Category Archives: research

Breaking news on the insulation front

This is a very good day – for all those who own a masonry building, who are interested in a deep energy retrofit and who would like to insulate the masonry walls from the inside.

The frustration has been that there was next to no information available on the pros and cons of insulating the interior of masonry walls, or on how to go about it without damaging the structure.

The Building Science Corporation has taken another step to fill this information gap with the release of a brand new research report (RR-1105) “Internal Insulation of Masonry Walls: Final Measure Guideline,” authored by John Straube, Kohta Ueno and Christopher Schumacher.

Regular readers of the blog will remember my epic search for reliable and sound information on this subject. At the time, I came across one document – to repeat, one document – on this subject, also published by Building Science Corporation.

Do you really want to make an insulation decision of this magnitude based on one document? No, not really. But that’s all that was out there, in addition to some other documents that offered tangential information and the occasional anecdotal evidence.

We had to knit the little information we had together and hope that we got it right. I am glad to report that I see our decisions confirmed, after having read the executive summary of the new research report.

If you have done research yourself on the subject of deep energy retrofits and how to insulate, you will have noticed the abundance of information available for framed buildings or new construction. I cannot fathom why the existing masonry building stock, which is rather significant in metropolises like Chicago, is left without resources.

If we are to get serious about reducing our energy consumption and carbon footprint, we have to get serious about retrofitting the abundant existing masonry building stock. Building new and green can’t be the solution alone. We have to begin to reuse the resources we have.

I am glad that the Building Science Corporation is not shying away from this complex subject.

New or reuse and formaldehyde

Our goal is to minimize the use of new stuff, maximize the integration of reused materials and achieve good indoor air quality (IAQ) levels.

How are these items connected? Through formaldehyde.

Many composite wood products such as plywood, particle board and fiberboard contain urea-formaldehyde resins. A lot of furniture products, including cabinets, are at least partially made of composite wood products and may release (outgas) formaldehyde into the air.

Formaldehyde has been classified as a probable human carcinogen by the U.S. EPA and as “carcinogenic to humans” by the International Agency for Research on Cancer (IARC). Because of the various adverse health effects, the presence of formaldehyde in our living spaces can become a major problem. A recent example is the FEMA trailer incident in the aftermath of Hurricane Katrina.

The new and CARB compliant

We need cabinets for the kitchen and the bathroom. One option is to buy new cabinets at a home improvement store. If so, we could select cabinets that are CARB compliant.

CARB stands for California Air Resources Board, which is a division under the California Environmental Protection Agency. This agency has been working on standards that reduce the emission of formaldehyde from composite wood products.

The CARB standard has been integrated into the “Formaldehyde Standards for Composite Wood Products Act”, which was recently signed into law.

Say we buy cabinets that are partially made from particle board and are CARB compliant. The permissible emission of formaldehyde is limited to 0.09 ppm (parts-per-million).

According to the EPA, typical formaldehyde levels in homes can range from well below 0.1 ppm to more than 0.3 ppm.

Let’s put these numbers into the context of the 0.09 ppm CARB compliant level. It means that we still would have some formaldehyde outgas into our living space, but at a greatly reduced rate compared to non CARB compliant products.

Time dependency

Here is another interesting fact. Formaldehyde in composite wood products is emitted at decreasing rates over time. In other words, particle board that comes hot of the press from the manufacturer is likely to emit significantly more formaldehyde than particle board that is several years old.

A graph on the University of Minnesota web site (School of Public Health), nicely demonstrates the time dependency of the emission levels. Another long term study describes the time dependency in term of ¾ and half life.

The reuse option

The alternative to buying new and CARB compliant cabinets is to source older and used cabinets, which were in all likelihood not CARB compliant.

Is it reasonable to assume that those cabinets are more likely to emit more formaldehyde? I am afraid that there is no black and white answer to this because of the time dependency factor.

There is a fair probability that new and CARB compliant cabinets would produce more formaldehyde emission than seasoned and used cabinets, because most of the formaldehyde has been already emitted.

Weighing the factors

If we buy new cabinets that contain some composite wood products but are CARB compliant, we would limit the emission to 0.09 ppm and declining over time.

If we buy older and used cabinets, the emission level may be significantly below 0.09 ppm, or way above – who knows. Although, if they would be way above, one probably would smell it. Formaldehyde has pungent scent typical of new plywood or particle board.

The other thing to keep in mind is that formaldehyde is always present at low levels in our environment. The University of Minnesota, School of Public Health lists 0.03 ppm as normal indoor and outdoor levels (less in rural and more in urban environments).

Also, formaldehyde can be easily removed from indoor environments through ventilation. This puts us in a good position with our ERV ventilation system.

But still, how much formaldehyde would we introduce and how much would be too much?


I wish I could present and nice and slick conclusion – but I can’t. We could limit formaldehyde emission by using furniture that does not contain composite wood products. That would be pretty nice but also expensive furniture.

I guess the whole formaldehyde question comes down to auxiliary factors, such as reuse versus new, time dependency, relying on my sniffer, cost and some common sense.

Hmmm. Variables, variables! Can you tell how my German toe nails begin to curl upwards?


I alluded in the last post (Utility sink) that we are ready to paint the freshly installed and finished drywall.

I will not delight you with another time lapse showing us painting, but rather talk about our product choice.

Based on our project principles and goal to provide good indoor air quality (IAQ), using anything but a zero-VOC product was non-negotiable.

I expected, in this day and age, to find a good choice and range of products and suppliers of zero-VOC paints.

Considering that zero-VOC paints are one of the lowest hanging ‘green’ fruits out there, and probably very popular with the ‘green’ and/or ‘green-wash’ minded population, I anticipated that commerce would drive this train fast and furious.

To my surprise, it took me a while to research and find a suitable and affordable product. My experience was vaguely similar to that described in the post Service Desert, although nowhere near as painful.

The Home Depot advertises their ‘eco-option’ products, and has had a strong showing at the USGBC Greenbuild conference over the past few years.

Yet, my local Home Depot does not carry zero-VOC paints. I would have to drive all the way to a store on Chicago’s north side, where they stock zero-VOC paints. And I am apparently not the only one running into this problem.

It appears that rather than leading the market, The Home Depot is following the customer.

Fair enough, let’s try my local Menards. Lo and behold, I find zero-VOC paint for a very good price – and a ‘Green Cert’ label. This is where I got suspicious. There are a couple of ‘green’ designations that I am aware off, such as LEED compliant or Greenguard.

And there are designations that, for whatever reason, feel they have to come up with their own label. This may be an effective marketing strategy, but also confuses the consumer and makes it difficult to separate the green-wash from actual sound sustainable products.

Does the average consumer have the time to research all this? Probably not, and nor have I. Why not turn to someone who has done the research for us, the consumers?

After a moment of thought and short trip, I find myself in the Green Depot, where I have access to a variety of zero-VOC paints in different price ranges.

We opted for the zero-VOC Ivy primer and paint. I didn’t know any better, but our neighbor Norman, who does quite a bit of painting and helped me out, commented about how nice it was without those nasty fumes.

Insulation update

The advantage of a slow moving project is that you don’t rush into decisions you may regret later on. This is certainly true for the decisions on insulation, which are rather significant.

I have researched and thought about the insulation for one and a half years and received numerous helpful comments and references. What once was a very exotic subject has become very familiar.
Insulation or outsulation?

We started with the dream of insulating the masonry shell from the outside (outsulation), leave the brick work exposed on the inside and use it as thermal mass. Whenever I advocated that idea, I was promptly discourage from doing so.

That said, it appears to be the favored option of some green industry professionals. The principle reasoning is that it protects the masonry structure from freeze-thaw cycles, which can be detrimental if the brick or stone work is saturated.

I bet there are existing masonry structures out there that lend themselves to outsulation, that have enough dimensional room around the building to accommodate the extra layers and have fire code requirements that would allow it.

We are not so lucky with the west side of our building partially located right along the property line and ornate architectural features on the front elevation that I will not dare to cover up.

So – insulation it is.

Recycling relieve?

My research on insulation materials pointed me pretty early on to spray polyurethane foam (SPF), as it performs a number of functions. It provides the air, vapor and thermal control layer.

The two things I could not shake, though, were the issues that a) SPF is a petroleum based product, and b) the question of end-of-life use—or, what happens to the foam once it gets ripped out?

As it turns out, spray foam scraps don’t have to go into a landfill, but can be turned back into resins and reused in another SPF application. I hope that this is not one of those “too good to be true” stories.

With regard to the petroleum based content, the industry is now also marketing foam products with renewable resource content derived from soy or castor beans. But even with the addition of renewable resources, SPF remains largely a petroleum based product. The other remaining question is how sustainable soy farming is.

How about a high recycled content material?

An idea emerged while we were installing the perimeter wall framing. Rather than spraying the entire six to seven inch interior wall cross section with SPF, we could only use the foam in the three inch gap between the masonry wall and the framing. Then we could fill the three and a half inches of framing with a batt system.

There are several products that have a high recycled content. The first one I investigated was a cotton batt product with 90% recycled content. The recycled cotton batts have good thermal resistance and sound absorbing properties, plus they are more economical than SPF.

What worried me a little is that cotton is good at absorbing moisture (think of the good old sweatshirt). Moisture content in the batts may reduce their thermal resistance and begs the question about mold growth.

To reduce the risk of mold the batts are treated with a borate solution (boric acid). I am not sure how I feel about introducing yet another chemical into our indoor environment.

At one point I listened to a podcast in which rock wool was mentioned as an insulation material. The one thing that really stuck with me is that rock wool – made out of rocks and slag – won’t burn. That did sound awfully attractive and I researched this some more.

Rock wool insulation is manufactured in batts of all sort of sizes, has good thermal resistance and is easy to handle and cut. It is not treated with boric acid, is manufactured with a high recycled content and even more economical then the cotton batts. Bingo!

Updating our insulation plans

We need an effective air seal to meet our energy goals. SPF is the most effective product to achieve this objective. Plus, SPF also acts as the vapor and thermal control layer in the wall assembly. We pay more, but we also get more.

It makes sense to stick with our original plan and use a one inch layer of closed cell foam on the masonry wall. That closed cell foam must have a perm rate of greater than one.

Rather than filling the rest of the wall cavity with open cell foam, we deviate from our original plan and plan on only adding two inches, which gets us to the back of the wall framing.

To reduce the environmental impact and drive cost down, we fill the wall cavity space in the framed section with rock wool batts.

This insulation assembly should give us an R-value of 26 to 28.

The insulation riddle is back!

It feels like the project and my life have been taken over by insulation issues—whether they have to do with physical prep work or keeping me mentally on my toes, thinking about how to insulate.

Interestingly enough, some things that seemed resolved suddenly make a surprise re-appearance.

I learned about the “point of diminishing returns” for spray polyurethane foam (SPF) in late 2009 but couldn’t quite wrap my head around it. In early 2010, a comment on the blog post pointed me to an Icynene publication that explained the phenomenon.

It turns out that it is not so much explaining as it is a marketing gimmick. One of the blog readers, Tom Donalek, submitted two interesting comments on the insulation riddle post, in which he mentions a discussion at

Tom points me to the comment section of that discussion that gets into the subject of diminishing returns:

… down in the comments, there’s some talk about this “mind bending” stuff about getting the “first 89% of the insulation value with 2 inches of foam.”  It appears to be some good old advertising statistics.  These numbers like “80% with one inch, and 89% with two inches” are in comparison to what, exactly?  One of the commenter points out that it’s in comparison to a wall with an R value of 1.

At the end of the first paragraph on page 2, they [Icynene] say, “Stated another way doubling the insulation thickness (R-value) and cost; only provides a modest 2% increase in heat flow reduction.  Based on this observation, it is very difficult to justify the additional cost of adding insulation beyond 6″ in thickness.”

I think that the above sentences were the whole goal of the exercise, and they had to do some gymnastics in order to create a starting point, no matter how odd, that would get them to that goal.  The cost of spray foam insulation is its main competitive disadvantage, and this exercise is intended to deflect from that disadvantage.  This comes at the potential cost of under-insulating a building, resulting in increased heating and cooling costs for years to come, with the associated carbon release.  As with the discussion I linked to […] it appears that Icynene may be quite willing to make some “extraordinary” arguments in order to benefit their product/business.

This isn’t quantum physics – it’s good old, straightforward low-energy physics.  Yes, convective heat loss (air leaks) is very important, and radiant heat loss also plays a role.  But most of a house’s heat loss is conductive.  When you plug through the simple math, R values are R values – there’s no mental gymnastics required.  R-40 means half the conductive heat loss as R-20, and R-80 would mean half as much again.  No “wrapping your head around it” required.”

And I guess no real point of diminishing returns either… You can read the unedited version of Tom’s comments at the “Insulation riddle resolved” post.

This type of confusing data and greenwash is a reoccurring problem in the green age and it is not always easy to separate the wheat from the chaff.

Having narrowly avoided this trap, I should take another look at our insulation strategy to make sure that we still meet our energy goals.