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  • From: Toby Hemenway <toby@patternliteracy.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Earthships
  • Date: Wed, 27 Jul 2016 21:51:20 -0700

Scott’s comments are excellent. I would add that the rate at which a tree
sequesters carbon is also dependent on where the other trees are . Nearly all
species of trees slow their growth rate enormously once the canopy closes as
they compete with other trees for light and nutrients. I’ve looked at tree
rings on many species of both hardwoods and softwoods, and the pattern is
universal: fast growth (fat growth rings) for the first 20-60 years, then
only slow growth after that. They store most of their carbon in youth.

Solution would be to selectively log when the canopy closes to open up light
gaps so the other trees can keep growing fast. Then cut those when they slow
down, and plant new trees in the gaps. Put it all in structures that last 500
years.

Cement: The minute you use even small amounts of cement, gone is all hope of
being carbon neutral; concrete is that big an energy hog. It takes hundreds
of millions of joules of energy to make a few pounds of cement. Almost
certainly the most energy intensive of any commonly used substance (cement is
#2 after water in tons transported per year).

Toby
tobyhemenway.com

Just out: my new book on urban permaculture, The Permaculture City. Order it
at your favorite bookseller or get a signed copy from me at
http://tobyhemenway.com/book/the-permaculture-city/



> On Jul 27, 2016, at 5:53 PM, scott@permaculture.org wrote:
>
> In the case of fast maturing trees that are harvested at maturity would be
> excellent building materials. But trees that are still growing should be
> allowed to continue to sequester carbon.
>
>> -------Original Message-------
>> From: Scott Vlaun <scott@moosepondarts.com>
>> To: permaculture <permaculture@lists.ibiblio.org>
>> Subject: Re: [permaculture] Earthships
>> Sent: Jul 27 '16 15:39
>>
>> To Georg's point, sequestering carbon in well built structures made from
>> wood harvested sustainably. Here in Maine there are short lived, fast
>> growing species like balsam and poplar that make decent building materials
>> and would otherwise die and quickly release carbon as they rot in the
>> forest.
>>
>> Scott Vlaun
>> Center for an Ecology-Based Economy 207 520 0575
>>
>>> On Jul 27, 2016, at 5:33 PM, Scott Vlaun <scott@moosepondarts.com> wrote
>>>
>>> My mother in law lives in a 25 year old earthship in NM. I've spent a lot
>>> of time in it and it is pretty fantastic. Can and bottle walls eliminate
>>> a lot of carbon intensive concrete as do massive Adobe thermal mass
>>> walls. The sculptural aspects, especially tile mosaic make for a very
>>> Inspired living space. Embodied energy per sq. ft. on these structures is
>>> extremely low and even in northern NM she gets by on less than. Cord of
>>> wood per year, only needed when cold and cloudy. I'm extremely sensitive
>>> to tire outgassing and have never even gotten a whit. Labor intensive to
>>> be sure though!
>>>
>>> To
>>>
>>> Scott Vlaun
>>> Center for an Ecology-Based Economy 207 520 0575
>>>
>>>> On Jul 27, 2016, at 5:07 PM, Georg Parlow <g.parlow@gmx.at> wrote:
>>>>
>>>> Thanks Lawrence and Scott for this dialogue. Valuable.
>>>>
>>>> However, one question, Scott:
>>>>
>>>>
>>>>> **Whenever possible eliminate using forest products in construction.
>>>>> The wood is much better used as a carbon sink.
>>>>
>>>> To my understanding wood IS a carbon sink - and if it sits in my house
>>>> for 200+ years this is just as fine as sitting (and maybe falling over
>>>> and rotting) in the forest. What is it I do not see?
>>>>
>>>> Georg
>>>>






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