GBlist: re: can we build without cutting trees

["Clifton Perry" <clifton.perry@att.net>]

In reply a Message from Jeannie:

----- Original Message -----
From: "Jeannie" <jeannie@babb.com>
To: "Clifton Perry" <clifton.perry@att.net>; <greenbuilding@crest.org>
Sent: Tuesday, November 21, 2000 12:01 PM
Subject: Re: GBlist: re: can we build without cutting trees


>  Mr. Perry,
>
>  We continually test for heavy metals and other contaminants in our
incoming
>  raw materials.  Thus far, we have not tested any ash with problems, but we
>  remain on the watch.

For a listing of trace elements in Class F fly ash see :
http://www.geocities.com/CapeCanaveral/Launchpad/2095/chemistry.htm .
I am sure you have not tested any flyash without heavy metals in it. Without
a problem is a rather vague statment. What would constitute a problem?  I
don't know. Who decides what constitutes a problem? I am never comfortable
if it is the manufacturer deciding what level of toxicity is acceptable in
my life. The manufactures of pressure treated wood say the aresnic content
is not a problem ,but I might feel it is not appropiate for my environment.
If you have tested your flyash why not post the results so people can decide
for themselves?

>
>  As to your concerns about R-value in a cold climate, you might find it
>  interesting to note that AAC is rapidly growing market share in Finland,
>  precisely because of the energy savings.
>
Enery savings over what?. If they were previously living in tents then I'm
sure there are energy savings. If they were buliding with SIP's it would be
hard to beleive. The following information on AAC is copied from this site:
http://www.buildinggreen.com/products/aaconcrete.html
       "  The thermal performance of AAC, as for other high-mass materials,
is highly dependent on the climate in which it is used. At about R-10
(RSI-1.8), an 8" AAC wall does not compare favorably with a wood-framed,
insulated structure. Heat does move through the material more
slowly than through light framing, however, which can be an advantage when
temperatures are fluctuating above and below the desired indoor
temperature. This thermal lag effect means that heat from midday only
reaches the inside of the wall at night. If outdoor temperatures have
cooled enough by then that the heat is not a problem, then the wall's
effective thermal performance is much better than that of an R-10 frame
wall. In a northern winter, however, when temperatures can stay cold for
weeks, that thermal lag makes little difference.

         Actual side-by-side tests just completed in Pittsburgh have borne
this out. Two identical houses were built, one with 8" AAC walls using
material from North American Cellular Concrete and the other with a 2x4 stud
frame and fiberglass insulation. Over the course of a year,
heating energy requirements for the two homes were nearly identical, while
the AAC home used about 5% less energy for summertime cooling         than
the frame house. In a Pittsburgh climate a 2x4 frame house is far from
current energy-efficiency goals, so the AAC house likewise falls
short. AAC houses are less prone to air leakage than frame houses, however,
so in temperate and hot climates, they represent an improvement         over
typical construction systems."

For a good overview of thermal mass issues I would suggest the following
article: http://www.buildinggreen.com/features/tm/thermal.html


>  Finally, regarding your insinuation of "bias".... Of course my enthusiasm
is
>  linked to my industry involvement.  Indeed, had I not seen what good
>  *environmental* sense AAC makes, I would have never invested in the
company.
>

In some situations I think ACC makes good environmental sence. I think you
have to weigh environmental impact against building life. The potential for
ACC  to last longer than wood seems certain. I view the practice of using
highly toxic chemicals to kill anything that might eat wood as a good reason
not to use wood. There are no perfect solutions. Everyhting has its place
,except perhaps 6 billion (and growing) people on a finite planet. No matter
how much energy we save, or how green we build, in the end the planet can't
sustain the kind of population growth it has seen recently.  I doubt it will
sustain even current levels for any length of time.



Respectfully,

Clifton Perry
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