you see the study done in the late 80s for the Bonneville power administration regarding radon and energy efficiency? I believe Lawrence did the study.