Sunday, February 28, 2010

File Cabinet

I'll have to revise this, but I've started making a publicly accessible filing cabinet for all the little (or big) spreadsheet calculators I create for some fairly specific energy and water modeling.

Sunday, February 21, 2010

Global warming potentials in spray applied foams (a work in progress)

I went to a PassivHaus seminar about a year ago, and it brought up a potentially disturbing fact about polyurethane foam in particular chemistries  in residential and commercial field applied purposes.  In the old days and occasional developing countries, these spray foams used blowing agents that have absurdly high global warming potentials. 

One might ask the question:  Is it possible for your insulation to have a higher carbon footprint than you are saving with the insulation? 
[oh, and you may have noticed that I’m posting a lot about foams lately—it’s been a hot topic, that’s all.  and I’ve been doing my research, so it’s on the brain.  I’ll get off this topic soon enough]
Proper Introduction:
I heard from someone recently outside of the South Bay who actually tried to read what I’m writing here, and really couldn’t understand much, so now I feel the appropriate responsibility to explain what the bigger picture here is so that most of you can go on caring about more important things. 
SO.  We want to save energy by insulating our houses.  There are myriad (ok, maybe not quite 10,000) ways to insulate, and all sorts of materials and such.  Spray-foam is among one of the options, which is especially nice for the building scientists among us, who like having the nice draft-free walls and roofs that the foams are pretty darn good at creating. 
Spray-applied foam in the residential industry generally comes in two flavors—open cell (aka low-density water blown foam) and closed cell (aka medium-density foam). 
The open cell foam is what most houses have, and it uses water as the blowing agent, and it releases CO2 upon curing.  Pound for pound, this CO2 ultimately doesn’t amount to much, and is generally vastly worthwhile in terms of insulating value.  
The closed-cell foam is the foam in question for this post.  It is generally among the most expensive insulation, but with stellar performance: high R-value per inch, and vapor impermeability qualities.  The closed-cell foam can’t use water as a blowing agent, unlike the open-cell—it has to use a much more finely crafted and specially tuned blowing agent in order to create its wonderful matrix of  tiny unruptured air bubbles (which is how the insulation insulates, after all). 
The standard blowing agent that I’ve heard used here in the US is HFC-245fa.   It has a global warming potential of ~1000x CO2.  That means for every pound of HFC-245fa that gets released in the atmosphere, it’s worth 1000 lbs of CO2 in terms of its impact on global warming. 
I don’t have an answer yet as to whether or not closed-cell foam is a dubious application for my particular geography, but the least I can do for now is to bring up the issue and provide a research study that gives some insight, if you’re interested. 
The chart below is pilfered from a study I really, actually want to reference and support: it shows the marginal payback (for just that one extra inch of foam) for various foams with different blowing agents. 
Danny Harvey, of the University of Toronto, created the graph, and it’s located in the study:
“Net Climatic Impact of Solid Foam Insulation Produced with Halocarbon and non-Halocarbon Blowing Agents”, Building and Environment 42(8): 2860-2879, 2007.
Link to study!

Wednesday, February 17, 2010

Radiant Floors: nice, but missing the point?

This is a variation on some points that this article effectively makes, except I'm going to be a little more academic about it:
We often think of radiant floors as inherently desirable for most projects.  For us temperate climate Northerners (and Southerners in Land of the Fuego), there’s an almost universal appeal of a very warm radiant energy source in the midst of a cold thermal environment.  It’s a neurological/evolutionarily programmed tendency.  When it’s cold, we are naturally drawn to warm things.  It keeps us from freezing to death, and therefore passing on our genes more successfully.

I’d like to suggest, here in this blog posting, that radiant floor systems are poor investments in most cases, compared to a well-insulated envelope.  Radiant floors in addition to well-insulated envelopes is good, perhaps expensive insurance. 

In most cases, radiant systems are placed into, and used most effectively (from a comfort standpoint) poorly insulated houses (e.g. Eichlers!).  The reverse is also true-- if you insist on poorly insulating the house (and that means cost-engineering out good windows) then radiant floors probably are a good way to make a comfortable environment.

Good insulation IS a good radiant floor. 
In fact, it’s a radiant house, not just a radiant floor. 
A prominent reason why we feel cold inside our homes in the winter is that the temperature of our surroundings (floor, wall, ceiling) is cold.  The same goes for feeling overheated in an air-conditioned house in the summer—the surrounding elements tend to be quite warm.

What defines comfort is that somehow the heat transfer and moisture transfer between our bodies and the local environment are in some comfortable equilibrium.  There’s LOTS of research and guidelines on this (go Bears!).  When we’re surrounded by coldness (cold walls/floor/ceiling), we need something pretty warm to balance out the energy transfer to/from our bodies.  This could be in the form of air temperature (convecting heat to our bodies) or radiant elements in our floors/ceiling.  The same goes for cooling as heating. 

For a house that has indoor wall/floor/ceiling temperatures that are fairly even around 65-75 degs, this should keep us comfortable all year long, regardless of outdoor temperature.

Radiant heating should be subordinate to insulation
The choice, in my mind, is how you provide such an even radiant environment in the floors/walls/ceiling.  One way is to not insulate well, but embed some sort of heating elements into your assemblies to counterbalance all the energy loss/gain to the outside.  You would consume a lot of energy, since all the energy you’re putting into keeping the environment the same radiant temperature leaks easily to the outside. 
The other way is to insulate really well, which should achieve the same goal 99% of the time.  In such a well-insulated system, you could go ahead and install a really expensive radiant element into your assemblies, but you’d really only be using 1% of the time.  And, who knows, that might be worth the expense—not my call. 

Fun/cheap backup heating sources
Standard practice: plug loads

In the Passive House certification program, the way they handle supplementary/backup heating is via things plugged into the walls—like refrigerators, lights, hair dryers, etc.  These all heat the house.  In a well insulated house, these are all you’d need to heat the house.  Passive House is very deliberate about quantifying these loads in their houses.  In a modern lifestyle where we leave everything on all the time, the problem is not that our house would ever get cold—it’s that it would be too hot all the time. 
Humans/Dance party?

For one of my projects considering Passive House, the backup heating was actually to just invite the neighbors over for a potluck.  Humans are roughly 200 Watt space heaters, so having a bunch of folk over for dinner would do wonders for heating the house on a cold day.  If it’s a really cold day, then maybe they would get a little dance party, and the heat from a 1 hour dance-fest should last the house for a couple of days of heating needs. 

Tuesday, February 9, 2010

Technicalities of code-compliance for Spray Applied Polyurethane Foam Insulations

Rebroadcast of last years' post on the technicalities of applying spray-foam in California 

Thicknesses of foams are limited in ICC evaluations.  Back in my freewheelin' days of classroom hand waving, me and my colleagues used to dream of filling 2x12 cavities full of petrochemical plastic foam insulation and watching for non-convexiities in utility functions for insulation, otherwise known as "tunneling through the cost barrier".  Other people call it "R-wars," but for the most part, those are a figment of our spreadsheets and our imaginations-- at least when it comes to spray applied foams as the sole insulator:  Why? (you might ask)

Well then... It turns out that those aren't really possible in reality, at least not in a while that's been tested and certified by certification agencies.  
For any foam plastic (spray foam) application submittal to a code-enforcement agency, it'll be good, if not essential to have some sort of testing report on specific assemblies that have been tested and approved:
here's an example ICC Legacy Report:

Energy Modeling Ramifications:  
As a Title-24 modeller, my hands are tied when it comes to representing the superior performance of foam plastic insulation, since the Joint Appendices (which is the Bible of Lookup Tables that I have to refer to for my R-value numbers) only gives a generic "Foam Plastic" R-value based on thickness.  This R-value reflects the most poorly performing foam plastic product that is registered with the state.  That's going to be really different than the ecstatic claims that you'll see on technical data sheets from specific insulation manufacturers.

State Testing results to verify manufacturer/product claims:  Fortunately, the energy modeling race hand-tying is closer to resolution.  The California Bureau of Home Furnishings and Thermal Insulation is on the case, and will eventually be playing well with it's bigger brother, the California Energy Commission.  Third-party verification of R-value claims can be verified in the following documents:

Workability of foam plastics:  
In terms of labor costs and such, foam plastics will take more time than the average crappy batt job, because you've got to spray it on (which takes a bit of time) and then come back a couple of days later and scrape off any overspray.  For the open-cell foam, it's fairly easy to scrape off, but for the closed-cell, it's a pain in the butt-- more like stone sculpture and less like .  Some foam plastics apply smoother than others, and so installers have this experience (or they should)-- in either case, it's usually preferable, if not essential to have at least 1" or 1-1/2" of "Slop", or extra space in the cavity for the insulation to expand into so that the installers have some fudge room and not have to shave off a whole bunch so the salivating sheet-rockers can get on with gyping houses and general contractors ;)
Here's a youtube video that shows what I'm kinda referring to here:

Oh yeah-- unventilated attic assemblies
These are not formally allowed in California code.  Any unventilated attic must be specifically permitted by the Authority Having Jurisdiction.  Talk to the code enforcer people.  They can be nice sometimes.  
One of these days, maybe I'll post the code reference up here for y'all to look at.

ya basta.

Passive Maus

Icynene's implicit campaign towards ignorance?

Hey all,
GreenBuildingAdvisor's Martin Holladay offered another provocative post today, that just so happened to match my own grumblings about Icynene's (and their various licensed contractors) various marketing campaigns. You can read the original post here:  
I encourage you to at least skim through it and at least get the gist of the conversation.  Per usual for this site, the comments are actually helpful and serve to carry on the conversation, and the understanding.  

R-value isn't the whole story?  (so sez icynene)
When one of the local suppliers of Icynene, I was a little astonished that they said that R-value was a conspiracy of the fiberglass industry to help advertise their product.  They said that Icynene is better because their R-value is better than the R-value of standard fiberglass.  I didn't want to be impolite at the time to our guests, so I didn't call Bull-.  So I'll reiterate here and now-- that is BULL-- R-value is R-value.  Icynene doesn't have special R-value.  And, contrary to what they said, the definition of R-value does account for the combination of conduction, convection, and radiation for reasonable approximations of building enclosures in the standardized lab conditions.  

This particular subcontractor, whom we have used many times, got knocked down a couple of levels in my estimation when they said this, which I've kept to myself thus far.  

New Marketing Campaign: Skimp on R-value because Icynene's R-value is better than the other
In the blog post, you'll read how Icynene is moving towards getting buildings to get a lower price point for insulation ars batt insulation by actually specifying Icynene thicknesses less than the code minima.  They argue that they should be able to be able to do this because the effective R-value of the assemblies with, say, R-13 Icynene is the same as that of an R-19 fiberglass batt cavity.  

And it's not to say that they don't have an argument-- they're just taking a curious stance on the issue. 

R-value is R-value:  it all assumes a well air-sealed wall.
Code mandates well air-sealed walls and insulation properly installed per manufacture specifications.  In standard construction practice, building assemblies are not well air-sealed and insulation is not installed per manufacturer's specs.  This is the reason why the labeled R-value on the Fiberglass batt package isn't accurate in the field.  
Energy efficiency isn't directly a safety issue, so code enforcers often glance over, or completely ignore the details of air-sealing and insulation.  This is the more complete problem statement.  

What's disappointing is that, while Icynene actually has a point about the sloppiness of standard construction practice, they aren't actually helping the issue by actually trying to educate the marketplace properly about the performance of sloppy building assemblies.  They appear to be going the low road instead and curiously putting builders at risk for non-code compliance in insulation thickness.  

All that said,
I'm fine with the product itself and it's competitors.  It seems to work quite well (with proper vapor management!!) and I look forward to using it in the future, after I get over my desire to boycott them for lame marketing.  

Yay for spray-foam plastics!
Boo on Icynene!