[GSBN] Fwd: Embodied energy comparisons: SB vs Stick-built
derek at unm.edu
Mon Feb 16 10:48:53 CST 2009
This is great, John. Would it be easy for you to run one more set of
numbers on these two houses in two sizes? Assuming conventional frame
construction, how much more wood and other carbon sequestering
materials are in the larger versions of these houses?
You've just told us that making the houses 50% larger increases the
emissions by 33%/28% annually. I want to add to this sentence that
"increasing the size uses X% more wood framing and other carbon storing
materials." Those numbers, plus knowing the amount of carbon in a
piece of framing lumber, would let us do a quick calculations on the
trade-offs between storing more carbon in a bigger house that consumes
We could start a betting pool. My bet is that it would take four years
for the increased energy use/higher carbon emissions of the enlarged
conventional house to equal and exceed the amount of carbon stored in
the extra framing.
--On Monday, February 16, 2009 7:59 AM -0800 John Swearingen
<jswearingen at skillful-means.com> wrote:
> I did a quick simulation of a conventional house in Boston, 2000SF in
> size, vs. an energy efficient one that uses "off the shelf"
> improvements (better windows, furnace, etc.), and got a difference of
> 4.2 times the emission for the conventional house. In quantity,
> that's about 24,000 more pounds of CO2 emitted annually (31,292 vs
> 7,352), which is a striking difference.
> If both of those houses were 50% larger, or 3000SF, the emissions
> are increased by about 30% (33% for the conventional and 28% for the
> efficient one). You can get up to about 15,000 SF before the
> efficient house burns as much as the smaller conventional house (but
> I wouldn't spread that around). So size matters but efficiency
> matters more.
> I've no idea how that compares with the carbon burned/sequestered
> during construction, the "net" numbers, and would certainly be
> interested to know.
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