[Ferro List] dougs fc parabolic video

[Doug Lacy]

Jon - 

The thermal performance of the PSS system is one of its strong points.  The last home I did is showing a marked reduction in energy usage for the winter time and it does not even have an insulated foundation.  The 'R' value of the densities I have used in the past is just over R-2 per inch and that just gets us past code requirements for insulation.  My engineer friend, who has helped evaluate the last project and will likely help me in the future, believes that less structural, lower density and more insulating fills are fine for the future.  Even with obtaining the required 'R' value for walls and roof, 'R' value is not an appropriate method for measuring the thermal performance of the homes because it is not just about restricting the change in temperature of the encased air envelope of your living space.  The medium stores thermal energy in its mass and because it is somewhat insulating, it will radiate that heat away from the thermal mass much more slowly.  If you have ever been in a well insulated rock house in the winter or hot summer, you can get a feel for the more appropriate body comfort measure I am talking about.  Its nice, very nice.  

As far as the structural aspects relating to the reinforcing standards for standard concrete, it is best to evaluate this system as a whole or at least the deformation resistance of a 2 dimensional cross-section because both the low shrink surface composite and the aerated fill are very different from standard concrete, as is the reinforcing scheme.  Fortunatley, this super thick shell system is easy to evaluate because it can be shown it is indeed achieving a true stress skin effect - meaning that the bend resistance is simular to the bend resistance of an equivelent shell that is made of the solid surface composite throughout.  In other words, stess skin means that if you glue plywood onto the surface of a thick weak Styrofoam slab, it will take simular work to bend and break it as if it were a stack of solid plywood of the same thickness.  Also, the wrap ties and hog ring ties can't fatique or be targeted by rust as easily as the welds and their cumilitive bonding effect is substantial.  Maybe you can rip a block off that has one hog ring tie but you can't if there is two and each block has many and the surface plate has a physical matrix bond to this internal reinforcing.  Nothing flimsy about it.

The name ‘Parabolic Stress Skin’ was chosen because Parabolic and Stress Skin are two key aspects of the system that interact in a way that brings better focus to the specifics of the building process in the context of a more whole architectural ideology.  ‘Parabolic’ relates to the base architecture where the interaction of curves and lines achieves a focused structural and design purpose with a high degree of efficiency.  ‘Stress-Skin’ relates to the internal architecture more and describes a specific method for an economy of form that results in a high-strength-to-weight-ratio through the stress-skin effect.  These principles of economy and geometry blend smoothly together, as they do in nature, for a building system that is integrated into the essence of success in nature.  This success in nature of harmony, economy, sustainability and sanctuary sets the stage for the theme architecture of the system.

The PSS system’s relationship to naturalistic architecture, or more specifically the principle of how living forms economize energy and resources to achieve a structural and design goal, seems to be most practically illustrated by the architecture of bones and seashells from a construction enthusiast point of view.  The Parabolic Stress Skin System, however, is about that but more about what those bones and shells are a part of because the system cannot be so disembodied from the whole if its core representation of economy of nature where authentic.  

This is why the system is connected to an eco village model called Shambhala Village.   The village reveals some potentials and places the system, and its architecture, into a more complete and meaningful context of economy, harmony and sustainability.  It also casually attempts to model a refitting of society back into an awareness of, and connection to, the ecology it is a part of.

Ferrocement and cellular concrete may seem disembodied from the PSS system in this seemingly esoteric explanation of its name, but it really helps illustrate how the Shambhala vision of enlightened society is directly dependant upon the connection to the base level, very practical, individual building blocks, and cohesion between them.  This can also serve as another Shambhala analogy that relates to the individual connection to the personal day-to-day grit level problem solving. 
It really just started with conversations with my brother Joe, about better ways to build. Discussions mostly for an escape from the high energy, expensive and hellish reality of three-coat plastering.  The further exploration is a very natural coarse from there.  It really seems to be an exploration of what nature, or all of us really, have been doing for a long time.  
It would be great to see how it evolves and what designs others come up with.  You should come and help me with this Hawk Nest Home.  We have to stick to the game plan on this project but we can explore new possibilities with discussion while we are working, if that is possible, or after or before work.  
The zig zag thing is a very cool possibility that we should talk about more.  The project is restarting soon.

Doug
PSS I posted a video of the roof shell going up.  
http://tw.youtube.com/user/ShambhalaVillage

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