[GSBN] Embodied/embedded energy figures

Mon Oct 17 09:53:09 UTC 2011

I would agree with Tom that we are losing sight of the importance of embodied energy.

If you compare a well built SB house to the equivalent Passiv Haus they can both reduce their energy in use to a similar level.
But looking at their total energy dept over 60 years, the Passiv Haus (built with conventional materials) will have a higher energy dept, with up to 40% of its dept tied up in the fabric of the building.

The more you reduce energy in use, the greater the proportion of your energy dept over time will be in the materials you use.

As Tom points out it depends on the source of figures you use, but using the Bath data a quick comparison of straw and expanded polystyrene is interesting:

To achieve the U value of a typical SB wall (0.17 Wm2K) using polystyrene, you would need a thickness of 135mm.
For each square metre of wall at the given thickness of each material:
The straw has an embodied energy of 9.5 MJ
The expanded polystyrene has an embodied energy of 419 MJ

So a short and simplified answer to the question 'why use straw?' could be 'because the conventional equivalent has over 40 times the embodied energy!'

This is a pretty gross generalisation, but is still food for thought!

I presented a paper called 'The Leechwell Garden House' at the PLEA conference in Brussels this summer that discussed this issue. You can download a copy from my website, along with other SB related research:
http://www.carfrae.com/downloads/index.html

Thanks

Jim

J M J Carfrae PhD
Environmental Building Group
School of Architecture
University of Plymouth
Drake Circus
Plymouth PL4 8AA
UK

jim.carfrae at plymouth.ac.uk<mailto:jim.carfrae at plymouth.ac.uk>
07880 551922
01803 862369

On 17 Oct 2011, at 09:12, Tom Woolley wrote:

Dear all

Here is the link to the Bath database that Bruce couldn't find

http://www.bath.ac.uk/mech-eng/sert/embodied/

However Craig Jones who has done most of the work on this has now moved into the private sector and works for "Sustain"
http://www.sustain.co.uk/
Craig.Jones at sustain.co.uk<mailto:Craig.Jones at sustain.co.uk>

While I think Craig and Geoff at Bath have done a great job on this, to keep the issue of embodied energy on the agenda,
 it worries me that the ICE database is treated with almost biblical respect in many refereed publications.

Bath has never had proper funding for original research on ICE and so much of the data has been gathered from here there and everywhere.
This means that the data provided by many commercial companies has not necessarily been independently verified
Some of us would question figures given for the embodied energy of natural materials for instance.

I would be interested to know where embodied energy figures on the agenda in other countries ( for something I am currently writing)
In the UK, organisations like the AECB and the Passiv Haus people are pushing the argument at the moment that energy in use is the only thing that matters.
I though we had got rid of this debate years ago but it has resurfaced

While the greenies have been dismissing embodied energy , the commercial sector has embraced it recently, a strange reversal
For instance see the work of Gareth Roberts at Sturgis on carbon profiling
http://sturgiscarbonprofiling.com/?paged=3
Its worth downloading their RICS Redefining Zero publication
While it doesn't say anything about strawbales it does provide a very interesting methodology.

We are launching the Alliance for Sustainable Building Products in Parliament on November 16th
I have a one page leaflet about this but I think you cannot add attachments to these emails so if anyone would like this please sent an email to my personal address
tom.woolley at btconnect.com<mailto:tom.woolley at btconnect.com>

Tom

On 14 Oct 2011, at 19:47, Bruce King wrote:

The University of Bath (UK) has the best database I know of, but I can't find the link.

Thanks,

Bruce King, PE
Director of EBNet
Ecological Building Network
the art and science of building well
bruce at ecobuildnetwork.org<mailto:bruce at ecobuildnetwork.org>
PO Box 6397
San Rafael, CA 94903 USA
(415) 987-7271
follow us on Twitter: @EBNetwork
blog:  http://bruceking.posterous.com/

On Oct 14, 2011, at 11:37 AM, Chris Magwood wrote:

Hi all,

I'm working on a research paper and I'm trying to find good, reliable information on embodied energy (or embedded energy) in building materials. I have some good papers from Australia and some stuff from CMHC, but I'd be glad to receive suggestions for other sources.

Thanks!

Chris

--
www.chrismagwood.ca<http://www.chrismagwood.ca/>
www.endeavourcentre.org<http://www.endeavourcentre.org>

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Tom Woolley

Rachel Bevan Architects
80 Church Road
Crossgar
Downpatrick
BT30 9HR
tom.woolley at btconnect.com<mailto:tom.woolley at btconnect.com>
028 44 830988
www.bevanarchitects.com<http://www.bevanarchitects.com>

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