[GSBN] High Performance Strawbale

[Kelly Lerner]

Hi Alfred,
Thanks for bringing up these important questions! I remember that David Arkin once posted an excellent energy report along with blower door testing info on a house that he had designed in northern CA. I've attached it. It would be great to collect all the blower door testing completed on strawbale houses in one location. I've been thinking about having some of my houses tested, just to get a good feel for how they are performing. 



The best insulation info for strawbale buildings can be found in "Design of Straw Bale Buildings", Bruce King et. al. 

Cheers, 

Kelly Lerner, Architect
One World Design Architecture
509-838-8812
www.one-world-design.com

Everyone does better when everyone does better.
Beautiful, Smart, Attainable, Sustainable

On Oct 3, 2011, at 8:49 AM, Alfred von Bachmayr wrote:

> Greetings all,
> Thank you for including me in this elite group of building scholars. 
>  
> I wanted to get feedback on some performance aspects of strawbale building that I have been confronted with by energy modeling and regulatory entities that question its thermal performance.  This resistance appeared when I contracted a Hers rater along with mechanical engineers who, in generating thermal models of a strawbale building I had designed, consistently gave it low ratings for R-value and infiltration.  In researching the R-value they had given to the walls, I found that from the resources they had found, the value was somewhere between R-23 and R-27.  I got a copy of the newly proposed International Green Conservation Code and found they rated bales laid flat at R-1.3 per inch and on edge R-2.  That equates to R-23.4 for flat bales (2 string) and R-28 for bales (2-string) on edge.  I don’t think this gives and accurate performance prediction of  the building.  In addition they considered the buildings to have high infiltration losses because of their opinion that they cannot be tightly sealed.  Their models indicated that the building could not be considered high performance due to the use of the straw thereby making my job of getting the building to the required Hers rating value much more difficult.  I am thinking I am not alone in this problem.
>  
> This made me realize that we need to generate more convincing documentation as to the performance and design detailing of straw buildings.  There appears to be little resources out there that engineering professionals access that address the infiltration and insulation values of straw.  This is important because without a sufficient HERS rating and a positive blower door test (now being required in many jurisdictions) a permit and/or a CO will not be issued.
>  
> What I would like to hear from you all is the location of resources documenting tight houses out of straw (like the passive houses) and specific techniques you have used to tightly seal up straw buildings.  Specifically what techniques have you used to seal around the windows and doors, at the bottom and top of the walls and at penetrations of the interior finish skins for electrical boxes.  Are there buildings out there that have gotten their HHI ratings down below 2 BTU/SF/DD?  If so what techniques did they use and what insulation and infiltration rates were used? 
>  
> Thank you for your help.
>  
> Saludos,
> Alfred
>  
>  
>  
>  
> VON BACHMAYR ARCHITECTS LLC
> 1406 Bishops Lodge Rd.
> Santa Fe, NM 87506
>  
> 505-989-7000  
> 505-984-1479     fax
> 505-470-6141     mobile
>  
> vbarch at comcast.net
>  
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