[GSBN] Embodied energy comparisons: SB vs Stick-built
ArchiLogic at yahoo.ca
Mon Feb 16 12:34:37 CST 2009
By way of putting some numbers to what Andrew was talking about earlier
WRT life cycle cost dwarfing embodied energy cost, an excerpt from a
recent post to the REPP/CREST Greenbuilding List:
" ... from the seminal paper done by Cole and Kernan years ago
==========copied material =============
The data shown here represent average operating energy consumption between
Vancouver and Toronto climatic conditions, assuming conventional levels of
envelope and equipment energy efficiency.
The initial embodied energy remains constant at 4.82 GJ/m2 over the 50
year period which was examined, while the recurring embodied energy
increases from zero at the time of building completion, to a cumulative
value of 6.44 GJ/m2 by year 50. The operating energy eclipses both forms
of embodied energy at a cumulative value of 70.28 GJ/m2 and represents
just over 85% of the total energy at the end of the 50-year period.
This relationship has prompted some practitioners to conclude that
embodied energy is comparatively irrelevant. However, as the level of
operating energy efficiency is improved, the contribution of embodied
energy to total energy becomes more significant.
=======end of copied material ========= "
And on the subject of tools for evaluating environmental impact, another
excerpt from a recent message posted to the same list:
========= copied material ============
... under the auspices of Canada Mortgage & Housing Corp
(www.cmhc-schl.gc.ca) a spreadsheet
application "OPTIMIZE" was developed to
"...assist building researchers and designers in estimating the
material flows and environmental impact of residential assemblies and
-- essentially a means to evaluate the Green-ness of a proposed design and
do the necessary tweaking at the design stage (ie before the mistakes have
been concretised in the Real World).
The output, in chart & table form, using recognisable English where text
was used, provided
- breakdowns for energy flows, both embodied and life-cycle
ie energies of materials aquisition,operating, maintenance/replacement,
construction, demolition, disposal/recovery, fuels)
- AsBuilt & Life Cycle Embodied Energy & Weight Breakdown by Commodity
for a list
of about 60 material types
- Breakdown of Air Emissions and External Costs
-Breakdown of Indoor Air Pollutants
-Breakdown of Outdoor Emissions with weights for each and their $ co$t
itemised for CO2, particulates, NOx, SO2, VOCs, Methane,CO,
Cadmium, Chromium,Copper,Mercury (blah,blah,blah,) ... Nuclear, Hydro
...with a dollar cost per person housed as the last line of output.
OPTIMIZE made its appearance well over 15 years ago and no doubt, there
have been a number of similar software programs put out there since then.
============ End of Copied Material ============
But back to Joyce's original query about embodied energy comparisons of
stick-built ve SB, as Andrew pointed out, it's like asking "how long is a
piece of string".
I would venture that one of el Lupo's (aka John Glassford)
earthen-plastered, loadbearing SB houses in Australia is several
magnitudes lower in embodied-energy than one of his
twin-brother-by-different-mothers (aka the Skillful Meany) Portland cement
plastered, seismic-resistant SBH on a thickened-edge reinforced concrete
slab foundationed California SB houses.
I would further venture that I could build a stick-framed house that is
more energy-efficient and lower in embodied energy than either. But I
could also build one that is higher in EE as well.
That is to say, a comparison such as that suggested by Joyce would
probably be meaningless.
It would be more useful I think, to simply provide charts (North American,
European, Aus/NZ sourced ) of the embodied energies of the most common
materials that are used in making a SB house and show a sample calculation
as to how to use the numbers, showing the same calculations for a
"typical" Green-built, stick-framed home for the sake of comparison so
that the reader will have an inkling of where her design stands in the
=== * ===
Kanata, Ontario, Canada
< A r c h i L o g i c at ChaffY a h o o dot C a >
(manually winnow the chaff from my edress in your reply)
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