[GSBN] Embodied energy comparisons: SB vs Stick-built

[Graeme North]

Here is Andrew's interesting reply

best

Graeme
Graeme North Architects
49 Matthew Road
RD1
Warkworth
tel/fax +64 (0)9 4259305

graeme at ecodesign.co.nz
www.ecodesign.co.nz


On 12/02/2009, at 12:57 PM, Andrew Alcorn wrote:

> Hi Joyce
>
> As Graeme says, I am nearing completion of a PhD thesis that looks at
> this question. Numbers are not quite complete yet, but the short
> answer is that the embodied energy is not such an important
> consideration, in terms of minimising environmental impact, as
> embodied CO2 emissions (ECO2) is. To build a house that has an
> (annualised) per-capita CO2 emission that is within what the planet
> can absorb, the only way possible is to incorporate as many low ECO2
> materials as possible. (Basically, plant materials, which have a
> 'negative' CO2 emission value.) And the only way to do that, simply
> considering the mass of stored carbon required, is to use straw bale
> as the insulating material. Of course, combining that with a stick
> frame adds even more stored carbon.
>
> So, if one is asking the question "What is better, stick frame of
> straw bale?", and one is asking this question from the point of view
> of minimising environmental impact (which, presumably, is why its
> framed in an embodied energy way) the answer is "Use both together".
>
> As far as actual numbers go, that's a "How long is a piece of string?"
> question. What size house? Is it completely load-bearing straw bale,
> or hybrid load-bearing and infill? Or just infill? What sort of
> cladding and lining? What are the exact design details? One would have
> to know the answer to all these (and other) questions to be able to do
> actual numbers.
>
> Anyway, the actual numbers for embodied energy would be an answer to
> the wrong question. Fortunately, the rule of thumb answer (to the
> "What is environmentally best?" question) is very simple: stuff as
> many plant materials into your design as you can.
>
> A judicious amount of mass is helpful too, of course, but by and large
> this is a lesser consideration that maximising stored carbon.
> Obviously, the usual strategies for minimising operating energy (and
> hence CO2 emissions) are important to incorporate too. The magic
> allowable CO2 per-capita number can't be reached just by using straw
> bale for insulation: you also have to use solar hot water, and reduce
> lighting, refrigeration and appliance load too. Oh, and minimise
> surfaces that have to be painted - over the years paint, surpisingly,
> amounts to a lot of embodied energy and CO2 emissions.
>
> I am happy for my email (jandrew.alcorn at gmail.com) to go out, and any
> part of this email too, if you want. Obviously there is much more to
> say, and I expect people may ask questions, like "Why is ECO2 more
> important than embodied energy?" The anser to ALL those question is
> what my PhD is about. (You can read it in a few months.) In the
> meantime, people may want to download a report of mine here:
> http://www.victoria.ac.nz/cbpr/documents/pdfs/ee-co2_report_2003.pdf
> It doesn't include earth of straw bale. The values for those are  
> attached.
>
> Best regards
> Andrew Alcorn
>
>
>
>
>
>
> 2009/2/12 Graeme North <graeme at ecodesign.co.nz>:
>> HI Joyce - info is scant on this but there is a researcher in NZ  
>> doing this
>> sort of work for  PhD though -
>> I've copied this through to him to  see if he is OK about his  
>> email being
>> available to others  hopefully he has these figures
>>
>> best wishes
>> Graeme
>> Graeme North Architects
>> 49 Matthew Road
>> RD1
>> Warkworth
>> tel/fax +64 (0)9 4259305
>>
>> graeme at ecodesign.co.nz
>> www.ecodesign.co.nz
>>
>> On 11/02/2009, at 12:27 PM, Joyce Coppinger wrote:
>>
>> Didn't get any replies on this one when I sent it out earlier so am
>> resending to see if anyone has any ideas of a source.
>> Can anyone suggest the best resources (past and present) to find  
>> technical
>> information on embodied energy of straw bale vs. stick-build  
>> structures.
>> Thanks
>> Joyce
>> -------
>> Joyce Coppinger, Managing Editor
>> The Last Straw journal
>> GPFS/TLS, PO Box 22706, Lincoln NE 68542-2706 USA
>> 402.483.5135, fax 402.483.5161
>> <thelaststraw at thelaststraw.org>
>> www.thelaststraw.org
>>
>> _______________________________________________
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>>
>> <EE and ECO2 for Adobe - SB - StrawClay.xls>

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