Not all SIPs (structured insulated panels) are created equal
Their insulating medium and the incumbent toxic gasses that occur under
conditions of combustion should be the determining factor in what they're
constructed with. Unfortunately, it's not. Rather, the industry glosses over
such questions and goes into deflect and distract mode by explaining how
they can meet residential and commercial fire code. Well that's all well and
fine, but that's achieved by various layers of gypsum wallboard and has
nothing to do with SIPs proper.
And it still doesn't address the issue of combustion toxicity. On that
front, the closest industry gets to addressing toxic gases is the usual
short dismissal about how low the formaldehyde outgassing is, and then
pointing out that it's not a problem of the insulation, but the OSB. But no
answer on combustion gases unless you crucify them to a wall and hold a
bloody nailgun to their heads.
Expanded polystyrene may be a great insulator, but it never has been and
will continue to not be a construction medium of choice if the first thought
of what if were considered. I certainly wouldn't want to include it as a
factor if I were trying to locate a missing child or remove an unconscious
adult in a fire scenario.
Rigid polyisocyanurate foam would be a far better option, even more
attractive if it were manufactured from vegetable-oil based polyols.
But the consuming public isn't supposed to think or worry about such things.
Why?
Because We're the experts! - experts being industry and regulatory
agencies. There's probably not much comfort in that assurance after
inhaling the first lungful.
It's a valid question as to whether or not polystyrene has been included in
the primary constrution of a building and a solid reason to walk away from a
home purchase no matter how good the price.
Todd Swearingen
- Original Message -
From: Steve [EMAIL PROTECTED]
To: biofuel@yahoogroups.com
Sent: Wednesday, December 31, 2003 10:37 PM
Subject: [biofuel] Re: food for thought
More and more local code enforcement agencies really are pushing every
new building towards higher insulation values. Only a few major
glitches that they seem to not understand or just totally ignore.
Tests by researchers show that fiberglass is good at 75 degrees... but
has no insulating value at 20 degrees F.
Second. How much insulation value is there in a building constructed
with Steel studs? Even the building industry admits steel is a super
great conductor of heat.. be it into or out of a building. Always
enjoy that they put batts between the studs.. and then you get a
thermal nose bleed every 16-24 inches.
Here is the reprint from Oakridge testing labs
Did you know that R-Value testing is done at 72 degrees Fahrenheit
with no infiltration/exfiltration, humidity at 40% or lower and with a
small temperature change for a short duration? This test, which is
the standard R-Value test was designed when the only insulation
material being evaluated was fiberglass. It was developed by the
Fiberglass industry, so it's hardly surprising that it would favor
them. When the conditions of the test are varied fiberglass doesn't
do well. For example, at 20 degrees F with 50% humidity, fiberglass
is R-0. EPs acually gets higher R-values as the temperatures
decrease, and humidity does not affect it at all. The test is an
unreliable guide to efficiency.
Imagine how effective insulation is when doors and windows are left
open. Essentially, infiltration and exfiltration issues are similar.
Air and moisture flow through the structure greatly reduce the energy
efficiency of the home. SIPs address this issue better than
conventional stick or steel frame construction. Blower door tests
indicate that SIPs are 20% tighter than very well built stick frame
homes and as much as 40% tighter than most conventional construction.
If you've ever used a space blanket, you've seen how effective
reflective radiant sheeting can be for insulating. Any material which
keeps radiant energy from converting to condutive energy is considered
good as a radiant barrier. Stick frame, steel studs and masonry are
all exceptionally bad at this and SIPs are good at it.
Some materials are slow to change temperature- they have inertia to
temperature change. Air and metal are very bad at this and
non-metallic solids are good at it. SIPs are excellent insulators
where thermal mass is a factor.
A standard stick or steel frame wall has studs every 16, which
translates to about 20% to 25% of the actual surface area. Obviously
there is no insulation where the framing is so the less framing, the
higher the insulation efficiency. According to Oak Ridge National
Labs, this one issue reduces the efficiency of a wood stud wall by 33%
and a steel stud wall by as much as 55%. SIPs rate a 7% loss of
efficiency.
SIPs are generally tighter at the window connections, but teh quality
of the window
