[Greenbuilding] embodied energy was Polyiso strength on roof (ErgoDesk)

Fri Dec 12 11:11:48 CST 2014

Definitely agree about context – have to consider all of these products as potential companions – hard to do a long hike in gumboots without blisters.

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Alan Abrams
Sent: December-12-14 6:09 AM
To: Green Building
Subject: Re: [Greenbuilding] embodied energy was Polyiso strength on roof (ErgoDesk)

not to muddy these already murky waters, but there are at least two other factors that come into play. 

One is the method of installation. Consider exterior sidewall insulation: A 4' x 8' panel of foam is a versatile, modular size, which can be handled by a carpenter on the inevitable make-shift scaffold, with relative safety. It can cover at least 32 SF and be temporarily secured with two nails, for example, while furring strips are prepared. It would take four pieces of Roxul to cover the same area, and more fidgeting where substrates are not modular. It would require more fasteners--each nail or screw with its own EE, and each a thermal bridge. Exterior cellulose insulation (like some Passive House approaches) requires an entire framing system to support it.

Another factor is permeability. This sword cuts the other way, because an assembly that must dry in both directions (for whatever climate related reason) favors both mineral fiber and cellulose. I'm not convinced that EPS has sufficient permeability to ignore its use on what ought to be a bi-directional breathing wall. Its use could therefore necessitate mechanical dehumidification in a moderate climate that wouldn't otherwise need AC. 

In the case of insulating an existing slab--which John Salmen has discussed at length in the past--EPS is a winner on both accounts: not only can it be fastened without screws or nails, but it is also where you would want a vapor barrier.

In summary, it is not enough to consider these materials in the abstract--they also must be evaluated in their context.

AA

Alan Abrams
certified professional building designer, AIBD
certified passive house consultant, PHIUS

certified passive house builder, PHIUS
cell     202-437-8583
 <mailto:alan at abramsdesignbuild.com> alan at abramsdesignbuild.com
HELICON WORKS  <http://www.heliconworks.com/index2.html> Achitecture and Education

On Fri, Dec 12, 2014 at 8:18 AM, John Straube <jfstraube at uwaterloo.ca> wrote:

I think the supply chain issue Alan and John are discussing is very valid and does indeed show how complex it is to make the “best” decision
But John, you have some facts wildly wrong. That about 1 pound of EPS can do 1 sq ft to R40 is correct although most people us Canadian Type 2, which is a higher density and R4 per inch. A rounding error.

But that high density stone wool is made by adding glue is not true. A 2 pound per cubic foot batt is definitely 95% or more stone, and the higher density products like 4 pcf wall insulation or 8 pcf roof insulation have MUCH more stone and may have a lower % of glue.  You could go to  factory and watch the stream of fibers on the conveyor belt being squished to different densities. The primary difference IS the amount of fibers in the product.
Also, you have a Roxul stone wool plant in Maple Ridge BC  — which is not 3000 km from where you are, it is very likely closer than the styrene plant in Alberta.  It is true that the amount of rock wool you have to ship for R40 is a LOT more, more than double (e.g., 3.3 pounds per square foot if you did it all exterior, I would use 2 pcf batt in the cavity to roughly get the first R20 and then 5” of pcf on the exterior for the next R20, so lets say 2.6 pounds per square foot versus 1 pounds per square foot)

The claim that 0.067 pounds of styrene makes 67 pounds of EPS is also incorrect. Norbert is correct. It is true that a 1 pound sample of EPS may contain only 0.1% of styrene monomer: this is one of the concerns with styrofoam to some (not me) because the monomer can move and potentially have health effects. It is often higher than 0.1% which is the problem.  But the remainder of that sample is polystyrene, the polymer. Pentane is mostly removed at the factor during expansion and moulding, and replaced with air which weighs about 0.075 pounds per cubic foot. So of the 1.2 pcf for EPS, 1.1+ is polystyrene.  To make polystyrene you react the styrene monomer to polymerize it.  So a pound of EPS in typical foam board is over 95% from styrene monomer.  Not 1%. The steam is used to expand the beads and mold them, it is not part of the chemical reaction and does not become part of the product.

How to compare the impact of 1 pound of styrene produced 1000 km away and 2.6 pounds of stone melted 400 km away and 3.5 pounds of cellulose with 0.5pound of borate?  I dont know.  This is tough.  Except for Ergo who knows the answer before the analysis begins: EPS is always best.

John

On Dec 11, 2014, at 11:38 PM, John Salmen <terrain at shaw.ca> wrote:

> Actually it is something to be considered.
>
> The EPS product I use is manufactured from polystyrene beads which combine styrene (0.1% by weight of finished product) and pentane (1% by weight of finished product). These beads representing 1.1% of the final product are manufactured in Alberta (about 1000 km from me). They are shipped to Vancouver (about 130 km from me) where they are manufactured into board stock using steam (local water and heat) and packaged into roughly 96 cu.ft. polyethylene wrapped bundles (88 sq.ft. of 2ml poly).
>
> Each bundle weighs about 67 lbs with .067 lbs (about 1 ounce) of styrene monomer and would insulate 64 sq. ft. of wall to roughly R40.  20 bundles could do the walls of a 1600 sq.ft. house – about 20 oz of styrene (equivalent to 10 milk jugs when they were made of styrene)
>
> So basically I had about 6.7 lbs of polystyrene beads shipped 1000km then converted into 67 lbs of finished insulation wrapped in 88 sq.ft of poly ( and shipped 130km where it gets put into buildings and hopefully subsequently taken out in board form and put into other buildings or whatever things get recycled into in the future – probably milk jugs).
>
> I’m not sure I can do better than that at this point with less impact for a local solution that works well in my climate –
>
> Straw would have to be shipped an equivalent distance (we have no local wheat) – ironically it would take about 20 bales (about 900 lbs) to insulate an equivalent area which takes about a ½ acre of farmland to grow and about .1 lb (1.6oz) of petroleum derived fertilizer to generate the growth.  Straw does not work in my climate.
>
> For cellulose the equivalent wall area or insulated area would be about 200 lbs of shredded newspaper – so I could collect and shred papers locally but I would still have to ship in 60 lbs or so of borates to make up that amount at at least 4  times the distance. Also we are getting more information that borates might not be as safe as we thought – not a well investigated material. Also I have spent a lot of time politically working on having newspaper recycled as pulp mills are a huge environmental liability in my region as is deforestation.
>
> For rockwool for walls the equivalent wall area would be about 162 lb and I would have to ship that about 3000 km (so double the weight and 3 times the distance – and 4 times the packaging). If I wanted to use a rockwool as a board material comparable to the eps for slabs the equivalent area weight would be about 800lbs (additional weight being formaldehyde binder for density).
>
> So it is a complex decision making process. All design decisions are.  Is 1oz of styrene as dangerous as 60 lbs of borate salt, chlorine pollution and tree loss, or potentially 600 lbs of formaldehyde glue,  or even the soil loss and petro fertilizer usage from something as green as strawbales. I don’t know and getting information to know a little more is a continuous process -  but am certainly not at this point going to accept simple arguments for simple materials having discovered long ago there is no such thing as a simple material. Some of the most ‘natural’ materials out there are still the most toxic and/or inappropriate.
>
>

John F Straube
jfstraube at uwaterloo.ca
www.JohnStraube.com

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