This news flash about a seemingly obscure topic is of immediate importance to all our architect Title 24 clients -and it’s good news for a change. The Quality of Insulation Installation credit is a HERS test that can help design projects to achieve Title 24 energy compliance, and we’ve had a couple of nasty surprises with it in the past.

Apparently, up until around yesterday, the California Energy Commission did not officially recognize the QII test as valid for open-cell spray foam. Our insulation expert James Morshead of SDI Insulation actually sent me an urgent email yesterday with the news, saying:

Today the California Energy Commission stepped out of the 1980′s and into the 1990′s! The 1/2 pound density spray foam QII check list has finally been approved after long delays.

There will be further revisions and refinements but our State has finally caught up in its own way. They have finally acknowledged what the rest of the country has known and what we have known in our area for years; spray foam works whether its closed cell 2 pound density or open cell 1/2 pound density.

Now on to fixing the U-Value tables!

Active lobbying at the CEC is necessary

As usual, James was an endless trove of insider information. Apart from the news itself, the way that this came about was very revealing of the CEC’s  inner working processes. Most of us don’t understand how or why regulations are the way they are, or how agencies like the CEC solicit input from the public. Apparently one must be prepared to show up in Sacramento at multiple hearings, cultivate deep relationships with CEC staff, sift through the raft of proposed changes for the few items that might be relevant to your industry or situation, and be prepared to pounce on proposed changes with a formally structured submittal process. In other words, hire a full-time lobbyist.

A QII teaching case with the New Solar Homes rebate

We’ve run into some issues on the QII test before, where we’d called it out for extra credit on a Title 24 report on a project that was going for the New Solar Homes rebate. The house had to beat Title 24 by 15% to qualify. James Morshead was actually the insulation installer on that job, and clearly remembered how the HERS rater – NOT one of our Green Compliance Plus Affiliates – flatly refused to accept the low-density spray foam. Closed-cell was fine, but open-cell? No way. This was maybe the first time we’d ever used the QII credit, and nobody, including our other HERS raters, could tell us much about this obscure little omission that suddenly threatened the validity of the project’s energy compliance documentation – and the NSHP rebate. There was much tearing of hair and gnashing of teeth all around.

This close-up shows examples of open cell and closed cell spray foam, also known as low-density and high-density foam. Each cell in the high-density foam is closed, making it a better air barrier - which increases its insulating value.

Whys’ this QII change so darned important?

What are the ramifications of this change and how did it come about? “The recognition of open-cell spray foam has been in process for six and a half years,” said James. “We at SDI didn’t know how the CEC process worked. We thought the CEC would be actively looking at the market to incorporate new developments in a proactive way. But they’re not set up to do that. They’re set up to be reactive, influenced by lobbying input from stakeholders in the marketplace.”

He mentioned a long-ago fight between manufacturers of cellulose and fiberglass insulation, each of whom pushed to have their own products recognized as higher efficiency (higher R value) than the other. “That’s normal business. The CEC is a government agency, and that means that they’re encumbered themselves by a lot of regulatory process. They’re restricted by the system themselves. They rely on input from competing parties, and they solicit information by saying, ‘We want your input.’ They rely on the stakeholders to approach them and provide the necessary technical information.”

But presenting this input to the CEC can be an uphill battle. James mentioned meetings that would be cancelled without notice, web site meeting schedules that were not updated to reflect changes or cancellations, and a very skeptical audience. “They’re coming from an analytical and academic standpoint, but they’re NOT in the field.” And that’s the main point of this discussion, is that until the CEC actually went out to see a low-density spray foam installation, they didn’t believe it worked AT ALL. “They were writing regulations without ever having seen it in action.”

James went on to emphasize that he didn’t fault anyone at the CEC, in fact he admired their work and didn’t envy their task. They’re overworked, underfunded, well-intended, and very committed to the overall goals of helping California to achieve greater energy efficiency. They are doing their absolute best within cumbersome bureaucratic processes that they can’t change, either. To get an an idea of how slow the cycles are for code revisions, consider that the current version of the California energy code, the 2008 code, actually didn’t go into effect until 2010. And, some of its provisions weren’t enforced across the board until October of 2011.

Meritage Homes – a study in foam

Then we got on the topic of Meritage Homes, a high-end home developer who was apparently instrumental in adopting and demonstrating the real value of spray foam. Meritage’s Green FAQ page actually talks about the building envelope as separate from the appliances. James told me that Meritage had decided to use 100% spray foam in all its new developments. Their homes weren’t selling, because of the economy of course – not because the homes were bad. Nobody was buying anything, no one could get financing.

“But then, someone convinced them to foam their homes. The first batch was in Houston, TX. And the spray foam was so effective as an insulator that it ended up causing them some problems early on. Suddenly, all the A/C units in the foam-insulated homes were grossly oversized! Short cycling and such. And they had mold problems as well. But they also realized: OMG! this foam works way beyond the calcs!”

Meritage Homes is a high-end home development company that has implemented energy efficient building envelopes as part of the core design.

And that’s where we get back to the CEC, and the California energy code, which has all sorts of tables and appendices with the allowable thermal values that you can use for various types of wall assemblies and insulations: wood frame, metal frame, etc. (They even have an appendix table for straw bales now.) So, even if your insulation is NASA-quality, the CEC’s Joint Appendices might disallow the use of its true performance capabilities when doing home energy calculations. Which isn’t really fair, considering how difficult it’s been to get even ordinary home designs to meet current California energy standards.

The deconstructed home as sales tool

Most of the time, developers will have a few finished-off model homes that prospective buyers can walk through to see what their home will eventually look like once it’s built. But Meritage did something different. They had a model home with cutout walls to show the interior building assemblies, including studs, wiring – and spray foam insulation. “I call it the deconstructed home,” said James.  “People now are smarter, more educated about building and energy efficiency. They want to see what’s inside. And sales took off! It was a totally new way to sell houses. Local building inspectors liked it, too.”

The homes weren’t selling for more money, but they were selling a lot faster – and, to investors, time is money. The quicker you can recover an investment, the less financing costs you have.

By showing a "deconstructed home" rather than the usual finished showcase model, Meritage Homes has educated homebuyers on construction techniques and efficient building envelopes. This image shows a deconstructed Meritage home from one of its San Antonio developments, as shown on housingzone.com.

CEC’s focus on new construction ignores issues for remodels

Then our conversation touched on another issue with the current California energy code, and that is its almost obsessive focus on NEW construction. One goal at the CEC is for all new homes built after 2030 should be Net Zero. But remodels to existing homes also impact the energy grid, and at least in California, remodels right now represent a significant portion of current construction activity. (This is according to James – I haven’t yet found any data specifically comparing either dollars spent or number of projects of each type, in CA).

Sometimes this results in a very artificial situation when we try to show compliance for a remodeling project. It becomes an exercise in hoping that the project qualifies for prescriptive and we don’t have to run an energy model. For example, if a remodel is not adding any square footage, but the total glazing area is over 20% of the floor area, there are situations where the project just doesn’t qualify for prescriptive compliance. And let’s say that this is a low-budget project; they’re changing out the heating system and enlarging a couple of windows and leaving the rest alone, maybe it’s mainly an interior remodel which doesn’t affect the building envelope.

Well, there are times we’ve had to run a whole-building model that included all portions of the existing home that aren’t being upgraded, but which aren’t built to current energy standards. It’s easy to go down a path of adding new energy measures that not only add to the cost of the project, but which can just get ridiculous. Open more existing walls to re-insulate? You could trigger a seismic upgrade. Replace all the windows? Well, maybe the old windows were still perfectly good, why throw them away? Is that “sustainable building”? I’ve spent hours reading the Residential Compliance Manual’s sections on alterations and remodels, and sometimes writing to the CEC, to find out what’s really allowable.

Trying to get a small remodel to pass California Title 24 compliance can be more agonizing than modeling new construction. This vintage contortionist image is from "The Circus, 1870-1950" published by TASCHEN.

QII checklists for each type of insulation didn’t include one for open-cell spray foam

James reminded me that the HERS rater has to follow different QII checklists based on which type of insulation is used in the project. So there’s one QII checklist for fiberglass batt insulation, and a different checklist to use for blown-in, etc. Here’s a nice checklist writeup from ConSol, an energy group based in Stockton.

This checklist does not affect allowable R-values used in the Title 24 performance calculations. All it does is say that insulation should be installed evenly with no air gaps, empty spots, or compression, and that wall cavities should be sealed to limit air flow through permeable insulation types. The extra credit is really a make-up because the assumption is that typical insulation installation procedures are so shoddy that substandard installations are the norm rather than the exception. So, what’s not to like about open-cell spray foam exactly? And yet, because the CEC had no official checklist that was specific to open-cell, and they didn’t want to lump open-cell and closed-cell together, the omission has led many HERS raters to conclude that low-density spray foam was simply not allowed for the QII credit. That may in fact have been the official CEC policy, too.

Some HERS raters have very extensive backgrounds in building efficiency, construction, and green building; others just don’t have the same depth of knowledge. That’s one reason we chose to list some HERS raters on Green Compliance Plus who we felt had a better grasp of the underlying principles behind Title 24 energy compliance. Our HERS rater affiliates are people with multiple credentials: some are HERS and GreenPoint Raters, some also have CEPE certification, and most have other creds ranging from Energy Star to BPI to LEED for Homes. They already have experience working with integrated project teams on custom home projects, and are more proactive about anticipating potential situations ahead of time or recommending solutions instead of just showing up for the inspection and saying, “Well, you fail, and there’s nothing I can do to help. You won’t get your rebate after all. ‘Bye, now.”

The CEC doesn’t always realize these ramifications until they’re pointed out

On the above mentioned NSHP case study, when James brought this up to the CEC staff and engineers, they were appalled. They had never dreamed that their policies would ever lead to a situation like this. The HERS rater had said, rather erroneously, “This product doesn’t work. Therefore, it’s not allowed.” What he really should have said was, “This product doesn’t have an authorized CEC checklist. And it’s still not allowed.”

Checks and balances to prevent cheating are well intentioned, but they can really gum up the works

“The CEC really wants to discourage cheating,” said James. There are certainly more steps to verification now than in the 2005 code. The whole CalCERTS registry process, with online filing of  the tandem forms for the Title 24 energy compliance report, the installation certificates, and then the HERS certificates, is a great idea but a royal pain in the bum. The online workflow is especially agonizing for custom remodel projects. The CalCERTS support folks are very nice and they also have to follow a ton of regulations that attempt to cover every possible home construction scenario; they’ve never had to consider a different workflow for custom homes where an architect is directly involved.

The code update process is complex and unforgiving, not unlike San Francisco’s planning and approvals process.

So – what if someone wants to advocate for, say, a better attention to remodels, or to custom architect-designed homes? You’d better have a full-time staff person on the job. “The process is so cumbersome, with hearings, submittals, and a lot of 45-day language,” said James. (Really it’s just like the SF planning process) “It’s really arcane – miss something and you’re dead.”

Other industries have their own issues to push for in the energy code. “HVAC, energy consultants, builders… there are a few people who practically sleep in their cars down at the SMUD building in Sacramento.”

It helps to establish a good rapport with the CEC staff, who got high marks from James for dedication and responsiveness. “If you know the system really well, you can know which events are important, but you can’t tell just by looking at the CEC site. It’s a labyrinth, and you need a guide. Try to have a relationship with the CEC staff. They can help you get your voice heard.”

Is the Net Zero goal realistic and achievable by 2030?

James thinks that the goal of having all new homes built in California after 2030 be Net Zero Energy is unrealistic, and not the best way to reduce overall building energy use statewide. “NZE should be affordable to more people than it is right now. We should be making it easier for people to comply even as we tighten the standards. It would be better to reduce energy consumption by 40-50% rather than try for some exotic concept like Net Zero. Go for more basic stuff – air sealing, HVAC sizing, more credit for unventilated roof assemblies.”

“Net Zero Energy is a great idea,” he continued. “But in the construction industry, there are so many different kinds of people involved. There are builders large and small, plan checkers, building inspectors, HERS raters, architects, energy consultants… no one knows how to do it right yet when it comes to energy compliance. Right now, this education is being force-fed into the system when people aren’t ready. NZE is such a complex concept, it requires a very integrated approach. If you push it on people too fast, it’ll be a disaster in the implementation.”

I can’t argue with him there.

Everything you think you know about insulation is wrong. That’s in a nutshell what I got from talking with James Morshead of SDI Insulation, Inc. in Burlingame, CA.  SDI is a full-service green insulation contractor offering “sustainable” versions of several common insulation types, including blown-in, spray foam, and fiberglass batts. I wanted to know about high-performing insulation products that would fit into small building cavities, because that’s often something we have to recommend for Title 24 performance modeling. But it’s one thing to say that a project has to fit R38 worth of insulation into a 4-inch roof space, and it’s quite another to find an affordable product that’ll actually do it – and where using that product’s self-reported rating is also acceptable for demonstrating Title 24 compliance.

Summary of the Problem

Insulation is one obvious way to make a home more energy-efficient. Sometimes, existing conditions may limit how much insulation can fit inside the wall, roof, and floor. The catch-22 is when a home needs a higher level of insulation than can easily be fitted inside the existing 2×4 frame walls, and a limited project scope won’t allow that shortfall to be made up elsewhere. In a remodel, retrofitting can be an issue; opening up too many walls could trigger a seismic analysis, and in other cases there may not be the budget to open up new areas.

But what’s the main standard for measuring insulation’s performance? In Title 24, it’s a measure called the R-value which measures the material’s resistance to heat transfer through a 1″ thick piece of that material. According to Morshead, it’s inadequate for the following reasons:

• It’s measured under unrealistically perfect conditions.
• It ignores the need for, and impact of, proper air sealing.
• It ignores the law of diminishing return.

What’s Missing From Insulation R-Values: Air Sealing and Installation Quality

Insulation products are measured in R-value per inch, and they vary widely, with typical fiberglass batt insulation around R 3.5 per inch. Fiberglass batt is the baseline because it’s so commonly used. It’s cheap, flame and pest resistant, and – if installed properly – it does a pretty good job. Two major assumptions that are built into Title 24 are that 1) you can fit up to R15 of fiberglass batts in a typical 2×4 wall, and 2) energy performance increases somewhat proportionally to the amount of insulation. Fiberglass batt insulation has other advantages: easy to install, affordable, fireproof, doesn’t attract moisture, mold, or termites.

But what if you’ve only got a very narrow gap inside the roof of an existing home, and Title 24 says that you need to make the roof R30 or even R38 to do your remodel? Well, one choice could be to go with a different type of insulation product, usually more expensive. But, if you really expect the insulation as actually installed in the home to live up to this expected rating, you will need to consider the factor of air sealing as applied specifically to insulation – and that’s something that’s not adequately addressed in the energy code, or even by insulation vendors themselves.

In many attics, the fiberglass batts are left exposed, without any kind of sealing on the inside. The insulation R value here would be greatly diminished.

This is where spray foam insulation outperforms batt insulation. Spray foam creates an air barrier whereas batt insulation, when left free and open as it is in many typical places like an attic, is as permeable as a mosquito net. “It’s a giant air filter!” said James. “It does absolutely nothing. Your R value could be less than 10% of what it’s supposed to be.”

This installation's a little better. The facing on the front acts as a vapor retardang. Presumably this project would also include a finish such as drywall or board applied flush against the batt insulation on the interior wall. If the builder really intends to prevent air from flowing through the insulation, further air sealing measures would be needed.

According to James, you can use spray foam at a lower R value than batt and still get better performance. [Wow… really?] “You have to bypass regulatory and industry forces that are pushing the R-value as the ultimate measure,” he said. “You have to take the position that you are seeking comfort and efficiency regardless of R-value”.

These two examples show how spray foam can be used to seal air leaks at joists or gaps, either as the main insulating agent or, on the right, in combination with other insulation types such as rigid insulation.

The First Few R-Values Are What Really Matters

The law of diminishing return implies that more is not always better when it comes to insulation. People may think that if R13 is the minimum, then R26 will be twice as good, and so forth with R30, R45, R60. “It’s the first 2 inches of spray foam that matter the most, or the first few increments of batt insulation R-value. There’s a sweet spot where you have enough insulation, and then you should spend additional money elsewhere,” advised James.

With insulation, it's the first few inches that matter the most. For any given climate, there's an optimal level beyond which it's not cost-effective to insulate further.

“At R10 – assuming ideal, airtight conditions – 97.9% of heat transfer is already eliminated,” said James [really??] “so why go to R25?” It’s because of the shortfalls in fiberglass installation techniques. “It’s like they’re saying, ‘Don’t pay attention to the physics, please.’ In reality, it doesn’t make sense to spend all that money chasing that last 10%, the way the Passive House people do. You can better spend your money elsewhere.” I can’t wait to hear the Passive House people screaming at that one.

Surface Temperature Control and R-Value

With insulation, what you are really trying to do is control the temperature of the interior surface of your wall, roof, or floor. James had a good analogy. “Imagine holding a paper cup filled with boiling water, and then imagine the same thing in a styrofoam cup. Which is easier to hold?” The styrofoam cup is a lot easier, obviously. But is R-value alone enough to account for this difference?

James offered a brain teaser for additional illustration. “Imagine a room that is 0 degrees adjacent to another room that’s 80 degrees, and your wall only has room for one inch of R6 insulation. It’s your refrigerator! And yet it obviously does work – why? Because that door stops air movement, which helps with controlling condensation.” Air movement within the building cavity can be exacerbated by a phenomenon called convective looping, as shown below.

One example of convective looping occurs when a warm but uninsulated interior surface heats cold attic air above, causing it to rise and circulate within a joist cavity. This in turn causes cold air to fall towards that warm surface. This example from BuildingScience.com shows actual air leakage from conditioned space into a joist cavity and back.

“R-value measures conducted heat in a bizarre test that is not reality. They take a 2″ thick sample and assume ideal conditions: that there is no air, no moisture, no convective looping – only conducted heat. It’s not the same as a real wall with gaps and air leakage. But we aren’t allowed to use terms like ‘effective’ R-value to distinguish among these conditions.”

(I found some good articles describing this phenomenon more in depth: one on wood pitched roof construction, and one on those ever-exciting floor-kneewall transitions.)

Air Sealing for Different Insulation Types

How you ensure airtightness depends on the type of insulation used.

• Spray foam provides its own air seal. One big advantage of spray foam insulation is that as it expands, it covers holes in the building envelope (such as openings made to accommodate electrical wiring or plumbing) with an air-impermeable barrier. Thus it can also be used prior to installing other insulation, to seal areas around joists, pipes, etc.

• Fiberglass batts must be air sealed on all 6 sides to be effective. “But that almost never happens in reality,” said James. Partly that’s because it’s very difficult to install fiberglass batts correctly, even for builders who’s love to do it perfectly. But here’s a good place to plug another great blog, Energy Vanguard, which has some great articles on just how tricky batt installation can be, including one on hidden air leakage sites in your attic and one on insulation and air infiltration

• With rigid insulation, failure to air seal on the inside can lead to condensation at the roof membrane itself. James responded to one of my questions with, “That’s where some of the horror stories come from. Someone stuck rigid in the roof and filled the cavity, but left it open on the inside so that interior air could flow around the rigid insulation up to the roof, which is cold – then they wonder why they’ve got water.”

• Blown-in insulation reduces air convection currents, and its advantage is, well, you blow it in till you fill the cavity. You don’t have to spend hours cutting and fitting every last piece, or ensuring a flush air barrier on all sides. And, you don’t have to rip the wall open, either.

Moisture

Allowing cold air to accumulate next to a warm but uninsulated surface also invites moisture and condensation to occur. In addition to allowing mold, rot, and deterioration, moisture ruins your thermal performance.

The accumulation of moisture inside a building cavity diminishes the performance of batt and cellulose insulation. Thermal images are a good way to detect water intrusion that's otherwise invisible, as shown in this infrared image of a flat roof. Moisture won't affect the performance of closed-cell spray foam as much, however.

The science of preventing condensation inside cavities varies by climate. The placement and use of air and vapor barriers is beyond the scope of this article, as is the topic of waterproofing (preventing direct water intrusion from the outside). For now we’ll just say that moisture affects some insulation types more than others.

• Cellulose or cotton batt will absorb the water directly, possibly leading to rot, plus the water degrades the insulation’s thermal performance.

• Fiberglass batt can absorb water even if the fibers themselves don’t swell, and the weight of built-up moisture can cause the instulation to sag, accumulate mold, or experience degraded thermal performance.

• Closed cell spray foams are vapor retarders and moisture resistant, although if water condenses inside the cavity somehow, it might affect adhesion.

• Open cell spray foam can absorb water from condensation in the air.

Ice Damming and Spray Foam

Snow melt is a special case that is less urgent in most of California, but I’ll mention it anyway. I was asking about some of the horror stories about spray foam and mold. James quickly leaped to the defense of spray foam. “It’s not the product, it’s the construction. Some of those horror stories involve insufficient R value or poor installation in snow load areas. R38 is OK for insulation against cold air alone, but in snow country you need R50 to keep the roof surface cool enough to prevent the snow on it from melting. The surface temperature of roof must stay below freezing to prevent ice damming. So, you can either ventilate the heck out of the roof, or you can use enough spray foam and ventilate the upper roof assembly instead.”

In snow areas, care should be taken to avoid "hot spots" on the roof that can cause snow to melt, re-freeze, and seep back into the house.

Ventilated vs Unventilated Roof Assemblies

James mentioned the possibility of an unventilated roof assembly with closed-cell spray foam. “You can do more cool architectural tricks with them.”

However, attics with ventilation are far more common, and James had a lot to say about them. “Conventional vented attics are energy sucks. A vented attic leaks heat both from the vents, and from insulation not being closed on all 6 sides. How many attics have you seen with the batts just exposed? All the summer heat goes into the attic, and while venting lets the hot air out, it does nothing about the radiant heat coming in. That radiant heat still transfers even with vents present, and that’s why so many attics are 130 degrees in the summer.”

“And all that vented air is moving over the open fiberglass. People say ‘I can’t get my house to cool off at night’ because the roof is still hot and it’s radiating heat into the interior.” Radiant heat actually radiates directly from the hot interior surface, even if the air itself is cold. “Radiant heat transfer is powerful force.”

“But if you move the building’s thermal envelope to the roof deck, with rigid foam or spray foam at the roof line, the interior surface temperature of the attic will be the same as the house.”

Moving the building's thermal envelope from the attic ceiling to the roof line helps keep the attic cooler.

Radiant Barriers and Cool Roofs

While not strictly “insulation”, radiant barriers also act to resist the transfer of heat from the roof into the home – specifically, solar heat gain. There are plenty of do’s and don’ts for these, starting with whether it’s even appropriate for your climate zone or not. James had a few suggestions: “Don’t put spray foam over a radiant barrier, because it won’t be able do its job. It needs an air space and a temperature difference. ”

James also noted that cool roofs can get so cold at night that they attract condensation, even during construction. But this should probably be a separate article.

Types of Insulation

James and I didn’t go through every possible type of insulation, but we did discuss some pros and cons of the main types. I’d refer readers to the Wikipedia article, which has a more exhaustive discussion of different types of insulation, their performance, and general pros and cons.

Fiberglass batt

Pros: common and cheap; doesn’t degrade; fire resistant; not a food source for pests or mold
Cons: If it’s not well sealed, dust and moisture can collect on it and then mold can grow.

“Fiberglass batt must be in contact with an air barrier on all 6 sides. It won’t perform if it has even one side exposed – too air permeable. If it’s not sealed, it’s just a giant air filter. To make fiberglass perform closer to its rated R-value is more labor-intensive. You need to do a very careful installation, and air seal it properly.”

Fiberglass batt insulation is one of the most commonly used insulation types, especially for homes.

Blown-in fiberglass or cellulose

Pros: Fills every crack. Denser, which restricts air movement. Provides an acoustic barrier. Simpler installation. Doesn’t require full opening of the building cavity. Non-toxic.
Cons: Not a full air seal; can be heavy on ceilings; can absorb moisture; settles over time.

“It’s OK for walls or attics, not so much for frame floors or roofs. It’s easy to install – for an open wall, you put a fabric blanket up on the wall and blow it in.”

Blown-in insulation can be a good choice for filling building cavities quickly and cheaply. Left: blown-in fiberglass insulation. Right: blown-in cellulose insulation.

Cotton batt

Pro: Its green appeal, being a recycled natural fiber. Fibers are non-irritating, unlike fiberglass.
Cons: Expensive; difficult to cut and fit. Moisture could be a problem if it gets into the wall. Not a complete air seal.

“They don’t come in standard sizes to fit a 15.5″ cavity. It’s 16″ wide and you have to cut it every single time. The manufacturers haven’t learned to size it for conventional building methods yet, and so it’s very labor-intensive to install. It’s a cool idea, and it feels green, but is it?”

Cotton batt insulation, or "blue jean insulation" is recycled and natural.

Spray foam
Comes in two types: closed cell and open cell. Difference is density. They both come with a liquid medium and an expander gas, which can vary as to what it is. Open cell is cheaper and not quite as insulating.

Pros: Airtight seal; closed cell is a vapor retarder and air flow retarder as well. Relatively high R value for the size.
Cons: Expensive; needs an experienced installer; requires fire rated barrier; toxic during installation; may emit toxic gases during a fire; keep away from direct sunlight and solvents.

Spray foam insulation creates an air seal. Shown here is low-density spray foam.

Rigid insulation

Pros: Same high thermal performance as spray foam. Can use on exterior wall, roof, or under-slab to control thermal bridging. Good for high R values in small spaces. Water resistant; can be used for foundation and under-slab insulation.
Cons: Requires air sealing to prevent air movement through the cracks; requires skilled installation and construction techniques to use; expensive; keep away from sunlight and solvents; may emit toxic fumes in a fire;

“Construction techniques are harder. Different jamb sizes and flashing. More cutting and fitting required. It’s harder to put in wiring afterwards, because you have to cut into the board.”

The term "rigid insulation" covers a wide spectrum of products. Left: sandwich of wood fiber and polystyrene. Center: phenolic foam board with foil backing. Right: Application of rigid foam panels as foundation insulation.

Best Bang for the Buck

After going on at such length about the virtues of spray foam, James did have a few good words for fiberglass batts, too. “You can achieve almost the same level of comfort with batt if you do it right, and youdon’t leave gaps or air leakage to create drafts. The surface temperature of the wall on both sides is important too. If a wall is cold, the home is less comfortable – not only because of lowered air temperature, but because of radiant heat loss as well.”

How “Green” are the Foams?

I asked James a few general “green” questions, since many of our Title 24 clients are interested in the larger issues as well as measurable energy performance. So how “green” is each type of insulation? Aside from the fact that using insulation at all is better than wasting energy, the “green” question could be addressed by looking at a number of factors:

• Whether off-gassing will somehow affect indoor air quality for the occupants

• Toxicity during a fire, even for materials that are themselves flame-retardant

• Global warming, could be result of ozone-depleting gases either during manufacture or after installation

• Energy used in the manufacture and transport of the materials, both amount of energy used, and whether it comes from fossil fuels
• Whether the insulation products themselves are made from petroleum by-products

• How much energy is saved over the lifetime of the building

Aside from cost and efficiency, some of our clients have voiced other concerns, especially with toxicity. It’s ironic that being “green” and reducing energy use might involve the use of toxic materials, but that’s one thing that could happen. Fortunately, it’s not inevitable, although some care should be taken when selecting individual products within a category.

How Green is Blown-In Cellulose?

Cellulose is “kind of green”, according to James, having a high recycled content. It does have some plastics, and printed paper with “unknown inks” although it seems farfetched that the ink on recycled cellulose insulation would have much of an effect on indoor air quality. Fire toxicity, maybe… but building a fireproof home is a different goal than making an energy-efficient one, and at some point you have to make choices about priorities.

Are Spray Foams Toxic?

James didn’t think that even the spray foams were toxic to people. “Not many products are toxic for indoor air quality,” he said. “A lot of that perception is just the industry players fighting each other – fiberglass vs. cellulose vs. foam – and promoting disinformation about the other products. The real test of whether something is sustainable is to ask ‘What will my grandkids think about what I’m doing now?’ What’s the impact on the environment, on the grid, and on quality of life?”

(The Wikipedia article on building insulation materials doesn’t completely back him up on this. First off, they contain petrochemicals. Second, they have to be correctly mixed in the field in order to “cure” correctly, and the installers must wear protective breathing apparatus. Third, some of the agents used, while not harmful to the ozone layer, are greenhouse gases. However, despite some reports of chemically sensitive people having a bad reaction to it, spray foam is still the insulation of choice for many green builders, and can be used in combination with other insulation products especially for air sealing.)

Both spray foam and rigid insulation can be made from a huge variety of substances, even soy, although even the supposed soy-based ones are still mainly petrochemical. Not being a chemist myself, I can’t discuss the issues particular to each: isocyanurate, isocyanate, polyurethane, polyicynene, cementitious foam, polystyrene, CFCs, HFCs, HCFCs. As with many other areas, one recommendation is to select a good builder who is familiar with installing the type of insulation desired – and in your climate area. Chemically sensitive people may want to evaluate samples prior to applying it all over their home, since it seems like some of the worst experiences are from do-it-yourself types or from improper installation.

Improper installation can also include poorly designed wall assemblies that permit moisture buildup. This can lead to toxic conditions if mold occurs, apart from any toxicity in the materials themselves.

Forget About Certifications – Just Save Energy!

It’s really the energy reduction as applied to many homes, not just one or two showcase LEED places, that will have the greatest impact on Spaceship Earth, asserted James. “LEED, Passive Houses, and Net Zero are playthings of the rich,” he opined. “If multiple homeowners spent a fraction of that on their own homes it’d do a whole lot more than one or two ultra-efficient showcase homes that no one else could afford to build. Even for the average home, a 30% reduction in energy use is achievable almost with your eyes closed. And, that 30% savings requires some mental energy in terms of good integration of systems and good choices.”

I pressed him about the Net Zero remark, and it’s the obsession with certification that he thinks is overkill. “Anyone can follow the Net Zero method and improve their home, or build using Passive House techniques. It’s not always worthwhile getting that last 10% of the way there for full certification.” I said that having a zero energy bill for the year was not a “plaything of the rich”, and James responded with, “My clients care more about budget and comfort than about what awards they’ll get.”

He also said, “These showcase homes are like concept cars. Maybe in another generation they’ll be the standard, but for now, it’s better to concentrate on the average home than on a few visionary early adopters.” While I agree that energy efficiency should be accessible to the Teeming Millions, I also think that early adopters are extremely important, because their homes are more than concepts – they’re long-term experiments that will ultimately prove (or not) the proposed concepts. And so what if they don’t work? That’s part of the risk of the experimenter, is to learn the right lessons from failure so the next attempt works better.

Since he spent lot of time bending my ear about the deficiencies in Title 24 itself asked James what he thought should be in the prescriptive performance standards. He responded, “Airtight construction, correctly installed insulation, and correctly sized HVAC systems. An average house should have all this without special consultants or green certification.”

Antiquated Standards

"California's Title 24 energy code is like using a whip and buggy to measure jet-engine technologies," says James Morshead, Senior Project Manager and Building Science Director at SDI Insulation.

“The current rating system for insulation is completely antiquated,” said James. Well, as a vendor, he’d probably want to make that point regarding his competitors. In fact, he did say “There’s a lot of disinformation out there, and much of it is due to industry competition. The fiberglass guys try to dismiss the spray-foam guys and vice versa.”

James wasn’t shy about critiquing Title 24 as a standard, either. “What ends up in the code can be largely political,” he said. “That’s why the Title 24 Quality of Insulation Installation credit recognizes closed cell spray foam insulation, but not open cell foam – at least, not yet.” (The QII test evaluates the quality of batt insulation installation, and it must be performed by a HERS inspector.) He went even farther than that by saying, “Title 24 can often a hindrance in highly innovative building envelope designs, because it focuses on numbers on paper without consideration for what actually works, or for cost. However, it does encourage overall improvements in the majority of typical projects, which is its intended purpose.” He’s right about the lag time. The code can’t keep pace with new developments, and often a newly invented measure that offers superior performance in the real world won’t always comply with what’s already in the code. It simply takes time for codes to be re-evaluated and updated to account for these new technologies. In those cases, it’s often up to the local building officials. “But they also have less leeway than they used to,” said James.

Interview with Bill Michelson, CEPE, San Joaquin County Building Inspector from November 2008

In GCP No.12, we had published an explanation of the slab edge insulation requirements which are required by Title 24 when specifying radiant heated floor slabs. We illustrated that prior discussion with examples of slab edge insulation as shown in the 2005 Residential Compliance Manual.

However, being practicing architects and architectural engineers ourselves, we also push projects through permitting, construction and final inspections, which allow us firsthand knowledge of how Title 24 requirements interface with building inspection requirements. So, after discussing those slab insulation details last week with one of our colleagues, Bill Michelson, CEPE who is a San Joaquin County Building Inspector, he mentioned one glitch in those Title 24’s details which Building Inspectors find troublesome in zones where termites are a problem, but he also recommended a solution, and here is that interview.

HUGENOT: Bill, as we have discussed previously slab flooring with built in radiant heat is becoming quite popular in residential design, because it has several advantages under title 24:

• Design simplicity.
• It can be poured in the slab which provides additional thermal mass.
• It requires no ducting and no duct maintenance.

But, from your onsite experience you have found that not all of the “approved” slab edge insulation details which are suggested on Page 3-45 of Title-24’s 2005 Residential Compliance Manual actually satisfy the termite ingress prevention requirements?

MICHELSEN: That’s right, while three of those shown do satisfy the requirements the fourth one, which shows the insulation on the “inside”, actually allows a path for termite ingress. It may look like it is sealed to someone without first hand on-site construction experience, but it is not sealed.

HUGENOT: So, then if I understand this correctly, the other three exterior insulation details satisfy because they are outside the slab. But, the detail entitled “inside insulation” actually allows a path for termite ingress?

MICHELSEN: Yes, and unless it is properly sealed against termites the insulation actually creates a path for termite ingress, unless it has a termite shield and is sealed with a gasket or caulked.

HUGENOT: So then, in order to prevent termite ingress, this detail needs to be modified, by the addition of a sill gasket (sealer) over a termite shield at the top of the foundation, similar to that shown in the details on page 11 of the attached PDF, to prevent termite ingress?

Note: The attached PDF is a two-page reprint from a longer document. Bill is referring to the printed page number.

MICHELSEN: Yes, most of those details do have termite shields, but may require additional caulking. Also some of them have the galvanized metal shield showing on the outside of the house, and this is most effective against termites. But, many owners find this distasteful because the exposed metal it may rust. The detail on the right on page 12 does not have this exposed metal, but may require additional caulking under the exterior fascia. Actually, most of these details will solve the problem if properly installed. But, I would prefer to see them use a system similar to the detail on the right of page 11 in the attachment which is the most effective.

Reprinted from Green Compliance Plus Vol. 1, No. 15, originally published November 17, 2008