[GSBN] Decrement factor of SB walls

[David Arkin, AIA]

Hi All:

Not long after the Real Goods Solar Living Center Showroom was built (in 1996), students from UC Berkeley did some monitoring, including tracking the transfer of heat through the bale walls.  My recollection is that they found a 12 hour lag of heat transfer between the exterior surface and the interior surface, making for a 'perfect' wall system relative to diurnal temperature swings and comfort.  The actual experience of the structure bears that out somewhat.

It's walls feature 3-string rice straw bales, laid flat, with approximately 3" (76mm) of PISE (earth-cement) on the interior and 4" (102cm) on the exterior.  

I will aim to locate the original paper.  I believe it has the actual recorded temperatures, and some other info. 

Best,

David


On Nov 28, 2011, at 5:35 PM, John Swearingen wrote:

> This is very interesting, and fortunately in English.  Unfortunately, I don't really know what it means.  Can you explain more?
> 
> U-value I know.
> Thermal bridges to nowhere, I know, but what is a "vented facade" (above).
> What are daily indoor heat capacities and sequential head capacities, and what does "strong" and "medium" mean?
> Phase shift mitigation?
> Thanks!
> 
> On Mon, Nov 28, 2011 at 3:40 PM, Van Krieken <vankrieken at gmail.com> wrote:
> Hi
> 
> The best source of information about this issue (and many others concerning insulation, thermal mass, etc) it is the book writen by Jean-Pierre Oliva and Samuel Courgey ( L'Isolation Thermique Ecologique).
> 
> Citing their book, page 175, concerning a wall with wood structure and straw bales with medium density (80 to 110 Kg/m3, strawbale section 34x46cm. Vented façade in exterior, and interior with clay render.
> 
> 
> Thermal loss U (W/m2K) / R (m2K/W) .................................. 0,13 / 7,76
> Losses due to thermal bridges............................................... 4%
> Daily indoor heat capacity (kWh/m2K)................................ 15 (strong)
> Sequential indoor heat capacity (kWh/m2K).......................25 (medium)
> Phase shift (hour) / mitigation of the heat flux (%)............... 16h / 13%
> 
> Unfortunately, this book is only in English. Jean-Pierre Oliva, is one of the best known french bio climatic architects, and since many years a great enthusiast of straw bale building. His books (also La Architectire Bioclimatique) can be found at Amazon.
> 
> 
> All the best
> 
> Jorge VK
> Portugal
> 
> 
> On Mon, Nov 28, 2011 at 10:55 PM, <strawnet at aol.com> wrote:
> Ken, Polly Cooper and Jennifer Rennick's chapter that John mention's in that Wiley book - Alternative Construction: Contemporary Natural Building Methods, has a lot of information on this though they don't use the term "decrement." They talk about this issue with straw and other types of wall systems and go into considerable detail. I would get in touch with them and see what they have to say. 
> 
> David Eisenberg
> 
> 
> -----Original Message-----
> From: Laura Bartels <laura at greenweaverinc.com>
> To: Global Straw Building Network <GSBN at sustainablesources.com>
> Sent: Mon, Nov 28, 2011 3:40 pm
> Subject: Re: [GSBN] Decrement factor of SB walls
> 
> Hi Martin,
> Without going back to the details, I could be mistaken, but it seems that a study by Ken Haggard a while back addressed this or similar properties. I found reference in a GSBN email from '07- see below. Is this the same metric?
> 
> Laura
> 
> 
> John,
> 
> There is that chapter from Ken Haggard and Polly Cooper on Natural
> Conditioning in the book Alternative Construction where they look at
> this. I was looking at it just recently for some curriculum development.
> 
> Laura
> 
> John Swearingen wrote:
> 
>> Very interesting paper, and well written.  Some time ago I remember hearing
>> someone toss out some similar observations about thermal storage, that on a
>> diurnal cycle, plaster is activated to a depth of about 2-3 inches
>> (5cm -7.5cm).  I have always figured that the exceptional thermal
>> performance of
>> straw bale buildings is not due solely to the high R-value.  The broad
>> thermal mass of the plastered walls, readily available to indoor air for
>> heat exchange, modulates temperatures like my pink Cadillac modulates bumps
>> in the road.
>> 
>> Does anyone know of research and measurements of short and medium thermal
>> storage in walls?
>> 
>> John "Diurnally Yours" Swearingen
> 
> 
> 


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